THE UNIVERSITY OF MICHIGAN INDUSTRY PROGRAM OF THE COLLEGE OF ENGINEERING THE EFFECT OF GAMMA RADIATION ON THE REACTION OF CHLORINE WITH ETHYL BENZENE W. M. Sergy J, Oishi J, JO Martin L, Co Anderson March, 1958 IP-278

ACKNOWLEDGMENT The authors wish to express their appreciation for the generous financial assistance of the United States Atomic Energy Commission wnlch supported a project for this study in the Fission Products Laboratory of the Engineering Research Institute of the University of Michigan. The authors also wish to acknowledge the efforts of the following persons who aided with the experimental work: Joseph F. Hanus, David E. Basket, Wan Y, Chon, Gerald H. Golden, Ernest W. Breland, Jr., and Mrs. Alla Pendill. ii

TABLE OF CONTENTS Page AC NOWLEDGMENT.. o o o o o o o o o o o o o o o o o o o o o o o o o o o o ii INTRODUCTIONo. o...o..........oOo.... o......... o...........o0 1 EXPERIMENTAL PROCEDURE,4..... o................... o 4 I. Preparation of Ethyl Benzene..............0............ 4 A. Distilled Ethyl Benzene (I).................... 4 Bo Sodiun-Purified Ethyl Benzene (II)......o....0..0 5 II. General Method ao.....o... o... ooo... o o 0..... 0 000 6 RESULTS o o...o.o o.o o o..o.ooo o ooo, o o o o oo o o o o o o.ooo. 7 I, Reaction of ChlQrine with Distilled Ethyl Benzene (I)..o 7 Ao Reaction Conditions........ o......oo o.......... 7 B. The Substitution Reaction....o, oo..... o....00.. 7 C, The Addition Reaction...,oo.6 o000o.....00 0. o....... 10 D. Product Analyses.o....oo.0 o 000 0o..........0o 0 13 II. Reaction of Chlorine with Sodium-Purified Ethyl Benzene (.II). 0 O 0 0. 000 0 000000000000...00000...0 16 Benzene (ll).............o............ oo.. o....... 6 A. Reaction Conditions.,.O,,,. o,.oo..ooo oo.. ooo... 16 B. The Substitution Reaction....................... 17 C, The Addition Reaction..o..oo....oo.........O..... 20 Do Product Analyses.............oo... oo.oo..o.... 25 IIIo Radiation Yields................ o,..................... 29 DISCUSSION AND CONCLUSIONS..........*.............,... 31 SUMMARY ooO..oo............e....X o.o........ o o o O OOOOOO0 34 BIBLIOGRAPHY oo0000o0oo0o............................00000 a 90 35 iii

INTRODUCTION

L The University of Michigan Engineering Research Institute INTRODUCTION The advent of the atomic energy program has stimulated many research activities to discover uses for the high-energy radiation made available directly or indirectly as the result of nuclear fission~ The accumulation of large amounts of radioactive fission products from the operation of nuclear reactors has presented serious and expensive problems of contamination and storageo These fission products, which are good sources of gamma and beta radiation, are at present considered waste materialso Six years ago, a broad program was initiated at the University of'Michigan to discover uses for these fission productso As part of this program, several groups in this laboratory have been concerned with the promotion of chemical reactions by the use of radiation present in the waste fission productso These studies have been conducted using the gamma radiation obtained from cobalt-60 sources Of the many types of chemical reactions studied in this laboratory, this group has concerned itself with the reaction of chlorine with various aromatic hydrocarbons in the presence of gamma radiationo Benzene and toluene were among the first compounds to be chlorinated in the presence of gamma radiation (1,2)o Some work on the reaction of chlorine with xylene, ethyl benzene, mesitylene, and naphthalene has also been reported (3,4)-. Recently, extensive studies were completed on the chlorination of mesitylene and naphthalene (5)o 2

The University of Michigan * Engineering Research Institute The chlorination of ethyl benzene has been studied extensively since the presentation of the initial data (3 4)o It has been established that this reaction can be completely inhibited by impurities present in the ethyl benzeneo These foreign materials present in the ethyl benzene are apparently introduced during the commercial synthesiso The results of this study are presented in two distinct parts The first part presents data which illustrate the effect of the inhibitors on the reaction rat eo The second part presents rate data, radiation yields, and product analyses for the chlorination of pure ethyl benzene o In general9 it is reported that ethyl benzene reacts with chlorine less readily than the methyl substituted benzenes and that the conditions of reaction govern the type of product obtainedo Reactions carried out in bright light (6,7,8) favored chain substituted chlorides and those carried out in the presence of a carrier, such as iodine or iron, favored nuclear substituted chlorides (8,9) No reference has been found for the reaction of chlorine and ethyl benzene by additiono Exhaustive chlorinations using both photochemical and carrier techniques in the same reaction have resulted in products which contain up to nine chlorine atoms substituted on an ethyl benzene molecule (798,9) Prolonged chlorination at high temperatures can result in cleavage of the ethyl benzene molecule with the formation of benzenehexachloride and assorted chloroethanes (9)o Dimerization (10) and the formation of thick 3

The University of Michigan * Engineering Research Institute resinous materials that are resistant to chlorination (7,8) appear to be the major side reactionso From the relatively high temperatures and lengthy reaction times of the photochemical chlorinations reported in the literature, it appears that it is quite difficult to affect substitution of chlorine on the ethyl benzene moleculeo The chlorinations using metallic carriers appear to proceed more readily than the photochemical chlorinationso It may be of interest to mention that polychloroethyl benzenes are used as intermediates in the preparation of chloro-fluoro derivatives of eth7yl benzene~ These chloro-fluoro derivatives are used in the processing of uranium metalo EXPERIMENTAL PROCEDURE Io Preparation of Ethyl Benzene During the experiments on the chlorination of ethyl benzene it was found that the ethyl benzene initially used contained some impurities which inhibited the reaction. After these impurities were removed, a vigorous reaction was obtained, Since it was desired to illustrate the effect of the impurities on the reaction rate, it became necessary to specify how the two reactant, had been prepared for useo Ao Distilled Ethyl Benzene (I) A commercially available grade of ethyl benzene was used. (Eastman Kodak 719)o The reagent was dried over calcium chloride and silica gel and subsequently distilled twiceo Only 4

The University of Michigan T Engineering Research Institute the middle 50 percent of the distillate was collected for useo The distilled ethyl benzene was completely colorless and was designated "ethyl benzene (I)", The commercial ethyl benzene was initially pale yellow in coloro After distillation. the discarded ethyl benzene was distinctly darker yellow in color and had an astringent.odoro Bo Sodium-Purified Ethyl Benzene (II) Distilled ethyl benzene (I) from the first purification procedure was treated with freshly-cut metallic sodium. Within minutes a flocculation occurred in the solutiono A bright yellow material was noted to be adsorbed on the surface of the sodium shavingso This was accompanied by the formation of a white flocculent material which slowly settled to the bottom of the solution~ Evolution of gas bubbles was evident during the precipitationo After five hours the ethyl benzene solution was filteredo The flocculated material was very gelatinous in texture and had a pleasant aromatic odoro The filtered ethyl benzene (I) solution was treated with several portions of metallic sodium during the course of one weeko When removed, each portion of sodium except the last had some bright yellow material adsorbed on the surfaceo The ethyl benzene was distilled when no further reaction with metallic sodium was apparento As before only the middle portion of the distillate was collected for useo This constituted "ethyl benzene (II)1' 5

The University of Michigan T Engineering Research Institute There was no noticeable difference in the color or odor of ethyl benzene (I) and (II)o Infrared spectrograms of these two samples of ethyl benzene were identical although the sodiumpurified sample contained much less impurity than the sample that was merely distilledo IIo General Method A complete description of the equipment and procedure employed in the chlorination studies has been presented in a recent report (5)o The rates of reaction of chlorine with ethyl benzene were calculated by an overall chlorine material balance on the reacting systemo The chlorine inlet gas flow rate was measured by a calibrated rotameter-type flow metero Samples of the exit gases from the reactor were absorbed in 0o2 N sodium arsenite in 3 N potassium hydroxide solutiono The amount of unreacted chlorine present in each sample of the exit gases was determined by titration with ceric sulfateo The amount of chloride ion present was determined by the Volhard titration method A thermocouple recorder-controller was used to control the temperature of the reacting systemo The radiation dose rate was measured by ferrous sulfate dosimetry (11)o The reaction products were fractionated in a simple vacuum distillation unito The total chloride content of each of the resultant distillate fractions was determined by chemical methods 6

The University of Michigan * Engineering Research Institute RESULTS Io Reaction of Chlorine with Distilled Ethyl Benzene (I) Ao Reaction Conditions For all runs the reactor was charged with 60 ml (0o49 mole) of ethyl benzene (I)o After the reactor had attained the operating temperature, chlorine gas was admitted at a rapid rate in order to saturate the ethyl benzene (I) During this period no odor of chlorine or HC1 was noted in the exit gas lineso After saturation was completed and the temperature became steady the gamma source was raised and chlorine gas was admitted at a constant flow meter settingo This was taken as zero timeo The data points shown represent the middle of the sample absorption periodo The experimental conditions used are summarized in Table Io Run 6 had data points taken at two different chlorine inlet rat eso The data show that this change in flow rate had no effect on the reactiono From Table I it can be seen that the chlorine inlet rate showed a slight variation in most of the runso However, during any given sample of a run, the chlorine inlet rate was constant at some value in the range shown in the last column of Table Io Bo The Substitution Reaction The kinetic data for the reaction of ethyl benzene (I) and chlorine by substitution are shown in -Figures 1, 2, and 3o Virtually little difference exists in the results obtained at the 7

2 09 U E O U z 0 I,, u wu 1 0 -1 0 10 20 30 40 50 60 TIME (MIN.) FIGURE 1. RATE OF CHLORINE SUBSTITUTION ON ETHYL BENZENE (I) AT 60~ C. (RUN 1) CL. CM E E I0 at 2 1 0 A1 0 RUN 2 (NON IRRADIATED) O RUN 3 (NON IRRADIATED) * RUN 4 (IRRADIATED) * RUN 5 (IRRADIATED) j:^:h^4^r- I 0 10 20 30 40 50 60 70 80 90 100 110 TIME (MIN.) FIGURE 2. RATE OF CHLORINE SUBSTITUTION ON ETHYL BENZENE (I) AT -5~ C. 8

z ul UJ CL IuJ Iu LU 3 2 1 0 -1 o RUN 6 (NON IRRADIATED) E RUN 7 (NON IRRADIATED) A RUN 8 (NON IRRADIATED) RUN 9 (IRRADIATED) E!0 - s-0 - 00 o 0 _ _ _ _ _ O _ mL 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 TIME (MIN.) FIGURE 3. RATE OF CHLORINE SUBSTITUTION ON ETHYL BENZINE (I) AT -25~ C.

The University of Michigan * Engineering Research Institute TABLE Io Summary of Experimental Conditions used in the Chlorination of Ethyl Benzene (I)o Run Noo 1 2 3 4 5 6 7 8 9 Reaction Tempo ~C 60 -5 -5 -5 -5 -25 -25 -25 -25 Dose Rate Sample Time Krep/hr mino 31o5 5 none 10 none 10 1302 10 13o2 10 none 5 Run Time min 65 84 101 96 96 83 82 88 65 Chlorine Inlet Rate mM/mino 13 o2 12o2 - 13ol 12o5 - 13ol 13.o3 - 14o2 13ol 13o9 - 14o0 21o7 - 21o8 14ol 14,0 - 14ol 14o3 - 14o6 none none 60o3 4 5 5 5 three different temperatures and radiation dose rateso Examination of the data revealed that gamma radiation had no measurable effect on the substitution reactiono Co The Addition Reaction Figures 4, 5, and 6 illustrate the rates of addition of chlorine to ethyl benzene (I) at three temperatureso From Figure 4 it can be concluded that no reaction by addition occurs at 60~Co Data from both the irradiated and non irradiated runs at -50C showed random scatter about the zero axiso No finite rates of addition could be determined from the data shown in Figure 5o 10

z ui IL 04 N u E uJ IO z 0 4 LU iJJ 0 5 10 15 20 25 30 35 40 45 50 55 60 65 TIME (MIN.) FIGURE 4. RATE OF CHLORINE ADDITION AT 60~ C. (RUN 1) TO ETHYL BENZENE (I) z CE LUJ CL rZ IX z 0 uJ LU iI 6 4 2 0 -2 0 RUN 2 (NON IRRADIATED) _ a RUN 3 (NON IRRADIATED) * RUN 4 (IRRADIATED) * RUN 5 (IRRADIATED) OE I____ 0 1 1o I__ __ I_ 1 o 1 o,<J, I __o:____ r__0 0 10 20 30 40 50 60 70 80 90 100 110 TIME (MIN.) FIGURE 5. RATE OF CHLORINE ADDITION TO ETHYL BENZENE (I) AT -5~ C. 11

20 18 z ul.i, LU CL aE LU I.z 0 u LU u 16 14 12 10 8 6 r) 4 2 0 TIME (MIN.) FIGURE 6. RATE OF CHLORINE ADDITION TO ETHYL BENZENE (I) AT -25~ C.

The University of Michigan T Engineering Research Institute The results of the four runs at -25~C showed an unusual effecto Figure 6 showed that gamma radiation had an inhibiting effect on the addition of chlorine to ethyl benzene (I)o The reaction rate under irradiation was significantly lower than that without radiationo This anomalous behavior was one of several factors which eventually led to the discovery and subsequent removal of impurities present in the ethyl benzene (I) Do Product Analyses The extent of reaction that had occurred in each of the experimental runs could easily be determined by performing a total chloride analysis on the reaction mixtureso Table II showed that very little difference existed in the extent of reaction in the runs conducted with ethyl benzene (I)o The relatively high values obtained for runs 2 39 49 and 5 in Table II were thought to be due to prQlonged contact with dissolved chlorine gas prior to analysiso TABLE IIo The Percentage of Total Chloride Present in the. Original Ethyl Benzene (I) Reaction Mixtureso Run Reaction Dose Rate %/ Total Chloride No Tempo Krep/hr in Reaction ~C _____ Mixture 1 60 31o5 3o4 2 -5 none 16o2 3 -5 none 18o4 4 =5 13o2 13o6 5 -5 13o2 13o4 6 -25 none 4o2 7 -25 none 8 =25 none 9 -25 60o3 906 13

The University of Michigan * Engineering Research Institute The reaction mixtures from the chlorination of ethyl benzene (I) were distilled under reduced pressure and the total chloride content of each distillate fraction was determinedo., Typical data obtained from the distillations at -5~C and -25~C are illustrated in Table III A large amount of unreacted ethyl benzene (I) was found to be present in each reaction mixtureo The fractions containing significant amounts of total chloride were of varying viscosities and were yellow in coloro The presence of a monochloro derivative was strongly indicatedo It is thought that the other fractions listed in Table III are mixtures of the monochloro derivative and some much higher chloro derivative possibly the tetrachloride compoundo At -5~C the experimental runs showed literally no difference in product compositiono Only two distinct fractions were isolated from each runo Some differences in product composition was noted for the runs at -25~Co For example, in run 8, the last distilled fraction contained only 3~6 percent by weight of total chloride, This indicated no product formation for the non irradiated runo The distillate fractions isolated from run 9 showed a high total chloride content These analytical data did not substantiate the kinetic data which showed a higher reaction rate for the non irradiated runs than for the irradiated runo i 14

- TABLE IIIo Typical Data Obtained from the Distillation of Chlorinated Ethyl Benzene (I) Reaction Mixtureso Type of Chloro Derivative Mono Theoretical Percent Chloride Exp e rimental Percent Chloride Run Fraction Number Number Boiling Point 25o2 25o0 2 I Pressure mmo Hgo 22-26 32-36 22-24 Temp o ~C 25ol 25 o5 3 I 61-74 60-75 -68-72 Fraction Volume mlo 3o5 4o0 2~5 -i m =r.' m o O m+ _. 4 I HC1 Di 40ol-40o6 Tri 50o4-50o9 5403 2 3 II II 22 28-32 80-152 105-152 3o5 4o3 53o7 5505 5403 4 9 9 II 22 103-153 2o5 0o7 m 00 _..o f3 0 _. 0 P+ 3" I~ I 74-86 Tetra 57o7-58o7 5703 II Oo3 85-90 lo0

The University of Michigan * Engineering Research Institute IIo Reaction of Chlorine with Sodium-Purified Ethyl Benzene (II) Ao Reaction Conditions The runs employing ethyl benzene (II) as a reactant were set up in the same manner as that previously described for ethyl benzene (I)o During the course of saturating the reactor with chlorine there was no evidence of reaction by substitutiono During saturations the exit gas stream was directed through a solution containing silver nitrateo No precipitate of silver chloride was observed until chlorine gas was actually visible in the exit lineso The chlorination of ethyl benzene (II) was conducted at the two temperatures for which extensive data was available using ethyl benzene (I)o A summary of the experimental conditions is given in Table IVo TABLE IVo Summary of Experimental Conditions Used in the Chlorination of Ethyl........ Benzene (I I) o........ Run Reaction Dose Rate Sample Time Run Time Chlorine Inlet Noo Temp ~C Krep/hro mino mino Rate mM/mino 10 -5 none 4 76 14 8-14 9 11 -5 6003 4 75 14o3-14o6 12 -25 none 4 76 14o7-14o9 13 -25 60o3 4 75 14o6-14o9 14 -25 60o3 5 97 14ol The runs at -25~C were extremely hard to controlo The chief difficulty was the large amount of chlorine dissolved in the ethyl benzene (II) during the saturation periodo The solubility of chlorine in ethyl benzene (II) was measured at two 16

.The University of Michigan * Engineering Research Institute temperatures using a calibrated flow metero The solubility values obtained were as follows: 0o51 gm per ml at -50C; 180 gm per ml at -25~Co This solubility data indicates that the best possible temperature control was mandatory for the runs at -25~Co Even a slight variation in temperature would make a material balance impossible o In all runs using ethyl benzene (II) 9 a temperature rise was observed when chlorine was first admitted to the reactoro This rise was 2 degrees for the runs at -5~Co For the runs at -25~C this temperature rise varied from 6 to 15 degreeso In the irradiated runs using ethyl benzene (II) a sharp temperature rise was observed when the gamma source was raised from its storage wello For run 14 this second temperature rise was 2 degreeso A rise of 4 degrees was noted in runs 11 and 13o The raising of the gamma source was also accompanied by violent gas evolution from the reactoro At -25~C this gas evolution disturbed the equilibrium to the extent that no data points were available for the early part of the reactiono The second temperature rise and sudden gas evolution from the reactor were not observed for the non irradiated runso These observations indicated that gamma radiation had a great effect on the reaction, This conclusion was later confirmed both by the kinetic and analytical datao Bo The Substitution Reaction Figures 7 and 8 illustrate the effect of radiation on the rate of chlorine substitution on ethyl benzene (II)o 17

7 z IS CL u E uJ z 0 LJ QL 6 5 4 H 3 2 1 0 o RUN 10 (NON IRRADIATED) * RUN 11 (IRRADIATED) — 02 ——, — o — o a -0 - -,- -t2__ 0.. 0 - I. — -0 - -I0- - OI ______ _____ __ _ _ _ __ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ -1 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 TIME (MIN.) FIGURE 7. RATE OF CHLORINE SUBSTITUTION ON ETHYL BENZENE (I) AT -5~ C.

m -.~ 7 z 65 LU m 3 z 0 - 2 V H LU 1 0 -1 0 5 10 15 20 25 30 35 40 45 TIME (MIN.) 50 55 60 65 70 75 80 85 90 FIGURE 8. RATE OF CHLORINE SUBSTITUTION ON ETHYL BENZENE (I) AT -25~ C.

I The University of Michigan * Engineering Research Institute There was no reaction by substitution in the non irradia= ted runs at -50C and -25~Co However, a significant amount of substitution did occur under irradiation at both temperatureso The irradiated curves of Figures 7 and 8 were characterized by plateaus during the early part of the reactiono In this plateau region, the reaction rate at -25~C was about 17 times larger than that at -50Co Examination of the areas under the plateau regions of the curves reveals that9 at both temperatures9 the reaction rate starts to decrease at the point where the ratio of the total moles of chlorine reacted by substitution to the total moles of ethyl benzene (II) charged is 1 to 2o The substitution curves were graphically integrated to obtain the amount of chlorine reacted in ten minute intervalso This data is presented in Table V and will be used in the calculation of radiation yieldso Co The Addition Reaction Kinetic data for the addition of chlorine to ethyl benzene (II) at -5~C and -25~C are shown in Figures 9 and 10o Smooth reaction rate curves were obtained under irradiation. However, comparison of the non irradiated data points of Figures 7 and 8 showed a distinct scatter about the zero axiso Further9 both non irradiated runs showed almost a sinusoidal variation about this axiso This observation indicated a possible temperature variation in the reactoro The effect of such a temperature variation would be an alternate evolution of dissolved chlorine followed by solution of the input chlorineo L 20

TABLE Vo Millimoles of Chlorine Reacted by Substitution in Successive Time Intervals During the Chlorination of Ethyl Benzene (II) -4.' 0 Cl ro 2Lb Reaction Dose Rate _ Millimoles of Chlorine Tempo oC Krep/hro Time Intervals9 minutes 1|~~~~ ~~Total i_ 010 1020 20-30 30-40 40=50 50-60 60-70 I ".- T " T - m —-*- l -r- C —P;DCPl- -~-~__________________ I 10 none 60o3 000 O00 4104 41o4 0o0 41 4 000 0o0 41,3 o00 Oo0 41o2 0oO 48o0 0o0 40o9 0oO 24 5 Oo0 36o0 000 15 04 -25 none 000 000 720o 000 283 o6 000 373o4 =25 60o3 72o0 71o8 69o7 m 00 - on S go 3 cM go

12 z CL GE LU I4u ad 10 8 6 4 2 0 O RUN 10 (NON IRRADIATED)__ * RUN 11 (IRRADIATED) 0 -- -- - -- ---- - I I — -- -- -- -- - I I I<l/,I Id To ~) O ro -2 -4 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 TIME (MIN.) FIGURE 9. RATE OF CHLORINE ADDITION TO ETHYL BENZENE (I) AT -5~ C.

14 I I! O RUN 12 (NON IRRADIATED) 12 * RUN 13 (IRRADIATED) * RUN 14 (IRRADIATED) 10 t LU 6 6 E ui 4 0Zo - L O0 -2 -4 -- 0 5 10 15 20 25 30 35 40 45 TIME (MIN.) 50 55 60 65 70 75 80 85 90 FIGURE 10. RATE OF CHLORINE ADDITION TO ETHYL BENZENE (1) AT -25~ C.

The University of Michigan * Engineering Research Institute The end result would be a sine curve in the chlorine material balance In the event that no reaction occurs this sine curve vwould be about the zero axis The non irradiated runs were established to represent a zero reaction rateo The major evidence for this conclusion was obtained from total chloride analyses on the original reaction mixtureso These data are present in Table VIo For examples in run 10 the reacted ethyl benzene (II) contained 3~2 percent by weight of total chlorideo This percentage is equivalent to a constant addition reaction rate of Oo3 mM chlorine per minute during the entire ^76 minutes of the runo This value has been considered negligi.le in comparison with the irradiated reaction rates and therefore has been designated as zeroo TABLE VIo The Percentage of Total Chloride Present in the Original Ethyl Benzene (II) Reaction Mixtureso Run Reaction Dose Rate % Total Chloride Noo Tempo OC Krep/hro in Reaction _ ~_________ ___~__ Mixtures 10 =5 none 3o2 11 -5 60o3 53o3 12 -25 none 3 0 13 -25 60o3 58o5 14 -25 60o3 58o6 All irradiated reaction mixtures yielded high percentages of total chloride0 These values substantiated the conclusions drawn from the kinetic datao 24

The University of Michigan ~ Engineering Research Institute - The irradiated reaction rate curves of Figures 9 and 10 were quite similar in appearanceo A period of induction occurred for the addition reaction at both temperatureso During this period the reaction rate was seen to increase to a maximum valueo This maximum reaction rate plateau was attained after 50 minutes at -5~C and after 80 minutes at -25~Co In this plateau region the reaction rate at -25~C was 16 times larger than that at -5~Co The difference in length of the induction periods at the two temperatures appeared to be related to the corresponding rates of substitutiono It is possible that the substitution reaction may occur preferentiallyo At -5~C the addition reaction rate had already exceeded the substitution reaction rate at the 16 minute marko However, at this temperature the substitution reaction rate was fairly lowo At -25~C the rate of substitution was quite high and here the addition reaction rate did not surpass the maximum substitution rate until the rate of substitution had fallen off by some 39 percento This occurred around the 46 minute marko The integration data of Table VII showed how the total amount of chlorine reacted per time unit increases with reaction timeo This data will be used in the calculation of radiation yields Do Product Analyses All reaction mixtures from the chlorination of ethyl benzene (II) were distilled under 0o2-0o5 mmo Hgo pressureo I 25

TABLE VII o Millimoles of'Chlorine Reacted by Addition in Successive Time Intervals During the Chlorination of Ethyl Benzene (II), m ro O.' 3 2_ Reaction Dose Rate Millimoles of Chlorine Temp o C Krep/hro Time Intervals 9minutes Total I 0-10 10-20 20-30 30-40 40=-50 50-60 60-70 I w~~~~~~~~............. _....,.........,.. none 60o3 none 6003 o0 9o6 000 10 Oo0 39o0 000 3o5 0o0 5802 00 12,0 o00 68o4 OoO 37 o0 0o0 73o0 0o0 69o0 000 7406 000 000 7407 0o0 000 -25 397o5 00o 322o0 -25 9300 10605 m m~ m "1 3. go 70 _.

The University of Michigan T Engineering Research Institute Samples of the reaction mixtures were taken for total chloride analysis after any dissolved chlorine had been removed from the reaction mixture but prior to the actual distillationo The distillate fractions obtained from the non irradiated runs were similar in number and appearance. Actually no product fractions were isolatedo The fractions consisted of unreacted ethyl benzene (II) and most of them contained less than one percent by weight of total chlorideo The last fraction in run 10 was 1 ml in volume and contained 8o5 percent total chlorideo In view of these results it was concluded that no reaction of chlorine with ethyl benzene (II) had occurred in the non irradiated experimentso The distillate fractions from the irradiated runs yielded no unreacted ethyl benzene (II) All fractions were colorless liquids of varying viscositieso The high boiling fractions were the most viscouso Table VIII contains all the data available for the distillation of the irradiated reaction mixtureso The range in the theoretical percent chloride column of this table is due to the possible formation of either substitution or addition products0 The data in Table VIII indicated the formation of a mono-chloro derivative of ethyl benzene (II) No distinct fraction corresponding to the di- or tri-chloro derivatives was obtained Also, only a few fractions were obtained which were related to the tetra- and penta-chloro derivativeso The majority of the distilled fractions corresponded to the hexa-chloro derivative of ethyl benzene (II)o In all probability this was the 27

TABLE VIIIo Analytical Data Obtained from the Distillation of Chlorinated Ethyl Benzene (II) Reaction Mixtureso Type of Chloro Derivative Mono Theoretical Percent Chloride 25.2 Experimental Percent Chlorid e 23 6 27o2 25o7 26.6 30o4 26,4 3004 Boiling Po Run Numb e r 11 11 13 13 13 14 14 Fraction Number I II I II III I II Pressure mm0 Hgo 005 0o5 005 003 003 0o2 003 )int Fraction Tempo Volume ~C mlo 27 30 23 27-28 29-30 28 28 11,5 2.2 0,2 906 103 806, o = yr. m r w) TO 2) Di Tri CO 00 4001-40o6 50 4-50 o9 57o7-58.7 62o8-63o7 Tetra 54o0 55ol 58o7 5803 6405 6208 64 6 13 14 11 13 11 13 14 IV III III V IV VI IV 053 002 005 003 005 005 002 42-85 45-111 90-112 95-100 105-120 100-109 105-123 4o2 7o0 11 0 206 205 407 5.2 Penta Hexa 6702-68o1 66,7 6604 68.9 6603 67.0 67o8 6805 66o3 67o2 6804 11 11 11 13 13 13 13 14 14 14 V VI VII VII VIII IX X V VI VII 0o3 0.3 0o4 003 0o3 003 0o3 0o2 0.2 0.3 124 129 131-136 141 109-112 1124116 116-126 126-132 116-122 124-134 131-151 8,00 5.6 008 506 8.9 208 405 603 800 6,00 m m. mf 0) In _. P+ s f_

The University of Michigan * Engineering Research Institute hexa-chloro addition product but this was not establishedo These analytical data obtained from the reaction of ethyl benzene (II) with chlorine are in good agreement with the kinetic datao IIIo Radiation Yields Radiation yields have been calculated for the chlorination of ethyl benzene (II)o These radiation yields have been expressed in terms of G values (molecules reacted per 100 electron volts of radiation energy absorbed) based on chlorine and are shown in Table IXo It is noted that separate G values have been given for the substitution and addition reactionso The G values presented in Table IX have a possible deviation of +5 percento This possible deviation arises from assumptions made in the calculationso As in the case of naphthalene (5) the G values have been calculated for specific time intervals throughout the experimental runso The overall G value for 70 minutes for the substitution reaction at -25~C was some 30 percent greater than that at -5'Co Such a direct comparison of G values could be made for the addition reactiono The kinetic data indicated that the addition reaction at -25~C had barely reached its maximum reaction rate after 70 minuteso At -5~C the maximum addition reaction rate was reached much earliero To obtain a valid comparison of G values for addition the reaction time would have to be increased to a point where the addition reaction had gone almost to completiono It may be of interest to note that, at the maximum 29

-Iq =1 -II Yb 0 M. c+ 4% TABLE IX o G Values Based on Chlorine for the Chlorination of Ethyl Benzene (II) I — ~-i ~ —-P~ —- -~ — P~~ —P -~ ~- -~ —- - -- ------- P L~-~~iPLL —L- Z~i-PI-~ L~-~ III~L —Y~li~L- -- - - I t G Values Based on Chlorine ~-.-~-~-.-~ *cL1 —- ~I — ---— ~- ~e —- - --- s- L- - ----- --- --- Time Intervals minutes ~~,, ~, J~c~, ~~ ____.._. I I _ I Reaction Temr. ~C( Type of Rea ct ion _ -! I I 10-20 20-30 30-40. 40-50 I I 50-60 0o0O:t —.LL.z, 0 % f - "., - -.. % - - -4 _.!,,- - - -- -= -.4 I --. _~~~ i - I A, I -L -_ CA -5 0 =5 -25 -5 -25 Substitution Substitution Addition Addition I 81 600 142 000 189900 1,970 81,9600 1429000 76,800 69 900 I 81,600 139,000 115 000 239600 T 81,600 137, 000 135 000 729600 T 81,200 93 300 144 000 136,000 -I 809600 46 200 147, 000 183 000 i 60=70 709 900 30,200 147 000 210 000 I 799 900 1049000 112, 000 909600 uverai~L for 70 Minutes.. _ l' - i --- I~ n a) 3 m -3 -I m c4 10 c OfP m

The University of Michigan * Engineering Research Institute addition reaction rates, the G value at -25~C is about 43 percent greater than that at -5~Co DISCUSSION AND CONCLUSIONS This study has demonstrated that ethyl benzene can successfully be chlorinated in the presence of gamma radiation~ However, the study shows that the presence of impurities in the ethyl benzene can inhibit the reaction almost completelyo These impurities are of a type which can be removed by treatment with sodium. The presence of possible inhibitors in ethyl benzene (I) was suggested by the anomalous kinetic and analytical data that were obtained from the early experimental runso In particular, the kinetic data for ethyl benzene (I) at -250C showed a lower rate of addition in the irradiated run than in the non irradiated runso Examination of the analytical data showed further discrepancies in the results0 Further9 the shape of the addition curves at -250C did not conform to that generally expected on the basis of previous experience with the chlorination of other aromatic compounds o It was subsequently established that ethyl benzene (I) was not a pure reagent Treatment of ethyl benzene (I) with metallic sodium resulted in the removal of at least two foreign materialso The ethyl benzene (II) thus obtained exhibited a much different behavior during reaction than did ethyl benzene (I)o The difference in reaction was assumed to result from some inhibiting effect of the foreign materialso At this writing 31

Irs- - -.9 ILA:- L-: — -~~~~) I r I Ine university oT iiicnigan * engineeriing C~dcarn insiurc' the impurities which were found in ethyl benzene (I) have not been identifiedo Although the ethyl benzene (I) was dried and distilled prior to reactions this general procedure was not effective in obtaining a reactant which was pure enough to allow reaction with chlorineo The ethyl benzene (I) used in part of the present study was the same reactant that was used in previous work reported from this laboratoryo However, the earlier data and G values (3,4) are not in agreement with the present data, and this can be explained on the basis of the erratic reaction of an impure compound and a difference in the method-of calculating G values, Several of the factors which are involved in the calculation of the earlier G values are listed in a report on the chlorination of mesitylene and naphthalene (5) Pure ethyl benzene [ethyl, benzene (II)] was found to react vigorously with chlorine in the presence of gamma radiation Virtually no reaction was obtained without radiation~ Thus9 the reaction of chlorine with pure ethyl benzene was found to proceed only under the influence of gamma radiationo The analytical data obtained from product analyses supported the conclusions drawn from the kinetic datao Since some chlorinated products were obtained with ethyl benzene (I) which were different in color from those obtained with ethyl benzene (II) it is possible that a reaction of chlorine with the foreign materials present in the former had occurredo In this case it might be that long continued chlorina tion of ethyl benzene (I) could result in removal of the foreign 32

I The University of Michigan * Engineering Research Institute materials by reactiono A reaction such as that obtained for ethyl benzene (II) could start if the concentration of the foreign materials in ethyl benzene (I) had decreased sufficientlyo Radiation yields for the reaction of chlorine with ethyl benzene (II) have been expressed in terms of "G" values (molecules reacted per 100 electron volts of radiation energy absorbed) in order to provide a comparison with other reactions found in the field of radiation chemistryo A discussion of several factors which are important in the interpretation of G values has been presented in an earlier report (5)~ The current G values have been based on chlorineo I -I 33

The University of Michigan * Engineering Research Institute SUMMARY 1o This study has presented data which illustrate the effect of impurities on the reaction of ethyl benzene and chlorine in the presence of gamma radiation0 2e The rates of chlorination of pure ethyl benzene have been measured under irradiated and non irradiated conditions 3o The reaction of chlorine with pure ethyl benzene was found to proceed only in the presence of gamma radiation. 4, Kinetic data showed that ethyl benzene reacted with chlorine both by substitution and by additiono 5o Both the substitution and addition reactions were favored by low temperature. This observation indicates that the reaction rate is a function of the chlorine concentration in the reaction mixture 6. Analytical datac have indicated that the ito..o...(,xa-..loro *clen~v-lt.Lve.I.) ui'. c-bh;..l benJer;:-; are the;)r'i ^..r^, ^ och.'..f reaction in the presence of radiation, 7, Radiation yields expressed as G values based on chlorine have been calculated for the chlorination of ethyl benzenee Maximum average G values of 104,000 for substitution and 112,000 for addition were obtained in a 70 minute reaction time. i 1 34

BIBLIOGRAPHY

The University of Michigan Engineering Research Institute - B IBL IOGRAP HY 1o Harmer, Do E,, Lo CO Anderson and Jo Jo Martin, Chemo Engo Prog. Sympo Series, Vol 50, No, 11, 253-57, (1954) o 2. Harmer, Do E,, Jo J. Martin and Lo C. Anderson, Chem. Eng. Progo Sympo Series, Vol0 52, Noo 19, 53-59, (1956) o 3. Anderson, L, C., Bo G, Bray, and J. J. Martin, Proceedings of the International Conference on the Peaceful Uses of Atomic Energy, Geneva, Switzerland, August 8-20, 1955, Volo 15l 235-41, United Nations, New York, 1956. 40 Martin, Jo Jo, Lo CO Anderson, et alo, Progress Report, 1943:4-60-P, Engo Reso Inst., the University of Michigan, Ann Arbor, Michigano March, 1956o 5o Sergy, Wo M., JO F. Hanus, J. Oishi, Jo Jo Martin and L. C. Anderson, The Chlorination of Mesitylene and Naphthalene in the Presence of Gamma Radiation, Engo Res. Inst. the University of Michigan, Ann Arbor, Michigan, May, 1957, (Submitted to the AoCoSO for publication) 60 Evans, Eo B., E, Eo Mabbott and Eo Eo Turner, Jo Chem, Soco (London), 1159-68, (1927)o 7. Harvey, PO G,, F. Smith, M. Stacey and J. C, Tatlow, J. Apple Chemo (London) 4, 319 (1954) 8, McBee, E, T,, H. B. Hass, G. Mo Rothrock, J, So Newcomer, Wo V.o Clipp, Zo Do Welch and Co I, Gochenour, Indo Engo Chemo, 39, 384 (1947)o 9o Harvey, P. Go, Fo Smith, Mo Stacey and J. C. Tatlow, Jo Appl, Chem, (London) 4, 325 (1954), Oo Tohl, B. and J. Eberhard, Ber, 26, 2944 (1893), 1, Weiss, J,, Nucleonics, 10, 28 (1952)o 9 J 4. - 36