WNWWill”NHNHINIUIWIHIHIWIWWW“ _.I IS: m—‘A llHllllllllllllHllllllllllllllllHlllllllllllllllllll ' runny 3 1293 10063 3902 Michigan State University This is to certify that the thesisentitled " PART I: PHOTOENOLIZATION' IN ALPHA- DIKETONES PART II: DISPROPORTIONATION VERSUS COUPLING IN PHOTOCHEMICALLY GENERATED RADICALS presented by John Thomas Kondilas has been accepted towards fulfillment of the requirements for ‘ __LS-_degree in 92mm I \/L/}/ f/Wx Ijor prole/ssor ‘Dam March L2. 1929 0-7639 OVERDUE FINES ARE 25¢ PER DAY V PER ITEM Return to book drop to remove this checkout from your record. PART I PHOTOENOLIZATION IN ALPHA-DIKETONES PART II DISPROPORTIONATION VERSUS COUPLING IN PHOTOCHEMICALLY GENERATED RADICALS By John Thomas Kondilas A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Chemistry 1979 H.- ewvaX/e ABSTRACT PART I PHOTOENOLIZATION IN ALPHA-DIKETONES PART II DISPROPORTIONATION VERSUS COUPLING IN PHOTOCHEMICALLY GENERATED RADICALS By John Thomas Kondilas The photochemistry of several l,3—diphenyl-l,2-pro- panediones was examined in an effort to elucidate the' mechanism of photoenolization. Unlike phenyl alkyl diketones, which undergo photo- enolization competitively with photocyclization, the phenyl benzyl diketone systems fail to enolize upon photochemical excitation. This apparent lack of photochemistry was ra- tionalized by charge-transfer complexation of the beta- phenyl ring with the excited carbonyl moiety. Although the system provided no mechanistic informa- tion, it'served as a precursor in the'synthesis of 1,3-di- phenyl—3—hydroxybutan—2-one. The photochemistry of the hydroxy ketone was studied in order to probe the reported inefficiency of the photoreduction of acetophenone by toluene. John Thomas Kondilas Upon absorption of light, the hydroxy ketone undergoes alpha—cleavage to produce an acetophenone ketyl radical and a phenylacetyl radical.l Subsequent decarbonylation of the phenylacetyl radical, resulting in a benzyl radical, was found to be inefficient. This contrasts the high ef— ficiency of decarbonylation in dibenzyl ketone and compli- cates the use of the hydroxy ketone for studying the inef— ficiency of the photoreduction. Indications for better studying the problem are offered in the conclusion. This work is dedicated to the three most important people in my life, my parents and my wife Valorie. ii ACKNOWLEDGMENTS The author wiShes to sincerely thank Professor Peter J. Wagner for his guidance, time and patience throughdut the course of this work. His sense of humor and personableness have made the requirements and respon- sibilities at Michigan State a much easier task. I would also like to extend my deepest gratitude to my fellow members of the Wagner group. Their tech- nical assistance and friendship will always be remembered. Finally, I would like to thank my wife Valorie, whose typing and retyping of the thesis, structural assis- tance and encouragement proved invaluable. iii TABLE OF C ONT ENTS Page LIST OF TABLES . E . . . . . . . . . . . . . . . . . .'. vii LIST OF FIGURES . . . . . . . . . . . . . . . . . .‘. . ‘ ix PART I. INTRODUCTION . . . . . . . . . . . . 1 General Mechanistic Process . . . . . . . . . . . 3 Kinetic Expressions . . . . . . . . . . . . . . . . . 4 Previous Study of Diketone Photoenolization 6 Objectives . . . . . . . . . . . . . . . . . . . . . 8 Results . . . . . . . . . . . . . . . . . . . . . . . 9 Discussion . . . . . . . . . . . . . . . . . . . . . 16 Enlightenment . . . . . . . . . . .-. . . . . . . . . 17 PART II. INTRODUCTION . . . . . . . . . . . . . . . . . 18 Norrish Type I Cleavage . . . . . . . . . . . . . . . -18 Background . . . . . . . . . . . . . . . . . . . . . l9 Photoreduction of Acetophenone . . . . . . . . . . . 22 Results . . . . . . . . . . . . . . . . . . . . . . . 24 Quantum Yield Determination . . . . . . . . . . . 24 Absorption and Emission Spectra . . . . . . . . . 24 Chemically Induced Dynamic Nuclear Polarization . 25 Discussion . . . . . . . . . . . . . . . . . . . ... 32 Conclusions . . . . . . . . . . . . . . . . . . . . . 34 EXPERIMENTAL . . . . . . . . . . . . . . . . . . . . . . 36 iv Page Preparation and Purification . . . . . . . . . . . . 36 Solvents and Additives . . . . . . . . . . . . . . 36 . Benzene . . . . . . . . . . . . . . . . . . . . 36 Acetonitrile . . . . . . . . . . . . . . . . . 36 Carbon Tetrachloride . . . . . . . . . . . . . 36 Methanol . . . . . . . . . . . . . . . . . . . 36 Hexane . . . . . . . . . . . . . . . . . . . . 37 t—Butyl Alcohol . . . . . . . . . . . . . . . . 37 Water . . . . . . . . . . . . . . . . . . . . . 37 Thiophenol . . . . . . . . . . . Q . . . . . . 37 Hexadecyltrimethylammonium Chloride . . . . . . 37 Internal Standards . . . . . . . . . . . . . . . . 37 Cycloheptane . . . . . . . . . . . . . . . . . 37 Cyclooctane . . . . . , . . . . . . . . . . . . 37 Tridecane . . . . ... . . . . . . - . . . . . . 37 Nonadecane . . . . . . . . . . . . . . . . . . 37 Diketones . . . . . . . . . . . . . . . . . . . . 37 Method A . . . . . . . . . . . . . . . . . . . 37 Method B . . . . . . . . . . . . . . . . . . . 38 Characterization . . . . . . . . . . . . . . . 39 Hydroxy Ketone . . . . . . . . . . . . . . . . . . 40 General Techniques . . . . . . . . . . . . . . . . . 41 Preparation of Samples . . . . . . . . . . . . . . 41 Degassing Procedure . . . . . . . . . . . . . .'. 41 Irradiation Procedure. . . . . . . . . . . . .‘. . ‘ 42 Sample Analysis . . . . . . . . . . . . . . . . . 42 Page Response Factors . . . . . . . . . . . . . . . . 43 Actinometry and Quantum Yields . . . . . . . . . . 43 Spectra . . . . . . . . . . . . . . . . . . . . . 44 LIST OF REFERENCES . . . . . . . . .'. . . . . . . . . . 46 APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . 49 vi Table 10. ll. .12. 13. LIST OF TABLES Kinetic Parameters for Photoreactions of Phenyl Alkyl Diketones PhCOCOR Photolysis of 0.022 M HK in Benzene, .v40% Conversion . . . . . . Photolysis of 0.05 M HK in Benzene, ~5% Conversion . . . . . Photolysis of 0.043 M HK in Hexane, ~7% Conversion . . . . Photolysis of 0.05 M HK in t- -Buty1 Alco— hol, rw2% Conversion . . . . . Photolysis of 0.05 M HK in Benzene with Benzene Thiol Present,ec2% Conversion . Photolyses of 0.01 M HK in a Micellar Solution; Micelle = Hexadecyltrimethyl- ammonium Chloride,e»1% Conversion . . Photolysis of 0.05 M HK in Benzene with Acetophenone Pinacol Present, M2% Conversion Response Factor Analysis . . . . . . Data for Photolysis of 0.022 M HK in Ben— zene ate~40% Conversion (3% hours) Data for Photolysis of 0.05 M HK in Ben— zene atrw5% Conversion (15 hours) Data for Photolysis of 0.043 M HK in Hex- ane at«v7% Conversion (15 hours) Data for Photolysis of 0.05 M HK in t—Butyl- Alcohol at/“2% Conversion (1% hours) vii Page 28 28 29 29 3O 3O 31 31 51 51 52 52 Table Page 14. Data for Photolysis of 0.05 M HK in Ben- zene with 0.03 M Benzene Thiol present atsz% Conversion (2 hours) . . . . . . . . . . 53 15- Data for Photolysis of 0.01 M'HK in.Mice1— lar Solution at«“1% Conversion (1% hours) 16. Data for Photolysis of 0.05 M HK in Ben— zene with 0.0045 M Acetophenone Pina— col.at«w7% Conversion (15 hours) . . . . . . viii Figure LIST OF FIGURES Modified Jablonski Diagram UV Spectrum of 3. 3 x 10 4 M Diketone (A) in n- Heptane . . . . . . . . . UV Spectrum of 0.06 M Diketone (A) in n— Heptane . . . . . UV Spectrum of 0.037 M Diketone (B) in Benzene with UV Spectrum of 0.035 M Enoll (F) in Benzene . . . . UV Spectrum of 0.05 M Diketone (A) in Benzene Prior to Photolysis and UV Spectrum of the Result of 16 hours Photolysis at 313 nm UV Spectrum of 0.0012 M Hydroxy. Ketone in n- Heptane . Fluorescence Spectra of 0.006 M HK versus 0.20 M Acetone in n—Heptane ix Page 12 13 14 15 26 27 PART I PHOTOENOLIZATION IN ALPHA—DIKETONES INTRODUCTION Photoenolization of ketones was first detected by Yang and Rivas in 1961.1 They studied the photoreduction of benzophenone in the presence of hydrogen atom donors. They noted the formation of benzpinacol via a ketyl radical. However, if benzophenone was substituted in the ortho position with an alkyl group bearing alpha- hydrogens, benzpinacol formation was suppressed com— .pletely. Intramolecular hydrogen abstraction predom— inates in the latter. 10% © (1) Deuterium incorporation in the photoproduct led to the identification of the enol intermediate. The chemistry of alpha—diketones parallels that of monoketones. Type I cleavage is an important reac— tion in the vapor phase of many alpha—diketones. In solution, the major reactions of alpha-diketones are cyclization2 and enolization.3 Cyclization occurs in alpha—diketones which have 2 hydrogens gamma to the number—one carbonyl group. The reaction proceeds by the following mechanistic scheme: 1F 7 :5? * .1 R H R hv PI. *9 fig? Ph Ph (2) H R P}, ' I H,R é fig 1... Initial absorption of light produces an excited singlet which then intersystem crosses to the excited triplet. It is from the excited triplet state that hydrogen atom abstraction occurs to produce a 1,4-biradical. The hydrogen atom abstraction step is revertible. Therefore, the 1,4—biradical may cyclize to the hydroxycyclobutanone (or may yield ground state diketone. Type II cleavage does not occur in alpha—diketones. This failure arises from the perpendicular orientation of the C-1 p orbital relative to the C—2, C-3 sigma bond in the biradical. For cleavage to occur, the two p orbi— tals should be parallel to the carbon—carbon sigma bond being broken. Such is not the case in alpha-diketones, as shown in equation 3.5 963 Phggg + W? ‘3’ General Mechanistic Process Before any further discussion on photoenolization of alpha—diketones is presented, a brief description of the fate of the electronic excitation is necessary to attain . a better understanding of the mechanism. A modified Jablonski diagram,6 Figure 1, illustrates the fate of a molecule absorbing light. Initial excita- tion occurs Vertically, according to the Frank—Condon principle, populating one of the upper singlet states, S3. It then rapidly decays (~1012sec-l) to the first excited singlet state by internal conversion. The lowest singlet state may decay to ground state by either fluorescence, kf, or radiationless decay, ki' It may also intersystem cross to the lowest excited triplet state, kisc' For phenyl ketones, intersystem crossing is generally much faster than fluorescence or radiationless decay and usu-' ally occurs with unit efficiency.7 The excited triplet state may then proceed to ground state by either radia- tionless decay, kd, phosphorescence, kp, or energy trans- fer to a quencher molecule, kq. The triplet may also react to form a biradical intermediate, followed by pro- duct formation. 3 1 l S l 2 4 T kic E 3 S1 : V T.2 k l k. q I SO . l E . T1 I \\ : ‘53 : . qu \\\ l :}%_ kf Ia .g I l I l l I I | I l I l l I I SO V/ Figure 1. Modified Jablonski diagram. Solid arrows re- present radiative processes, corresponding to absorption or emission of light. Dashed and wavy lines represent non-radiative unimolec- ular and bimolecular processes respectively. Kinetic Expressions In order to obtain information about the paths by which an electronically excited molecule disposes of its energy, the term quantum yield must be defined. The quantum yield,d§, is simply:8 i I CbEschPI (5) where (DES represents the probability that absorbed light will produce the requisite excited state; (bR is the prob- ability that the excited state will undergo the primary photoreaction necessary for process i; P.l is the proba— bility that any metastable ground state intermediate will proceed to stable product.9 In terms of rates, the quantum yield (43°) for pro— duct formation in the absence of quencher is expressed as: (to = ——————kr (6) kr + kd where kr is the rate constant for the particular reaction and kd is the summation of first order rate constants for deactivation of the excited state undergoing reaction. In the presence of added quencher, the expression for the quantum yield becomes: (1) = k kl“ (7) r + kd + kq[Q] where kq is the rate constant for the bimolecular quen- ching process by quencher, Q, and is generally diffusion 6 controlled. Dividing equation (6) by (7) we obtain: kr + kd + kq[Q] CPO/<1) = kr + k (8) d By slight manipulation of equation (8), we arrive at the familiar Stern-Volmer expreSSion: o _ . . (p /(p — 1 + quO[Q] (9) where 7; is the reciprocal of the sum of the rates of all 'reactions undergone by the excited state and therefore represents the lifetime of the excited state in the ab- sence of quencher.lo Previous Study of Diketone Photoenolization Recent work in the area of photoenolization of alpha— diketones was reported by Wagner and Turro.ll They studied the photoreactions of phenyl alkyl diketones and discovered that enolization (Equation 10) competes with cyclization. PhggCHZR —93> Ph—g-C .moQSP commmwoo .anMom ca EC mom 9 es esoeeENe a mo.o no EOHPNNUNNNHN 0.0 m.m o.NH Hm.o em.o m5 Mrom re m-oez-m N.N m.m m.e, Ne.e sN.o N% Nae Nre N-ae-o - o.em so.a - -wN.o mflmm eve w 0 com o.m ma.o mm.o mao.o NAmg Nmovmo N m.N - NN No.0 - mfimmovommo e - . - AN.HV Am e.ovmm.o om.o eEeEEONmo m - N.H o.ma AN.st.m Ame. came. 0 Aoe.ovaw.o NAmmovroN re s AN.HV - 10.02 ANN. ev ANN.OV NreNeeMse e-m AN.NVe.H N.m Ae.Nva.s Ems. came. 0 Aos.ova.e maeN re Nre N AN.HV - Ammv ANH. ov Ammo.ov mEONmo Q-N Am.Nve.N ea.o em ANN. case. 0 Emso.ovso.o NeeN as N Amso.ov - - - - nae m-a Amo«ovmm.o - . oma Ho.o - mmo a H-emoa.flee+eev a-mmoa.»e na-21peeN-oa peogmv pmomv m esoeexam .H enema smoooonm monopoxfla Hzxad ammonm mo mCOHPQMopoponm 90m mHoPoEMEMm oapmcflx Objectives This research effort was directed at elucidating the mechanism of photoenolization. A system was chosen in which enolization was reported to be the priniciple‘ photoreaction12 in order to eliminate the effects of‘ structure-reactivity upon competing photoprocesses. The system chosen was:' (11) By altering the substituents on the phenyl rings, it was hoped that information on the mechanism would be obtained. The method chosen for monitoring the photoprocess was ultraviolet—visible spectroscopy. The diketones are yellow in color, whereas the enols are colorless. There- fore, monitoring the disappearance of the nJfl‘* absorption of the diketone in the visible region would provide the kinetic data for enol formation, providing that enoliza- tion is the only photoprocess occuring. RESULTS In order to obtain mechanistic information per- taining to photoenolization, both electron-donating and electron—withdrawing substituents on the phenyl rings were examined. The following diketones were synthesized: It .(A) Q. . . o . c, It c 0* (E) etc Also, in the course of recrystallizing the p-Cl—diketone (B) from 90% ethanol, tautomerization occurred, generating the enol (F): 10 The enol was a quite stable solid and provided useful spectroscopic information. Benzene.solutions, from 0.02 M to 0.05 M in diketone (A) were degassed and irradiated in parallel at 366 nm, relative to a benzophenone sensitized cis-piperylene actinometer. Analysis of the extent of photoreaction was conducted after 4, 12, 36, and 62 hours of irradiation. In all cases, the yellow color remained intense and the visible spectrum indicated no disappearance of diketone. It was then decided to conduct the photolysis at 313 nm, since the intensity of light was greater at this wavelength. Appropriately concentrated solutions of di- ketone (A) were prepared, degassed and irradiated versus a valerophenone actinometer. Again no disappearance of diketone occurred. Photolysis of diketone (A) was also conducted at 435 nm, to check the possibility of a wavelength de— pendent photoreaction. No photoreaction at this wave- length was detected, however. Diketone (B) gave the same results. Photolysis of diketone (B) in the presence of its enol (F) gave no change in concentration of (F). Dif- ferent solvents also had no effect upon the results, or 11 lack of, as the case may be. Preliminary photolysis of diketone (A) in benzene indicated an apparent photoreaction. After several days irradiation at 313 nm, the yellow color faded. UV [analysis of the product showed disappearance of the shoulder of the long wavelength nifl‘* band. This was believed to be the result of photoenolization and no further attempt was made to analyze the-photoproduct. After photolysis, polymeric material was found coated to the inner walls of the tube. However, this was attributed to the polymerization of benzene. If enolization had indeed occurred, the inefficiency of the reaction would preclude the use of this system in a mechanistic study. 12 3.0- 200‘q A 1.0-4 04 I I V 1 T K T 200 300 Mm) 400 500 Figure 2. UV spectrum of 3.3 x 10—4 M diketone (A) in n—heptane. . i llll loo-q, 13 Figure 3. 400 Adm) 550 UV spectrum of 0.06 M diketone (A) in n-heptane. 600 14 3~0‘ 2 . 0" A l a 0d 0__ ‘1 v ‘I I I ' I 400 Mm) 500 600 Figure 4. Solid line represents UV spectrum of 0.037 M diketone (B) in benzene and dashed line represents UV spectrum of 0.035 M enol (F) in benzene. 15 3.0~ \ \ \ \ \ \ 2.04 \ \ \ \ \ \ A \ \ \ \ \ \ \ \ .100“ \ \ \ \ \ \ \ \ \ \ \ '04 ‘ ' ubo . 5bo 660 AMINO Figure 5. Solid line represents UV spectrum of 0.05 M diketone (A) in benzene prior to photolysis: dashed line shows UV spectrum of the result of 16 hours photolysis at 313 nm. 16 Discussion A postulated mechanism for photoenolization involves a 1,4—hydrogen transfer by the excited triplet to yield a relatively stable oxyallyl system. Intersystem crossing of the triplet to the ground state surface, followed by a proton shift.to either end of its enolate moiety would yield product enol and ground state diketone. This 13 mechanism is illustrated below: * 1 up 9/ng Ph (OH ‘ R p- L— (12) V$\\\\\\ F3h / Substitution of the R group by a phenyl group might have a dramatic effect on the rate of deactivation of the triplet ketoue. Studies of beta—phenyl substituted dial- kyl ketones reveal low photoreactivities for these sys- tems.lLL Beta—phenyl substitution in butyrophenone decreases its triplet lifetime in benzene by two orders of magnitude. An explanation for the apparent lack of photoreactivity may be a rapid irreversible, intramolecular 1? quenching process by the beta-phenyl ring competing with enolization. A charge transfer interaction would occur resulting in exciplex formation. The metastable product [would have to revert to ground state diketone with near 100% efficiency.l5 l6 Enlightement Although the results of this profect were not revel- atory with respect to the mechanism of photoenolization, the alpha-diketone (A) provided a route for the prepar- ation of a related compound, whose photochemistry was also of interest. Addition of methyl Grignard to the diketone'gives an alpha-hydroxy ketone, whose Type I photochemistry could reveal information on the extent of disproportionation versus coupling in photochemically generated radicals. PART II DISPROPORTIONATION VERSUS COUPLING‘ IN PHOTOCHEMICALLY GENERATED RADICALS INTRODUCTION The purpose of this research was to study the extent of two competing processes of photogenerated radicals, disproportionation and coupling. The reported ineffi- 1? ciency of acetophenone photoreduction by toluene stim- ulated an effort to determine the amount of in—cage dis— proportionation between acetophenone ketyl radicals and benzyl radicals. A system was chosen, which upon photo— chemical excitation, could produce both radicals. The molecule studied was l,3-diphenyl—3éhydroxybutan-2-one: (l4) - The molecule is a slight modification of dibenzyl ketone, whose photoreactions have been thoroughly investigated and to which parallel may be drawn.18 Norrish Type I Cleavage The formation of radicals from the photolysis of ketones is called Norrish type I cleavage. Homolysis of the 1,2 bond results in the formation of an acyl and 'alkyl radical pair in acyclic aliphatic ketones. Type I 18 19 or alpha cleavage also occurs in other classes of com- pounds, such as acyl halides, acids, and aldehydes, to name a few. Secondary reactions depend upon structural features of the radicals. Decarbonylation, dispropor- tionation, coupling and radical substitution are avail— l9 able paths, as shown in the scheme below: l 1 b0, ' + . . free ¢———' ' (1' '——+> radicals b h j —-——> >]. + C0 (15) M -——> WNW-7% r Alpha cleavage processes in solution are of minor importance if the.excited state can undergo other pro- cesses, such as Norrish type 2 reactions. Decarbonylation often occurs during alpha cleavage reactions in the gas phase, but only when the alkyl radical is very stable does it occur in solution.20 Background Decarbonylation is found to be very efficient when a t—butyl or benzyl radical is produced. Upon irradiation of dibenzylketone, a statistical ratio.of coupling products is found in agreement with the intermediacy of completely 20 free radicals.21 PhCHZ-C0;CH2Ph PhCHZCHZPh + ——Qi——> PhCHZCHPhZ 93%, 1:2:1 (16) PhZCH—CO-CHZPh PhZCHCHPhZ Engel studied the photoChemistry of dibenzyl ketone, in an effort to determine the nature of the excited state. The decarbonylation proceeds in 100% yield With a quantum efficiency of 0.7 at 313 nm. Quenching studies were per- formed with two dienes. He found that 1,3-cyclohexadiene decreases the efficiency of C0 formation more than it in— hibits ketone disappearance. This effect was attributed to capture of the short—lived phenacetyl radicals by diene. The fluorescence quantum yield was determined to be 0.04, with a singlet lifetime of 3.6 nsec. Since 1,3- pentadiene inhibited dibenzyl ketone disappearance much more than it quenched its fluorescence, decarbonylation was thought to proceed via the excited triplet state, whose lifetime is 10—10 sec. Robbins and Eastman studied photoreactions of substituted dibenzyl ketones and found that the p-dicyano ketone fails to decarbonylate.23 This failure arises from internal triplet quenching of the carbonyl by the lower triplet energy cyanobenzene moiety. That decarbonylation occurs from the triplet state has also been verified by CIDNP studies.24 The decarbonylation reaction was shown to occur in a 22 21 stepwise fashion, proceeding through a short-lived phen- acetyl radical. Tri—n—butyltinhydride was ineffective in reducing the radical. Therefore, 2,2,6,6-tetramethyl— piperidine—l—oxyl radical was employed. Both benzyl and phenacetyl radicals were trapped giving a 3:2 ratio of benzyl ether to phenyl acetate. PhCH 80H Ph W \ PhCH - + '8CH Ph 2 2 / 2 2 diff ,coupling , , PhCHZCHZPh ~< -CO PhCH2 + 8CH2Ph (l7) trapping N—OCHZPh + ( -JBCH2Ph 3 : 2 The formation of phenylacetate indicates that photodecar- bonylation proceeds via a two-step mechanism involving the formation of the phenacetyl radical outside of a solvent cage. The rate of decarbonylation was determined to be of the order of 10—8 sec.25 Turro has recently reported the effect of irradiation of dibenzyl ketone in detergent solution.26 Above the critical micelle concentration, detergent molecules aggre- gate to form globular micelles, having a hydrocarbon in— terior and a hydrophilic exterior. Control of the ketone/detergent ratio allows the photolysis of a single 22 molecule within a micelle. Photolysis of an unsymmetrical dibenzyl ketone, ACOB, resulted in formation of in cage coupling products, A—B, exclusive of out of cage coupling products, AA and BB. hQ PhCH28CH2Ar “r“——9 PhCHZCHZPh + PhCHZCHZAr + ArCHZCHZAr ACOB AA AB BB (18) Homogeneous 25% 50% 25% Detergent Solution 0% 100% 0% Photoreduction of Acetophenone The photoreduction of acetophenone in solution pro- ceeds by intermolecular hydrogen abstraction from a donor molecule by the excited acetophenone triplet. This re- sults in the formation of hydrogen donor radicals and ketyl radicals of acetophenone. These radicals may then undergo characteristic reactions depending on the condi- vtions employed, as shown below: I ! 0H 9 . PhCCH + DH ¢______ PhQCH3 + D° 3 8H OHOH 2Ph CH ——-> Ph—C— —Ph ' 3 CH H 3 3 (l9) 2D° ——-——4> D—D q? H PNCH3 + D' -—-—-€> Ph—§-D H3 23 A study of the photoreduction of acetophenone in toluene was reported by Wagner and Leavitt.27 The effi— ciency of the reaction is governed by the formation of products from radical coupling. The kinetics of the reaction follow the equation below: 4P — k \ (m) 560 '6'00 Figure 7. Fluorescence spectra. Solid line repre- sents 0.006 M HK and dashed line repre-O sents 0.20 M acetone in n-heptane at 25 C. 28 Table 2. Photolysis of 0.022 M HK in Benzene, -40% Conversion. Phqtoproduct Quantum Yield Tol 0.013 PAA 0.060 AP : 0.19 BB 0.056 -Alc 0.045 Pin 0 Table 3. Photolysis of 0.05 M HR in Benzene, -5% Conversion. Photoproduct Quantum Yield ' Tel 0 PAA 0.044 AP 0.28 .133 0.052 Alc 0.030 Pin 0 29 .Table 4. Photolysis of 0.043 M HK in Hexane, “7% Conversion. 'Photoproduct ’ Quantum Yield T01 '0.012 PAA 0.047 AP 0.34 BB . 0.079 Alc . 0.01 Pin 0 Table 5. Photolysis of 0.05 M HK in t—Butyl Alcohol, -2% Conversion. Photoproduct Quantum Yield T01 ,0. PAA 0.025 AP 0.10 , BB1 0.009 Alc 0.009 Pin 0 30 Table 6. Photolysis of 0.05 M HK in Benzene with Benzene Thiol Present,-M2% Conversion. Photoproduct Quantum Yield T01 0.13 . PAA 0.10 AP 0.30 BB 0 .:A1c 0.018 Pin 0 aValues obtained from 2 different concentrations of benzene thiol, 0.026 M and 0.0321 M. Table 7. Photolysis of 0.01 M HK in a Micellar Solution, Micelle = Hexadecyltrimethylammonium Chloride ”1% Conversion. Photoproduct Quantum Yield fiiDTC1] = 0.5 Na 0.3 Mb T01 . 0 - .022 PAA .02 .11 AP .056 .21 BB Alc Pin 0 aOrganic material extracted with ether after photolysis. bDirect on—column injecti0n of aqueous photolysis mixture. 31 Table 8. Photolysis of 0.05 M HK in Benzene with . Acetophenone Pinacola Present,-7% Conversion. Photoproduct Quantum Yield T01 0 PAA 0.043 AP 0.28 BB 0.041 Alc 0.019 Pin No Disappearance aPin = 0.0045 M, before and after photolysis. Table 9. Response Factor Analysis. Photoproduct . Abbreviation Response Factor Toluene . T01 Tel/C7a = 1.12 ‘ Tel/0.0.b = 1.22 Phenylacetaldehyde PAA PAA/Cl9 = 3. Acetophenone AP AP/C19 ' = 3. Bibenzyl BB BB/Cl9 = 1.56 1,2—Diphenyl-2-propanol Alc Ale/0l9 = 1.80 Acetophenone pinacol Pin Pin/Cl9 = 1.62 Hydroxy ketone HK HK/Cl9 = 1.5 c AP /013 1.1 aCycloheptane. bCyclooctane. CAcetophenone produced from valerophenone. 32 Discussion The expected results of the photolysis of the hy— droxy ketone would have yielded a somewhat statistical ratio of coupling products. If decarbonylation were extremely efficient, the following scheme would repre- sent the course of the reaction: H E Phjb/Z/Ph 23 \7 Ph ' CH + -CH Ph CH3 ‘ ' ‘ 3 2 0H PthH + CH Ph + Ph—l—CH Ph < 1“ cage 3 3 CH 2 3 (22) 0H 0H ,diffusion PhCHZCHZ Ph + Ph—l—CH2 Ph + PhEE—C-lH—Ph coupling 3 3 / diffusion Ph80H3 + CHBPh \ disproportionation Out of cage coupling could have been eliminated with benzene thiol present to scavenge the free radicals. Elimination of out of cage disproportionations could haVe been affected by photolysis within a micelle. This would have left only in cage reactions and the extent of the two in cage processes would have been determined from product analysis. 33 From the tables of quantum yield results, it is seen that decarbonylation is not as efficient as in dibenzyl ketone. The multiplicity of the excited state is the same, an n-TT* triplet, in both cases, as determined by the CIDNP study. Their quantum yields of fluorescence are also verymclose. However, the amount of phenylacet- aldehyde product formed complicates the original goal of this project. Upon examining the ratio of products arising from- the acetophenOne side of the molecule versus the phen— acetyl side of the molecule, it is seen that the products do not add up correctly. The products from the former outweigh the production of products from the latter. This problem is extremely difficult to confront. Another complication arises upon examining the ratio of out of cage coupling products. Acetophenone pinacol formation is completely suppressed. It was thought that perhaps the pinacol formed was dissociating into some acetophenone. However, upon photolysis of the hydroxy ketone with pinacol present, all is accounted for after photolysis. The crossed alcohol product would have been thought to occur in higher yields also, being both an in and out of cage reaction product. From the radical scav— enging experiments it appears that the crossed alcohol product is solely an in cage reaction product, or that very little arises from out of cage combinations. This lack of out of cage coupling would explain the absence of 34 pinacol. The micelle experiments show that disproportionation of acetophenone with phenacetyl radicals occurs to a large extent. The experiment is not as quantitative since the micelle environment inhibits quantum yields. Also, analysis is very difficult in that injection of the aqueous mixture onto the go causes horendous peaks throughout the trace and only the ratios are significant. Attempting to extract the organic photoproducts is also difficult in view of the concentrations employed. Conclusions The results of the various photolyses show that the efficiency of hydroxy ketone photolysis is much lower than that of dibenzyl ketone. Fast recombination of the initially formed radicals would account for the low effi- ciency. Phenacetyl radicals which do not recombine are rapidly reduced by the acetophenone ketyl radicals before they can'escape the solvent cage and undergo subsequent decarbonylation. This hinders the use of this system for studying acetophenone-benzyl radical cage reactions. The larger amount of product formation from the ace: tophenone portion of the molecule remains a puzzle. Ace— tophenone oxidation is extremely efficient and could occur from slight traces of impurity, for example, metal. How- ever, the unaccountability of the benzyl radicals compli— cates the analysis. Phenylacetaldehyde production is 35 consistent throughout except in the case of added benzene thiol, where increased production occurs. The benzene thiol might be interfering with the in-cage reaction. Selection of an alternate compound is necessary to determine the fate of acetophenone ketyl and benzyl radicals. A molecule which undergoes decarbonylation very efficiently might be the 1,1-dimethy1 hydroxy ketone. Photolysis of this molecule would result in ‘formation of acetophenone ketyl and cumyl radicals. H CH \ 3 POHh— - -H§ -3h ——5 Ph/C\CH + ‘C‘Ph (23) 0 H ’ 3 / 3 3 CH3 Decarbonylation to give the tertiary radical in this com— pound should be highly efficient. Another possible sys— tem is benzyl—2—hydroxy-2-pheny1propanoate. 0H 1.0 , PI’IPIZ-g- OCH ZPh 76—? Ph/&\CH + CHZPh (214') C 3 3 Here loss of C02 would leave the radicals of interest. EXPERIMENTAL Preparation and Purification Solvents and Additives Benzene: (Mallinckrodt) was purified by stirring ~over concentrated sulfuric acid for several days. The benzene was washed with additional sulfuric acid until it remained clear, followed by neutralization with sat- urated aqueous sodium bicarbonate and finally with-sat- urated aqueous sodium chloride. The benzene was dried over anhydrous magnesium sulfate and distilled from phos- phorous pentoxide, collecting the middle 60%. Acetonitrile: (Fisher Scientific) was distilled from potassium permanganate and sodium carbonate. The final cut was retained. Carbon Tetrachloride: (Mallinckrodt) was purified by stirring over hot, concentrated alcoholic potassium hydroxide. This was followed by washing several times with water, drying over calcium chloride and distilling from phosphorous pentoxide. The middle 60% was retained. Methanol: (Fisher Scientific or Mallinckrodt) was distilled from magnesium turnings. The middle fraction was collected. 36 37 Hexane: (Mallinckrodt) was purified in the same manner as benzene. t-Butyl Alcohol: (Fisher Scientific) was purified by distillation from magnesium turnings. collecting the middle 60%. fl§I§£= distilled water was passed through three Sargent-Welch mixed—bed ion—exchange columns and then distilled again prior to use as a photolysis solvent. -- Thiophenol: (Aldrich) was used as received. Hexadecyltrimethylammonium Chloride: (Eastman) was used as received. Internal Standards Cycloheptane: (Aldrich) was purified in a manner analogous to that of benzene. Cyclooctane: (Aldrich) was purified in a manner analogous to that of benzene. Tridecane: (Aldrich) was purified by distillation, collecting the middle fraction. Nonadecane: (Chemical Samples) was purified by recry- stallization from petroleum—ether. Diketones Two methods were used to prepare the diketones. Method A:32 (General Procedure) Benzaldehyde, or the para—substituted benzaldehyde, was dripped into 10% aqueous NaOH and ethanol. Acetophenone, or the para- substituted compound, was then dripped into the solution 38 ./ maintained at 250 C. After several hours of stirring, the thick mixture wasplaced in a freezer over night. The product was then collected and rinsed with ice water until a neutral pH was obtained, and finally with ice- cold ethanol. The benzalacetophenone obtained was dis— solved in ethanol, and to it was added a 30% hydrogen peroxide solution. Into this solution was dripped 5%. aqueous NaOH. The mixture was cooled to 00 C to preci— pitate the epoxide, which was then collected and rinsed with ice-cold ethanol. The epoxyketone was then placed in an equal volume of glacial acetic acid while passing dry HCl gas through the stirring mixture. The solution was saturated with HCl at 00 C and then placed in a freezer overnight. Distillation under aspirator pressure removed the acetic acid and distillation under high vacuum afforded the diketone in good yields CV60%). Final puri— _fication was achieved by recrystallization from petroleum ether. ' Method B:33 (General Procedure) Phenethyl bromide in ether was dripped into magnesium turnings also in ether in order to prepare the Grignard reagent. Benzonitrile was then added to the Grignard, followed by acid hydrolysis and ether extraction. Rotory evaporation afforded the 1,3—diphenyl-1-propanone. The ketone was then dissolved in glacial acetic acid and liquid bromine was dripped into the solution, which was heated to 500 C to decolorize the bromine. This solution was poured into ice—cold saturated 39 . aqueous NaCl and extracted with ether. Removal of the solvent left sufficiently pure alpha-bromoketone. This was then dissolved in acetonitrile to which was added AgNo3 in acetonitrile and allowed to stir in the dark for 2 days. The AgBr was then filtered and rinsed with ether. The ether washings and acetonitrile were combined and eVaporated under reduced pressure. The crude product was redissolved in ether, washed with water and dried over MgSOu. The ether was evaporated and the nitratoketone was dissolved in DMSO. To the mixture was added a sus- pension of sodium acetate in DMSO. This was stirred at 250 C for ninety minutes and then poured into ice-cold saturated NaCl. Ether extraction, NaHCO3 washing, and evaporation of the solvent yielded the crude diketone. Distillation under high vacuum, followed by recrystalli- zation from petroleum ether, afforded the pure alpha— _diketones. Characterization 1,3—Diphenyl-l,2-propanedione: mp 350 C: IR(C014) 3000, 1710, 1675 cm’1 ; NMR(CDC13) 4.09(S,2H), 7.07(S,5H), 7.6-8.0(dd,2H), 7.3(m,3H); m/e 224(M+). l—Phenyl-3—(p-chlorophenyl)—1,2-propanedione: mp 680 C; IR(CC14) 3000, 1710, 1675 cm—1 ; NMR(CDC13) 4.09(S,2H), 7.07(s,4H), 7.6-8.0(dd,2H), 7.3(m,3H); m/e 258(M+). 1-Phenyl—3—(p—methoxyphenyl)~1,2—propanedione: mp 720 c; IR(C014) 3000, 1710, 1675. 1250 cm—l;NMR(CDC13) 40 3:67(S:3H)3 “009(872H)! 6°7‘7°5(m:7H)9 7-6-8-O(dd92H)3 m/e 254(M+). ' l—(p-Chlorophenyl)—3-phenyl—l,2-propanedione: bp 1850 C Pvzmm); IR(neat) 3000, 1710, 1675 cm‘1 : NMR(CD013) 4.09(s,2H), 7.07(s,4H), 7.6—8.0(dd,2H), 7.3(m,3H): m/e 258(M+). l-(p-Methoxyphenyl)-3-pheny1—l,2—propanedione: 'bp 2350 c tv2mm); IR(neat) 3000, 1710, 1675, 1250 cm’l; NMR(CDC13) 3.67(s,3H), 4.09(s,2H), 7.2(s,5H), 6.7-6.9 (dd,2H), 7.8—8.0(dd,2H); m/e 254(M+). l—Phenyl-3—(p—chlorophenyl)—2—hydroxy—l-propen-3-one: 1 mp 950 C: IR(CC14) 1700, 1630, 1250 cm- ; NMR(CD013) 6.24(s,1H), 7.1-7.8(m,9H); m/e 258(M+). Hydroxy Ketone 1,3-Dipheny1-l,2—propanedione is added to methyl 34 magnesium iodide in a 1:2 mole ratio. This mixture is allowed to stir for several hours after which it is poured into concentrated H280“ in ice to hydrolyse the magnesium salt. The solution was extracted with ether, washed with saturated aqueous NaHCOB, saturated aqueous NaCl and dried over anhydrous MgSOu. Removal of the solvent affords the crude hydroxy ketone. The crude product was then dis— tilled under high vacuum to give the hydroxy ketone de— void of all starting material. The compound was then chromatographed through alumina which enabled crystalli— zation. The hydroxy ketone was further purified by 41 several recrystallizations from ether—petroleum ether, achieving'V99% purity: mp 54—560 C: NMR(CDC13) l.9(s,3H), 3.6(s,2H), 6.9-7.4(m,10H); IR(0014) 3460 cm‘1 2900-3050 cm'l, 1725 cm'l; m/e 222(Mt18). General Techniques Preparation of Samples All photochemical glassware, including class "A" pipets and class "A" volumetrics, was heated for two days in Alconox, followed by heating for several days in-dis- tilled water. After this time, the glassware was dried in a 1500 oven for one day. Photolysis tubes (13 x 100 mm pyrex culture tubes) were cleaned analogously, and the necks were elongated by heating over a gas-oxygen flame. Samples weighed directly into the volumetric flask were diluted to the line with the appropriate solvent. A 5 cc syringe fitted with a 6" needle was used to transfer 3.0 ml of the solution into the test tube with the constricted neck. Degassing Procedure After the tubes were filled with the appropriate solutions, they were attached to a vacuum line with one- hole rubber stoppers (size 00). The tubes were then sub- merged in a liquid nitrogen bath and allowed to freeze slowly. After the tubes were frozen, the stopcocks were opened and the tubes were pumped on for fifteen minutes at 10-3 Torr. The stopcocks were then closed allowing 42 the tubes to thaw completely, thus completing a cycle. this freeze—pump—thaw cycle was performed three times. After completion of the third cycle, the tubes were again frozen, opened to the vacuum line and pumped on for a few minutes. A gas—oxygen torch was then used to remove the tubes from the line, by easily melting and sealing the constricted portion of the tube. Irradiation Procedure The degassed tubes were allowed to thaw and then I placed in a rotating merry—go—round apparatus which was immersed in a water bath maintained at 250. The tubes were irradiated in parallel to ensure that samples re- ceived the same amount of light. The light source was a 450 watt (Hanovia) medium—pressure mercury lamp, cooled by a quartz or pyrex immersion well. A filter solution, 0.0002 M potassium chromate in a 1% aqueous potassium‘ carbonate solution, was used to isolate the 313 nm band of light. The 366 nm region was isolated by using a set of Corning No. 7-83 filters. Sample Analysis Analyses of photoproducts were conducted on a Varian Aerograph 1400 gas chromatograph equipped with a flame ionization detector. Relative peak areas were determined using a Leeds and Northrup Speedomax—H recorder attached to an Infotronics Automatic Digital Integrator. Sample 'injections were made with a Hamilton 1.0 microliter syringe / onto one of two columns. 43 -Column #1: 8' x 1/8" aluminum column containing 3% QF—l on 60/80 mesh chromosorb G. —Column #2: 6' x 1/8" aluminum column containing 5% SE-30 on 60/80 mesh chromosorb W. Response Factors Concentrations of photoproducts were determined by comparison to internal standards, whose concentrations were known. Standards were chosen so as not to overlap with product peaks and also to come off in the immediate vicinity of product peaks. Correction factors were deter— mined to correlate the molar response of the detector to the different products. The response factor was used to determine the molar concentration of product by the fol- ‘10wing equation: Prod. Area [Prod{] = RF°[Int. Std]' Int. Std. Area (25) The various response factors are listed in Table 9. Actinometpy and Quantum Yields In order to calculate the quantum yield of the reac— tion, the amount'of light that was absorbed by the system had to be determined. Actinometer tubes, containing 0.10 M valerophenone and a known concentration of tridecane, were irradiated in parallel with the sample tubes. The known quantum yield for acetophenone formation from valerophenone iS 0-33-35 Analysis for acetophenone was performed on column #1. The quantum yield for product formation was, 44 therefore, determined by the following expression: . P d 9...; He . where [Acet]val refers to the molar concentration of acetophenone produced from valerophenone. Spectra Proton magnetic resonance (nmr) spectra were recorded on a Varian T—60 spectrometer in CDCl3 or CDBCN solutions relative to TMS as an internal standard. Infrared spectra were taken on a Perkin—Elmer 237b grating spectrometer as thin films or in CClu solutions using polystyrene (1601 cm—1) calibration. The mass spectra were run on.a Hitachi-Perkin— Elmer RMU-6 mass spectrometer. Ultraviolet spectra were measured on a Carey 17 spectrophotometer. A Beckman DUR spectrophotometer equipped with a Gilford model 220 linear absorbance converter was used for routine UV work. Fluor- escence spectra were measured on an Aminco-Bowman model #4i8202 spectrophotofluorometer equipped with a Perkin- [Elmer recorder. Chemically Induced Dynamic Nuclear Polar- ization (CIDNP) spectra were measured by degassing ben— zene-d6 and acetonitrile-d3 solutions of ketone and trans- ferring them to nmr tubes in a glove-bag under argon at- mosphere. A quartz light—pipe was inserted and sealed to the tube. Samples were irradiated in a Varian model A56/60D nmr spectrophotometer by focusing pyrex and water filtered light from a 1000-W Hanovia high pressure Xenon—Mercury lamp onto the light—pipe. Proton nmr spectra were recorded 45 before, during, and after irradiation. LIST OF REFERENCES 10. ll. 12. LIST OF REFERENCES N. C. Yang and C. Rivas, J. Am. Chem. Soc., 83, 2213 (1961). (a) W. H. Urry and D. J. Trecker, ibid., 84, 713 (1962). - ' (b) W. H. Urry, D. J. Trecker, and D. A. Winey, Tetrahedron Letters, 609 (1962). P. J. Wagner, R. G. Zepp, K. C. Liu, M. Thomas, T. J. Lee, and N. J. Turro, J. Am. Chem. Soc., 8, 8125 (1976)- P. J. Wagner, P. A. Kelso, and R. G. Zepp, ibid., 94, 7483 (1972)- P. J. Wagner, P. A. Kelso, A. E. Kemppainen, J. M. McGrath, H. N. Schott, and R. G. Zepp, ibid., 94, 7506 (1972)- J. G. Calvert and J. N. Pitts, Jr., "Photochemistry," John Wiley and Sons, Inc., New York, 1966, p. 285. A. A. Lamola and G. S. Hammond, J. Chem. Phys., 43,- 2129,(1965). N. J. Turro, ”Molecular Photochemistry," W. A. Benjamin, Inc., Massachusetts, 1974, p..6. P. J. Wagner, "Creation and Detection of the Excited State," Vol. I, Marcel Dekker, New York, 1971, p. 175. J. A. Barltrop and J. D. Coyle, "Excited States in Organic Chemistry," John Wiley and Sons, London, 1975. p- 521- P. J. Wagner, R. G. Zepp, K. C. Liu, M. Thomas, T. J. Lee, and N. J. Turro, J. Am. Chem. Soc., 98, 8125 (1976). P. J. Wagner, R. G. Zepp, K. C. Liu, M. Thomas, T. J. Lee, and N. J. Turro, ibid., 8, 8125 (1976). 46 13. 14. 15. 16? 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 47 P. J. Wagner, R. G. Zepp, K. C. Liu, M. Thomas, T. J. Lee, and N. J. Turro, ibid., 8, 8125 (1976). (a) F. R. Stermitz, D. E. Nicodem, J. P. Muralidharan, and C. M. O'Donnell, M01. Photochem., 2, 87 (1970)- (b) D. G. Whitten and W. E. Punch, ibid., 2, 77 (1970)- P. J. Wagner, P. A. Kelso, and A. E. Kemppainen, ibid., 2, 81 (1970). Special thanks goes to Allen Puchalski for the enlightening discussion regarding the title of this section. P. J. Wagner and R. A. Leavitt, J. Am. Chem..Soc., 22. 5806 (1970)- P. s. Engel, ibid., 92, 6074 (1970). P. J. Wagner, Topics in Current Chemistry, fig, 1 (1976)- J. A. Barltrop and J. D. Coyle, "Excited States in Organic Chemistry," John Wiley and Sons, London, 1975, p. 180. G. Quinkert, K. Opitz, W. W. Wiersdorff, and J. Weinlich, Tetrahedron Letters, 1863 (1963). P. S. Engel, J. Am. Chem. Soc., 92, 6074 (1970). W. K. Robbins and R. H. Eastman, ibid., 92, 6076. (1970)- M. Lehnig, Chemical Physics, §, 419 (1975). 1W. K. Robbins and R. H. Eastman, J. Am. Chem. Soc., .22. 6077 (1970). N. J. Turro and w. R. Cherry, ibid., 100, 7431 (1978). P. J. Wagner and R. A. Leavitt, ibid., 92, 5806 (1970). P. J. Wagner, I. E. Kochevar, and A. E. Kemppainen, ibid., 94, 7489 (1972). R. F. Borkman and D. R. Kearns, J. Chem. Phys., 44, 945 (1966)- . . 30. 31. 32. 33- 34. 35. 48 (a) M. Tomkiewicz and M. P. Klein, Rev. Scientific Instr., 43, 1206 (1972). (b) The author thanks Dr. Cynthia Chiu for conducting all CIDNP experiments. ‘ R. Kaptein, Chem. Comm., 732 (1971). E. P. Kohler and R. P. Barnes, J. Am. Chem. Soc., 5Q, 211 (1934). 8, 865 (1966). N. Kornblum and H. W. Frazier, ibid., E. P. Kohler and N. Weiner, ibid., 56, 434 (1934). P. J. Wagner, I. E. Kochevar, and A. E..Kemppainen, ibid., 94, 7489 (1972). APPENDIX This section contains the raw experimental data, such as internal standard concentrations, product to standard ratios and analytical conditions employed in the analyses. The arrangement of the tables is as follows: the particular photolysis is described in the title, which includes the percent conversion and irradiation time. Below the title appear the concentrations of the parti— cular standards employed; column 1 lists the photopro- ducts; column 2 lists the gc columns used for the analy— ses; column 3 shows the temperatures at which the analy— ses were made; column 4 lists the concentrations of photo— '7 products; in column 5 is tabulated the ratios of photo- product to standard. All photolyses were conducted at 313 nm. Toluene was analysed with respect to either cyclo- heptane or cyplooctane. The actinometer in all cases was valerophenone. Acetophenone from valerophenone was analysed with respect to tridecane in all cases. The re— maining photoproducts were analysed with respect to nona- decane.' ' Abbreviations used in this section.are: C = 7 49 5O cycloheptane; C-O. = cyclooctane; Cl9 = nonadecane; C13 : tridecane; T01 = toluene; PAA = phenylacetaldehyde; AP — acetophenone; BB = bibenzyl; Alc = 1,2-diphenyl—2-pro— panol; Act = actinometer, and represents acetophenone pro- duced from valerophenone. 51 Table 10. Data for Photolysis of 0.022 M HK in Benzene atl~40% Conversion (3% hours). 0.00468 M C7, 0.00425 M 019, 0.0271 M C 13 Photoproduct Column # Temp. 0C [Prod],x103 M Prod/Std '/ Tol 1 35 3-09 0-59 PAA 2 150 1.38 0.11 AP 2 150 5.79 0.46 BB 2 150 1.33 0.20 AlC 2 150 1.07 0.14 Act 2 140 7.83 0.27 Table 11. Data for Photolysis of 0.05 M HK in Benzene ‘ at-5% Conversion (1% hours). 0.00392 M 0.0., 0.00242 M C 0.0282 M c 19’ l3 Photoproduct Column # Temp. 0C [Prod],x103 M Prod/Std T01 2 35 0 0 PAA 2 150 0.294 0.041 AP 2 150 1.65 0.23 BB 2 150 0.313 0.083 .Alc 2 150 0.205 0.047 Act 2 140 2.11 0.070 52 Table 12. Data for Photolysis of 0.043 M HK in Hexane atw7% Conversion (1% hours). 0.0104 M C 0.0197 M C 7, 0.00685 M C19’ 13 Photoproduct Column # Temp. 0C [Prod],x103 M Prod/Std Tol 1 35 0.0733 0.0063 PAA 2 150 0.288 0.014 AP 2 150 2.26 0.11 BB 2 150 0.470 0.044 A10 2 150 0.059 0.0048 Act 2 140 1.96 0.093 Table 13. Data for Photolysis of 0.05 M HK in t-Butyl ' Alcohol atvv2% Conversion (1% hours). 0.0262 M C 0.00339 M C.O., 0.00242 M 019, 13 Photoproduct Column # Temp. 0C [Prod],x103 M Prod/Std Tel 2 35 0 0 PAA 2 150 0.160 0.022 AP 2 150 1.16 0.16 BB 2 150 0.208 0.055 Alc 2 150 0.030 0.0069 Act 2 140 ' 1.25 0.044 Table 14. 53 Data for Photolysis of 0.05 M HK in Benzene with 0.03 M Benzene Thiol Present at'*2% Conversion (2 hours). 0.00339 M C.O., 0.00190 M Cl 9’ 0.0209 M C 13 Photoproduct Column # Temp. 0C [Prod],xl'03 M Prod/Std Tel 2 35 1.08 0.26 PAA 2 150 1.03 0.18 AP ' 2 150 3.42 0.60 BB 2 150 0 0 Alc 2 150 0.109 0.032 Act 2 140 3.45 0.15 Table 15. Data for Photolysis of 0.01 M HK in Micellar Solution at/V1% Conversion (1% hours). 0.00339 M C.O., 0.00238 M C 19’ 0.0234 M C 13 Photoproduct Column # Temp. 0C [Prod],x103 M Prod/Std Tol PAA AP BB Alc Act 35 150 150 150 150 140 NNNNNN 0.014 0.0435 0.0928 0 0 1.38 0.0034 0.0061 0.013 0 0 0.055 Table 16. 54 Data for Photolysis of 0.05 M HK in Benzene with 0.0045 M Acetophenone Pinacol at:~7% Conversion (1% hours). 0.0212 M C ' 0.00650 M 0.0., 0.00272 M 019, 13 Photoproduct Column # Temp. 0C [Prod],x103 M Prod/Std 'Tol -PAA AP BB Alc Act 2 35 0 0 2 150 0.277 0.034 2 150 1.88 0.23 2 150 0.259 0.061 2 150 0.117 0.024 2 140 2.09 0.092 MICHIGAN STATE UNIV. LIBRARIES lllllWIllllllHIHWI”llIllIIHIHUHNIHHHIHWI 3129310fl6339®2