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I

KINGS OF THE HYDROLYSIS 0F
DIPHENYLDICHLOROSILANE

Thesis for the Degree of MS
MCHIGAN STATE UNIVERSFTY
ALAN R. BOND ’

1973

 

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ABSTRACT

KINETICS OF THE HYDROLYSIS OF
DIPHENYLDICHLOROSILANE
by

Alan R. Bond

The rate constants for the hydrolysis of diphenyl-
dichlorosilane were determined from concentration data
for Ph281012 and Phasi(OH)2 in a tubular reactor of various
lengths.‘ The data were analyzed assuming plug flow in
the reactor system and that the reactions proceed in a
stepwise, irreversible manner. The rate constants were
determined based on a steady—state approximation for the
intermediate PhZSi(OH).

The second order rate constants for the hydrolysis

of the first and second chlorine atoms were 2.1 and 20
1 1

1. mole“ sec , respectively at 27°C.

KINETICS OF THE HYDROLYSIS OF

DIPHENYLDICHLOROSILANE

By

,,.\2

:4”
Alan R? Bond

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
Department of Chemistry

1973

4/1

&) ‘39 ACKNOWLEDGMENTS

I am indebted to Dow Corning for both time spent
on this work and the materials for the experiment. My
thanks are extended to Dr. Hawley (MSU) for the original
motivation, Dr. Shinohara (Dow Corning) for consultation,
and Dr. Bond (my father) for proof reading. My gratitude is
given to Jodi, Daniel and Lynn (my family) for their

patience.

ii

TABLE OF CONTENTS

Page
I. INTRODUCTION . . . . . . . . . . . . . . 1
II. PREVIOUS WORK . . . . . . . . . . . . . A

III. EXPERIMENTAL . . . . . . . . . . . . . . 8
A. Reagents . . . . . . . . . . . . . . 8

B. Reactor . . . . . . . . . . . . . . 8

C. Apparatus . . . . . . . . . . . . . 12

IV. EXPERIMENTAL CONDITIONS . . . . . . . . 16
V. INTERPRETATION OF IR SPECTRA . . . . . . 18
VI. CALCULATION OF CONCENTRATIONS . . . . . 20
VII. MODEL OF PhasiClz HYDROLYSIS . . . . . . 28
VIII. EXAMPLE . . . . . . . . . . . . . . . . 38
IX. RESULTS AND CONCLUSIONS . . . . . . . . NO

X. LIST OF REFERENCES . . . . . . . . . . . “1

iii

LIST OF TABLES

Experimental Concentration . . .

Absorption Coefficients and Band
Maxima . . . . . . . . . . . . .

Steady State Calculations . . .

Rate Constants and Calculated
Residence Time, Runs 1.1, 2.1—A

iv

10.

ll.

12.

13.
IA.

LIST OF FIGURES

Infrared Spectrum of PhZSiClz

Infrared Spectrum of PhZSi(OH)2 .

Continuous Flow Tubular Reactor . . . .

Hydrolysis Experimental Flow System . .

Infrared Cell Mount . . . .’.

Mole

Fraction of Total Silane

Residence Time (Run 1.1). . .

Mole
Time

Mole
Time

Mole
Time

Mole
(Run

Plot

Plot

Plot

Fraction of Total Silane
(Run 201). o o o o o o 0

Fraction of Total Silane
(Run 2.2). . . . . . . .

Fraction of Total Silane
(Run 203). o o o o o o 0

Fraction of Total Silane
2. )0 0 O I O O 0 O O 0

of 2.3

2AO-Wo

Log A(B+Ao)

AO(B+A)'
of d{(thsi(OH)2}/dt vs.

of A, B, C vs. t;

Spectra from Run 2.3 . . .

Run 2.“

Page
9
10
11
13
15

Charge vs.

23’

Charge vs.

Charge vs

2”

25

Charge vs.

Charge

vs.t . .

{H20} . .

26

27
32

3A
35
39

I. INTRODUCTION

The objective of this work was to study the
hydrolysis of diphenyldichlorosilane. The rate con-
stants, k; and kg, for the hydrolysis reactions were
determined from concentrations of reactive species
at various lengths in a tubular flow reactor.

The experimental system used in this study is the
one that was tested and used in a previous study of
phenyltrichlorosilane.1 Fast reactions (those with
second order rate constants 2 2000 M"1 sec-1) may
be studied in the flow system used for this study.
The rate constants for hydrolysis of most chloro—
silanes are of such magnitude as to consider them fast
when compared to those determined in conventional
batch studies. A continuous flow tubular reactor
was used in conjunction with an infrared spectrometer
as a detector to monitor and characterize intermedi-
ates and products at various reaction times. Our
work demonstrates that this novel system can be used
for accomplishing our major objective, determining
the rates of hydrolysis of diphenyldichlorosilane,
and in addition it has general applicability for
determining rate constants for other chlorosilane

reactions.

2

Early work on the rate of hydrolysis of chloro—
silanes has involved conductOmetric experiments. Princea
monitored the hydrolysis of triphenylchlorosilane and
triphenylchlorostannane in a flow system conductomet-
rically; no intermediate hydrolysis products formed
are analysed.

In the work reported by Princez, the rate constants
for pseudo-unimolecular hydrolysis were calculated;
these constants depended on the initial water concentra-
tions.

Schaffer andIFlanigen3,u studied the conductro-
metric titration of chlorosilanes. They observed both
hydrolysis and condensation in their batch experiments.
Later, Princes, and more recently Prince and Timm11,12’13,
studied the solvolysis of mono—silicon, germanium and
tin chlorides and acetates. However, these experiments
were not designed to determine a stepwise hydrolysis
of a multifunctional species.

We were able to follow the rapid, step—wise
hydrolysis of phenyldichlorosilane, using the continu-
ous flow tubular reactor system. The reactions were
carried out in dinethoxyethane at 27°C and A3°C. This
solvent has no major absorption bands in the 800—A00
cm‘1 region and kept the reaction homogeneous. Steady-

state conditions in the flow system enabled us to record

1
complete infrared spectra for the BOO—A00 cm“ region.

The absorbance data for each species at differing reactor

lengths were analyzed as a function of time.

3

The conversion of reactor length to time requires
analysis of the flow in our tubular reactor. Hawley
land Kleinhenz15 have reported on the "Plug Flow Approxi-
mation of Laminar Flow Tubular Reactor". They found that
the reaction velocity constants determined by assuming
a plug flow model even for experiments involving laminar
flow, gave reasonably good estimates of the actual con-

stants. The plug flow model was used in this work with

no corrections.

II. PREVIOUS WORK

The hydrolysis of Group IV halides has been studied
by several workersI-la. However, these conductometric
and titrimetric methods follow the hydrolysis of all
species present. Our method, like that of Kleinhenz
et all, follows the hydrolysis of the individual species
present in the reaction.

Prince2 and Shaffer and Flanigen3,u employed con-
ductometric methods for following hydrolysis. Results
of the study by Shaffer and Flanigen3 of the hydrolysis
of alkyl and aryl chlorosilanes were that the products
indicated by the conductometric end-points are chlorine
end-blocked siloxane hydrolysis intermediates. However,
diphenyldichlorosilane gave only diphenylsilanediol as
the hydrolysis product for 1,2-dimethoxyethene at 0°C.
They indicated the possible presence of PhasiCl(0H) in
this system.

They then studied the rates and mechanisms of hydroly-
sis in homogeneous solutions in the presence of excess

h
HCl . The kinetics of the reaction of water with chloro-

silanes was expressed as:

d(2H20) .. k(HaO)m(ESiCl)n(HCl)p
dt

 

5
Values of m and n were determined, but not p. The
value for m in all cases is one, first order for the
first 0.01 to 0.02 mole of chlorosilane is two in RSiC13
systems.

Prince2 developed an apparatus for the study of
fast hydrolysis reactions of organometallic halides
under both constant and plug-flow conditions. The
reactions were followed by conductivity change. The

3
first order rate constant for PhasiCl (1.9 x 10 M)

with H20 (2.10 M) in MeZCO + Et20 (1.6:1 v/v) is 2.6A

1

sec in a constant flow experiment. There also was
a "marked effect of water concentration on hydrolysis

2
rate..." .

Prince5 studied the solvolysis of organotin and
silicon chlorides. The solvolysis of triisopropylsilyl
chloride in propan-2-ol "has abnormally low steric
factor and is catalyzed by pyridine"5. Hydrolysis in
MeZCHOH is second order and is not catalyzed by pyridine.
"Data are consistent with a synchronous displacement
of tin and silicon in which steric effects are important

5
in determining reactivity" . The second—order rate

2
constant for triisopropylchlorosilane is 2.5 x 10'

1

1
1 mole sec .

6
Chipperfield and Prince used rapid reaction

2
techniques to follow hydrolysis of chlorotriphenyl-
dermane and chlorotriphenylsilane. The silane was

faster than the germane; e.g., in acetone the first-

6

1

order rate constants are: k = 0.02, k , = A.0 sec“
Ge 31 .-

at 25°C 2M aqueous solution.
7 2
The same authors used a rapid reaction technique

in studying the rates of hydrolysis in organic solvents
of a series of halides R3MCI, where M = Si or Ge and R
is alkyl or aryl. Also the mechanism of the hydrolysis
is discussed. In acetone, with excess water (2M) there

was a first order dependence of the hydrolysis rate on
I;
the halide concentration over the rage studied (10' —

A
-‘

IO M).

At 25°C the first—order rate constnat equals A.03

1

sec“ . They concluded that their data favor the follow—

8
ing hydrolysis mechanism .

R R
\/
(H20)n + RaMCl H-O°'°M°°°Cl _______>

' '

(H20) 0°. H R
n-l

 

> HOMR3 + +H(H30) + Cl"
n-l
Many of the later papers deal with the mechanism
of nucleOphilic displacements on organosilicon halides.
This work deals with the hydrolysis of silicon halides

9,10

with alcohols (solvolysis) and hydrolysis of silicon

7

11:12:13 113
acetates Sommer details various mechanisms

in his book, including the hydrolysis of the silicon-
chlorine bond with water in ether which is described
as proceeding via a Snz—Si mechanism.

We have shown, Kleinhenz, et all, that the hydrolysis
of PhSiCla in 1,2-dimethoxyethene proceeds by the step-
wise breaking of each 8101 bond. The second-order rate

1

constants were found to be 1500, 77.5, and 1000 1.mole" -

1
sec" for the first, second and third chlorines, res-

pectively. A tubular flow reactor system was used.

III. EXPERIMENTAL
A._ Reagents
Diphenyldichlorosilane (Ph281012) was obtained

from Dow Corning Corporation. The IR spectrum of this
material indicated no siloxane species, a purity of 95%
or better (See Figure l). 1,2-Dimethoxyethane (DME) was
used as a solvent and was obtained from the Ansul Corpora-
tion. The solvent, as received, contained 3-A% water, as well
as inhibitors. These were removed by shaking the solvent
over potassium hydroxide pellets and then distilling it
under dry nitrogen while in contact with potassium hydrox-
ide pellets. Only the middle cuts, b.p. 8A.0 - 8A.5°C,
were used.

Diphenylsilanediol‘was obtained from Dow Corning
Research Department. An infrared spectrum, obtained on a
nujol mull, indicated a purity offiz90% since there was no
siloxane absorption (Figure 2). The IR spectrum of this
compound was compared with the spectra of the hydrolysis
products of PhaSiClz. This identified the major species
a Ph28i(OH)2.

B. Reactor .

Figure 3 is a sketch of the tubular reactor connected

to the infrared cell. The reactor was constructed of 2.16 mm.

inside diameter stainless Steel tubing, which was jacketed

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with a one inch copper tube. Water was added to the
reactor through a stainless steel hypodermic needle;
the end of the needle was closed and the water was forced
through two radial holes near the end of the needle. The
length of the reactor could be varied merely by changing
the position of the water inlet. The windows of the infrared
cell were thallium iodide-bromide. The sample chamber was
0.1 mm. thick, 25 mm. high and 10 mm. wide. The cell was
connected to the reactor so that the flowing fluid had to
make a 30° turn before passing through the cell.

C. Apparatus

Figure A is a schematic of the flow system used

for this experimentation. The Ph281012 and 1,2—dimethoxy—
ethane were mixed in one of the Stainless steel tanks while
water mixed with 1,2-dimethoxyethane was contained in the
other. Nitrogen pressure was used as the driving force to
(cause flow. Rotameters were calibrated and used to monitor
the flow of the water and the chlorosilane solvent mixture.
The temperature of the reaction was controlled by circulating
water or other controlled temperature fluid from a constant
temperature bath through the jacket of the reactor.

The infrared cell was connected to the end of the
reactor. This was specially constructed to allow for the

connection of the reactor to the normal sample area of a

13

NITROGEN PRESSURE

WATER PhSiCI3
ETHER ETHER

 

 

 

 

 

 

 

 

 

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FIGURE 4. HYDROLYSIS EXPERIMENTAL FLOW SYSTEM.

1A

Perkin Elmer 337 infrared spectrometer. A diagram of the
cell is shown in Figure 5; the cell was constructed of
stainless steel for added strength. Therefore, the reactor
could be attached directly.

.The P.E. 337 Spectrometer is a grating instrument.
The gain and drift were checked before each run to Optimize
performance. A 0.1 mm. reference cell was used to compensate
for minor absorptions by the solvent, 1,2-dimethoxyethene.

Values of absorbance versus reactor length were obtained
at various flow rates of water and PhasiC12. The absorbance
data were converted to concentrations. Reaction times were
calculated from the flow rates and the reactor lengths.-
Finally, frOm these data the rate constants were obtained.

Temperature was controlled by means of a water bath
. through which the reactants flowed before entering the
reactor. Heat exchange was accomplished by means of two
helical stainless steel coils, 0.25 in 0D. Water from the

water bath was also pumped through the reactor jacket.

'v—r— I

 

 

 

......

 

 

 

 

INFRARED CELL MOUNT

(STAINLESS STEEL)

 

 

 

FIGURE 5.

 

 

 

 

 

 

 

 

IV. EXPERIMENTAL CONDITIONS

The hydrolysis of Ph281012 was carried out at 27°C
in one run, and “2°C in three runs. The desired reactant
concentrations were obtained by controlling flow rates of
the reactants, as shown by rotameter readings. Time was
varied by changing the length of the reactor; this was
accomplished by changing the axial position of the hypou
dermic needle which introduced the water—solvent mixture
(See Figure 3).

The reaction model was develOped from concentrations
of reaction quantities at various times and initial con-
centrations. A summary of the initial concentrations of
chlorosilane and water for the experiments is given in
Table 1.

The initial molar ratios of water to chlorosilane
varied from 1.AA to 3.87. These high molar ratios were
Vneeded to drive the reaction to completion. At a water to
chlorosilane ratio of about 1:1 a small but relatively

constant amount of monochloro intermediate was detected.

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V. INTERPRETATION OF IR SPECTRA
Our results are based on comparisons of the infrared
spectra of reacting mixtures with the spectra of the
hydrolysis products of Pr.SiC12. This provided a unique
examination of individual hydrolysis species. The
following assignments were made for Ph28i012 and its

hydrolysis products.

1

Ph28i012 620, 590, 520 cm“
J.
PhasiC1(OH) 550 — 520 cm’ (postulated)
1
Ph2$i(0H)2 510 cm”

Diphenyldichlorosilane and diphenylsilanediol are
stable compounds and their spectra are well documented12
(Figures 1 and 2). The infrared absorptions of phenyl—
silanes have been described by A. L. Smithla. The strong
bands in the 500-600 cm"1 region are due to silicon-chlorine
stretching. The 580-590 bands are due to the asymmetric
Si-Cl stretch and the 520 band in PhZSiC12 is due to the

symmetric SiCl stretch. The band at 510 cm“1 is the Si-O
symmetric stretch. Also present in this region are some bands
due to the aromatic ring. These are generally weak; they
occur below 500 cm'l.

During the hydrolysis experiments, no new band was
found for a PhZSiCl(0H) type of species. It is expected
1

that a band in the region of 550-520 cm” would occur

for a mono-chloro intermediate. The fact that there was

18

l9 . I
1

no large change in the ratio of the 580 cm- band to the
535 cm"1 abs ption suggested that if the monochloro
species existed, it was only at very low concentration
and was assumed to be in steady state. In the earlier
work of Kleinhenz, et all, the concentration of the
PhSiCl(OH); species was found to be low. No specific
PhSiCl(OH) species was observed.

To test the stability of the silanol species, a
sample of Phasi(0H)2 was allowed to react at room tem-

perature with concentrated HCl in 1,2-dimethoxyethane.

No Change was observed in the IR spectrum of the PhZSi(OH)2.

VI. CALCULATION OF CONCENTRATIONS
The bands at 580 cm‘z, (PhSiClz) and at 510 cm”1,
{PhZSi(0H)2} were measured using a "beer stick", a log
ruler, by placing infinity on IO and measuring the peaks
by the baseline technique. The concentrations were
obtained from experimentally obtained Beer's law plots
(or e values) of the respective species. The values

of the concentration C, were corrected for the path

length of the infrared cell by means of this equation:

C = A/el

Where A = absorbance
e = absorption coefficient
A = path length

The cell was calibrated for each series of runs by running

an empty (air) cell and counting the interference fringes,

A = (no. of fringes)

 

2(v1 - V2)

where v1 and v2 are the measured fringes. Absorption
1 1
coeffecients of the 580 cm and 510 cm" bands are given

in Table 2.

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Figures 6, 7, 8, 9, and 10 are graphs of mole fraction
of total silane (the concentration of silane species
divided by the initial silane concentration) versus the
residence time in the reactor. Reaction time, t, was
determined by dividing the volume of the reactor, V, by

the total flow rate, w.

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VII.
MODEL OF Ph231012 HYDROLYSIS AND DETERMINATION OF RATE CONSTANTS
The following reactions were assumed to represent

the hydrolysis of Ph281012:

Ph281012 + H20 _Ei__9. PhasiCl(OH) + HCl

PhZSiC1(OH) + H20 __Ea__s, PhZSi(OH)2 + HCl

It was assumed that the reactions were first order
with respect to each reactant, second order overall, and
irreversible.

Plug flow was assumed and was shown to be a valid
approximation by Kleinhenz and Hawleyls. Since the rate
controlling step was treated as second order and irrever-
sible, the calculated rate constant from the plug flow
model should be within 15 percent of values determined

from a laminar flow model. The data were analyzed by

assuming the following reaction scheme:

A + W __Ei___9. B + H

B + w __££___9. C + H

where, A Ph281012

CD
II

PhZSiCl(OH)

28

C)
II

H:

2‘.
II

29
PhSi(OH)2
HCl

water

The rate equations are:

-dA/dt = klAW (I)
dC/dt = szW (3)

In the experiments the concentration of B, [PhZSiCI(OH)],

was always observed to be small. Therefore, the steady-

state approximation on B was assumed, i.e., dB/dt = 0.

The following equation was used to analyze the data.

 

2.3 log A(B+AO) = klt
2AO-WO AO(B+A)
Where, . B = (WC-2AO)/(2 + kl/kz)
or, since k2 >> k1,
B = (WC—2AO)/2.

This equation was

A ~A moles

moles

S
'J

2.
II

moles

derived from the following:

of A reacted
of W reacted

of A reacted plus moles of 0 formed.

30

If dB/dt = 0, then from (2):!

B = klA/kz
AO-A = B+C;WO—W = AO—A + C e B + 2C

AOLA = kl/sz + C

therefore, C = A0 - (1 + kl/k2)A (A)
wO - w = A0 _ A + A0 - (1 + k1/k2)A

= 2A0 - (2 ‘I' k1/k2)A
therefore, W = WO - 2AO + (2 +k1/k2)A ' (5)

Substitute (5) into (1):

dA/dt = ~k1A(wo — 2AO + (2 + k1/k2)A)
= -k1(2 + k1/k2)A(B + A)
= -k1'A(B + A) » (6)
where, k1, = k1(2 + k1/k2)

e = (wO - 2AO)/<2 + k./k.>

Integration of (6) by partial fractions:

M/A + N/(B + A) = l/A(B + A)

(B + A)M + NA =1

II
I
Z

M + N = O M
Therefore, BM = l M = l/B
l/BA e l/B(B + A) = l/A(B + A)

31
dA/BA — dA/B(B - A) = dA/A(B + A)

integrating, 1/8 In B + AO ) -k t (7)
A0

 

(B + A)

This gives (8) used to analyze the data:

2.3 10 A(B + A0 = k1t (9)
2A0-WO A0 (6 + A)

Figure 11 is a plot of (8) for Runs 1.1, 2.3-.A.

 

Table 3 gives the slopes, the calculated rate constants
and the initial concentrations.

The rate constant k2,(20 1 mole.1 sec—1) can be
obtained empirically by plotting C, [PhZSi(OH)2] vs. t,
and obtaining the initial slope, dC/dt. The SIOpe of a
plot of dC/dt versus W, [H20] (Figure 12), give k2 since
dC/dt = szW; k.’ = kzs. Therefore, from the es imates
of B, kg was determined; B was obtained by difference,
since A and C were known. Figure 13 is a plot of A, B,
0 versus time. These calculations gave k1 = 2.1 1 mole-
sec"1 and k2 = 20 1 mole-sec"1 (Table A).

A Runge—Kutta computer solution to the rate expressions
was available. The output of this program is a series
of concentrations for all reactants at specified times
for chosen rate constants. The rate constants found to

_1 1
give the best fit were: k1 ~ 1 and k2 ~ 10 1 mole sec’

32

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FIGURE 13. PLOT OF A,

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Our statement that there is no silanol condensation
of intermediate, or condensation product (monochloro—
disiloxane), is very low is valid since the reaction time
is very short for our experiment. It was expected that
condensation did not occur. Also the data indicate
that two moles of water are consumed per mole of di-
phenyldichlorosilane. Finally, the infrared spectra
show no indication of tetraphenyldichlorodisiloxaneIflufil

compared with a reference spectrum.

VIII. EXAMPLE

Spectra of Run 2.3 are shown in Figure 1A. The
reference spectrum was determined before addition of
water. The spectra show changes due to hydrolysis at
varying reactor lengths. Throughout a run, the silane-
solvent and water—solvent flow rates were held constant.
Time was varied by changing the reactor volume. This was
acComplished by withdrawing the hypodermic needle from
.about 1 to 60 centimeters as described.

The absorptions of the two species, PhZSiClz and
PhZSi(OH)2 are given in Table 2. The molar concentrations
were calculated from the cell thickness and the absorption
coefficient taken from Figure 11. _The concentration of
PhZSiCIOH was calculated by means of the mass balance
since the concentration of two species was determined

and a step—wise hydrolysis was assumed.

38

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IX; RESULTS AND CONCLUSIONS

It was demonstrated that the hydrolysis of PhZSiClz
could be followed by means of infrared spectroscopy. This
study again demonstrates our novel flow system and the
usefulness of an infrared spectrometric detection system.

The hydrolysis reactions of the individual chlorines
of PhaSiClz, in l,2-dimethoxyethane, were followed at
_O°C. Reaction times of 0.05 to 3 seconds could easily
be measured. Silanol condensation reactions generally
require more time than this.

The hydrolysis reactions are adequately modeled
as first order with respect to each species and second
order overall; the reactions are irreversible. To minimize
flow problems, the flow rates of each silane and of water
were kept constant. Both steady state approximation and
direct analysis were found to give values in agreement
with the rate constants obtained from a Runge—Kutta
computer solution of the rate experssions. The reaction
'velocity constants were determined to be as follows:

-1 1 .
2.0 1 mole” sec" and

1 1
k2 = 20 1 mole sec"

R

1:;

The fact that our plot of the second order expression

goes through zero substantiates our model.

U0

10.

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12.

13.

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150

l6.

17.
18.
190

X. LIST OF REFERENCES

Hawley, M.G., Larson, W.D., Bond, A.R., Dow Corning
Report No. 605, 1968.

Prince, R.H., Trans. Farady Soc., 53, (G) 835 (1958).

Shaffer, L.H., and Flanigen, E.M., J. Phys. Chem.,
9;, 1591, (1957).

Shaffer, L.H., and Flanigen, E.M., J. Phys. Chem.,
§_1_. 1595. (1957).

Prince, R.H., J. Chem. Soc, 1783 (1959).

Prince, R.H. and Chipperfield, J.R., Proc. Chem. Socl,
385. (1960).

Chipperfield, J.R. and Prince, R.H., J. Chem. Soc.,
3657’ (1963).

Sommer, L.H., Angew. Chem. (Internat. Ed.), ;,
1H3 (1962).

Petersen, R.C. and Ross, S.D., J.Am. Chem. Soc. 85,
3169 (1963).

Sommer, L.H., Parker, G.A., Lloyd, N.C., Frye, C.L.
and Michael, K.W., J.Am. Chem. Socl, 89, 857 (1967).

Prigce, R.H. and Timms, R.E., Inorg. Chim. Acta, 129
(19 7).

Pringe, R.H. and Timms, R.E., Inorg.Chim. Acta, 257
(196 ).

Prigge, R.H. and Timms, R.E., Inorg. Chim. Acta, 260
(19 ).

Sommer, L.H., "Stereochemistry, Mechanism and Silicon",
Mcgraw-Hill, New York, 1965.

Kleinhenz, T.A., and Hawley, N.C., Engineering
Research Report, M.S.U. (1970).

Hawley, M.C., Larson,W.D., and Bond,A.R., "Variable
Length Reactor", Patent Applied for 1970.

Tyler, L.J., J.Am. Chem. Soc., 770 (1959).
Smith, A.L., Spectrochimica Acta, 1075, (1967).
Gill, R.K., IBM-FSP, Dow Corning Corp., (1968).

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