ABSTRACT CARBONIUM ION REARRANGEMENTS IN THE PROPYL SYSTEM by James Leslie Fry The purpose of this investigation was to study the mechanisms of several reactions whose conditions could potentially permit the formation of propyl cations. The reactions studied were: the 99% formic acid solvolysis of l-propyl tosylate (i-propyl pftoluenesulfonate), the basic hydrolysis of 1—bromopr0pane, the aqueous silver ion-assisted hydrolyses of 1-bromopropane and 2—brom0propane, and the aluminum bromide catalyzed interconversion of the bromo— propanes. In all cases, the fate of the propyl species was studied by using isotope-position labeled reactants and ob- serving the position(s) of the isotope label in the products by means of mass spectrometry and nuclear magnetic resonance (n.m.r.) spectroscopy. When solvolyzed in 99% formic acid at 750, 1-propyl tosylates prepared from 1-propanol-l,1—g2 gave 94% l—propanol and 6% 2—propanol. The solvolysis of 1—propyl tosylate pre- pared from 1-propanol-2,21g2 gave 98% l-propanol axui 2% 2-pr0panol. Mass-spectral analysis of the trimethgfllsilyl exjner derivatives proved the absence of isotope-positicml.rearrangey' ments in the l-propyl product. This product was interpreteC1 . . . . CH1 as ariSing from an 8N2 attack on the unionized tosnglate Or the incipient tight—ion pair. James Leslie Fry The identity of the mass spectra of the trimethylsilyl ethers of I and 1' shown below proved that no isotope— position rearrangements had occurred during the preparation or hydrolysis of 1- and 2-bromopr0panes in 15% aqueous silver nitrate solution (R = CH3CH2CD2-, CH3CD2CH2-, (CH3)2CD-). The hydrolysis was interpreted as occurring by an 5N2 attack on a bromOpropane—silver ion complex. PBrai 15% aq. AgN03 1_ ROH RBr or 10% aq. NaOH‘r_ ROH I I. A similar identity of the mass spectra of the trimethyl— silyl ethers of I and I' was observed for hydrolysis in 10% aqueous sodium hydroxide at steam bath temperatures (R = CH3CH2CD2-, CH3CD2CH2-). A thermodynamic equilibrium mixture of 1—bromopropane and 2—bromopropane in the ratio 6/94 was obtained at 00 when either bromopropane was isomerized with aluminum bromide in a 5.7/1 molar ratio. 1-RBr —§%%£fle>- 1—R'Br + 2—R'Br (R = CH3CH2CD2-, CH3CD2CH2-, CH3CH213CH2-) The above isomerization was run to various stages of completion and the products were converted to the alcohols by silver ion—assisted hydrolysis. N.m.r. and mass—spectral James Leslie Fry analyses of the products and their derivatives showed that, for short reaction times, whereas the 2-propyl product was the result of a single intramolecular 1,2-hydride shift, the recovered 1—bromopropane was extensively intramolecularly isotope-position rearranged. This rearrangement was inter— preted in terms of partially equilibrating edge-protonated cyclopropanes. The occurrence of intermolecular hydride transfers at longer reaction times was established. The isomerization of 2-bromopropane to 1—bromopr0pane occurs primarily by an intramolecular 1,2—hydride shift. 2—RBr —§%§£fie> 1—R'Br + 2-R'Br (R = (CH3)2CD-, (CD3)2CH-, and 1:1 mixture of both) CARBONIUM ION REARRANGEMENTS IN THE PROPYL SYSTEM BY James Leslie Fry A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 1967 /’? .99 I .7" ~v’1 0.2] .1/ ,. To Sara ii ACKNOWLEDGMENTS The author wishes to express his gratitude to Professor G. J. Karabatsos for the guidance which he gave and for the tolerance and friendship exhibited throughout the course of this investigation. Appreciation is extended to Mr. Seymour Meyerson of the Research and Development Department of the American Oil Company, Whiting, Indiana, for his invaluable mass— spectral analyses. The Petroleum Research Fund is thanked for financial support from January, 1965 to June, 1967. iii TABLE OF CONTENTS Page INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1 RESULTS. . . . . . . . . . . . . . . . . . . . . . . 19 I. Formic Acid Solvolysis of 1-Propyl Tosylates 19 A. 1—Propyl-1,1figg Tosylate. . . . . . . . 19 B. 1-Propyl-2,25g2 Tosylate. . . . . . . . 27 II. Bromopropane Hydrolyses. . . . . . . . . . . 27 A. Silver Ion-Assisted Hydrolysis. . . . . 31 B. Basic Hydrolysis. . . . . . . . . . . . 56 III. Aluminum Bromide Catalyzed Isomerizations of Bromopropanes. . . . . . . . . . . . . . . . 56 A. Labeled 1-Bromopropanes . . . . . . . . 42 1. 1-Bromopr0pane-1,1jg2. . . . . . . 44 2. 1-Bromopropane—2,2:g2. . . . . . . 61 5. 1-Bromopropane-1-13C . . . . . . . 71 B. Labeled 2- -Bromopropanes . . . . . . . . 7S 1. 2- -Bromopropane- -2- d . . . . . . . 81 2. 2——Bromopropane-1,1,1,5,5,5-—d5. . . 81 5. Mixture of 2— —Bromopropane- -2— —g_and -1,1,1,3,3,55d6. . . . . . . . . . 84 DISCUSSION . . . . . . . . . . . . . . . . . . . . . 91 I. Formic Acid Solvolysis of 1-Pr0pyl Tosylates 91 II. Bromopropane Hydrolyses. . . . . . . . . . . 93 III. Aluminum Bromide Catalyzed Isomerizations of Bromopropanes. . . . . . . . . . . . . . . . 94 IV. Summary. . . . . . . . . . . . . . . . . . . 99 EXPERIMENTAL . . . . . . . . . . . . . . . . . . . . 101 Vapor Phase Chromatography (V.P.C.). . . . . 101 Infrared Spectra (I.R.). . . . . . . . . . . 101 Nuclear Magnetic Resonance Spectra (N.M.R.). 101 Preparation of Trimethylsilyl Ether and Benzoate Ester Derivatives of 1- and 2- Propanol . . . . . . . . . . . . . . . . . 102 Preparation of 1-Propanol-1,1-§2 . . . . . . 102 iv TABLE OF CONTENTS - Continued Preparation'of 1-Propyl-1,1-g2 proluene— sulfonate. . , , . . . , , , , , . , , , , , Preparation of 1-Propyl-2,2-gé‘p-Toluene- sulfonate. . . . . . . . . . Hydrolysis of 1-Propyl pfiToluenesulfonates in Aqueous Formic Acid. . . . . . Preparation of 1-Bromopropane-1,1 Preparation of 1-Bromopropane~2,2 Preparation of 1-Bromopropane-1-l Preparation of 2—Propanol-2fid . Preparation of 2—Bromopropane—2- . . . . . . . Preparation of 2—Pr0panol-1,1,1, 5,5jd5. . . . Preparation of 2-Bromopropane-1,1,1,5,3,5,ids . Silver Ion-Assisted Hydrolysis of BromoprOpanes Basic Hydrolysis of Bromopropanes . . . . . . Aluminum Bromide Catalyzed Isomerizations of BromoprOpanes. . . . . . . . . . . . . . . . Preparation of 2—Propanol~1,1jg2. . . . . . . . 112...... g2..... c . é 5, REFERENCES . . . . . . . . . . . . . . . . . . . Page 105 104 105 106 107 108 110 111 111 112 112 115 114 115 118 TABLE II. III. IV. VI. VII. VIII. IX. XI. XII. XIII. XIV. LIST OF TABLES Mass spectrum of unlabeled CH3CH2CH20Si(CH3)3. Mass Spectrum of CH3CH2CD208i(CH3)3 from pre- cursor for 1-propyl-1,1jgg tosylate used in runs 1 and 2, and 1-bromopropane-1,1fid2 used in runs 4, 10, and 15. . . . . . . . . . . . . Mass spectrum of CH3CH2CHQOSi(CH3)3 from 1- propanol product of run 1. . . . . . . . . . . Mass spectrum of CH3CH2CHEOSi(CH3)3 from 1- propanol product of run 2. . . . . . . . . . . Mass spectrum of unlabeled (CH3)2CHOSi(CH3)3 . Mass spectrum of (CH3)2CHOSi(CH3)3 from 2— propanol product of run 2. . . . . . . . . . . Mass spectrum of CH3CD2CH205i(CH3)3 from pre- cursor for 1-propyl-2,2fid2 tosylate used in run 5, and 1—bromopropane-2,2—g2 used in run 5 Mass spectrum of CH3CH2CH2081(CH3)3 from 1- propanol product of run 5. . . . . . . . . . . Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol product of run 5. . . . . . . . . . Mass spectrum of CH3CH2CH205i(CH3)3 from 1- propanol product of run 4. . . . . . . . . . . Mass spectrum of CH3CH2CHQOSi(CH3)3 from 1- propanol product of run 5. . . . . . . . . . . Mass spectrum of (CH3)2CDSi(CH3)3 from pre- cursor for 2-bromopropane-2jg used in runs 6, 19-210 0 o o o o o o o o o o o o o o o o o o 0 Mass spectrum of (CH3)2CHOSi(CH3)3 from 2— propanol product of run 6. . . . . . . . . . . Mass spectrum of CH3CH2CH208i(CH3)3 from 1- propanol product of run 7. . . . . . . . . . . vi Page 21 22 25 24 25 26 28 29 50 52 54 55 57 LIST OF TABLES - Continued TABLE xv. Mass spectrum of CHgCHgCHgOSi(CH3)3 from 1- propanol product of run 8. . . . . . . . . . . XVI. 1-Bromopr0pane + aluminum bromide reaction at o O . . . . . . . . . . . . . . . . . . . . . . XVII. 25Bromopr0pane + aluminum bromide reaction at 0 . . . . . . . . . . . . . . . . . . . . . . XVIII. Labeled 1—b50m0propane + aluminum bromide re- action at 0 . . . . . . . . . . . . . . . . . XIX. Mass spectral analysis of CH3CH2CHEOSI(CH3)3 from 1—propanol obtained from recovered 1- bromopropane. Runs 10-16 and 18 . . . . . . . XX. Mass spectral analysis of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from 2-bromopropane Runs 11-18 . . . . . . . . . . . . . . . . . . XXI. Mass spectrum of CH3CH2CH208i(CH3)3 from 1- propanol obtained from recovered 1—brom0pro— pane of run 10 . . . . . . . . . . . . . . . . XXII. Mass spectrum of CH3CH2CD208i~ ROH + -CX3 —:§?>- :CXg _. _. -- + .. RO+:CX2——'>X+ROCX—_>‘R+CO+X or, - - + + RO +:CX2———>‘ 2X +ROC ——>— R +co When 1-propanol was reacted under these conditions, the C3H6 products were found to be propylene and cyclopropane in a 9:1 ratio. Skell observed that this same ratio of propylene to cyclopropane was also obtained in the deamination of 1- aminopropane and suggested that a short—lived protonated cyclopropane intermediate might be common to both reactions (14): ””’EH1\- {EIQH ______ ‘ .___.S. __.._ . CH2 CH2 2—————-—CH2 > IV CH CH2+-———* 3\‘CH§// T___ Later, 1-propanol-1,1—d2 was deoxidated to yield cyclo— propane which was 94 i_2% C3H4D2 and 5-6% C3H5D (15). It was thus established that the process was cationic and not carbenoid; however, in view of Reutov's deamination studies (6), the formation of cyclOpropane was interpreted as proceeding yi§_1,5 ring closure with loss of a proton, rather than by way of protonated cyclopropane such as IV. The formation of cyclopropane-d_was explained as a 1,5-inter— action resulting in a 1,5-hydride shift which proceeded through the 1,5—hydrogen—bridged transition state V and was followed by ring closure with loss of a deuteron or proton. CH2 In 1965, Baird and Aboderin revealed the fact that cyclo- propane, when stirred with 7.5 M D2804, underwent hydrogen- deuterium exchange to give C3H5D and C3H4D2 species in addi— tion to undergoing solvolytic ring opening to gfpropyl products. The rate of solvolysis was about twice that of exchange (16). When the ring-opened products from solvolysis in 8.4 M D2804 were examined, they were found to consist of 1-propanol with traces of 2-propanol (<0.5%) and difig-prOpyl ether (17). The isotopic composition of the 1-propanol was examined by n.m.r. and found to correspond to a deuterium distribution of 0.58.: 0.05 deuterium atom at C—1, 0.17.: 0.04 at C-2, and 0.46.: 0.05 at C-5. (Demo and co-workers report equal amounts of deuterium at C-1 and C-2 (18).) 1-Propanol-1,1-§2 did not undergo isotOpe-position rearrange- ment when subjected to conditions more rigorous than those used in this experiment. The mechanism shown in Figure 1 was suggested to account for these results. (A variation of this mechanism has also been suggested by K. B. Wiberg (19).) (CHgD CHQ‘ CHD ’l’ + \\ A \\-3- ‘ZH III ‘\\\ 1’ \\ <__ ‘\ / I \\ (1) CH§===CH2 CH2——-CH2 CH2 ------ (CH3 VI CH / 2/ D Hg—CHg ) \J (2 \\\\E3 CH2- VII VIII ml .5 H “ CHgDCHZCHgos CHD ~\+‘;D + C//// H2““CH2 CHgCHgCHDOS 33;"79H3 X ‘H’ IX SOH k' SOH k S S CHgDCH2CHZOS CH3CHDCH208 Figure 1. D2804 solvolysis of cyclopropane. Baird and Aboderin state that the experimental results are best explained on the assumption that the solvolytic ring opening occurs with the hydrogen—bridged ions VII, IX, and X, rather than with the methyl—bridged ions VI and VIII. This led to the postulation that a 1-pr0pyl cation, or its immediate precursor (such as formed in deamination or deoxidation reactions), should be able to undergo a variety of reactions, including the loss of a proton, the addition of solvent, rearrangement to the 2-propyl cation, and cycli- zation to the hydrogen-bridged ion, XI, 1,3,, an edge—proton- ated cyclopropane. Ion XI could, of course, either undergo solvolytic ring Open- ing, or lose a proton to form cyclopropane. Proton equilibra— tion could occur as shown in Figure 1. The extent to which such equilibration could proceed would depend on how fast the ring protons could exchange into the hydrogen-bridging position compared with how fast the ion could undergo solvoly— sis or loss of a proton. If the former process were very fast compared with the latter two, then the intermediate might appear to be a symmetrically "face—protonated" cyclo- propane IV, as originally postulated by Skell (14). Molecular orbital calculations indicate, qualitatively, that the methyl— bridged ion III is more stable than an Open 1-propyl cation (20) and that the edge—protonated cyclopropane XI is, in turn, more stable than III (21). The deamination of 1-aminopropane-5,5,5—g3 led to 45.: 1% cyclopropane-g2 and 57 i.1% cycloprOpane—g3 (19). Baird and Aboderin argued thatif the cyclopropane arose by the 1,5—interactions described by Skell (15), then no more than 6% cyclopropane-g3 should have been formed if there were no isotope effects on deprotonation, and only 51% if KH/kD were as large as 7. They rejected Skell's mechanism and stated that the results could be explained by equilibration of ions such as XI, by a mechanism like that in Figure 1, if an iso- tope effect of KH/kD = 2.7-5.0 were in operation for de- protonation. They concluded by postulating that 1,5-rearrange- ments could be more readily interpreted in terms of protonated cyclopropane intermediates than yia_equilibration of the primary cations. They warned, however, that care should be taken in extending this interpretation into other systems. Soon after this, both Lee and Karabatsos and their co— workers published data from reinvestigations of the 1-amino- propane deamination. Lee found (22) that the deamination of 1-amin0propane-1jt produced 1-pr0panol containing 1.2-1.5% of the tritium label at C—2 and 1.6-1.7% at C—5. 1-Amino- propane-1-14C was once again deaminated (25), yielding 1-propanol containing 2.2% carbon-14 at C-2 and 1.9% at C-5. These data ruled out the possibilities of successive 1,2- hydride shifts or a 1,5-hydride shift and it was postulated that 4-6% of the 1-propanol product was formed from a pro- tonated cyclopropane intermediate or transition state. The experimental data did not allow a distinction to be made between a face—protonated species such as IV or a rapidly equilibrating edge—protonated species such as XI. Karabatsos and co—workers studied the isotopic composi— tion of C-1 of the 1-propanol products from the deamination of deuterated 1-amin0propanes by mass spectrometry (24). Thus, 1-aminopropane-1,1-§2 and -2,2-g2 gave the following product compositions: O CH3CH2CD2NH2 ’flfi‘ C2H5*CD20H + C2H4D-CHDOH + C2H3D2‘CH20H 100%.g2 95.7% 1.0% 5.8% CH3CD2CH2NH2 ——+ 100%.g2 1.2% 0.9% 97.9% These data were explained in terms of the equilibration of edge-protonated cyclopropanes through a mechanism like that of Baird and Aboderin in Figure 1. The intervention of protonated cyclopropane intermediates has been suggested for a wide variety of reactions and condi— tions, such as the acylation (25) and bromination (18) of cyclo- propane, the hydrogen bromide catalyzed gas phase rearrangement of cycloprOpane to prOpene (26), and in various rearrangements occurring in the mass spectrometer (27,28). The reported moist aluminum bromide catalyzed isomerization of propane-l-lac to a mixture containing 55% propane-2-13C may also proceed by such a mechanism (46). The formation of bicyclo[5.1.0]hexane (2%) from the deamination of cyclohexyl amine has been interpreted as going gig a protonated cyclopropane inter- mediate, as have various rearrangements observed upon deamination of alicyclic d—aminoketones (29). Although it has not been interpreted as such, an intermediate of this type could serve to explain the 1,5-hydride shifts reported to accompany the solvolysis of cyclohexyl tosylate (10,50) and the deamination of cyclohexyl amine (10,51). The forma— tion of tricyclo[4.5.1.0] decane systems from the deamination of trans-9—decalylcarbinyl amines could also involve a protonated cyclOpropane (52). It is well, however, to heed the warning of Baird and Aboderin, urging caution in the broad generalization of such a mechanism into other systems. Friedman and his co—workers have studied the deamination of various systems in aprotic solvents (55,54) and have found that cations generated under such conditions are of a higher energy than the same cations formed under conditions in which they may be stabilized through solvation. Such high energy cations have a tendency to give products of kinetic, rather than thermodynamic, control. Thus, nfi,.§gg-, and isobutylamine (but not Efbutyl) all gave methylcyclopropane, along with other products, when deaminated under these conditions (55,56). This product has been explained as arising from edge-protonated cyclo— propane intermediates common to all three reactions. Both p: and isobutyl (but not sggf or tfbutyl) alcohol gave methyl- cyclopropane under deoxidation conditions (15). 10 Significantly, Karabatsos and co—workers have shown, by using isotopically labeled amines, that in aqueous media pathways involving protonated cyclopropane intermediates can not be important to the formation of the alcoholic solvolysis products from the deamination of either nfbutyl or isobutyl amine (57,58). Small amounts of ethylcyclopropane and dimethylcyclo» propane have been reported in the deoxidation of 2-methyl-1— butanol (59). Although an appreciable quantity of dimethyl- cyclopropane is produced on deamination of 5—methyl-2—amino- butane in anhydrous acetic acid, the solvolysis of 5-methyl- 2—butyl tosylate under the same conditions produces none (40,41). It seems very likely that this difference may be ascribed to the lack of formation of a "free" 5-methyl-2— butyl cation in the tosylate solvolysis. It may be that a cation formed by the loss of a small, stable molecule, such as nitrogen on deamination or carbon monoxide on deoxidation, is "freer" in the sense that it is less strongly solvated ("hot" carbonium ion) and, hence, tends to give more products of kinetic, rather than thermodynamic, control, much as observed in Friedman's study of poorly solvated cations. The neopentyl (2,2-dimethyl-1-propyl) system undergoes many reactions in which Erpentyl (2-methyl-2-butyl) products are formed. Since this rearrangement formally proceeds by a 1,2-methyl shift, it would seem possible that protonated cyclopropanes might be involved. This does not appear to be 11 the case, since neither substituted cyclopropanes, nor evi— dence for anything occurring other than a simple 1,2-methyl shift to the tertiary cation have been observed while studying deoxidations (15,42), deaminations, solvolyses (45,44), or acid treatment of neopentyl alcohol (45). In general then, the possibility of protonated cyclo— propane species intervening appears to be greatest for the propyl system and diminishes for higher homologs. Thermody- namically, this would seem to indicate that unsubstituted protonated cyclopropane must have a stability intermediate between the 1—propyl cation and the 2—propyl cation, and so can compete favorably with both for product control. Apparently, the substituted protonated cyclopropane is not as stable, in relation to the other ions potentially formed, and so it intervenes to a much lesser extent, being detected only by formation of cyclopropane products, if at all. In the extreme case, that of the neopentyl cation XII rearranging to the tfpentyl cation XIV, the substituted protonated cyclo- propane must be much less stable than the tertiary ion; so much so that the methyl-bridged ion XIII could now be at, or close to, the maximum free energy on the reaction coordi- nate. Thus, it never equibrates ring protons at all, but instead proceeds directly to the more stable tertiary ion XIV. CH3 CH3 I ‘. | / + \ + CHg‘Cl:-CH2+ —> ----- CH2 —_9 (CH3) 2CCH2CH3 CH3 CH§’/ XII XIII XIV 7 CH 3 Karabatsos and co—workers have pointed out (57,58) that as hydrogens on the ring of various protonated cyclopropanes are replaced by alkyl groups, the protonated cyclopropane may become progressively less stable due to unfavorable steric interactions caused by eclipsing of adjacent groups. \ + ‘,‘H The purpose of the work reported in this thesis was to obtain a better understanding of the nature of rearrangements occurring through cationic species in the propyl system under widely different conditions. For this reason the solvolysis of 1-pr0pyl tosylate in nearly anhydrous formic acid and the aluminum bromide catalyzed isomerization of bromopropanes were chosen for study by means of isotope—position labeling. Published work regarding the former reaction will be discussed later. 15 The isomerization of 1-bromopropane (1-BrPr) to 2-bromo- propane (2-BrPr) by the action of aluminum bromide has been known since the 1870's and has been extensively studied since then (47). Brown and Wallace found that at 00 only 2-bromopropane was obtained if either 1-brom0propane or 2-bromopropane were reacted with aluminum bromide for 9 hours in a 22) 4:1 molar ratio (48). Hydrogen bromide was evolved during the isomerization, but addition of it to the starting material did not affect the reaction. Doering and his co— workers (49) had earlier reported that the addition of deuter— ium chloride did not affect the aluminum chloride catalyzed isomerization of 1-chloropropane to 2-chlor0propane at 00, and that no deuterium was found in the product. It was also shown that under these conditions the rate of addition of hydrogen chloride to propene to form 2—chloropropane was slower than the observed rate of isomerization, thus ruling out reversible dehydrochlorination as a mechanism. It was suggested CH CH CH Cl CH CH=CH + HCl —-——=- CH CHClCH 3 2 2 22;;IET 3 2 <_____. 3 a that the reaction could proceed by the formation of a carbon- ium ion or its equivalent, followed by an intramolecular hydride shift and recombination with chloride from the catalyst. In view of these facts, Brown postulated that the 1- to 2- bromopropane isomerization could proceed by one of two paths; either ionization "assisted" by a 1,2—hydride shift, 14 H + H .. .. l _ H3C-Cl-CH2:Br1 AlBr3 '——)’ HBC-IC-CHZ AlBr4 H H or by a sort of concerted hydrogen—bromine shift with no ioni— zation occurring. H} ‘H‘ H3C-(Ilwr: AlBr3 ‘——>‘ H3C-C-CH2 H :Br: AlBrg The latter mechanism would not appear to be valid, however, in view of the report that bromine exchange between 82Br labeled 1-bromopr0pane and aluminum bromide in carbon di- sulfide solution occurs much faster than the formation of 2—brom0pr0pane (the exchange reaction is oneJhalf order with respect to 1-bromopropane and second order with respect to aluminum bromide) (50). Douwes and Kooyman have studied the kinetics of this reaction in carbon disulfide solution at -200 and found that it was quite complex, with the molecularity depending on the initial molar ratios of the reactants (51). Unlabeled 1- bromopropane isomerized 5.4 times faster than did 1-bromo- 'propane-2,2-g2 and in the presence of deuterium bromide no deuterium was incorporated into the 2-bromopropane product. Furthermore, in 1—bromopropane-2—g, the hydrogen shifted 5.5 times faster than the deuterium atom. They also observed that when the labeled reactants were used the mass spectra 15 of both the 1- and 2-bromopropanes recovered contained the same number of deuterium atoms as did the starting materials. The mass spectrum of the recovered 1-bromopropane was identi- cal to that of the starting material. They interpreted these results as ruling out intermolecular deuterium exchange or intramolecular scrambling, including carbon skeletal iso- merization. They noted, however, that 1,5-hydride shifts were not excluded, and suggested the following mechanism: . fast + - _ _ fl - n AlBr3 +‘Q propyl bromide (g_propyl AlnBr5n+1 ) + - slow . . _ —____> (n propyl AlnBr5n+1 ) isopropyl bromide They pointed out that the "g-propyl+ should not be regarded as a fully developed cation but may be merely a gfpropyl fragment carrying a significantly greater positive charge than in free grpropyl bromide." Adema and co—workers studied this same isomerization in carbon disulfide solution at 240 by a microwave technique (52). They found that both bromopropane isomers formed 1:1 complexes with aluminum bromide under these conditions. 2(1-BrPr) + AlgBre —-—"2(1—BrPr'AlBr3) 7 K1 1.5iO.5 l/mole 7.5010.14 l/mole 2(2-BrPr) + AlgBre'—-—*-2(2-BrPr’AlBr3) ; K2 The following three kinetic expressions could be obtained for the isomerization: 16 k[1-BrPr][Al2Br6] < II V = k“[1-BrPr-A1Br3][AlgBrBJl/z v = k"[1-BrPr-A1Bl‘31‘2[1"131'Pr1—l Although several mechanisms were compatible with these rate expressions, they favored the one shown below. + _ AlgBre -—£3§EA~ AlBr2 + AlBr4 V_____ 1—BrPr-AlBr3 + AlBr4— —§l9!4- 2-BrPr‘AlBr3 + AlBr4- Y_____ The transition state was pictured as: Br - (EH3 I|3r - Br-Al—Br --- CH—:—CH2-—— Br—Al-Br Br ‘1? Br 1-Chloropropane-1-14C is reported to be rapidly converted to 2-chloropropane-1-14C (10) when treated with aluminum chloride. In contrast to this, when treated with an excess of zinc chloride and concentrated hydrochloric acid, 1-chloro- propane-1-14C was partially converted into 1-chloropropane—5- 14C with only traces of 2-chloropropane being formed (55). No 1-Chloropropane-2-14C was found and the reaction proceeded only in the presence of hydrochloric acid. The amount of 1-Chloropropane-5-14C formed depended on the reaction time, varying from 2.5% for reaction at 500 for 20 hours, to 16% for reaction at 200 for 1,500 hours. 1-Chloropropane-5fid was also partially converted to 1-chloropropane-1fig under 17 these conditions. When 1—chloropropane was treated with zinc chloride and concentrated hydrochloric acid containing deuterium.chloride,rm>deuterium was incorporated into it. Under the same conditions, deuterium was exchanged into 2—chloropropane (10). When 1-bromopropane-5—§_was treated with zinc chloride in concentrated hydrochloric acid, a mixture of products including 2-chloropr0pane, 2-bromopropane, 1—Chloropropane-1- d, and -5-g, and 1—bromopropane-1fid, and -3-g_was formed (no percentages or experimental details were reported) (54,10). It was argued that since chloride was present in large excess, the 1—brom0pr0pane-1-g wouldn't have been ,formedjtfa free cation were an intermediate, and so the 1,5- shift must have proceeded by the mechanism shown below. + _ o 6 AC ’ —; o o o o o o CHgDCHQCHgBr CH2DCH2CH2 Br AC \ Z:\C ‘\ ,Br\ I \\ II \\ c\ ‘,C H// ‘x .x’ \H _ + H’ c5 c3 1%; BrCHDCH2CH3 -————* Ac---Br---CHDCH2CH3 -Ac + (Ac = Lewis Acid, ZDXg or H ) Since no quantitative data were given, it is difficult to judge the merits of such a proposal. However, if the amount of 1-bromopropane-1-g formed were small, it seems conceivable that the rearrangements could also have proceeded by 18 nucleOphilic attack on a bridged intermediate, as shown below, with the small amount of bromide ion present compet- ing with chloride ion. + _ O O A CHgDCH2CH2Br —9-—¥ CH2DCH2CH2 - ~ ~Br- - -Ac \ ’H /H - D x O \ z’6+ \ C<-:--/-C~/—--Br——Ac H CH2 1 Br- ”— ,H\ m 5" D\ / BrCHDCH2CH3 + BrAc' +— Br---/\—C"\CH 2/{-Br- A—C J RESULTS I. Formic Acid Solvolysis of 1—Propyl Tosylates When 1—propyl tosylate (1-propyl pftoluenesulfonate) was heated in anhydrous formic acid at 500 for 40 hr. and then worked-up (see Experimental), 85% of it was recovered and no other products were observed. The same results were obtained when 1-propyl tosylate was heated in formic acid which was 0.556 M in water (0.86% by weight) at 600 for 72 hr. However, when heated in the latter solvent at 750 for 115 hr., a mixture of 1—pr0panol (95.: 2%) and 2—propanol (7.1 2%) was obtained in 50—55% yield. The absence of formate esters in the product was established by vapor phase chromatography (v.p.c.). This absence may have been due to the basic conditions used in the product work-up, which could have caused the hydrolysis of any esters formed to their respective alcohols. Only 1-pr0panol was recovered (56%) when it was heated with an equimolar amount of pfitoluenesulfonic acid in the nearly anhydrous formic acid at 750 for 40 hr. A. 1—Propyl-1,1—gg Tosylate 1-Propyl—1,1jg2 tosylate was solvolyzed in formic acid (0.556 M in H20) at 75 4 10 for 144 hr. A mixture of 1-propanol (94.: 2%) and 2-propanol (6.: 2%) in 56% yield 19 20 was obtained. Trimethylsilyl ethers of the alcohols were prepared and subjected to mass-spectral analysis. Both ethers were prepared from run 2, while only the 1-propyltri— methylsilyl ether was prepared from run 1. The results are shown in Tables I—VI. In all of the reported mass spectra, the monoisotopic peak heights have been corrected for the presence of contaminating hexamethyldisiloxane (HMDS). The peak at m/e 147 was used for this correction. Under the mass—spectral conditions used, the parent-less— methyl ion [(P-Me)+] is produced solely from silicon-carbon bond cleavage in 1-propyltrimethylsilyl ether (24). Analysis of this ion gives the isotopic composition of the entire propyl group. The parent—less-ethyl ion [(P-Et)+] arises from cleavage of the carbon—1-carbon—2 bond of the propyl group. Analysis of this ion gives the isotopic composition of the d—methylene group of the propyl moiety. CH3 <:) | l I CH3’CH2+CH2‘O-?iTCH3 | CH3 'CgHs’ -CH3o 9H3 + CH3 + CHZ-O-Si-Cfia ‘ CHs-CHZ-CHg-o-si CH3 CH3 (P-Et)+ (P-Me)+ 21 Table I. Mass spectrum of unlabeled CH3CH2CH20Si(CH3)3 M/e Pk. Ht. Mono 122 0.1 0.0 121 0.9 0.5 120 6.5 0.9 119 95.0 11.5 + 118 222.0 1.7 , (P-Me) 117 2050.0 2054.2 99.5% at mass 117 116 2.9 1.6 115 12.1 ‘12.1, 2 2067.9 106 1.5 0.4 105 18.0 1.5 + 104 42.2 1.5 . (P-Et) 105 424.0 422.7 91.0% at mass 105 102 4.6 1.7 101 50.0 29.6 100 1.5 0.5 99 10.4 10.4. 2 464.7 147 4.0 Conc. HMDS = 0.08 vol. percent 22 Table II. Mass spectrum of CH3CH2CD2051(CH3)3 from precursor for 1-propyl-1,1-gg tosylate used in runs 1 and 2, and 1-bromOpropane-1,1fig2 used in runs 4, 10, and 15. M/e Pk. Ht. Mono. 122 5.0 0.1 + 121 91.2 0.7 (P—Me) 120 246.6 0.4 . Mono. Dist‘n. 119 2266.0 2262.6 99.5% of 2262.6 99.0%g2 116 26.6 26.0 2 = 2507.0 24.2 1.0% g; 117 5.6 4.8 2507.0 116 7.1 7.0 115 0.7 0.7 2 2525.5 108 0.6 -.2 + 107 17.2 0.0 (P-Et) 106 42.7 —.5 Mono. Dist‘n. 105 446.0 444.5 91.4% of 444.5 98.5% g; 104 9.9 7.2 2 = 452.1 7.2 1.6% g; 105 26.6 26.1 0.6 0.1% do 102 5.7 5.1 452.1 101 5.1 4.5 100 5.7 5.6 99 1.5 1.5 96 9.5 0.5 97 0.2 0.2 2 494.6 147 1.0 Conc. HMDS = 0.017 vol. percent 25 Table III. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-pr0panol product of run 1. M/e Pk. Ht. Mono. 122 5.1 0.4 + 121 51.4 0.5 (P—Me) 120 158.0 -.7 ‘ Mono. Dist'n. 119 1290.0 1266.1 99.5% of 1288.1 96.6% Q2 116 17.0 16.5 2 = 1505.5 15.4 1.2%.01 117 5.9 5.5 1505.5 116 4.0 5.9 115 0.7 0.7 2 1512.7 106 0.6 0.5 + 107 10.1 0.6 (P-Et) 106 24.0 0.2 , Mono. Dist'n. 105 246.5 245.1 90.6% of 245.1 97.6%62 104 7.5 5.7 2 = 250.7 5.6 2.2%-gl 105 16.1 15.7 250.7 102 5.5 5.1 101 5.0 2.7 100 5.0 2.9 99 0.9 0.6 96 0.7 0.7_ 2 276.7 147 1.8 Conc. HMDS = 0.04 vol. percent 24 Table IV. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol product of run 2. M/e Pk. Ht. Mono. 122 5.1 —.1 + 121 96.0 -2.4 P-Me) 120 265.7 —5.7 Mono. Dist'n. 119 2467.0 2465.5 99.5% of 2465.5 96.9%.62 118 51.7 50.6 2 = 2510.6 27.1 1.1% g; 117 6.5 5.5 2510.6 116 7.7 7.6 115 0.7 0.7 114 0.2 0.2 2 2526.5 107 16.2 0.2 (p—Bt)+ 106 44.2 —1.1 _ Mono. Dist'n. 105 466.0 466.1 91.0% of 466.1 96.2%62 104 10.9 7.9 2 = 474.4 7.9 1.7% g; 105 50.2 29.4 0.4 0.1% go 102 6.2 5.5 474.4 101 5.7 5.1 100 6.1 6.0 99 1.5 1.5 2 521.3 147 6.5 Conc. HMDS = 0.15 vol. percent 25 Table V. Mass spectrum of unlabeled (CH3)2CHOSi(CH3)3 M/e Pk. Ht. Mono 122 0.1 0.1 121 0.2 0.2 120 5.0 0.5 119 89.2 0.1 + 118 240.5 -1.1 (P-Me) 117 2250.0 2248.5 99.1% at mass 117 116 8.2 6.7 115 15.5 15.2 2 2268.2 106 0.1 105 0.5 104 0.9 105 5.1 102 5.2 101 57.1 100 1.0 99 5.6 147 59.7 Conc. HMDS = 0.79 vol. percent 26 Table VI. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol product of run 2. M/e Pk. Ht. Mono. 122 0.2 - 1 + 121 5.0 —.1 (P-Me) 120 14.9 0.6 Mono. Dist'n. 119 129.6 126.9 99.1% of 126.9 76.7% d2 118 18.2 15.5 = 165.5 15.5 9.4%_c_1_l 117 24.5 24.0 25.1 15.9% go 116 0.7 0.6 165.5 115 0.2 0.0 2 167.0 106 0.2 105 2.1 104 1.0 105 7.0 102 1.0 101 1.0 147 29.0 Conc. HMDS = 0.71 vol. percent 27 The cracking pattern of 2—propyltrimethylsilyl ether is more complex and will be discussed later. B. 1-Propyl-2,2jd2 Tosylate 1—Propyl-2,2—g2 tosylate was solvolyzed as in runs 1 and 2 to give a mixture of 1-propanol (97.7.: 0.6%) and 2-propanol (2.5.i 0.6%) in £3, 48% yield (run 5). The tri— methylsilyl ether derivatives were prepared and analyzed by mass spectrometry. The results are shown in Tables VII-IX. No meaningful data were obtained for the isotopic composition of the 2-propanol product. From the ratio of Z 105/2 117 for the 2—propyltrimethylsilyl ether (Table IX), it seems probable that it was contaminated with an inde- terminate amount of what may be 1—propyltrimethylsilyl ether and therefore the calculated distribution is not valid. The benzoate ester of the 2-propanol was analyzed, but it was found to contain an unknown impurity which contributed to m/e 166. An accurate isotopic distribution was thus im— possible. II. BromoprOpane Hydrolyses As a prerequisite for additional studies, it was neces— sary to demonstrate that isotopically labeled propanols could be converted to bromopropanes and back to the respec- tive propanols without undergoing isotOpe-position rearrange— ments. 28 Table VII. Mass spectrum of CH3CD2CH208i(CH3)3 from precursor for 1—propyl-2,27d2 tosylate used in run 5, and 1-bromoprOpane-2,2fidg used in run 5. M/e Pk. Ht. Mono. 122 5.6 0.5 + 121 60.6 5.7 (P—Me) 120 156.0 0.6 _ Mono. Dist'n. 119 1445.0 1440.0 99.5% of 1440.0 98.5% d2 116 27.1 26.5 2 = 1465.6 25.6 1»7%.éi 117 4.6 4.1 1465.6 116 4.9 4.9 115 0.4 0.4 2 1475.9 107 0.6 0.5 (P-Et)+ 106 0.9 0.2 ‘ Mono. Dist'n. 105 12.0 1.9 90.6% of 1.9 0.6%-g2 104 27.0 2.2 2 = 247.5 2.2 0.9% 01 105 256.6 256.2 245.4 96.5% go 102 5.0 4.5 247.5 101 5.8 5.4 100 5.6 5.5 99 0.9 0.8 96 0.7 0.7 2 275.2 147 2.5 Conc. HMDS = 0.05 vol. percent aAnother sample prepared from+this same alcohol gave the fol— lowing distribution: (P—Me) , 98.4% Q2, 1.6%.Q17 (P-Et)+, 0.6% 62, 0.5% 91. 99.1% Q0 (55). 29 Table VIII. Mass spectrum of CH3CH2CH2051(CH3)3 from 1-propanol product of run 5. M/e Pk. Ht. Mono 122 5.9 0.1 + 121 72.0 -.5 (P-Me) 120 195.5 —1.4 ‘ Mono. Dist'n. 119 1627.0 1625.4 99.5% of 1625.4 96.4%762 118 52.6 52.0 2 = 1655.5 50.1 1.6% g; 117 4.1 5.4 1655.5 116 6.0 5.6 115 2 0 2.0, 2 1666.6 106 0.9 0.5 + 105 15.1 0.6 (P-ET) 104 51.5 0.5 ‘ Mono. Dist'n. 105 525.0 522.2 91.2% of a 507.0 100.0% go 102 5.5 4.9 2 = 507.0 101 4.8 4.4 100 4.2 4.1 99 0.9 0.9 2 556.6 147 2.2 Conc. HMDS = 0.06 vol. percent aLess than m/e 105. 50 Table IX. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol product of run 5. M/e Pk . Ht . Mono . 122 2.1 0.1 + 121 58.5 -.5 (P-Me) 120 118.5 0.7 , Mono. Dist'n. 119 999.0 951.5 99.1% of 951.5 65.0%.912 116 407.0 595.2 2 = 1465.6 595.2 26.9%_gi 117 126.9 124.9 _116.1 6.1% g. 116 5.0 4.4 1462.6 115 2.6 1.7 114 0.1 0.1 115 0.7 0.5 2 1476.1 106 1.0 0.4 105 9.0 5.9 104 12.6 2.4a 105 102.0 99.5 102 15.0 11.5 101 5.9 4.9 100 0.9 0.0 99 0.9 0.9 2 116.6 147 117.0 Conc. HMDS = 5.21 vol. percent a The large m/e 105 peak suggests the presence of an unknown amount of contaminating CH3CH2CH208i(CH3)3 which casts seri— ous doubt on the validity of the calculated distribution. A. Silver Ion-Assisted Hydrolysis 1- and 2—BromoprOpaneS were prepared by phosphorous tribromide treatment of their respective alcohols. The bromides were stirred in 15% aqueous silver nitrate solutions at room temperature for 70-95 hr. Trimethylsilyl ether derivatives of the alcoholic products were prepared for mass—Spectral analysis. 1-Brom0prOpane-1,1-g2 (98.7%_d2 and 1-3%.Ql by parent ion analysis) produced 1—propanol in 72% yield (run 4). The results are shown in Table X. Table II gives the isotopic composition of the 1-propanol-1,1-g2 precursor to the 1-bromopropane-1,1-g2. 1-Bromopropane—2,2-g2 (98.4% d2 and 1.6% g; by parent ion analysis) produced 1—pr0panol in 59% yield (run 5). The results are shown in Table XI. Table VII gives the iso- tOpic composition of the 1—propanol-2,27d2 precursor to the 1-bromopropane-2,2—d2. 2—Bromopropane-2fid (99.0%_gl and 1.0%_go by parent ion analysis) produced 2-prOpanol in 22) 80% yield (run 6). The mass spectrum of the trimethylsilyl ether of this product is shown in Table XIII. The mass Spectrum of the trimethyl- silyl ether of the 2-propanol-2—g precursor (98.8.i 0.2% g; and 1.2.: 0.2%_do by parent ion analysis of the benzoate ester) to the 2-bromopropane-21g is shown in Table XII. 52 Table X. Mass spectrum of CH3CH2CH208i(CH3)3 from 1—propanol product of run 4. M/e Pk . Ht . Mono . 122 4.5 -.6 + 121 92.1 1.2 (P-Me) 120 247.0 -.1 Mono. Dist'n. 119 2296.0 2294.7 99.5% of 2294.7 96.9%7§2 116 29.6 26.6 2 = 2519.7 25.0 1-1%.§i 117 6.0 5.2 2519.7 116 7.1 7.1 115 0 5 0.5 2 2556.1 108 1.0 0.2 + 107 17.1 0.0 (P-Et) 106 42.7 -.5 Mono. Dist'n. 105 446.0 444.2 91.4% of 444.2 96.0%.512 104 10.6 6.1 2 = 455.2 6.1 1.6% gi 105 27.0 26.5 0.9 0.2% go 102 5.6 5.1 455.2 101 5.5 4.7 100 5.6 5.7 99 1.5 1.5 96 0.2 0.2 97 0.2 0.2 2 495.6 147 5.0 Conc HMDS = 0.05 vol. percent 55 Table XI. Mass Spectrum of CH3CH2CH203i(CH3)3 from 1&propanol product of run 5. M/e Pk. Ht. Mono. 122 4.7 0.1 + 121 66.4 0.1 (P-Me) 120 255.5 0.6 Mono. Dist'n. 119 2161.0 2176.6 99.5% of 2176.6 98.4%.g2 118 40.5 59.6 2 = 2212.1 55.5 1.6% Q; 117 4.9 4.1 2212.1 116 7.0 7.0 115 0.2 0.2 2 2227.7 + (P-Me) 106 1.0 0.2 ‘ Mono. ,Dist'n. 105 16.2 1.1 91.4% of 1.1 0.5%—g2 104 56.6 0.9 2 = 574.0 0.9 0-2%.91 105 590.0 569.2 572.0 99.5%.90 102 7.0 6.5 574.0 101 5.7 5.2 100 5.0 4.9 99 1.1 1.1 96 0.5 0.5 97 0.2 0.2 2 409.2 147 1.0 Conc. HMDS = 0.017 vol. percent 54 Table XII. Mass Spectrum of (CH3)2CDSi(CH3)3 from precursor for 2—bromopropane-2-ga used in runs 6, 19-21. M/e Pk. Ht. Mono. 122 0.2 0.2 121 4.5 -.2 + 120 85.9 -1.1 (P-Me) 119 228.0 -2.7 ‘ Mono. Dist'n. 118 2146.0 2146.4 99.1% of 2146.4 99.6% 63, 117 19.9 15.9 2 = 2151.2 4.6 0.2% 60 116 5.8 2.9 2151.2 115 7.8 7.5 Z 2170.7 106 0.9 105 2.6 104 5.2 105 26.0 102 8.9 101 2.0 100 1.2 99 0.2 147 55.5 Conc. HMDS = 0.69 vol. percent aParent ion analysis of this bromide gave an isotopic dis— tribution of 99.0% g1 and 1.0% go. Table XIII. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol product of run 6. M/e Pk. Ht Mono. 122 0.5 0.5 121 5.0 0.2 + 120 90.0 -.7 (P-Me) 119 245.0 -4.0 ‘ Mono. Dist'n. 116 2292.0 2269.6 99.1% of 2289.6 99.5% g; 117 22.4 21.5 2 = 2500.9 11.5 0.5%-QO 116 5.6 2.6 2500.9 115 8.2 8.0 114 0.1 0.1 2 2521.8 106 1.0 105 2.0 104 12.5 105 9.5 102 28.8 101 9.9 100 2.0 99 1.4 147 20.4 Conc. = 0.40 vol. percent 56 B. Basic Hydrolysis 1-Bromopr0panes were hydrolyzed by heating in 10% aqueous sodium hydroxide solution at steam bath temperature for 70 hr. 1-Bromopropane-1,1jg2 (same as used in run 4) produced 1-propanol in 55% yield (run 7). The mass Spectrum of the trimethylsilyl ether of the product is given in Table XIV. 1-Bromopropane-2,2fid2 (same as used in run 5) produced 1-propanol in 49% yield (run 8). The results are shown in Table XV. III. Aluminum Bromide Catalyzed Isomerizations of Bromopropanes 1-Bromopropane and 2-bromopropane may be interconverted by the action of aluminum bromide on the neat liquid. Results from a study of this interconversion at 00 are Shown in Tables XVI and XVII. As may be seen, an equilibrium mixture contain- ing 6% 1-bromopropane and 94% 2-bromopropane was attained from either Side within an hour when a mixture of bromoprOpane and aluminum bromide in a £2: 5.8/1 molar ratio was used. O AlBr ,0 CH3CH2CH2Br a ‘ CH3CHBrCH3 AF2730 = -1.5.i 0.1 kcal./mole By approach from the 2-bromopropane side, this equilibrium mixture was attained after 6 minutes; from the 1-bromopropane Side, after about 10 minutes. 57 Table XIV. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol product of run 7. M/e Pk. Ht. Mono. 122 4.6 -.5 + 121 91.6 0.6 (E—Me) 120 248.1 0.5 Mono. Dist'n. 119 2504.0 2500.7 99.52 of 2500.7 96.9%532 118 50.0 29.1 2 = 2526.6 25.9 1.1% g; 117 6.2 5.4 2526.6 116 7.0 6.9 115 0.9 0.9. 2 2545.0 108 1.0 0.2 + 107 17.2 0.0 (P-Et) 106 45.0 -.1 Mono. Dist'n. 105 447.0 445.2‘ 91.4% of 445.2 96.1% gs 104 10.6 7.9 2 = 454.0 7.9 1-7%.§: 105 27.0 26.0 0.9 0-2%.Qo 102 5.9 5.5 454.0 101 4.9 4.5 100 5.7 5.5 99 1.6 1.6 96 0.5 0.5 97 0.5 0.5, 2 496.7 147 1.7 Conc. HMDS = 0.05 vol. percent 58 Table XV. Mass Spectrum of CH3CH2CHgOSi(CH3)3 from 1-propanol product of run 8. M/e Pk. Ht. Mono. 122 4.9 0.0 + 121 92.4 0.6 (P-Me) 120 249.5 -.1 Mono. Dist'n. 119 2516.0 2511.5 99.5% of 2511.5 96.4% 52 118 42.4 41.7 2 = 2546.6 57.5 1.6%-g1 117 5.0 4.2 2546.6 116 7.5 7.4 115 0.6 0.6, 2 2565.2 + (P-Et) 106 1.0 0.2 Mono. Dist'n. 105 17.0 0.9 91.4% of 0.9 0.2%;2 104 41.2 1.1 2 = 596.1 1.1 0.5% g; 105 415.0 414.2 596.1 99.5% go 102 7.5 6.6 596.1 101 6.0 5.4 100 5.6 5.7 99 1.2 1.2 96 0.5 0.5 97 0.2 0.2 , 2 455.6 147 2.0 Conc. HMDS = 0.055 vol. percent 59 .mflmmamcm .o.m.> mm .xmmHm mo puma Home: CH muma< meow uomusoo #0: CH0 pH .umumla mo coHuHUUm muommn muma¢ ou Umoom mCHHOCHSU mo unmam>flsom umaoe cmnu who: .umumla wo COHHHUCM muommn mumam OH @0000 umnum Hmnumflo mo unmam>fldom HmHoE :mnu mnoz .Hmumla mcfluumum CH Hmnum Hmnumflp mo momma .Hmumlm cam Hmumua m0 85m .mCHHOCHSv nuHB Umnocmso m 0 U U Q m 9m ma mm o.m 4.5 M m.ofla.¢m m.on.m mm 0.0m m.m b mm ma mm o.m m.m H H mm mm o.mfi 04.0a m mm mm mm o.m N.ma U 0 00d In o.m Um.mfi m o OOH II o.m om.ma H mm mm mm o.m 0N.mfl Q am mm mm o.w om.ma 0 mm mm mm m.m om.¢a m mm mm mm o.m om.¢d am Rom”... .umumum RNH 263$ “:80qu .995 :33 655655 com m npmum>oumm mmEHB .me mumam\umumla .00 um coauommu mUflEOMQ ESCHESHM + mammoum060umlfi .H>x magma 40 .mflmmamcm .o.m.> mm .Hmumlm cam Hmnmla m0 85m .mcHHOCHSU SUHB Umnocmsom U mm 5 00a 0.5 m.m m mm m 00d O.m >.m 0 mm m 00a O.N m.m m mm N 00a o.a m.m m 6m 5 om m.ONfi m.m Q m.OHm.mm m.ofla.m mm 0.0w m.m U «m w mm 0.0 m.m m mm 5 mm O.m m.m ¢m RNH .Hmnmlm oRmfl..Hmumla unmoumm .Hmum A.CHEV A0H0E\0HOEV cam nomum>oomm mmEHB .me mnmad\umumlm . o um coauommu mCHEOHQ ESCHESHM + mammoumofioumlm .HH>N magma O 41 Attempts were made to determine other products, in addition to the 1- and 2—bromopropanes, that might have formed. For reaction times of 6 minutes or less, no evidence for any other products could be found. After reaction times of 1 hour, many small, indistinct peaks resembling baseline noise could be detected in the vapor phase chromatograms of the reaction mixtures. These peaks could be obtained regardless of whether 1-bromopropane or 2—bromopropane was used as the reactant. The retention times were not repro— ducible, however, and the compounds were present in such trace amounts that they could not be isolated or identified even when mixtures from scaled—up reactions were fractionated. Small amounts of brown, polymeric residues were formed in all of these reactions. There are large discrepancies in the literature regard— ing the formation of gaseous products in this reaction. Some workers have reported large amounts of hydrogen bromide being evolved (48,56), while others have reported the complete absence of any gaseous products (57). In the present study, hydrogen bromide was evolved rather slowly after about 10 minutes reaction time. If the reaction mixture was allowed to warm to room temperature, then hydrogen bromide evolution became quite rapid. Qualitatively, it was observed that there appeared to be less hydrogen bromide evolution when the reactants were carefully purified beforehand than when they were not. 42 Gas from the reaction of both 1—bromopropane and 2-bromo- propane was trapped by being bubbled through carbon tetra- chloride. Bubbles were generally formed after 10-15 minutes reaction time. The reaction time varied directly with the rate of stirring in the reaction flask. The resulting carbon tetrachloride solutions were the same, regardless of whether 1-bromOprOpane or 2—bromopropane was used as the initial reactant. The infrared spectrum of this solution was identical to that of an authentic solution of 2—brom0propane in carbon tetrachloride. The 60 Mc./sec. nuclear magnetic resonance Spectrum of this solution showed signals for 2-bromopropane (doublet centered at T 8.50, multiplet centered at T 5.78) and a complex multiplet with a Sharp Signlet at T 9.09. The spectrum of this solution is shown in Figure 2. When the gases were collected in benzene, the n.m.r. spectrum again exhibited signals for 2-bromopropane; a doublet now centered at T 8.66, and a Sharp singlet of the multiplet at T 9.15. These Signals did not arise from solvent impurities. The portion of the spectrum not attributable to 2—bromoprOpane was found to be identical to the Spectrum of an authentic solution of propane and in agreement with the published Spectrum of propane (58). A. Labeled 1-Bromopr0panes Labeled 1-bromopropanes were partially isomerized to 2-bromoprOpaneS and converted to the alcohols by Silver 45 0a mZB 00 um Aaum.mv mUHEOMQ ESCHESHM Com mcmmoumoaounlm mo COHuommu 0:0 Eoum «HUD CH Cmuomaaoo mam mo Esuuommm .H.E.C .omm\.oz om .N musmflm m m m m m P _ 44751443433454} 3313.342? 44 ion-assisted hydrolysis. Their isotopic compositions were studied by mass-spectral analysis of the trimethylsilyl ethers of the alcohols. The reaction conditions used in the various runs are summarized in Table XVIII. The mass-spectral analyses of the trimethylsilyl ethers derived from the re- covered 1-bromopropane and 2—bromopr0pane products are sum- marized in Tables XIX and XX, respectively. 1. 1—Bromopropane—1,1-§2 Runs 10-14 were made with 1-bromopropane-1,1jd2 and the results of the mass-spectral analyses are given in Tables XXI-XXX. In order to facilitate interpretation of these data, it is necessary to correct for slight rearrangements occurring in the mass spectrometer and to subtract contributions from the g; Species in the reactant when discussing the isotOpic composition of the 1-prOpyl products. The results of run 15 are used to illustrate the procedure employed. The trimethylsilyl ether of a known sample of 1-propanol— 1,1-52 gave: (P—Me )+, 99.0% 92, 1.0% 911; (P-Et)+, 96.5% 512, 1.6% Q1, 0.1% do (Table II). If it is assumed that all of the deuteria are at C-1, then rearrangement in the mass Spectrometer has added an apparent increase of 0.6% to g; and 0.1% to do at the expense of Q; in the parent-less—ethyl ion. The trimethylsilyl ether of the 1-propanol derived from i the recovered 1-bromopropane of run 15 gave: (P—Me)+, 98.9% + _d_2, 1.1% 511: (P-Et) , 76.2% 52, 6.4% 511, 15.4% go (Table xxx/11). .Hmnmlfi maeuumum CH H0300 Hmnu0flo mo 000MB .mflmmamcm .U.m.> mm .Hmumlm Ucm Hmumlfi M0 65m .0CHHOCH50 £ua3 0050:050 C U Q 0 45 om om ooa o.m s.m ummmooammommo ma mm ma 9m 4.9 4.0 ummmooammommo >9 mm mm 9m 0.8 s.m ummmomooomo ma mm m4 ms o.m s.m ummmomooomo ma em 0 em o.oma o.m ammoommommo «a om om ooa 0.0 56.0 ammoommoomo ma me am mm o.m 0.0 ummoommoomo ma m4 mm mm 0.0 m.oa ummoommoomo as we mm em 0.0 5H.oa 00000000600 09 RN H. RN H. uC0UH0m .umum A.CHEV A0HOE\0HOEV Hmumld czm .Hmumlm U.Hmumlfi QU0H0>oo0m m0EHu .me mumH4\Hmumlfi .00 um COfluom0H 0CHEOHQ ESCHEgam + 0C0moumofiounla U0a0£04 .HHH>X 0HQMB 46 DNA Rfi.mm sUmd Rm.mw UmH &¢.m¢ .Uma R©.¢m ma ow $3.8 5m wad ~mm &¢.m Hm RoQ ‘mm R045 .3 om Rmém .& Rams, .mm wag Hm «Rm; .mmRfiém ma om R53 am “V3.8 ‘mm Roam om 0%.0 5m &m.m 5%. R95 6m Rim 3 om 0&6; 5m $6 5% Rug: Hm $4 ‘mm Rmém 3. om R93. gm Rog.“ .mm «Rfmm Hm Rm; ‘mm. R53 ma om RUTN Am &m.m .mm &«.mm am 0%4 1% Roda S om Rad 5m Roxw .mm Raga 1m RNA .mm $33 3 +Aumnmv +Amzumv cam .mfi Ucm waned mcsm .mcmmoumofiounlfi Umum>oomn Eoum wmcflmuno Hocmmoumlfi Eonm mammUvaOmmommommU mo mflmmamcm Hmuuummm mmmz .NHN magma 47 Table XX. Mass spectral analysis of (CH3)2 CHOSi(CH3)3 from 2—propanol obtained from 2~bromopropane. Runs 11-18. Run (P-Me)+ 11 84.9%.g2, 1.6% gl, 13.5%_go 12 84.9%.g2, 1.8% g;, 15.5% go 15 84.6%_g2, 2.1%.gl, 15.5% go 14 5.5%.g3, 72.4%.g2, 10.9%.g1, 11.1%gO 15 80.9% g2, 18.6%.gl, 0.5% go 16 81.1% g2, 18.2%‘g1, 0.7% go 17 24.1% 13c, 75.9% 12c: 18 45.6% 13c, 54.4% 12c 48 Table XXI. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol obtained from recovered 1-bromopropane of run 10. M/e Pk.Ht. Mono. 122 4.7 0.2 + 121 84.5 0.02 gp-Me) 120 229.8 0.1 . Mono. Dist'n. 119 2158.0 2152.8 99.5% of 2152.8 98.8%,g2 118 28.2 27.5 2 = 2158 7 25.9 1-2%.§1 117 8.8 5.8 2158.7 118 7.1 7.0 115 1.0 1.0 2 2175.9 108 0.8 0 8 + 107 18.0 0 2 (PvEt) 106 39.7 0 1 MonoL_ Dist'n. 105 410.0 408.2 91.2% of 408.2 97.1%792 104 11.2 8.4 2 = 420.2 8.4 2.0% g; 105 27.8 28.9 5.8 0.9% go 102 5.9 5.5 420.2 101 5.0 4 4 100 5.5 5 1 99 1.7 1.8 98 0.8 0.8 2 480.7 147 3.0 49 Table XXII. Mass spectrum of CH3CH2CD208i(CH3)3 from precursor for 1—bromopropane-1,11Q2 used in runs 11, 12, and 14. M/e Pk. Ht. Mono 125 0.2 0.2 122 5.2 0.02 + 121 97.5 0.2 (P-Me) 120 261.0 —5.5 ‘ Mono. Dist'n. 119 2480.0 2458.8 99.5% of 2458.8 99.09882 118 50.9 50.2 2 = 2481.2 24.6 1.0%.g1 117 4.1 5.2 2481.2 118 8.0 7.9 115 0.8 0.8 2 2498.7 108 0.9 0.1 + 107 18.5 0.2 (P-Et) 106 45.5 —.1 Mono. Dist'n. 105 471.0 489.1 91.2% of 489.1 98.2%702 104 10.8 7.8 2 = 477.7 7.8 1.8%_d_l 105 29.5 28.5 0.8 0.2%-gO 102 8.5 5.8 477.7 101 5.7 5.1 100 8.0 5.8 99 1.7 1.7 2 525.8 147 3.9 Conc. HMDS = 0.08 vol. percent Table XXIII. 50 Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol obtained from recovered l-bromo- propane of run 11. M/e Pk Ht. Mono. 125 0.2 0.2 122 5.0 -.2 + 121 98.1 -1.5 (P-Me) 120 260.1 -4.4 ‘ Mono. Dist'n. 119 2480.0 2458.8 99.5% of 2458.8 99.0%;2 118 29.8 28.9 2 = 2480.8 25.8 1.0765;l 117 4.8 5.7 2480.8 118 8.0 7.9 115 0.8 0.8 2 2498.1 - 108 1.0 0.2 + 107 17.8 0.04 (P-Et) 106 43.2 ~1.0 ‘ Mono. Dist'n. 105 457.0 454.5 91.2% of 454.5 95.47651;2 104 14.8 10.8 2 = 478.4 10.8 2.2%gl 105 40.0 59.5 11.5 2 4%.98 102 8.5 5.8 478.4 101 5.4 4.8 100 8.1 5.9 99 1.7 1.7 2 522.4 147 1.0 Conc. HMDS = 0.02 vol. percent 51 Table XXIV. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-pr0panol obtained from 2-bromopropane of run 11. M/e Pk . Ht . Mono 122 3.8 0.1 + 121 68.6 —1.8 (P-Me) 120 188.1 -3.6 Mono. Dist'n. 119 1791.0 1775.5 99.1% of 1775.5 84.9%};2 118 88.4 54.5 2 = 2091.1 54.5 1.6%_d1 117 297.0 298.8 281.1 15.5%gO 116 3.2 3.2 2091.1 115 0.3 0.3 1 2 2110.1 105 1.7 104 3.3 103 18.3 102 8.3 101 9.1 100 1.0 99 1.0 147 6.1 Conc. HMDS = 0.12 vol. percent 52 Table XXV. Mass spectrum of CH3CH2CH20Si(CH3)3 from 1-prOpanol obtained from recovered 1-bromopropane of run 12. M/e Pk. Ht. Mono. 125 0.2 0.2 122 5.2 0.1 + 121 95.7 -.7 (P-Me) 120 258.9 -3.6 Mono. Dist'n. 119 2459.0 2454.8 99.5% of 2454.8 98.736512 118 38.1 57.2 2 = 2487.8 52.8 1.5%_d_l 117 8.2 5.4 2487.8 118 7.1 7.0 115 0.8 0.8 2 2485.0 108 0.8 0.1 + 107 14.8 -.1 (P-Et) 108 57.8 -.5,' Mono. Dist'n. 105 591.0 585.5 91.2% of 585.5 82.7%.42 104 51.4 25.1 2 = 488.1 25.1 5.0%.01 105 84.8 85.8 57.5 12.5%};O 102 8.9 8.2 488.1 101 5.9 5.5 100 5.7 5.5 99 1.7 1.7 2 511.1 147 2.7 Conc. HMDS = 0.05 vol. percent 53 Table XXVI. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2—propanol obtained from 2—brom0propane of run 12. M/e Pk. Ht . Mono . 122 3.9 0.1 + 121 70.5 -1.8 (P-Me) 120 194.1 —2.5 ‘ Mono. Dist‘n. 119 1850.0 1815.9 99.1% of 1815.9 84.9%;12 118 71.8 59.5 2 = 2157.7 59.5 1.8%,Q1 117 500.0 299.8 284.5 15 5%.90 116 3.7 3.6 2137.7 115 0.8 0.7 2 2157.2 106 0.2 105 2.0 104 3.7 103 19.3 102 8.4 101 9.3 100 1.1 99 1.2 147 10.9 Conc. HMDS = 0.21 vol. percent 54 Table XXVII. Mass spectrum of CH3CH2CH203i(CH3)3 from 1-propanol obtained from recovered 1-bromo— propane of run 13. M/e Pk. Ht. Mono. 125 0.2 0.2 122 4.7 0.5 + 121 82.3 -.1 (P—Me) 120 224.1 0.5 Mono. Dist'n. 119 2082.0 2077.1 99.5% of 2077.1 98.8%;2 118 28.1 25.5 2 = 2102.4 25.2 1.1%-81 117 11.8 9.5 2.0 0.1%_go (2) 118 8.5 8.2 2102.4 115 1.5 1.5 , 2 2117.2 107 12.5 0.1 (P—Et)+ 108 31.4 0.2 Mono. Dist'n. 105 520.0 515.5 91.2% of 515.5 78.2%?82 104 54.7 25.5 2 = 400.8 25.5 8.4% g; 105 85.8 82.9 82.0 15.4%51O 102 8.5 5.8 400.8 101 5 7 5.2 100 4.8 4.8 99 1.7 1.8 98 0.8 0.8 2 459.5 147 10.0 207 20.5 aCorrected for silicone grease impurity (from m/e 207). Table XXVIII. 55 Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from 2-bromopropane of run 13. M/e Pk. Ht Mono. 125 0.2 0.2 122 5.9 0.2 + 121 89.2 -.8 (P-Me) 120 192.0 0.05 Mono. Dist‘n. 119 1785.0 1788.8 99.1% of 1788.8 84.872782 118 74.9 45.4 2 = 2090.2 45.4 2.1%.g1 117 295.0 292.2 278.0 15.5%;1O 118 4.5 4.1 2090.2 115 0.9 0.7 2 2109.2 108 0.5 105 2.7 104 4.0 105 25.7 102 8.7 101 9.5 100 1.1 99 1.1 147 27.3 Conc. HMDS = 0.54 vol. percent 56 Table XXIX. Mass spectrum of CH3CH2CH205i(CH3)3 from 1-propanol obtained from recovered 1—bromo- propanea of run 14. M/e Pk. Ht. Mono. + 122 10.1 0.1 (P-Me) 121 96.0 0.6 _ Mono. Dist'n. 120 588.0 145.2 99.5% of 145.2 6.1%.d3 119 2040.0 2022.8 2 = 2525.5 2022.8 87.0%_g2 118 155.0 150.5 150.5 8.5%.01 117 21.0 18.0 9.0 0.4%gO 118 7.0 8.5 2525.5 115 2.2 0.7 114 0.1 0.1 115 0.9 0.5, 2 2541.7 107 8.1 0.0 (P---2t)+ 106 19.0 0.1 ‘ Mono. Dist'n. 105 171.5 152.9 91.0% of 152.9 36.0%_d2 104 114.5 94.5 94.5 22.5%5;1 105 202.2 199.5 178.7 41.7% go 102 10.0 7.7 424.1 101 8.5 6.3 100 5.0 5.5 99 1 8 1.8 2 488.0 147 184.2 Conc. HMDS = 3.7 vol. percent aParent ion analysis of this bromide gave an isotopic distribu— tion of 7.6%.d3, 85.7% 52, 8.1% 5;, and 0.8% 80. Table XXX. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2—propanol obtained from 2-bromopropanea of run 14. M/e Pk. Ht. Mono. + 122 7.5 0.2 (P—Me) 121 66.0 —.4 . Mono. Dist'n. 120 282.5 108.8 99.1% of 108.8 5.870g3 119 1407.0 1575.9 1575.9 72.4%.g2 118 251.5 207.5 207.5 10.9% gl 117 225.5 222.8 209.7 11.1% 08 118 5.8 5.4 1899.7 115 1.0 0.8 2 1917.0 108 0.4 105 2.4 104 8.9 105 18.9 102 10.0 101 7.9 100 1.1 99 1.1 147 22.2 Conc. HMDS = 0.44 vol. percent aParent ion analysis of this bromide gave an isotopic distribu~ tion of 8.0% g3, 82.2% g2, 10.8% g1, and 1.2% go. 58 After correction for rearrangement in the mass spectrometer, the composition of the d-methylene group of the 1-pr0panol derived from recovered 1-bromopropane becomes 78.9%.d2, 5.8% g1, and 15.5% go. Since about 80% (78.9/98.9) of the 1-propyl product is unrearranged, the original 1—bromo- propane-lfigl (1.1%) contributes 0.9%_d1 and O-2%.Qo to (P-Et)+ of the ether of the product. The contribution to the d-methylene group of the product which results solely from 1—bromoprOpane-1,1fig2 (98.9%) is, therefore, 78.9%_g2, 4.9%.g1, and 15.1% do. Normalization then gives the follow— ing results for run 13: CH3CH2CD2Br —'>‘C2H5-CD2BI + C2H4D—CHDBI' + C2H3D2-CH2BI 100% 79.8% 5.0% 15.2% Similar treatment of the data from runs 10-12 yields the distributions which are shown below. The presence of d3 species in the product of run 14 precludes this treatment. CH3CH2CD2BI ——+ CgHS-‘CDgBr + C2H4D-CPIDBI' + CgHng—CHgBr 100% Run 10 99.0% 0.2% 0.8% 11 97.1% 0.8% 2.5% 12 84.5% 5.5% 12.2% Interpretation of the data from analysis of the iso— propyltrimethylsilyl ethers derived from the 2—bromopropane products is more difficult, for these ethers can produce a parent-less-methyl-ion either by fission of a carbon-silicon 59 bond (path a) or of a carbon—carbon bond (path b). H3 {9 7H3 7 I fi:$:0—si—+CH3 CH3 CH3 a / -883. \ CH3 CH3 + CH3 CH3 + H-4—0-51——CH3 H—é-o-éi 0H3 0H3 0H3 Mass—spectral analysis of the trimethylsilyl ether of 2-propanol-1-13C (19.7% 13C and 80.3% 12C by parent ion analysis of its benzoate ester) gave a parent—less—methyl ion distribution of 17.0% 13C and 83.0% 12C, indicating that 27% of these ions were formed from path b and 73% from path a (55). Analysis of the trimethylsilyl ether of 2-propanol- 1,1,1,5,5,5—_q6 (Table XXXI, 98.4%.916 and 5.8%51S by parent ion analysis of its benzoate ester) gave a parent—less-methyl ion distribution of 72.1% dB, 2.4% 85, 0.1% g4, and 25.4% g3, indicating that 25.2% of these ions were formed by path b and 74.8% by path a. It is apparent that a slight isotope effect favors cracking by path a for the highly deuterated species. From Tables XIX and XX, it may be seen that, although the isotopic compositions of the trimethylsilyl ethers de— rived from the recovered 1-bromopr0panes vary considerably, those from the 2~bromopropane products are practically the same (for runs 11-13). If the 2-bromopr0pane product were 60 Table XXXI. Mass spectrum of (CD3)2CHOSi(CH3)3 from 2-propanol-1,1,1,3,3,3-_d_6.a M/e Pk. Ht. Mono. 128 1.8 0.1 + 125 51.2 1.5 (P-Me) 124 80.9 -.4 Mono. Dist'n. 125 755.0 749.8 99.1% of 749.8 72.1% gs 122 55.1 24.4 2 = 1059.4 24.4 2.4%.gS 121 50.4 1.5 1.5 0.1% g. 120 287.9 287.5 285.7 25.4%g3 119 5.2 5.1 1059.4 118 0.5 0.2 117 0.5 0.5 2 1048.8 108 0.8 107 5.8 108 5.8 105 2.0 104 4.0 105 8.5 102 0.5 101 0.8 147 1.1 Conc. HMDS = 0.03 vol. percent aParent ion analysis of the benzoate ester of this alcohol gave 96.4%‘g6 and 3.6% g5. 61 formed from 1-bromopropane-1,1-§2 by a simple 1,2-hydride shift, then it would have been exclusively 2-bromopropane- 1.1—02. The trimethylsilyl ether of a known sample of 2-prOpano1— 1,1:g2 (98.5% §2 and 1-5%.§l: Table XXXII) gave a parent-less— methyl ion distribution of 84.5% g2, 1.8% g1, and 13.7%_do. Assuming that the 2—bromopr0pane products have the same gross isotopic compositions as their 1-bromopropane precursors, it is calculated that the 2—bromopropanejg2 products from runs 11-13 must be composed of at l§2§£.97% (run 13) 2-bromo- propane—1,1-d2. 2. 1-BromoprOpane—2,2—g2 In runs 15 and 16, 1—bromoprOpane-2,2jd2 (96.1% g2 and 3.9% g; by parent ion analysis) was used as the reactant. The results of the mass—spectral analyses are given in Tables XXXIII-XXXVII. The isotopic compositions of the trimethylsilyl ethers derived from the recovered 1-bromopr0panes were corrected for rearrangements occurring in the mass spectrometer (0.3% udg and 0.3% g; subtracted from (P—Et)+) and contributions from Q; species in the starting material, as was done in runs 10-13. The results, normalized to 100% isotopic purity, are shown below. CH3CD2CH2BI ——‘,’ CgHS—CDgBr + C2H4D'CHDBI‘ + C2H3D2—CH2BF 100% Run 15 1.5% 5.0% 95.5% 16 2.1% 5.8% 92.1% Table XXXII. 62 Mass spectrum of CH3CH[OSi(CH3)3]CHD2 from 2-propanol-1,1fi<_i_2.a M/e Pk . Ht . Mono . 122 2.7 2.5 + 121 43.8 5.4 (P-Me) 120 111.3 1.4 . Mono. Dist'n. 119 1028.0 1018.8 99.1% of 1018.8 84.5%Tg2 118 40.5 21.7 2 = 1202.9 21.7 1.8% g; 117 175.1 172.9 184.4 15.7%;3O 116 2.2 2.2 1202.9 115 0.2 0.2 2 1215.8 108 0.2 105 2.0 104 5.0 105 45.8 102 4.8 101 5.8 100 0.9 99 0.9 147 2.8 Conc. HMDS = 0.07 vol. percent aParent ion analysis of 98.9%512 and 5.1% gl. products prepared from deuteride have been at that this value is too limit for the isotopic 1.5%.gl- the benzoate ester of this alcohol gave However, in view of the fact that other the same source of lithium aluminum least 98.7% g2 species, it would seem low for percent g2. A reasonable lower purity of this alcohol is 98.5% g2 and Table XXXIII. 63 Mass spectrum of CH3CD2CH20Si(CH3)3 from precursor for 1—bromopropane-2,2-§2 used in runs 15 and 16. M/e Pk. Ht. Mono. 125 0.5 0.1 122 5.7 0.5 + 121 97.8 4.4 (P-Me) 120 252.0 —3.8 Mono. Dist'n. 119 2584.0 2554.7 99.5% of 2554.7 98.7%82 118 85.1 84.2 2 = 2455.8 81.1 5.5%_§1 117 8.9 8.1 2455.8 118 7.5 7.2 115 0.8 0.8 2 2455.0 (P—Et)+ 106 0.9 0.0_ Mono. Dist'n. 105 18.5 1.8 91.2% of 1.8 0.4% gs 104 41.8 0.5 2 = 408.4 0.5 0.2%_g_l 105 428.0 425.1 408.1 99.5% 80 102 8.2 7.4 408.4 101 8.7 8.1 100 5.8 5.7 99 1.2 1.2 , 2 447.8 147 0.7 Conc. HMDS = 0.01 vol. percent Table XXXIV . 64 Mass spectrum of CH3CH2CH208i(CH3)3 from 1-pr0panol obtained from recovered 1—bromo- propane of run 15. M/e Pk. Ht. Mono. 122 5.2 0.1 + 121 94.8 -1.3 (P—Me) 120 257.1 -4.8 Mono. Dist'n. 119 2450.1 2424.2 99.5% of 2424.2 98.1% g; 118 52.5 51.8 2 = 2472.2 48.0 1.9%.9; 117 8.5 5.5 2472.2 118 7.7 7.8 115 0.7 0.7 2 2489.8 107 0.5 0.5 (P-Et)+ 106 2.1 0.1 Mono. Dist'n. 105 24.7 7.4 91.2% of 7.4 1.8%71. 104 54.0 15.9 2 = 418.1 15.9 5.5%_§1 105 415.0 414.0 594.8 94.9% 08 102 8.5 7.5 416.1 101 8.8 8.2 100 8.2 8.1 99 1.2 1.2 2 458.5 147 2.0 Conc. HMDS = 0.04 vol. percent 65 Table XXXV. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from 2-bromopropane of run 15. M/e Pk. Ht. Mono 122 3.9 0.3 + 121 68.4 -1.2 (P—Me) 120 197.7 -4.1 , Mono. Dist‘n. 119 1779.0 1755.4 99.1% of 1755.4 80.9% 02 118 401.0 598.2 2 = 2145.2 598.2 18.8% 011 117 24.5 25.5 11.8 0.5% 08 116 6.6 6.4 2145.2 115 1.3 1.2 2 2164.7 106 0.1 105 2.0 104 4.7 103 16.8 102 17.0 101 3.8 100 1.3 99 0.8 147 16.6 Conc. HMDS = 0.32 vol. percent 66 Table XXXVI. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol obtained from recovered i-bromo- propane of run 16. M/e Pk. Ht. Mono. 125 0.1 0.1 122 4.8 0.02 + 121 88.8 -1.4 (P—Me) 120 241.5 ~4.2 Mono. Dist'n. 119 2280.0 2274.7 99.5% of 2274.7 97.9% g; 118 47.0 45.5 2 = 2522.8 45.5 2.0%‘gl 117 12.2 11.4 2.8 0.1% 80(2) 118 8.9 8.8 2522.8 115 0.8 0.8 2 2559.2 + 107 0.2 — 2 (P—Et) 106 2.7 0.2 Mono. Dist'n. 105 28.5 9.5 91.2% of 9.5 ”2.4%,82 104 81.5 24.8 2 = 594.8 24.8 8.2% g; 105 580.0 579.1 580.7 91.4%5;O 102 8 0 7.2 594.8 101 8.5 5.7 100 5.7 5.8 99 1 2 1.2 2 452.7 147 2.9 Conc HMDS = 0.06 vol. percent Table XXXVII . 67 mass spectrum of (CH3)3CHOSi(CH3)3 from 2-prOpanol obtained from 2-bromopropane of run 16. M/e Pk. Ht. Mono. 122 5.7 0.2 + 121 84.8 -1.8 (P-Me) 120 189.9 -3.2 Mono. Dist'n. 119 1704.0 1882.9 99 1% of 1882.9 81.1% 82 118 577.0 574.0 2 = 2051.5 574.0 18.2%91l 117 28.8 28.0 14.8 0 7% do 118 8.5 8.2 2051.5 115 1.0 1.0 2 2070.1 108 0.1 105 1.5 104 5.8 105 15.8 102 18.8 101 5.2 100 1.5 99 0.8 147 5.9 Conc. HMDS = 0.12 vol. percent 3‘ r. :4 fr u 68 The 1—propanol derived from the recovered 1-bromopropane of run 16 was examined by n.m.r. (Figure 3). Integration showed that the deuterium distribution of this alcohol (not corrected for g; species) corresponded to 0.10.: 0.03 deuterium atom at c-1, 1.72 4 0.02 at c-2, and 0.18 _t 0.04 at C—3. This distribution agrees with the mass—spectral analysis (0.10 deuterium atom at C—1). The isotopic distributions for the trimethylsilyl ethers derived from the 2-bromopr0pane products of runs 15 and 16 are somewhat anomalous. If the 2—bromOpropane—g2 was formed from the 1—bromOpropane—2,27d2 by a simple 1,2-hydride (deuteride) shift, then it would have been exclusively 2—bromOprOpane—1,2-d2. The isotopic distribution of the parent—less—methyl ion of the trimethylsilyl ethers derived from runs 15 and 16 would thus be predicted to be, roughly, 84.8% d2, 14.7% d1, and 0.5% do. Inspection of Tables XXXV and XXXVII shows that the actual distribution is different by d; being about 3.5% higher than predicted. In order to resolve this anomaly, the n.m.r. spectrum of the 2-propanol derived from the 2-bromopropane product of run 16 was obtained. This spectrum is shown in Figure 4. From the lack of any C—2 proton signals, or C—1 proton splitting, it must be concluded that the 2—bromopropane formed from 1—bromopropane-2,2-g2 in runs 15 and 16 is primarily, if not exclusively, 2-bromoprOpane-1,25d2, 3,2,, the result of a simple 1,2-hydride (deuteride) shift. The anomalous mass- spectral distributions may arise partially from an unexpected 69 .wa sou mo mammoumofiouglfi pmum>oowu Eoum ©0>Hu0© 2.50 ca 53 .mmc Hocooouoé mo 838.0on .uéé .oou\.oz co 7} mZB .m musmam 70 U®>HH0© AvHUU CH Rom ——O§ mZB .wa can mo pospoum mommonmoEOuQIN Eouw .mmg Hocmmonmlm mo Esuuommm .H.E.c .00m\.ozqom .¢ musmflm 71 fragmentation in the mass spectrometer for this particular species. It is likely that the 2-propyl products contain a larger percentage of g; species than the reactants or recovered 1-bromopropanes because of preferential hydride shift in g1 species in the reactants. 3. 1-Bromopropane-1—13C Run 17 was conducted by using 1-bromopropane—1-13C which was 28.8% 13C and 71.2% 12C (Table XXXVIII). The recovered 1—bromopr0pane was examined by n.m.r. at 100 Mc./sec. Careful integration of the lower field carbon—13—proton satellite from lsC—1 and the upper field satellite from 13C—3 gave a 13c—5/13c—1 value of 0.206.i 0.002. c-1 was 25.5 4.0.5% 13c by direct integration. The amount of carbon-13 at C-2 was found by difference. After correction for the natural abundance of carbon—13 was made, normalization to 100% isotOpic purity gave the following distribution: CH30H213CHgBr ——->- CH3CH213CHgBr + CHngCHgCHQBr + lsCHgCHgCILLQ‘ 100% BO-Z-i 1-1% 6 5.: 1.8% 15.5.: 0.4% 13C product The n.m.r. spectrum of the 2—bromopropane- showed no evidence for any carbon-13 at C-2. From the mass spectrum of the trimethylsilyl ether (Table XXXIX) derived from this product, it was calculated that the 13C Species were exclusively 2-bromopropane-1-13C. 1-Bromopropane—1-13C which was 54.6% 13C and 45.4% 12C (Table XL) was used as the reactant in run 18. From the Table XXXVIII . 72 Mass spectrum of CH3CH213CHZOSi(CH3)3 from precursor for 1-bromopropane-1-13C used in run 17. M/e Pk. Ht. Mono. 121 1.0 0.2 + 120 20.0 0.5 (P-Me) 119 87.1 -.1 Mono. Dist'n. 118 580.0 452.0 99.5% of 452.0 28.8% 120 117 1119.0 1118.4 3 = 1589.8 1117.8 71.2% lac- 118 4.1 5.4 1569.8 115 8.9 8.9 114 0.2 0.2 2 1580.9 108 5.9 0.0 (P-EtL+ 105 17.2 0.3 , Mono. Dist‘n. 104 114.0 95.9 91.2% of 95.9 28.8% 1SC 105 254.0 252.8 2 525.9 ._252.0 71.2% 12c 102 8.4 7.0 525.9 101 18.0 15.8 100 5.0 2.5 99 5.8 5.8 2 557.4 147 1.6 Conc. HMDS = 0.04 vol. percent 73 Table XXXIX. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from 2-bromopropane of run 17. M/e Pk. Ht. Mono. 121 0.8 0.1 + 120 17.4 -0.5 (P-Me) 119 86.1 -1.4 , Mono. Dist'n. 118 520.0 598.7 99.1% of 598.7 24.1% 130 117 1257.0 1255.8 2 = 1652.9 1254.2 75.9% 120 118 7.2 8.4 1852.9 115 7.1 7.0 2 1887.9 105 0.5 104 0.8 105 2.1 102 8.2 101 21.0 100 1.0 99 2.2 147 16.3 Conc. HMDS = 0.42 vol. percent 74 Table XL. Mass spectrum of CH3CH213CHEOSi(CH3)3 from pre- cursor for 1-bromopropane—1-13C used in run 18. M/e Pk. Ht. Mono. 122 0.5 0.1 121 2.9 0.4 + 120 50.9 5.0 (P-Me) 119 147.3 1.9 Mono. Dist'n. 118 1221.0 1150.9 99.5% of 1150.9 54.9% 130 117 955.0 952.0 2 = 2081.4 950.5 45.1% 12c 118 7.8 7.5 2081.4 115 5.7 5.8 114 0.1 0.1 2 2075.9 107 0.8 0.1 + 108 10.1 0.9 (P-Et) 105 28.6 1.4 Mono. Dist'n. 104 248.4 251.5 91.5% of 251.5 54.8% 130 105 195.0 195.1 2 = 425.8 192.5 45.4% 120 102 18.7 15.2 425.8 101 14.1 15.5 100 8.7 8.2 99 5.1 5.1 H 2 484.2 147 7.1 Conc. HMDS = 0.15 vol. percent 75 60NML/sec. n.m.r. spectrum of the recovered 1—bromopropane (Figure 5), a 13C-3/l3C-1 value of 0.145.: 0.007 was ob- tained. The amount of carbon—13 at C-1 was found to be 46.9% 18C by mass—spectral analysis of the trimethylsilyl ether derivative (Table XLI). The following distribution was calculated for run 18 after correction for carbon—13 natural abundance and normalization to 100% isotOpic purity: CchHZl‘BCHgBr ——> CH3CH213CHgBr + CH313CH2CH2Br + lsCHgCHngiiBr 100% 85. 740.2% 5. 710.9% 10. 6.10. 8% In addition to being more precise, these results should be more accurate than those of run 17, since the amount of carbon-13 at C-1 was determined by mass spectrometry rather than by n.m.r. integration. Both the n.m.r. spectrum (Figure 6) of the recovered 2—bromopropane-13C and the mass spectrum of the trimethylsilyl ether derived from it (Table XLII) showed that the 13C species were exclusively 2-bromopropane-1-13C. B. Labeled 2-Bromopropanes IsotOpically labeled 2—bromopropanes were partially isomerized to 1-bromopropanes and the isotopic compositions studied by mass-spectral analysis as previously described for the 1—bromopropanes. The reaction conditions used in the various runs are summarized in Table XLIII. 76 .mfi can Eonw UmalmcmmoumoEounnfi pwum>oomu wo Eouuummm 0a m m “HOEOC .00m\.02 ow .m musmflm LO ’ \ t€~ 77 Table XLI. Mass spectrum of CH3CH2CHZOSi(CH3)3 from 1-pr0panol obtained from recovered 1-bromo- prOpane of run 18. M/e Pk. Ht. Mono. 121 1.9 0.0 + 120 44.8 -1.3 (P-Me) 119 144.9 -2.1 ‘ Mono. Dist'n. 118 1255.0 1141.1 99.5% of 1141.1 54.8% 130 117 951.0 949.9 2 = 2089.8 948.5 45.4% 12c 116 8.0 7.5 2089.6 115 5.6 5.5 114 0.1 0.1 115 0.2 0.2 2 2104.3 108 8.1 0.1 (P—Et)+ 105 26.2 0.1 Mono. Dist'n. 104 222.5 202.1 91.5% of 202.1 48.9% 130 105 251.9 229.8 2 = 451.2 229.1 55.1% 120 102 17.1 15.8 451.2 101 14.9 14.1 100 6.1 5.6 99 5.1 5.1 2 472.3 147 17.2 Conc. HMDS = 0.37 vol. percent 78 .md cow Eoum poopoum UmaumcmmoumoEouQum m0 Eduuomam .H.E.c .00m\.02 Ow .m madmam Ofi m m m m 2. .3 my; 79 Table XLII. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from 2-bromOprOpane of run 18. M/e Pk. Ht. Mono. 121 1.7 0.2 + 120 55.0 -0.9 (P-Me) 119 123.0 -2.0 Mono. Dist'n. 118 975.0 875.8 99 1% 873.8 45.8% lac 117 1047.0 1045.8 2 = 1918.2 1042.4 54.4% 12c 116 9.4 8.9 1916.2 115 5.3 5.2 2 1933.7 105 0.2 104 0.9 103 4.0 102 14.0 101 18.2 100 1.3 99 2.0 147 6.7 Conc. HMDS = 0.15 vol. percent 80 .Absoamz sac m.om\m.ma mo oaumu HmHoE CH amrumumum Ucm omrumumlm muquwz U .mflmmamcm .o.m.> mmo .umumlm 0cm umumld mo 85mg .0CHHOCflSU Sufi? Umsucmsom omoumooomo cam m.oue.mm m.ofib.e ooa 0.0a e.m coooummoooo mm em m 008 0.0a e.m mooummoooo mm mm a as 0.8 a.m omoumooomo Hm mm 8 mm o.oma m.m omoquOomo om am 8 am 0.0ma m.m omoumooomo ma Rd H. R d H. unmoumm .Hmum A.CHEV A0HOE\0HOEV Hmumnm cnm .Hmumlm 0.Mmumla QUmu0>oomm mEHu .cxm mumH¢\HmumIN .00 um coauommu 0©HEOHQ ESCHEDHM + mammoumoEonfllm Umamnmq .HHHAx manme 81 1. 2—Bromopropane—2jg 2-Bromopropane-2jd (99.0%_d1 and 1.0% go by parent ion analysis) was used in runs 19-21. The mass spectrum of the trimethylsilyl ethercxfthe 2-propanol-2jd from which this bromide was prepared is given in Table XII. In runs 19 and 20, the 2-bromopropane was in contact with aluminum bromide for 2 hours. The mass Spectrum of the extensively isotope—position scrambled trimethylsilyl ether derived from 2-bromopropane recovered from run 19 is shown in Table XLIV. The bromides obtained from run 20 were puri— fied and their isotopic compositions determined by parent ion analysis. The composition of the 1—bromopropane was 4.0% g2, 78.7% g;, and 17.3% go. That of the 2—bromopropane was 2.8% 532, 77.4% 531, and 19.8% 80. In run 21, the 2-bromOprOpane was in contact with aluminum bromide for only 6 minutes. Parent ion analysis of the products yielded an isotopic composition of 0.6% g2, 95.5% g;, and 3.9% go for the 1-bromopropane and 94.5% g1, and 5.5% do for the 2—brom0propane. Verification of the composition of the recovered 2-bromoprOpane was shown by parent-less-methyl ion analysis, 94.7%_gl and 5.3% g0 (Table XLV), of the trimethylsilyl ether derived from it. 2. 2-Bromopropane-1,1,1,3,3,3-g5 2-Bromopropane-1,1,1,3,3,3—dfi was used in run 22. The mass spectrum of the trimethylsilyl ether of the Z-prOpanol 82 Table XLIV. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from recovered 2-bromo- propane of run 19. M/e Pk. Ht. Mono. 122 0.5 0.1 + 121 6.1 0.1 (P-Me) 120 63.0 1.2 Mono. Dist'n. 119 255.4 88.5 99.1% of 68.3 5.7%[82 118 1592.0 1544.1 2 = 1827.5 1544.1 75.8%;l 117 440.0 ' 422.0 415.1 22-7%.§o 118 9.1 4.2 1827.5 115 18.0 5.1 114 0.8 0.1 115 4.7 0.5 2 1844.1 107 1.1 108 2.0 105 15.8 104 15.2 105 22.0 102 28.7 101 22.9 100 2.0 99 2.5 147 1380.0 Conc. HMDS = 27.4 vol. percent 83 Table XLV. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-propanol obtained from recovered 2-bromo- propanea of run 21. M/e Pk. Ht Mono. 122 0.3 0.3 121 4.3 -0.04 + 120 81.1 —0.9 (P-Me) 119 224.4 -2.1 Mono. Dist'n. 118 2079.0 2085.4 99.1% of 2085.4 94.7%.gl 117 128.0 124.8 2 = 2181.5 118.1 5.5% go 116 3.9 2.8 2181.5 115 8.8 8.3 114 0.2 0.2 2 2201.3 106 1.0 105 2.0 104 8.9 103 8.5 102 26.4 101 10.5 100 2.1 99 1.3 147 63.8 Conc. HMDS = 1.2 vol. percent aParent ion analysis of this bromide gave an isotopic dis- tribution of 94.5%.gl and 5.5% go. 84 from which it was made is given in Table XLVI. The mass spectrum of the trimethylsilyl ether derived from the 1—bromopropane product is shown in Table XLVII, while that derived from the recovered 2-bromopropane is given in Table XLVIII. 3. Mixture of 2-BromOpropane-2—g_and -1,1,1,3,3,3-g5 A mixture of 2—bromOpropane-2jg and 2-bromopropane- 1,1,1,5,5,57g6 (same as used in run 22) was prepared in a 50.2:49.8 molar ratio by weight. A portion of this mixture was converted to the alcohols bysfiJAmn:ion—assisted hydrolysis. The mass spectrum of the trimethylsilyl ether from this mix- ture is shown in Table LXIX. The bromide mixture was isomerized under the same conditions as used in run 22. The mass spectra of the trimethylsilyl ethers derived from the 1-bromopropane and 2—bromopr0pane products recovered from this isomerization (run 23) are shown in Tables L and LI, respectively. 85 Table XLVI. Mass spectrum of (CD3)2CHOSi(CH3)3 from precursora for 2-bromopropane-1,1,1,3,3,3fig6 used in run 22. M/e Pk . Ht . Mono . 128 5.0 —0.1 + 125 58.5 1.7 (P—Me) 124 152.7 -2.7 Mono. Dist‘n. 125 1457.0 1450.2 99.1% of 1450.2 72-O%.Qo 122 72.4 51.9 2 = 1988.4 51.9 2.8%g5 121 58.1 5.1 5.1 0.2%914 120 510.0 508.9 501.2 25.2%513 119 10.0 10.0 1988.4 118 0.5 0.5 117 0.1 0.0 2 2004 4 109 0.8 108 1.2 107 8.8 108 6.8 105 4.0 104 7.6 105 11.0 102 0.7 101 1.0 147 11.4 Conc. HMDS = 0.24 vol. percent aParent ion analysis of the benzoate ester of this alcohol gave 98.0% as and 4.0% g5. 86 Table XLVII. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol obtained from 1-bromopropane of run 22. M/e Pk. Ht. Mono. 126 4.5 0.2 + 125 80.9 -0.1 (P-Me) 124 221.1 -1.9 . Mono. Dist'n. 125 2052.0 2040.4 99.5% of 2040.4 94.174351.5 122 107.7 106.3 2 = 2187.1 108.5 4.9%_§5 121 8.8 5.8 5.8 002%.94 120 27.0 28.5 16.8 0.8%g3 119 4.7 4.4 2187.1 118 0.5 0.0 117 2.2 1.0 116 0.5 0.0 115 0.9 0.2 2 2182.4 109 0.7 0.4 _(_P-Et)+ 108 1.4 —0.3 Mono. Dist'n. - 107 19.0 8.9 91 0% of 8.9 2.5%fgla 108 59.0 10.8 2 = 298.7 10.8 5.8%.gaa 105 289.0 286.5 . 281.0 94.1%.02 104 18.2 15.4 298.7 105 7.2 8.0 102 5.4 2.8 101 1.0 0.2 , 2 528.2 147 93.6 Conc. HMDS = 1.99 vol. percent a . . . These values have no real meaning and must have arisen through rearrangements in the mass Spectrometer. TABLE XLVIII. 87 Mass spectrum of (CH3)2CHOSi(CH3)3 from 2-pr0panol obtained from recovered 2-bromo— propane of run 22. M/e Pk . Ht . Mono . 128 2.8 0.0 + 125 54.1 -0.8 (P-Me) 124 150.0 -0.9 Mono. Dist'n. 125 1592.0 1585.4 99.1% of 1585.4 71.1% 0. 122 87.0 88.5 2 = 1948.0 88.5 5.4%gS 121 85.0 12.5 12.5 0.8%_g. 120 489.0 487.8 ,_484;g 24.9% g. 119 15.1 15.0 1948.0 118 0.8 0.8 117 0.4 0.5 2 1985.7 109 0.2 108 1.1 107 8.5 108 7.0 105 4.1 104 8.7 105 21.1 102 0.9 101 1.0 147 6.0 Conc. HMDS = 0.13 vol. percent 88 Table XLIX. Mass spectrum of (CH3)2CHOSi(CH3)3 derived from the 2—bromopropane-2fid and -1,1.1,3,3,3-gfi mix- ture used as reactant in run 23. M/e Pk. Ht. Mono. 128 2.0 0.0 + 125 38.0 -0.6 (P-Me) 124 102.9 —3.2 Mono. Dist'n. 125 978.0 972.1 99.1% of 972.1 55.4%_gs 122 81.2 47.1 2 = 2907.8 47.1 1.8% gs 121 45.8 2.8 2.8 0.1%_g. 120 410.0 548.7 548.7 12.0%933 119 171.0 6.2 8.2 0.2%_gg 118 1555.0 1550.9 1550.9 52.7%gl 117 19.1 18.4 2907.8 116 2.6 2.5 115 5.7 5.6 2 2954.2 109 0.5 108 1.1 107 4.5 108 5.0 105 5.5 104 7.0 105 15.2 102 19.1 101 7.0 147 15.9 Conc. HMDS = 0.34 vol. percent 89 Table L. Mass spectrum of CH3CH2CH208i(CH3)3 from 1-propanol obtained from 1—bromopropane of run 23. M/e Pk. Ht. Mono. 128 1.2 0.0 + 125 22.1 0.5 P-Me) 124 60.2 0.2 Mono. Dist'n. 125 552.0 548.9 99.5% of 548.9 55.2%.;6 122 29.0 28.7 2 = 1852.5 28.7 1.7%g5 121 4.0 1.5 1.5 0.1% g. 120 48.7 4.8 4.8 0.5%g3 119 114.9 0.7 0.7 0.1%_§2 118 1082.0 1080.5 1080.5 84.2%_g1 117 15.1 15.9 7.6 0.4%9O 118 4.1 5.9 1852.5 115 2.1 1.5 2 1884.0 (P-Et)+ 108 0.7 0.3 Mono. Dist'n. 107 5.1 1.7 91.0% of 1.7 0.8% gla 108 11.7 5.5 2 = 279.9 5.5 1.5% d3a 105 87.5 78.5 78.5 28.0% 82 104 28.0 8.8 8.8 5.1% d1 105 195.9 195.8 187.4 87 0% 50 102 15.4 14.4 279.9 101 5.1 2.0 100 5.7 5.1 99 2.0 2.0 2 507.8 147 78.7 Conc. HMDS = 1.68 vol. percent -0..v a . . These values have no real meaning and must have arisen through rearrangements in the mass spectrometer. 90 Table LI. Mass spectrum of (CH3)2CHOSi(CH3)3 from 2—prOpanol obtained from recovered 2—bromopropane of run 23. M/e Pk. Ht . Mono. 128 1.2 -0.5 + 125 27.2 -0.7 (P-Me) 124 77.4 0.9 Mono. Dist'n. 125 705.0 700.8 99.1% of 700.8 35.8%:g6 122 44.1 55.8 2 = 1958.0 33.6 1.7% as 121 55.1 8.5 8.5 0.5%-g4 120 288.0 247.4 247.4 12.7%;3 119 109.5 6.0 6.0 0.5%;2 118 980.0 957.8 957.8 48.9% g; 117 20.0 19.8 8.5 0.5%91O 118 1.8 1.5 1958.0 115 5.1 5.0. 2 1975.8 109 0.5 108 0.5 107 5.2 106 5.4 105 2.5 104 5.0 105 10.0 102 12.0 101 4.5 100 1.0 147 6.9 Conc. HMDS = 0.15 vol. percent DISCUSSION I. Formic Acid Solvolysis of 1-Propyl Tosylates Comparison of the data of Tables III and IV with those of Table II shows that the 1-propyl product of run 2 is isotope-position unrearranged and that of run 1 not more than 0.4% rearranged. Comparison of the data of Table VIII with those of Table VII shows that the 1—propyl product of run 3 is similarly unrearranged. The analyses of the trimethylsilyl ethers derived from the 2-propanols are uncertain. The spectrum of the derivative from run 2 (Table VI) is less than one-tenth as intense as that normally observed in these analyses; the ether from run 3 was contaminated (Table IX). In view of the small amount of 2-propyl products obtained, it is highly probable that little "free" propyl cation is formed under these conditions. Rather, it would seem likely that most of the 1—pr0pyl product arises from an SN2-like attack on the tosylate or on an incipient tight-ion pair. The 2-propyl product is probably formed by a 1,2—hydride shift occurring in a tight-ion pair. Shortly after this work was completed, Lee and Kruger reported (59) on a study of the anhydrous acetic and formic acid solvolyses of 1—propyl—1-14C tosylate. Solvolysis in 91 92 acetic acid at 1150 gave, in addition to a small amount of 2-prOpyl acetate (23. 1%), 1—propyl acetate which had under— gone no isotope-position rearrangement. Solvolysis in reflux- ing anhydrous formic acid produced 1-propyl formate which had 0.15% of the carbon—14 label at C—2 and 0.68% at C-3, plus some 2-propyl formate (1-2%). These data were explained by assuming that a small portion of the reaction proceeded through a pathway involving edge—protonated cyclopropanes whose lifetimes were too short to permit complete equilibra- tion of the carbon atoms, while most of the product was pro— duced from an 8N2 attack on the tosylate or on a "covalently solvated carbonium ion.” A study of the solvolyses of isotopically labeled cyclo— hexyl tosylates in acetic acid of varying water content has indicated that a rather striking difference exists for the optimum solvent composition which promotes 1,2-hydride shifts XS. 1,3-hydride shifts in this system (30). Whereas the amount of 1.2-hydride shift varied inversely with the water content in the solvent range of 94-100% acetic acid, the amount of 1,3—hydride shift went through a maximum that occurred at 97-98% acetic acid. While one is on admittedly tenuous grounds in extending these results to include the formolysis of propyl tosylate, nevertheless, it is conceivable that the discrepancy between the two studies might be due to differences in the water content of the solvent. 93 II. Bromopropane Hydrolyses From the identity of the mass spectra of the trimethyl- silyl ether derivatives of the starting alcohols and the product alcohols (compare Table II with Table X, VII with XI, and XII with XIII), it is apparent that isotope-position labeled 1—propanols and 2-propanols may be successfully con- verted to 1-bromopropanes and 2-bromopropanes by treatment with phosphorous tribromide and then converted back to their respective alcohols by hydrolysis in 15% aqueous silver nitrate with overall integrity of the isotope-position label being maintained. Since 1-bromopropane yielded no 2-propanol upon hydroly— sis, it is reasonable to assume that this reaction proceeds through nucleophilic attack by water on the side opposite that of the partially ionized carbon—bromine bond. + 0+ . 0+ CHgCHgCHgBr —£*—9———> CH3CH2CH2----Br----Ag __I129_> CH3CH2CH20H + + H + AgBr Comparison of the data of Table II with those of Table XIV and of the data of Table XII with those of Table XV Shows that the hydrolysis of isotope-position labeled 1-bromopro- panes to 1-propanols is accomplished in 10% aqueous sodium hydroxide with no isotope-position rearrangements. These ob- servations are in agreement with the report that 1-bromo- propane-1,1jd2 is hydrolyzed to 1-propanol-1,1-§2 with no 94 isotope—position rearrangement by treatment with 10% aqueous potassium carbonate at 1400 (60). The data are in accord with an 8N2 type displacement of bromide by hydroxide. III. Aluminum Bromide Catalyzed Isomerizations of Bromopropanes For the reaction of 1-bromopropane with aluminum bromide for less than 6 minutes, the results of runs 10-13 and 15-18 have several things in common. First, the recovered 1—bromo- propanes Show extensive rearrangement of the protons (deuteria) and the carbon Skeleton. Second, the 2-bromopropanes are, within tflie limits of measurement, formed from 1-bromopropane by a 1,2—hydride shift and exhibit no carbon skeletal rearrange- ments. Although several possible mechanisms can be devised to account for these observations, it is possible to discount most of these at the outset. The absence of any as species in the products from deuterium labeled starting materials (runs 10-13 and 15—16) rules out the importance of any inter— molecular hydride transfers, bimolecular reactions, or elimi- nation-addition reactions for short reaction times under these conditions. The results of runs 15 and 16 also rule out either 1,2-methyl shifts or 1,3-hydride shifts by themselves as the exclusive cause of rearrangement in the products. A combination of rapid 1,3—hydride shifts and classical 1,2- methyl Shifts might be used as an explanation. However, there is no reason to believe that 1,2—hydride shifts should not be 95 competitive under such circumstances. Such 1,2—hydride shifts would have led to extensively isotope-position scrambled 2—bromopropane product. That was not the case. The contribution to the scrambling observed in the re- covered 1—bromopr0pane by multiple 1,2-hydride shifts proceed— ing through the 2-propyl cation cannot be very important. Such a mechanism fails to account for the carbon skeleton scrambling and predicts a measurable amount of deuterium scrambling in the 2—bromopropane product. In addition, in order for CgHs-CDgBr Species to be formed from CH3CD2CH2Br exclusively through multiple 1,2-hydride shifts, it is neces- sary that 10 times as many C2H4D—CHDBr species be formed. The actual ratio obtained was 1:2.0-2.8 (runs 15 and 16). The combined data are most readily accommodated by a mechanism in which the incipient carbonium ion from the 1-bromopropane-aluminum bromide complex may take one of the two separate and distinct paths; path a, in which a single 1,2-hydride shift leads to 2-bromopropane, or path b, which leads to isotope—position rearranged 1-bromopropane through partially equilibrating edge-protonated cyclopropanes. CH2 ........ ..H» + 8' ?CH2‘\ + x’ ‘— + 0 Cngqf-fl'i 7+1] CH3CHCH3 +a—' CH3CH2CH2--Br-—A1Br3 ”11" CH2 \Cf'lg \‘ ’1 L 1241er ‘\ H;-J;-;.CH.2 \‘cfi CH— CH3CHBrCH3 \— W 9- ‘ i) l AlBr4 CH3CH2CH2BI 96 The results of runs 17 and 18 indicate that a methyl— bridged ion can not be the first species formed in path b, for if it were, then the carbon-13 label should be distributed either equally between C-2 and C—3, or unequally with more at C-2. Incomplete equilibration of the edge-protonated species, however, predicts more label at C-3 than at C-2. Experimentally more label was found at C-3. It is difficult to speculate on how "free" the protonated cyclopropane of path b is from its gegenion. It is reasonable to assume that its degree of freedom iS somewhere between that of the intermediate formed from the deamination of aminopropane or deoxidation of 1-propanol on the one hand, and that of the intermediate formed in the reaction of zinc chloride and hydrochloric acid with 1-chloropropane on the other. The presence of as species in the products of run 14 (Tables)OCD(and XXX) indicates that some form of an inter- molecular hydride transfer or elimination-addition reaction assumes some importance at a reaction time of 2 hours. If the deuteria were statistically scrambled in the 1-brom0propane recovered from this reaction, the parent-less—ethyl ion dis- tribution for its trimethylsilyl ether derivative should be, roughly, 5.1% oz, 48.8% 511, and 48.1% _<_i_o (calculated from (P-Me)+ distribution). The actual distribution of 32.2% g2, 22.5% 81, and 41.7% Q0 (Table XXIX) indicates that the alumi- num bromide catalyst may become deactivated at long reaction times. 97 The results of runs 19 and 20 show that after 2 hours of reaction, 2-bromopropane-27g has also undergone rather extensive amounts of either intermolecular hydride transfers or elimination—addition reactions, or some combination of the two. The net effect, however, has been a loss of deuterium with replacement by hydrogen for the 2-bromopropane, and, to a lesser extent, for the 1—bromopropane product. At a reaction time of 6 minutes, the recovered 2-bromo- propane had completely lost about 5% of its deuterium. The 1-bromopropane product retained slightly more of its isotopic purity. It is tempting to suggest that a set of reactions such as those represented by equations 1-4 may contribute to a + + CH3CDBrCH3 + CH3CDCH3 —> CH3CD2CH3 + CH3CBrCH3 (eq. 1) + + CH3CBrCH3 + CH3CDBrCH3 ——’— CH3CDBrCH3 + CH3CBrCH3 (eq. 2) + CH3CBrCH3 + CH3CDBrCH3 ——>— CH3CHBrCH3 + CH3cn—.+_—.<;H2 (eq. 5) \Br( + CH3C\D:..—::(;H2 + CHgCDBrCH3 —>- cnscngcngsr + CH3CBrCH3(eq. 4) \ + 7 ‘BH small extent to the rearrangements in this system, since these reactions explain the formation of propane, and the greater net loss of deuterium from the recovered 2-bromopropane than from the 1-bromopropane product. Presumably, the 2-bromo-2- propyl cation could also lose a proton and polymerize. Such 98 a path would explain the deactivation of the catalyst and the formation of hydrogen bromide at longer reaction times. By analogy with the results of run 21, one might expect the formation of some 2—bromopropanejg7 from 2-bromopropane- 1,1,1,3,3,3jg5 when similarly treated. No 87 species were formed after 10 minutes reaction time in run 22. Unfavorable isotope effects prevailing in this system, however, might prevent detectable formation of species from bimolecular re- actions. This is especially true if equation 3 is the rate determining step. Taken collectively, the results of runs 19-23 suggest that the main path by which 2-bromopropane is converted to 1—bromopr0pane is by an intramolecular 1,2—hydride shift. The results of run 23 indicate that the less highly deuterated g1 species is isomerized more rapidly than the QB species, and that at short reaction times no appreciable amount of hydride or deuteride transfer between the two species need occur for this conversion. Relatively slow intermolecular hydride transfers do become important, however, at long re- action times. The results suggest, but neither prove nor disprove, the possibility that reactions such as those repre— sented by equations 1-4 may intervene to a small extent in this system. IV. Summary The following points have been made salient by the work described in this thesis: 1-Propyl tosylate is hydrolyzed to 1-propanol in 99% formic acid at 750 without undergoing isotope-position rearrangements. 1—Bromopropane prepared from isotope-position labeled 1—propanol may be converted back to 1-propanol with overall maintenance of isotope-position integrity by hydrolysis either in 15% aqueous silver nitrate at room temperature or in 10% aqueous sodium hydroxide at steam bath temperature. Isotope-position labeled 2—bromopropane may also be hydro— lyzed in silver nitrate solution without undergoing isotope- position rearrangements. When 1-bromopr0panes are partially isomerized to 2-bromopr0panes by the action of aluminum bromide, the re— covered 1-bromopropanes are extensively isotope-position rearranged, while the 2-bromopropanes are the result of a 1,2-hydride shift and are not extensively scrambled. The data are most easily interpreted by assuming that the isotope- position scrambled 1-bromopropanes arise from a reaction path involving equilibrating edge-protonated cyclopropanes. The major pathway for the conversion of 2-bromopropane into 1-bromopropane is an intramolecular 1,2—hydride shift. 99 100 At longer reaction times, intermolecular hydride transfers can become important. The exact mechanism for these trans- fers has not been unambiguously established. EXPERIMENTAL Vapor Phase Chromatography (V.P.C.) V.p.c. analyses were performed using an Aerograph A-90-P, equipped with a thermal conductivity detector and employing helium as the carrier gas. Relative peak areas were deter- mined either by planimetry, or by multiplication of peak height times the width at half height, depending on the reso- lution and shape of the peaks. In a few cases the peaks were cut out and weighed. Infrared Spectra (I.R.) I.r. spectra were determined, in most cases, on a Perkin- Elmer 237B double beam grating spectrophotometer and, in a few instances, on a Beckman IR-5 instrument. Samples were run either as 5—10% solutions in carbon tetrachloride in 0.1 mm. cavity cells or as thin films between sodium chloride plates. Nuclear Magnetic Resonance Spectra (N.M.R.) N.m.r. analyses, unless otherwise stated, were performed on a Varian Associates A-60 Analytical NMR Spectrometer with a probe temperature of ca. 380 or on a JEOLCO C-6QH at room temperature. Signal areas were integrated electronically. 101 102 Preparation of Trimethylsilyl Ether and Benzoate Ester Derivatives of 1- and 2—Propanol Trimethylsilyl ether derivatives were prepared by adding a small drop of trimethylchlorosilane (Stauffer) to a 2:1 molar mixture of the alcohol and hexamethyldisilazane (Metallomer Laboratories) in a small flask fitted with a water—cooled reflux condenser topped with a "Drierite" drying tube and warming the mixture overnight over a steam bath. The ethers were purified by vapor phase chromatography (V.p.c.) from a 20‘ x 1/4" 20% Carbowax 20M on 60/80 Chromosorb W column at 60—800, 30 p.s.i.g. He. Benzoate esters were prepared by overnight refluxing of an equimolar mixture of alcohol and benzoyl chloride (Baker Analyzed Reagent) over a steam bath. The esters were puri- fied by V.p.c. from a 6' x 1/4" 20% Apiezon L on 60/80 Chromosorb W column at 155-1650, 30 p.s.i.g. He. Preparation of 1—Propanol-1,1jg2 A slurry of 5.00 g. (0.119 mole) of lithium aluminum deuteride (Metal Hydrides) in 100 ml. of anhydrous diethyl ether, freshly distilled from lithium aluminum hydride, was prepared in a 300 ml. 3-necked flask equipped with a "Drierite" drying tube fitted to a water-cooled reflux con- denser, a "Teflon"-bladed Tru-bore stirrer, and a 50 ml. addition funnel with equalizing tube. A solution of 12.7 ml. (12.8 g., 0.098 mole) of distilled propionic anhydride 103 (Matheson, Coleman and Bell, b.p. 58-90/11 mm.) in 25 ml. of anhydrous diethyl ether was Slowly dripped into the rapidly stirred slurry at a rate sufficient to cause gentle reflux- ing. After addition was completed, the pale gray slurry was stirred for an additional 20 hr. and then hydrolyzed at 00 by careful addition of first 10 ml. of water and then 10 ml. of 5% aqueous sodium hydroxide solution. The mixture was stirred for 17 hr. at room temperature and the dlear ether supernatant decanted off. The white precipitate was rinsed six times with 15 ml. of ether and the ether portions com- bined and dried over anhydrous magnesium sulfate. Distilla- tion of the ether solution through a 4" glass Spiral packed column yielded 9.98 g. of product boiling above 900 (thermom- eter reading fluctuated a great deal). Analysis by vapor phase chromatography (6' x 1/4” 20% Carbowax 20M on 60/80 Chromosorb W, 750, 30 p.s.i.g. He) showed this product to be pure 1-pr0panol. Vacuum distillation of the residue yielded an additional 0.53 g. of product which V.p.c. analy— sis showed to be 1—pr0panol containing a trace of unidenti— fied higher boiling impurity. The yield of 1-propanol-1,1-§2 was 87%, based on propionic anhydride used. A trimethylsilyl ether derivative was prepared and purified in the usual manner for mass-spectral analysis. Preparation of 1-Propyl—1yi-g2.p-Toluenesulfonate The method used was that of Tipson (61). Distilled pftoluenesulfonyl chloride, 21.00 g. (0.110 mole), in 40 ml. 104 of pyridine (Matheson, Coleman and Bell, dried over barium oxide) was slowly added to 5.91 g. (0.0952 mole) of 1- propanol-1,1fig2 in 20 ml. of pyridine at -50 and then allowed to stand overnight in a refrigerator freezer. Seventy ml. of water was then added to the reaction mixture at 00, the first 10 ml. being added Slowly and in very small portions. The mixture, consisting of an upper aqueous layer and a lower, pink organic layer, was extracted with 155 ml. of diethyl ether in three portions. The combined ether extracts were then washed four times with 50 ml. portions of cold 10% hydro- chloric acid, once with 50 ml. of water, and twice with 50 ml. of saturated aqueous sodium bicarbonate solution. After drying over anhydrous magnesium sulfate, the ether was stripped off in a rotary evaporator at 400 with maximum water aspirator vacuum and the resulting crude tosylate distilled at reduced pressure. The first distillation yielded 18.51 g. of slightly yellow product, b.p. 128.5—1300/0.7-0.8 mm. Redistillation yielded 18.31 g. of colorless 1-propyl tosylate, b.p. 115-6o/O.4 mm., which was pure by n.m.r. analysis. The yield was 90%, based on 1-propanol-1,1fig2 used. Preparation of 1-Propyl—2,2-d2 p-Toluenesulfonate pfiToluenesulfonyl chloride, 14.22 9. (0.0747 mole), in 40 ml. of dry pyridine was reacted with 4.00 9. (0.0642 mole) of 1-propanol—2,21g2 (supplied by C. E. Orzech, Jr., prepared by repeated exchange of methylmalonic acid with deuterium oxide, 105 followed by decarboxylation to propionic acid and lithium aluminum hydride reduction to 1—propanol) in 20 ml. of pyridine and worked-up as described for 1—propyl-1,1figg.p-toluenesul— fonate. The reaction yielded 11.20 g. of 1-propyl—2,27g2 pftoluenesulfonate,b.p. 108-108.50/0.1 mm., which was pure by n.m.r. analysis. The yield was 81%, based on 1-propanol-2,2- .dg used. Hydrolysis of 1-Pr0pyl proluenesulfonates in Aqueous Formic Acid Anhydrous formic acid was prepared by the method of Winstein and Marshall (62). Two kg. of 98% formic acid (Matheson, Coleman and Bell) was placed in a still pot and distillation begun through a 20" Vigreaux column until a dis- tillation temperature of 98.50 was reached. The remaining acid was then allowed to stand over 330 g. of boric anhydride for 5 days and decanted into a still pot containing 85 g. of boric anhydride. The anhydrous acid was then distilled off under vacuum as needed. The boiling point was 29.5-30.00/51 mm. Anhydrous acid was added to water to bring the water concentration to 0.556 molar (9a. 0.86% by weight). This mix- ture was used in the 1-propyl tosylate solvolyses. In a typical experiment, 4.52 g. (0.021 mole) of 1—propyl- 1,1-§2 pftoluenesulfonate was dissolved in 50 ml. of the aqueous formic acid in a 100 ml. flask equipped with a calcium chloride drying tube fitted to a water—cooled reflux condenser 106 and maintained at 75:10 for 143.5 hr. At the end of this time, the straw colored liquid was carefully diluted with 100 ml. of water at 00 and the pH adjusted to 11 by addition of 65 ml. of 50% sodium hydroxide solution. After addition of 40 ml. of diethyl ether the aqueous layer was saturated with sodium chloride. At this point, the salted-out sodium tosylate was removed by means of a glass wool filter, the layers separated, and the aqueous layer extracted twice with 20 ml. portions of ether. The combined ether extracts were then washed once with 25 ml. of saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Distil— lation produced 0.47 g. of product boiling above 360. Vapor phase chromatographic analysis (6'x 1/4" 20% Carbowax 20M on 60/80 Chromosorb‘fl, 750, 30 p.s.i.g. He) showed it to be composed of 6% 2-propanol and 94% 1—pr0panol, with a trace of diethyl ether. The trimethylsilyl ether derivatives of the alcohols were prepared and purified for mass-Spectral analysis. The hydrolysis of 1-prOpyl-2,2jd2.p-toluenesulfonate was performed in the same manner. Preparation of 1-Bromopr0pane-1,1-g2 To 5.00 g. (0.081 mole) of 1-pr0panol-1,1-g2 in a 50 ml. 3-necked flask equipped with a "Drierite" drying tube fitted to a water-cooled reflux condenser, a 50 ml. addition funnel with equalizing tube, a stopper, and a small "Teflon" covered 107 magnetic stirring bar was slowly added with moderate stir— ring at 00 3.3 ml. (9.4 g., 0.035 mole) of phOSphorous tribromide. Stirring was continued for 23 hr. at room temperature, during which time HBr was evolved, and then 10 ml. of water was added at 00. The upper aqueous layer was extracted twice with 8 ml. of distilled pentane. The pentane extracts were combined with the colorless lower organic layer, washed with 10 ml. of ice-cold 5% aqueous sodium carbonate solution, and dried over anhydrous magnesium sul— fate. Distillation through a 4" glass Spiral packed column yielded 5.56 g. of 1-bromopropane, b.p. 69—700, which was shown by vapor phase chromatographic analysis (6' x 1/4“ 20% Carbowax 20M on 69/80 ChromosorbfiW, 750, 30 p.s.i.g. He) to be pure except for a trace of pentane. N.m.r. analysis re- vealed no trace of d-protons. The yield of 1—bromoprOpane- 1,1—g2 was 56%, based on 1-prOpanol-1,1-g2 used. Preparation of 1-Bromopropane-2,2-§2 The reaction of 10.19 g. (0.167 mole) of 1-propanol— 2,2-g2 (supplied by C. E. Orzech, Jr.) with 6.5 ml. (18.5 g., 0.068 mole) of phosphorous tribromide yielded 11.22 g. of 1-bromopropane, b.p. 68.5-70.00, which was pure by V.p.c. analysis (6' x 1/4" 20% Carbowax 20M on 60/80 Chromosorb W, o 75 , 30 p.s.i.g. He). The yield of 1-bromopropane—2,21d2 was 57%, based on 1-propanol-2,2-g2 used. 108 Preparation of 1-BromoprOpane-1-13C 1-Brom0propane-1-13C was prepared by 13C02 carboxylation of ethylmagnesium bromide to form propionic acid-1-13C, fol— lowed by lithium aluminum hydride reduction of the acid to 1-propanol-1-13C, and treatment of the alcohol with phosphor- ous tribromide. A solution of ethylmagnesium bromide in 800 ml. of anhy- drous ether was prepared from 7.32 g. (0.301 g. at.) of magnesium turnings and 23.0 ml. (33.4 g., 0.307 mole) of ethyl bromide (Matheson, Coleman and Bell) in a 2 l. 3*necked flask equipped with a 250 ml. addition funnel, a "Teflon"—bladed Tru- bore stirrer and a water—cooled reflux condenser. A tube leading to a calcium chloride drying tube and then to two gas scrubbers containing 25% aqueous barium chloride solution was fitted to the top of the condenser. The addition funnel was then replaced by a 12 mm. o.d. glass tube which extended below the surface of the ether solution and was connected to two sulfuric acid gas scrubbers and then to a 300 ml. 3—necked flask fitted with a "Teflon" covered magnetic stirring bar, a stopper, and an addition funnel, the top of which served as an inlet for a source of dry nitrogen. Aqueous perchloric acid, 35%, was placed in the addition funnel and 40.00 g. (0.20 mole) of barium carbonate-13C (Merck, Sharp and Dohme of Canada, 56.5 atom percent 13C) placed in the flask. After all tubing connections were tightly wired and glass tapers were held in place with heavy rubber bands, the entire system was swept with dry nitrogen for 15 minutes and the ethyl— 109 magnesium bromide solution was cooled to 00. Carbon dioxide was then bubbled into the rapidly stirred solution by slowly dripping dilute acid onto the barium carbonate. After 3 hr. (92, 75 ml. of acid used), the barium car- bonate was consumed and the system was swept with dry nitrogen for 20 minutes. The bubbler tube was then replaced by an addition funnel and the intermediate complex was decomposed by addition of 100 ml. of 10% aqueous hydrochloric acid and stirred for 1.5 hr. To this was added 25 ml. of 57% aqueous hydrochloric acid, the lower aqueous layer was saturated with sodium chloride and the mixture was stirred overnight. The aqueous layer was then extracted three times with 50 ml. of ether and the ether portions combined and dried over anhydrous magnesium sulfate. Distillation produced two cuts boiling above 360. The first cut, b.p. 86-1270, 1.94 g., was shown by vapor phase chromatographic analysis (6' x 1/4" 15% FFAP on 60/80 Chromosorb W, 1350, 30 p.s.i.g. He) to be a mixture of g3, 75% 3-pentanone and 25% propionic acid, with a trace of diethyl ether. The second cut, b.p. 138-1410, 12.51 g., was shown to be propionic acid containing traces of 3-pentanone and diethyl ether. Infrared Spectra of these fractions con— firmed the product assignments. The yields were 87% for propionic acid and 8% for 3-pentanone, based on barium carbon— ate used. No barium carbonate was recovered. To a slurry of 6.50 g. (0.171 mole) of lithium aluminum hydride (Metal Hydrides) in 200 ml. of ether, was added 12.5 g. (0.167 mole) of the propionic acid-1-13C in 50 ml. of anhydrous diethyl ether and the product was worked-up in the 110 usual way. Distillation produced 8.68 g. of 1-propanol which was pure except for traces of diethyl ether and ethanol (V.p.c., 6' x 1/4" 15% FFAP on 60/80 Chromosorb‘W, 65O , 30 p.s.i.g. He). Vacuum distillation of the residue yielded an additional 0.80 g. of 1-propanol which contained 9a. 5% of a higher boiling impurity. The yield of 1-prOpanol-1-13C was 93%, based on propionic acid-1-13C used. A trimethylsilyl ether derivative was prepared and purified in the usual manner for mass- spectral analysis. The reaction of 5.13 9. (0.0845 mole) of 1-propanol-1-13C with 3.2 ml. (9.1 g., 0.034 mole) of phosphorous tribromide, as previously described for the preparation of 1-bromopropane— 1.1—g2, yielded 6.45 g. of 1-bromopropane (b.p. 69-710) con- taining a trace of pentane, and an additional 0.78 g. of 1—bromopropane containing a trace of higher boiling impurity. The later portion was purified by vapor phase chromatography (6' x 1/4" 15% FFAP on 60/80 Chromosorb W, 550, 30 p.s.i.g. He). The yield of 1-bromopr0pane-1-13C was 69%, based on 1-pr0panol-1-13C used. Preparation of 2—Propanol-2—d Ten g. (0.173 mole) of acetone (Baker Analyzed Reagent, dried over anhydrous magnesium sulfate) was reduced with 2.18 9. (0.0518 mole) of lithium aluminum deuteride (Alpha Inor— ganics) to obtain 7.01 g. of 2—propanol, b.p. 79.5-80.50, which was pure by V.p.c. analysis (6' x 1/4" 15% FFAP on 60/80 111 Chromosorb W, 550, 30 p.s.i.g. He). Infrared analysis con— firmed the absence of carbonyl impurities. Vacuum distilla- tion of the residue yielded an additional 1.14 g. of 2-propanol which contained traces of diethyl ether and ace— tone. The yield of 2-propanol-25g_was 77%, based on acetone used. Preparation of 2-Bromopropane—2jd 2—Propanol-2fid, 5.15 g. (0.0843 mole), was reacted with 3.3 ml. (9.4 g., 0.035 mole) of phosphorous tribromide (Eastman), as previously described for the preparation of 1-bromopropane-1,1fidg, to yield 5.94 g. of 2-bromopropane, b.p. 57.5-58.50, which was pure by V.p.c. analysis (6' x 1/4" 15% FFAP on 60/80 Chromosorb W, 550, 30 p.s.i.g. He). The yield of 2-bromopropane-2fig was 57%, based on 2-propanol—2jg used. Preparation of 2—Propanol—1,1,1,3,3,3fig6 The reduction of 10.33 g. (0.161 mole) of acetone—g5 (Merck, Sharp and Dohme of Canada, > 99.5 atom percent D) with 2.00 g. (0.053 mole) of lithium aluminum hydride (Metal Hydrides) yielded 9.00 g. of 2-propanol, b.p. 79.5-81.00, which was pure by V.p.c. analysis (6' x 1/4" 15% FFAP on 60/80 Chromosorblfl, 550, 30 p.s.i.g. He). Infrared analysis confirmed the absence of carbonyl impurities. The yield of 2—propanol-1,1,1,3,3,3jg8 was 85%, based on acetonejgs used. 112 Trimethylsilyl ether and benzoate ester derivatives were prepared and purified in the usual way for mass-spectral analysis. Preparation of 2—BromOpropane-1,1,1,3,3,3fid6 2-Propanol-1,1,1,3,3,3fid6,5.16 g. (0.078 mole), was reacted with 3.0 ml. (8.3 g., 0.030 mole) of phosphorous tri- bromide (Eastman), as previously described for the preparation of 1-bromopropane-1,1fig2, to yield 5.8 g. of 2-bromopropane, b.p. 56.5-58.00, which was pure by V.p.c. analysis (6' x 1/4“ 15% FFAP on 60/80 Chromosorb W, 550, 30 p.s.i.g. He). Vacuum distillation of the reaction residue yielded another 0.3 g. of product consisting of 2—bromopropane and a trace of un- identified higher boiling impurity. The yield of 2-bromo- propane-1,1,1,3,3,3-g5 was 61%, based on 2-propanol-1,1,1. 5,3,5—gfi used. . Silver Ion-Assisted Hydrolysis of Bromopropanes In a typical experiment, 4.89 9. (0.0392 mole) of 1—bromo- propane-1,1ig2, 8.69 g. (0.0511 mole) of silver nitrate (Baker and Adamson Reagent), 50 ml. of water, and a small "Teflon" covered magnetic stirring bar were placed in a 100 ml. flask equipped with a water-cooled reflux condenser. The entire apparatus was wrapped with aluminum foil to exclude light. The mixture was stirred for 82 hr. at room temperature and the pale yellow—green silver bromide (6.85 9., 0.0364 mole) 113 filtered out on a glass sinter. After addition of 50 g. of potassium fluoride, the aqueous filtrate was extracted with 50 ml. of diethyl ether in three portions. The combined ether extracts were dried over anhydrous magnesium sulfate and dis- tilled to yield 1.63 g. of product, boiling above 800, which was found by V.p.c. analysis (6' x 1/4" 20% Carbowax 20M on 60/80 Chromosorb W, 750 , 30 p.s.i.g. He) to be 1-propanol with a trace of diethyl ether. 1-Bromopropane-2,2jd2 and 2—bromopropane—25d were also solvolyzed to their respective alcohols in this way, as were the propyl bromide products of various isomerization reactions described elsewhere in this thesis. Trimethylsilyl ether de- rivatives of the alcohols were prepared and purified in the usual way for mass—spectral analysis. Basic Hydrolysis of Bromopropanes In a typical experiment, 4.14 9. (0.0331 mole) of 1-bromopropane-1,1-g2, 5.00 g. (0.125 mole) of sodium hydroxide, and 50 ml. of water were placed in a 100 ml. flask fitted with a water—cooled reflux condenser and heated over a steam bath for 71.5 hr. After addition of 50 g. of potassium fluoride, the clear, aqueous solution was extracted with 50 ml. of diethyl ether in three portions. The combined ether extracts were dried over anhydrous magnesium sulfate and distilled to yield 0.74 g. of product, boiling above 700, which was shown by V.p.c. analysis (6' x 1/4" 20% Carbowax 20M on 60/80 Chromosorb 114 W, 750, 30 p.s.i.g. He) to be 1-propanol containing a trace of diethyl ether. 1-Bromopr0pane-2,2-g2 was also hydrolyzed to its respec— tive alcohol by this technique. The trimethylsilyl ether derivatives of the alcohols were prepared and purified in the usual way for mass-spectral analysis. Aluminum Bromide Catalyzed Isomerizations of Bromopropanes Both 1- and 2-bromopropanes were reacted with aluminum bromide by the following technique: A small round-bottomed flask (93. 20 ml.), equipped with two side arms, one sealed at the end and bent downward and the other topped with a rubber septum, was charged with a weighed amount of aluminum bromide (Fisher anhydrousL and a small "Teflon" coated mag- netic stirring bar in a dry nitrogen—filled dry bag and con- nected to a vacuum line. The flask was evacuated and the aluminum bromide was distilled onto the dry ice-cooled flask bottom by gentle heating of the side arm with a small, cool flame. Dry air was then admitted to the system and the flask was surrounded with an ice water bath. Stirring was commenced and timing begun as the bromopropane was injected with a calibrated syringe through the septum onto the aluminum bromide. Timing was stopped upon addition of quinoline to the pale yellow, homogeneous reaction mixture. The flask was closed to the atmosphere and surrounded by a warm water bath and the volatile reaction products distilled under vacuum into 115 a liquid nitrogen-cooled receiver. They were weighed, im- mediately analyzed by vapor phase chromatography, and then converted to their respective alcohols by hydrolysis in 15% aqueous silver nitrate. The trimethylsilyl ether derivatives were prepared and subjected to mass-spectral analysis. Preparation of 2—Propanol—1,1-§2 2-Propanol-1,1-§2 was prepared by lithium aluminum deuteride reduction of n—octylformate to methanolfigg, con- version of the methanol to methyl—d2 iodide by treatment with red phosphorous and iodine, formation of methylsgg-magnesium iodide, and addition of acetaldehyde to it. A solution of 33.67 g. (0.213 mole) of gfoctyl formatey (K & K, redistilled, b.p. 62.5-63.50/2.5 mm.) in 55 ml. of dispebutyl ether (Matheson, Coleman and Bell, redistilled from lithium aluminum hydride, b.p. 64-50/50 mm.) was reduced by addition to a slurry of 5.02 g. (0.120 mole) of lithium aluminum deuteride (Metal Hydrides) in 160 ml. of butyl ether. After being stirred for 17 hr., the mixture was hydrolyzed with 10 ml. of water and 10 ml. of 5% aqueous sodium hydroxide and stirred another 12 hr. Work-up in the usual manner yield- ed 4.73 g. (65%) of product, b.p. 64-50, which was shown by vapor phase chromatographic analysis (6' x 1/4" 15% FFAP on 60/80 Chromosorb W, 550, 30 p.s.i.g. He) to be methanol con- taining 22: 5% of butyl ether. This reduction was not run in diethyl ether, because the azeotrope of methanol and diethyl ether makes purification extremely difficult. 116 Methanol-d , 4.55 g. (0.134 mole), was slurried with 2.06 9. (0.0166 mole P4) of purified (63) red phosphorous in a 50 ml. round—bottomed flask containing a small "Teflon" covered magnetic stirring bar and fitted with a water-cooled reflux condenser. Iodine (Baker and Adamson, resublimed, U.S.P.), 22.80 g. (0.09 mole Ia), was then slowly added through the condenser over 1.5 hr. at 00 and the resulting blood-red mixture was stirred overnight at room temperature. The con- denser was replaced by a still head and 16.5 g. of crude methylfigg iodide, b.p. 40—30, was distilled off. This was dissolved in 22 ml. of dry butyl ether to facilitate handling and washed once with 17 ml. of cold 10% aqueous sodium car- bonate solution and once with 20 ml. of ice water. After drying over anhydrous magnesium sulfate, the solution was distilled, yielding 11.25 g. (58%) of methyl iodide, b.p. 42-50, which was pure by V.p.c. analysis (6' x 1/4" 15% FFAP on 60/80 Chromosorb W, 550, 30 p.s.i.g. He). A solution of methyl-gg-magnesium iodide in 25 ml. of anhydrous diethyl ether was prepared from 1.57 9. (0.0654 g. at.) of magnesium turnings and 5.15 9. (0.0358 mole) of: methylfigg iodide in a 100 ml. 3-necked flask equipped with a calcium chloride drying tube fitted to a water-cooled reflux condenser, a "Teflon"-bladed Tru-bore stirrer, and an ice water-jacketed addition funnel with equalizing tube. A 2.25 ml. (1.8 g., 0.041 mole) portion of freshly distilled acetal— dehyde (Matheson, Coleman and Bell), dissolved in 4 ml. of 117 ether, was slowly added to the Grignard solution at 00. The solution was stirred for 3 hr. at room temperature and 45 min. at reflux. The addition of 3.5 ml. of saturated aqueous ammonium chloride solution to the mixture at 00 immediately caused a hard, yellow mass to precipitate. After standing overnight, the ether layer was decanted off and the salts were washed several times with ether. 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