ENGINEERING R E S EAR C H INST I T U T E THE UN IV E R S I T Y OF M I C H I G A N ANN AR B O R MIC H I G A N Report On EFFECT OF GAMMA RADIATION ON THE REACTIONS OF SOME UNSATURATED ORGANIC COMPOUNDS by N, G. Kothary L. Yemin J. J. Martin, Project Supervisor U.So Atomic Energy Commission Contract AT (11-1)-162 Chicago 80, Illinois August, 1957

The University of Michigan * Engineering Research Institute I ACKNOWLEDGEMENT The authors wish to express their appreciation for the financial support of the United States Atomic Energy Commissiono The authors also wish to acknowledge the assistance given in the study by Rohinton Bhada and Yu-Tang Hwango ii

The University of Michigan Engineering Research Institute TABLE OF CONTENTS P age Io INTRODUCTION1 IIo REACTIONS INVESTIGATED Ao Olefin-Hydrogen Sulfide Reactions1 o Preliminary Work 2 2o Further Experimental Work 2 (a) Equipment and Materials 3 (b) Experimental Procedure 4 (i) Loading 4 (ii) Irradiation 4 (iii) Product Recovery 4 (iv) Analysis of Products 5 3. Discussion of Methods and Results 5 Bo Miscellaneous Reactions 10 1, Ethylene-Propylene Copolymerization 10 2o Acetylene Reactions 12 35 Olefin-Sulfur Dioxide Reactions 12 IIIo CONCLUSIONS AND PROPOSALS FOR FUTURE WORK 14 IV. BIBLIOGRAPHY 15 iii I1

The University of Michigan * Engineering Research Institute ABSTRACT The effect of radiation on several reactions of unsaturated organic compounds was studied, The summary of experimental studies and results is as follows, The addition reaction Qf hydrogen sulfide to olefins showed a substantial effect. The effect on the reaction of hydrogen sulfide and propylene was studied at a temperature of -78o5~C, varying compositions, dose rates, and times of radiation. The results of conversions and product analysis are reported, Other studies included copolymerization of ethylene and propylene, reactions of acetylene alone and with ethylene and acetic acid and copolymerization of sulfur dioxide with allyl bromide, allyl chloride, hexene-2 and 2-methyl pentene-l1 The reactions of acetylene were not successful. The effect on other reactions were substantial and the results are included in the report, iv

The University of-Michigan Engineering Research Institute I INTRODUCTION This report covers preliminary investigations on the effect of gamma radiation on some reactions involving several unsaturated organic compounds. This work is an extension (2) of previous work done in this laboratory and published elsewhere( The addition reactions between hydrogen sulfide and propylene, hexene-l, octene-1 and decene-1 were studied with emphasis on the addition reaction to propylene. The effect of radiation on mixtures of ethylene and propylene, and reactions involving acetylene alone and with ethylene and acetic acid, and the copolymerization of sulfur dioxide with allyl bromide, allyl chloride, hexene-2 and 2-methyl pentene-1 was also studied. IIo REACTIONS INVESTIGATED Ao Olefin-Hydrogen Sulfide Reactions It is known that the addition of hydrogen sulfide to olefinic bonds takes place only under rather severe conditions, A number of workers have studied the reaction and have employed temperatures from 150~C to 750~C, various catalysts, and usually elevated pressureso Hydrogen fluoride, boron trifluoride, peroxide catalysts or silica-alumina catalyst etco are used, In most cases the yields are low, The products are primarily mercaptans and sulfides, but complex by-products are also formed-' o The addition reactions also occur under the influo (6) ence of light having a wavelength less than 3000A l The mechanism of the addition is described as one of a free radical 1

The University of Michigan T Engineering Research Institute chain and is dependent upon the preliminary dissociation of hydrogen sulfide This study was conducted to find the effect of gamma radiation on the addition reaction. 10 Preliminary Work The preliminary work was conducted to find suitable olefins and optimum operating conditions, for a more detailed studyo The olefins studied were propylene, hexene-l, octene-1, and decene-lo The reactions were carried out at -78o5~C, 0~C and ambient temperatures Glass vials were used at subatmospheric pressures, while at elevated pressures, steel reactors were usedo The reaction vessels were irradiated at a dose rate of about 40 Krep/hro for 0 to 40 hourso All the reactions were run with composition of 1:1 mol ratio of hydrogen sulfide and olefino The reactions were followed by observations of odor change, volume change, pressure change or chromatographic analysis o The reactions with hexene-1 and decene-1 were found to proceed very slowly at room temperature Octene-1 reacted slowly at -78o5~Co The reaction with propylene was the most sucessful among the olefins triedo Since propylene would be expected to give less complex products than higher olefins, it was decided to first consider the addition reaction between propylene and hydrogen sulfide 2o Further Experimental Work As reported earlier in the section on preliminary investigations, the major emphasis during the work on olefin-H2S reactions was on the propylene-H2S reaction0 The following 2

The University orf Michigan Engineering Research Institute - operating variables were selected as a result of preliminary data: Temperature - 78o5~C Composition (a) 1:1 mol ratio propylene: H2S (b) 1:1l7 mol ratio propylene: H2S Radiation Time - 0 to 40 hours Dose Rate - 40 to 80 Krep/hro At the temperature of -78,5~C, the vapor pressures of the reactants are below atmospheric pressure and hence a glass system is quite suitableo A description of the equipment follows this section. (a) Equipment and Materials The reaction vials were made out of 22 mm, diameter pyrex tubing. The upper end of the vial was constricted and a vacuum stopcock attached to the neck. The vials were approximately 8" in body length. The loading system consisted of a glass manifold with two loading lines, two lines for vials, and a vacuum lineo It is similar to the schematic drawing in Figure 6, Report Noo 1943-4-60-P (2) The reactants were of C oP grade and used as supplied by The Matheson Coo. Hydrogen sulfide and propylene have minimum purities of 99o8 % and 99o0 % respectively, These same gases were used for the chromatography standards, Pure propyl mercaptan, sulfide and disulfide were used as supplied by Eastman Kodak Cooo 3

The University of Michigan T Engineering Research Institute (b) Experimental Procedure (i) Loading All loadings were done after evacuation to about 700/$ o The loading was done by a two step condensation of the reactants. Each reactant was condensed in a graduated vial (from the gas tank) to make an exact measurement of the amount, and then transferred to the reaction vial by evaporation and condensationo This was done at dry ice temperature (-78.5~C) and liquid nitrogen temperature (-190~C)o Throughout the whole process of loading the pressure was sub-atmospheric and as far as possible, no air was allowed to enter the systemo (ii) Irradiation The reaction vials were kept at constant temperature by placing them in Dewars with constant temperature mixtures cooled by dry iceo They were placed before the gamma source and radiated for fixed amounts of time, The dose rate was measured by employing the oxidation of ferrous sulfate solution in one case (2)o This measurement was applied to find a correction factor on dose rates in air as found from charts available in the laboratoryo The correction factor comes in as a factor for shielding by the glass reactoro The dose rates in other cases were then found by applying this correction factor and the charts described (iii) Product Recovery After irradiation the unreacted materials were driven off by gradually raising the temperature of the vials from -78o5~C to room temperature0 Any remaining dissolved reactants 4

The University of Michigan * Engineering Research Institute will have a detectable effect in the analysis of the product on the chromatography unito By connecting the outlet of vials to cold traps it was made certain that no appreciable amounts of products were lost by evaporation or entrainmento The products were collected and weighedo (iv) Analysis of Products Several methods of analysis were triedO The chromatography unit was found most suitableo The na ss spectrometer and the infrared spectrometer data were fairly hard to interpreto In several cases fractionation was used as a preliminary step to further analysiso A Fisher-Gulf Partitioner was. used for analysis. The machine was operated at temperatures of 85~0 100~, and 140~ depending upon the column usedo Two types of column were triedo The first column was filled with 30-60 mesh ground firebrick on which tricresyl phosphate was depositedo The second column was filled with Tide (30-60 mesh)o Helium was used as carrier gas in all cases, Known samples of reactant gases and products were used to find the retention times for individual components in the various columns usedo 3o Discussion of Methods and Results The chromatography method for analysis of products will now be discussed. It was found that bothtrycresyl phosphate and Tide columns had respective advantages, The first column needed a temperature of 140~C for operation while the second column required a temperature of 85~C, to get suitable peakso 5

The University of Michigan T Engineering Research Institute The trailing effect was lower with Tideo However the reproducibility with Tide was lower compared to tricresyl phosphate columno This however, may be due to other experimental errors. With known samples of propyl mercaptans and propyl sulfides, the chromatography analysis always showed lower mercaptan and higher sulfide percentage (error of about 3 % ). The exact reason is not yet known. It may be due to volatilization of mercaptan, However, several other reasons are possible. A linear correlation was found between the actual percent weight of mercaptan in a known sample and the one found on the chromatography unit0 A summary of results is given in Tables I and II and Figure 1 o The data presented on the propylene and hydrogen sulfide addition reaction is only a part of the intended studyo Hence, no definite conclusions are made However, the following is indicated: Gamma radiation can induce the addition of hydrogen sulfide to olefinso The products obtained for addition reactions of hydrogen sulfide and propylene were primarily n-propyl mercaptan and n-propyl sulfide. The reaction proceeds at a moderate rate up to about 40 % consumption of hydrogen sulfide at 1:1 miol ratio of reactants and -78o5~Co G values basted on hydrogen sulfide, varied from 1800 to 95000o The lower G values may be wrong because of the presence of air It was found that the yields were low for experimental runs conducted with the presence of slight amounts of air in the 6

TABLE Io Summary of Reactions of H2S and C3H6 Made at -78,o5C and 1:1 Mol Ratio of Reactants (Millimoles H2S charged = Millimoles C3H6 charged Run Noo 174270-1 174270-2 174270-3 174270-4 - 174272-1 174272-2 Dose Rate Krep/ hr o 40 40 40 40 40 40 Dose Krep 89 160 398 600 1610 1610 Irradiation Time Min o 133 240 598 899 2430 2430 Weight of Product Gm. 0o831 1o436 1.056 1.323 5o576 3 867 Analysis of Product Propyl Mercap wt a 60 80 64 75 61 7605 Propyl Sulfide Wt ~ 40 20 36 25 39 23o5 Millimoles of Mercap tan in Product 6054 15e08 8083 13o26 44o66 38083 169) Millimoles of Sulfide in Product 2 81 2.43 3,24 2.65 18.38 7o68 Percentage Conversion of S 5,5 10o4 7.1 904 37 o2 27o5 Co v G 8,280 8,820 2,430 2,130 3 150 2,330 -1 r C: ro _t* m - 0 S~ n =* OQ* 0) 174272-3 174272-4 174273-1 174273-2 174274-1 174274-2 174274-3 174274-4 174282-1 174282-3 174282-2* 63 63 63 63 80 80 80 80 80 80 80 127 1530 355 1040 40 80 902 2560 166 166 121 1458 338 998 30 60 678 1920 125 125 4 070 5,153 50687 6 285 3.980 4.559 5o921 6,177 4 o029 20825 0 308 67 61 65 64 74 67 61 6504 80 8002 89 33 39 35 36 26 33 39 34o6 20 19,8 11 35098 41 23 48o58 52o65 38o67 40o10 47 o42 53 04 42031 29075 3059 11o28 17o02 16o80 19,24 8075 12o72 19o53 18008 6o81 4o72 24o5 3405 39 o5 4205 2800 31o2 3905 4200 29o0 2003 30,700 2 900 14 800 5,680 m 3 3m Sr 0 95,500 539200 2 5,9960 2,240 235700 - 16, 900 19860 =?I+ 166 125 0 28 Note Reactor radiated with slight amount of air inside.

TABLE II, Summary of Reactions of H2S and C3H6 Made at -78.5~C and with Varying Ratios of Reactants Millimole s charged PropyRun Noo H2S lene 174255-1 176 148 174256-A 122 75 174256-B 212 124 174256-C 154 91 174258-1 156 91 174258-2 160 95 174258-3 156 91 174258-4 170 101 Ratio (mcie) H2S: Propylene i 1 638O1 lo63 1 1,7:1 1.7:1 lo71:1 1o7:1 1.71 1 1,68:1 Dose Rate Krep/ hr. 40 40 40 40 40 40 40 dark run Dose Krep 280 660 938 162 120 240 400 0 Irradiation Time Mino 420 989 1398 243 180 360 600 7200 Analys Wt Prodt of ProPro- pyl duct Merco gmo wt 00426 3.178 0.966 Trace 1.089 2,963 0 000 76 66 71.5 74.8 76.1 3is of tct Prop Sulfide wt o 24 34 28.5 25,2 23.9 4.25 27.6 9.09 10.7 29.6 0.865 9.15 2034 2.35 6,02 Mercap- Sultan fide in in Pro- Produc t, duc t, Milli- Mlimole mole Percentage Conversion of H2S 4o2 1703 705 802 20.9 =I cr ro - C m 3 f4 -+ -**\ a 4I 3 doQ 0 3 =1 0 rm 3 SQ 3 oro m <^ -r 3* 7ro;v w ro =) u, n 3-1 r+ C rt fl

Ld 0 C en 3 In 4 -0 _. a Io _. S:r _. rn =r 3D) 3 0 M _Q 3 UI AS ro;m 5 _. 0 2) In n r+ rl+ ro 1200 1400 1600 RADIATION TIME, MIN Figure 1o Addition of Hydrogen Sulfide to Propylene

The University of Michigan * Engineering Research Institute reactoro This might indicate that the lower G values resulted from insufficient evacuation of the reactor before loadingo Bo Miscellaneous Reactions 1, Ethylene-Propylene Copolymerization Attempts were made to copolymerize ethylene with propylene in the vapor phaseo After unsuccessful attempts at 20~C in glass vials one run was made at 2000 psig and 120~C in a steel bomb which yielded a viscous liquid product. The conditions are summarized in Table IIIo Five runs differing only in the concentration of the reactants were made in the glass vials at 110 psig and 20~Co The vials, made of heavy-wall glass tubing, were first evacuated, then loaded at 20~C to 100 psig with the desired proportion of ethylene and propylene, and finally cooled to -78~C before being sealedo No reaction was observed during any of the runs in the glass vialso In a further attempt to obtain a reaction in this system, one run was made in a high pressure Aminco bomb at initial conditions of 2000 psig and 120~Co The bomb was loaded with an equimolar mixture of ethylene and propylene to a pressure of 740 psig at 20~C and heated to 120~C before irradiation* A temperature of 100-120~C was maintained during the runo At the end of 140 hours of irradiation the pressure had dropped to 1850 psig at 120~Co A product consisting of 14.7 gmo of a viscous liquid was obtainedo No analysis was made of the liquid or gaseous products of any of the ethylene-propylene runso 10

TABLE IIIo Effect of Radiation on Mixtures of Ethylene and Propylene Conposition, mol / Ethylene Propylene Vial No Total Pressure Charge psig Temp 0~ Radiation Rate Time Krep/ hrs. hro __ Results I -m _. - (3 O =r mQ 0 105 cco 100 2 0 3 50 100 50 75 25 105 cc. 105 cc. 105 cco 105 cc. 110 110 110 110 110 20 20 20 20 ^,20 60 60 60 45 45 45 45 No observable products 4 25 HH 5 75 60 45 Aminco bomb 50 50 444.5 gmis 2000 psig (0 hrso 120~C) 100120 15-20 140 Viscous liquid 14.7 gmso L 1850 psig (140 hrs. 1200C) m 3 m~ -r 5 -1 r. r+

The University of Michi-gan * Engineering Research Institute 2o Acetylene Reactions Several runs with acetylene in various systems were made in an attempt to obtain radiation induced reactionso Reactions involving acetylene alone, acetylene with ethylene, and acetylene with acetic acid were attemptedo The conditions of the five runs are given in Table IVo All the reactions were conducted in a 1500 cc high pressure Aminco bomb fitted with a 340 psig blow-out disco The pressure before and after each run was noted and the vessel was examined for evidence of productso No reaction was detected in any of the runs but since the initial weight of acetylene in the bomb was very small, no definite conclusions can be reachedo 3o Olefin-Sulfur Dioxide Reactions The work of Bray (1) on polysulfone production is being extended0 Several preliminary runs have been made using three compounds which had been referred to as inhibitors by earlier workerso These compounds, allyl bromide, hexene-2, and 2-methylpentene-1 have all been found to copolymerize with S02 at appropriate temperatures under gamma radiation. Allyl chloride, which is known to react with S02, copolymerized rapidly even before irradiation. This was probably due to impurities in the systemo Neither allyl bromide nor 2-methylpentene-l showed any noticeable reaction when irradiated at 20~C but both gave appreciable yields of polymer at -78~Co One of the two hexene-2 runs showed some polymerization during the warming up period between loading at -78~C and irradiation at 20~Co There was, however, no apparent additional reaction induced b'y the radiationo The other sample 12

TABLE IV Effect of Radiation on Acetylene Reactions Run NOo Components Pressure psig Temp o ~C Radiation Rate Time Krep/ hrs. hr o Remarks _, m ro O 3m m, 3 1 Acetylene 25 - 25 15-20 168 No observable products9 fishy smell CA 2 Acetylene-dissolved in 25 cco of acetone 3 suspended on asbestos 4 Acetylene 25 mol ~ Ethylene 75 mol, 5 Acetylene gas phase 1500 cc. bomb connected to a glass vial containing 5 cco acetic acido 10 25.- 25 - 25 15-20 100 No observ-able products, 100 No observable productso 85 No observable productso 40 No observable productso 85' 25 15-20 10 - 25 15-20 m 3 rI m, -I o r r+ r.

The University of Michigan * Engineering Research Institute was irradiated at -78~C and showed no obvious reaction even after standing at room temperature for several dayso The vial -containing this sample has not yet been opened and it is possible that some polymer is present but dissolved in the monomer-S02 solution0 Attempts were also made to polymerize allyl chloride, allyl bromide, and 2-methylpentene-l alone, without the presence of SO20 Only in the allyl chloride run was any evidence of reaction visibleo III CONCULSIONS AND PROPOSALS FOR FUTURE WORK The results obtained for the addition reaction of hydrogen sulfides to olefins show a substantial' effect of radiation on the.reactiono The effect on the propylene-hydrogen sulfide system will be studied further from the viewpoint of kinetics and mechanism0 Other olefins may also be investigatedo No further work is planned on reactions involving acetylene or on ethylene-propylene copolymerization. The work on polysulfone reactions is being extended to include diolefins and cyclo-olefinso Kinetic studies are planned for a somewhat later date~ 14

The University of Michigan Engineering Research Institute IVo BIBLIOGRAPHY (1) Bray, B. Go, "The Effects of Gamma Radiation on Some Polysulfone Reactions", Engo Reso Inst., Univo of Mich, Ann Arbor, (1957)o (2) Martin, J. J., Anderson, L, Co et alo "The Effect of Gamma Radiation on Chemical Reactions", Progress Report No. 1943:4-60-P Engo Res, Insto Project M943, Univ. of Micho Ann Arbor, March, 1956.. (3) Ibid, Progress Report Noo 1943:4-70-To June, 1956, (4) Schulze, Wo A., Lyon, J. Po, and Short, G. Ho, "Synthesis of Tertiary Mercaptans" Ind. & Engro Chemo 40, 4308 (1948)o (5) Ibid, Ind. & Eng, Chem, 40, 4308 (1948) (6) Vaughn, W. E. and Rust, F. F., "The Photoaddition of Hydrogen Sulfide to Olefins" Journal of Organic Chemistry 7, 472-476 (1942)o 15