iiugust, 1960
RADIOLYSIS OF CHLOROFORM AND CARBON TETRA CHLORIDE
1023
RADIOLYSIS OF CHLOROFORM AXD CARBON TETRACHLORIDE BY T. H . CHES, K. I'.WOSGASD
17.
J. JOHSSTOS
Department of Chemzstry, University of Louisville, Louisville 8, Kentucky Recezved February 8 , 1960
Irradiation of pure degassed CHC13 with cobalt-60 gammas results in the formation of HC1 with G ~ c = l 11.4 j=0.4. C2Cla and a liquid wnich boiled a t approximately 165' also are produced. KO Hz or Clz was observed and these must be formed with efficiencicbs of GH, < 0.003 and G ~ I < , 0.002. The irradiation of pure degassed CClr results in the formation of C1: with G(cI,, = 0.66 I!= 0.4. -4solid which is essentially pure CrC16 is the only other observed product. X o Cl, is produced in mixtures of CHCl2 and CCla in which N C H CisI ~greater than i Z0.008 a t a dose of 1.06 X 1021e.v. per gram of mixture. HC1 yields from CC1.t-CHC13 mixtures indicate that an important part is played by energy transfer in this system.
Schulte, Suttle aiid Wilhelm' have studied the yinduced decomposition of CHC13 in t'he presence of 02. Clz, HC1, C0Cl2 and oiie or more peroxides were the mitjor products. X o definite conclusion regarding the mechanism of the reaction could be made. Their results! however, suggested the possible use of chloride production from t,his system as a dosimeter. Hill2 studied the gas phase decomposition of puze CHC13 in a Row system by light of 1935 to 2100 A. He observed only HC1 as a product, the yield corresponding to a quantum yield of 4. He proposed the series of reactions 1 t'hrough 4 to explain his result's. CHCla --+ CC1, + H (1)
H?Analysis.-Attempts t o measure Hz produced in the reaction were made by the Saunders-Taylor t e c h n i q ~ e . ~ Radiation Source.-Irradiations a ere carried out at 22 f 2" in a cobalt-60 source of the type described by Burton, Ghormley and Hochanade1.j This source contained chambers affording dose rates of 404, 240 and IT0 kr./hr., as determined on March l , 1959, on the basis of Fe +*-Fe + 3 dosimetry. The experiments were carried out during the period from December, 1956, t o January, 1960, and appropriate corrections were made for intensity changes over this period. The source was so designed that the radiation field in the chamber of highest intensity was everywhere uniform to vithin 37,. The Pnergy distribution ivtts less uniform in the chambers of lower intensity.
Results Radiolysis of CHC13.-Production of HC1 from pure degassed CHC13is directly proportional t o the amount of energy absorbed to at least 2 X lo2' e.v. CHC18 +CHCl, + '21 (2) per gram of CHC1, aiid is essentially independent -3 + CHCla +CHC12 + HC1 (3) C1 + CHCln +cC13 + HC1 of the intensity. The G-value for HC1 production (4) ~ ) 11.4 i 0.4. Evaporation of the CHCl? Schulte3has studied the y-induced decomposit'ion is G ( H C = from a sample which had been subjected to a total of CC1, and the simultaneous exchange of C1 hetween Clz arid CCL,. Clz was produced li-ith G(c1,) = dose of 2.5 X l o z 2e.\'. per gram left a solid and a 0.80 and C:C16, the only other observed product, liquid as a residue. The liquid phase (containing a was formed n-ith essentially the same yield. The G- m a l l amount of the disiolved solid) boiled a t 165'. value for the 7-induced exchange, G,, = 3.5, was The complexity of the infrared spectrum of the liquid phase preyented the definite characterization assumed t'o equal G(c1)and Gcccl,). of any component. The spectrum and the boiling We have measured the HC1 production from degassed CHCl,, the C12 production from degassed poiiit, however, suggest the presence predominantly CC14,and the HC1 product'ion from degassed CC14- of 2-carbon compounds coiitaining C-H and C-C1 linkages. The solid upon resublimation exhibited C.HCl, mixtures. a sealed tube transition temperature of 180.3". An Experimental infrared spectrum of the solid showed peaks identiReagents.~-"Bakt,r Analyzed" reagent grade CI€CI,
