AN ABSTRACT OF THE THESIS OF j-9jç for the- S.___in_ahenaity-___ (Nam) (Degree) (Majrr) Date T1esjs _____ Tit1e_A tud oLtbe_E1 trQ an Aqueous Solution - Abstract Approved: (jor Professor) An investigation hes been niade of the electrolysis of an aqueous solution of hydrochloric acid. in the presence of ethylene chiorohydrin In an electrolytic diaphra cell into which ethyiene was being intro ducod at a rate equal to its rate of absorption into the electrolyte. Ethylene chlorohdrin has been prepared in tho cell described. A possible reactIon niechanisni was proposed. Th3 variables considered over a limited range wore hydrochloric acid concentration, ethylene chloro hydrin concen:ratIon, and current density at the anode. Evidence shows neither the concentration of the hydrochloric acid or the concentration of ethylene hlorohydrIn Is independent of the other in liniit Ing the concentration of eth . ylene ehlorohydrin att1n able before the formation of ethylene chloride sets in extensively. Higher current. densities favor higher rates of electrolytic oxidation of ethylene. A STUDY OP TEE ELECTROLYSIS OP AN AQUEOUS SOLUTION OP HYDROCHLORIC ACID IN TEE PRESENCE OF ETHYLENE CHLOROHYDRIN AND ETHYLENE by WILLIAM EARL ROAE A THESIS submitted. to the OREGON STATE COLLEGE in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1942 PPPfl1T1 In Charge of Major Chairman of School Grad.uate Committee ACITOVvIEDGMEET The author is deep1 grateful for the help and. suggestions of G. C. Ware and. G. W. Gleeson. An appreciation is due the Department of Chemical Engineering, Oregon State College, which supplied. sorne of the materials used in this investigation, and. the Department of Chemistr3, Oregon State College, which supplied the necessarì apparatus and chemicals. W. E. R. TABLE OP CONTENT8 Page Introductiou . , . i Apparatuo . s . e s I I I S I I I S a Operational Prooed.ure . 10 i n.aiytioal Prooednre . , . i 12 D180U8810]2 . , . 14 P late I .......,............................ 18 Plate I]: ................................... 19 Plate III ......................,.......... 20 Oonolusion . , . s s . i i . s s s . s s 21 Bibliography . 22 Appendix . 23 A STUDY OP THE ELECTROLYSIS OP AN AQUEOUS SOLUTION OP HYDROCHLORIC ACID IN THE PRESENCE Q1' TYLENP CEIOROHYDRIN MID ETHYLENE INTRODtJCTI ON Ethylene ohiorohydrin is an important building block in today's synthetic organic chemical industry. It finds use as an intermediate in the production of ethylene glycol, ethylene oxide, and. their derivatives, anesthetics, extraction solvents, hardenable resins, etc. Although Wurtz (1) discovered ethylene chiorohydrin in 1b59, the literature has failed to reveal much about its commercial production, the only method of technical signif- icance being the interaction of ethylene with hypochlorous acid or chlorine water. Ethylene chiorohydrin is produced by the addition of hypoohlorou acid to ethylene. Hypochiorous acid. has been used. in the form of calcium hypoohiorite (2), sodium hypo- chlorite (3), or aqueous hypochiorous acid. prepared by the (1) urtz, Ann., 110, 125, (1859); Ellis, Carleton, The Chemistry of PetroTm Derivatives, The Chemical CataT3 Co., Inc., New York, (1934); Carius, Ann., , 197, (1863). (2) Prahm, E. D. G., Reo. Tray. Onim., 50, 261-7, (1931); O. A., 25, 2690, (1931); Norris, O. A., 13, 2740, (1919). (3) Prahm, E. D. G., loo. cit.; Essex & Ward, U. S. Pat. 1,594,608; C. A., 20, 3170, (1926). 2 interaction of chlorine and. water (4). Irvine and. Haworth (5) proposed. the use o± a 0.1% cupric chloride solution as a catalyst. If ethylene is passed. into an electrolytic cell where a sodium chloride solution is being electro- lyzed., ethylene ohiorohydrin is formed (6). Goinberg (7), in his extensive investigation of the system of chlorine, water, and. ethylene, in speaking of the reacti on EOH + 012 HOOl + HOi + + 0H2:0H2 0H2:0H2 'i. 002: 0H201 HOCH2 0H201 states, "........ the principal factor likely to determine the ratio of ethylene chloride to chiorohydrin must lie, after all, in the relative velocities of the two reactions, ...... between ethylene and chlorine on the one hand, and. between ethylene and h,ypoohlorous acid on the other. In case the second reaction occurs with greater velocity than the first, then we should be dealing with a (4) Prahm E. D. G. loo. cit.; Gornberg, M., J. 0. 5., ±., 1414, f1919); O. A., 13, 2369, (1919). (5) frahm, E. D. G., 1cc. cit.; Irvine & Hawortb, U. S. Pat. 1,496,675; 0. A., 18, 2345, (1924). (6) McElroy, K. P., U. 8. Pat. 1,253,617; 0. A., 12, 703, (1918); Haddan, R., Brit. Pat. 140,831; J. Soc. Chem. md., 39, 426, (1920). (7) Goniberg, M., J. A. 0. 5., 41, 1414, (1919). ca$e of mobile eq,nilibrium, and. the principal product would be chlorohydrin, ...... provided that care be taken to maintain stirring, so that ethylene reacts on1i with the chlorine in solution and not with the gaseous chlorine. Experinents proved that such is actualli the ease." Ex- periniental evidence show$ that the formation off ethilene chlorohydrin in this reaction continues practically un- hindered. up to chlorohyd.rin concentrations of 7 to 8% (8), above which concentration the formation of diohiorides and higher chlorides proceeds at a rapidly increasing rate. Attempts to remove the h,ydrochloric acid Îormed in the reaction by the addition of calcium or sodium carbonate retards the formation of ohlorobydrin. Removal of the chloride ions by precipitation methods has, in some instances, nearly stopped the formation of the chlorides, leading investigators to believe that the chloride ion concentration is the controlling factor in causing these undesirable side reactions (9). Shilov (10) states that the hydrogen ion acte as a catalyst in the formation of ethylene chiorohydrin. (8) Gomberg, M., loo. cit.; Bozza & Marnoli, Giori. Ohim. md. e Applicata, 12, 283-92, (1930); Gleeson, G. W., Private Ooiumunication, (1942). (9) Gleeson, G. W., Private Communication, (1941). (lo) Shilov, E. A., J. Chem. md.. (Moscow), 5, 1273-6, (1928); 0. A., 23, 2973, (1929). Frahm (ii) refutes the theor3 of the direct addition of hypochlorous acid. to ethi1ene by stating the reaction as an oxidation of ethy1ene to ethylene oxide followed by addition of hydrochloric acid to form ethi1ene cillero- hydrin. He supports his theory by the fact that formation of ethylene chlorohd.rin is catalyzed by copper, nickel, cobalt, and iron salts which also accelerate the decompo- sition of hypochiorous acid into oxygen and hydrochloric acid. further support is given by the formation of both isobutylene oxide and trimethy]. carbine]. by passage of isobutylene into a solution of iodine and. potassium iodide (12). If this be the case, then any reaction, chemical or electrolytic, which oxidizes ethylene to ethylene oxide should, in the presence of hydrochloric acid, yield ethyl- ene chlorohyd.rin, other factors permitting. owever, in. aqueous solutions of hydrochloric acid. ethylene glycol is the product of the hydrolysis of ethylene oxide. omberg (7) indicates that ethylene chiorohydrin in concentrations up to i normal is of least influence in limiting the attainable concentration of ethylene choro- hydrin, and. hydrochloric acid up to 2 normal concentration does not hinder the exclusive formation of ethylene chioro- (li) 'rahm, E. D. G., loo. cit.; C. A., 25, 2690, (1931). (12) B'rahm, E. D. G., loe. cit.; Pogorzelski, Chem. Zentr., I, 797, (1905). hrin, but 2 nornial hroeh1oric acid in the presence of 3% eth3lene chlorohydxin, or a nornial concentration of each simu1taneous1 present favors the formation of ethylene chloride rather than ethylene chiorohydrin. Bozza and Marnoli (is) state that the action of chlorine on ethylene ohlorohydrin becomes appreciable only when the concentra- tion of the latter becomes one molar, and that in the presence of pure hypoohiorous acid the velocity of the chiorohydrin forming reaction is independent of the con- centration of the acid. over a wide range. It is with these facts in mind that an investigation of the electrolysis of an aqueous solution of hydrochloric acid and. ethylene chlorohyd.rin in the presence of ethylene has been carried out, with the intention of obtaining evi- dence substantiating, or not substantiating some of these statements, and. possibly suggesting a process whereby the commercial production of ethylene ehlorohydrin in an elec- trolytic cell might be feasible. (13) Bozza & Mamoli, Giorn. Chini, md. e Applicata, 12, 283-92, (1930); Brit. Chem. Abs., A, 1269, (1930); 11Ts, Carleton, loe. cit., 489. APPARLTUS The electrolysis was carried, out in a cell designed. with the following intentions; separation of anolyte and catholyte, removal of hydrogen gas from the cathode, sealing against gas loss in the anode compartment, re- circulation of ethylene ana chlorine, thorough mixing of ethylene with anolyte, temperature control, and, low, variable current density. The cell, as shown in figure 1, consisted. of an 800 cc pyrex beaker (a) of dimensions approximately 6 x covered with a glued-up cork stopper (b) of proper dimen- , a ])JT sions 3" x porous cup diaphragm (e) , a cathode cooling coil (d) , a platinum wire spiral cathode (e) , a four inch cylindrical platinum screen anode (f) of one inch diameter, a gas recirculation pump and. stirrer (g) eq,uippeö. with a mercury seal (h), an anode cooling coil (i), an ethylene inlet and sampling opening (j), a hydrogen outlet (k) , and. a thermometer (i). ,,s an added. precaution against gas leakage, the cork cover was held. on with heavy rubber bands said the whole cover sealed with paraffin. The ethylene gas was supplied, to the celi under a slight pressure from a twelve liter gas reservoir. The gas was forced into the cell by a small and. nearly constant hydrostatic pressure supplied by an automatic valve ar- Isvel 4 Iectrolytic Cell fig. i rangement (shown in figure 2) sensitive to pressure changes of one millimeter of mercury. The stirrer and gas recirculation pump was desigûed.