APRIL1965
NOTES
showing a correct analysis for Cl8HZ2.Its infrared spectrum waa identical with the authentic sample; infrared maxima (liquid film): 3080, 3050, 2950, 2880, 1615, 1500, 1455, 1032,905, 746, and 697 cm.-l. A minor fraction, n z 4 1.5453 ~ (0.3 g.), appeared to be isomeric diphenylhexane(s); infrared maxima (liquid film): 1380 cm.-l. G.1.c. (PEG 20,000) analysis of the lower boiling fraction gave three peaks in the ratio of 1 : 14:26. The components were separated by preparative g.1.c. (PEG 20,000, 200'; Nz,120 cc./min.) and were identified as described below to be n-hexylbenzene, 1,4dimethyltetralin, and l-ethyltetralin, respectively. When the reaction was conducted at 80-83" for 6 hr., distillation of the reaction products gave two fractions: b.p. 111-112' (26 mm.), 6.6 g., and b.p. 135-148' ( 1.5 mm.), 3.1 g. A sample (1 g.) of the higher boiling fraction waa purified by chromatography on an alumina column to afford 0.5 g. of pure ~ which showed a correct analysis 1,64iphenylhexane, n Z 61.5437, for ClaHZ2,and 0.5 g. of isomeric diphenylhexane(s), 12% 1,5446; infrared maxima absorption (liquid film): 1380 cm.-l. G.1.c. of the lower boiling fraction gave three peaks: n-hexylbenzene, 1,4-dimethyltetralin, and l-ethyltetralin in the ratio of 14:6.2: 29. The n-hexylbenzene fraction showing a correct analysis for C12H18had an infrared spectrum which waa identical with that of authentic sample'; infrared maxima (liquid film): 2970,2880, 2810,1610,1500,1450,1380, 1030,745,725, and 700 cm.-'. The 1,4-dimethyltetralin fraction showed a correct analysis for C12H16had an infrared spectrum which was identical with that of authentic 1,4-dimethyltetralins; infrared maxima (liquid film): 3130,3060,2990,2910, 1960, 1930, 1850,1815,1715,1615,1590, 1500, 1470, 1450, 1380, 1330, 1025, 780, and 750 cm.-l. Dehydrogenation of this fraction (0.1 g.) by heating with 0.04 g. of sulfur a t 230-240" for 2 hr. gave 1,4-dimethylnaphthalene which was identified in its picrate form, m.p. 142" (lit.s m.p. 143'), showing a correct analysis for C18Hl6N30,. The l-ethyltetralin fraction also showing a correct analysis for C12H1e had an infrared spectrum which was identical with the one of authentic l-eth~ltetralin~;infrared maxima (liquid film): 3130,3070,2990,2910, 1960, 1930, 1850, 1810, 1610, 1590, 1500, 1460, 1380, 750, and 730 cm.-.' trans-l,2-Dichlorocyclohexane,b.p. 80-82' (25 mm.), n z l . s ~ 1.4898, was prepared by the method of Kharasch and Brown" from cyclohexene and sulfuryl chloride and its trans configuration was established by comparison of infrared data with published This preparation gave a single peak on g.1.c. n's-l,2-Dichlorocyclohexane.-The reaction of 2-chlorocyclohexanolzowith thionyl chloride in the presence of pyridine according to the method of Stevens and Grummital gave a mixture of cis- and trans-1,2-dichlorocyclohexanes(g.1.c. showed two peaks in the ratio of 3: l ) ,from which pure cis isomer waa obtained by repeated fractionation, b.p. 84-92' (17 mm.), n m . s ~1.4960. This sample gave a single peak on g.l.c., the retention time being 1.93 relative to trans-l,2-dichlorocyclohexane. cis- and trans-l,4-Dichlorocyclohexanes.-This mixture, b.p. 72-80' (12 mm.), was prepared by the method of Kwestroo, Meijer, and Havinga,12 and g.1.c. showed two major peaks with retention times of 1.25 and 1.33 relative to trans-1 ,a-dichlorocyclohexane. Upon cooling, the crystalline trans-1,Pdich~orocyclohexane, m.p. 102' (lit.13 m.p. 102-102.8'), was obtained and its relative retention time on g.1.c. was observed aa 1.33. Izomerization of trans-l,2-Dichlorocyclohexane.-A mixture of 50 g. of trans-l,2-dichlorocyclohexane,8.9 g. of aluminum chloride, and 150 ml. of carbon disulfide was stirred a t room temperature for 10 hr. The dark reaction product was decomposed with ice-water and acidified with hydrochloric acid; the solvent was removed by steam distillation. The residue waa taken up in benzene and the benzene layer was washed and dried (CaCh). Evaporation of benzene followed by distillation in vacuo gave a colorless oil, b.p. 58-60' (9 mm.), nZ1D1.4907, which weighed 28.2 g. and showed a correct analysis for CeHl&lz. (18) M. S. Kharasch and H. C. Brown, J . A m . Chem. SOC.,61, 3432 (1939). (19) P. Laeboe, J. J. Lothe, and K . Lunde, Acta Chem. Scand., 11, 1677 (1957). (20) M. 5. Newman and C. A . VanderWerf, J . A m . Chem. Soc., 67, 235 (1945). (21) H . C. Stevens and 0. Grummit, ibid.. 79, 4876 (1952). (22) W . Kwestroo, F. A. Meijer, and E. Havinga, Rec. trau. chim., 78, 717 (1954).
1305
The g.1.c. data are given in Table I and the n.m.r. spectrum (recorded on Varian-A60 in carbon tetrachloride solution using tetramethylsilane aa an internal reference) had two multiplets whose chemical shifts were 1.5-2.5 and 3.8-4.5 p.p.m., respectively. No methyl signal waa observed. In another run, the corresponding fraction (26.4 g.), b.p. 6077' (12 mm.), was redistilled and the lowest boiling fraction, b.p. 65-69" (11 mm.), was cooled at -35" in a solution of 50 ml. of n-pentane. Thus ca. 1 g. of colorless crystals melting a t 102-102.5' after recrystallization from ethanol was obtained. Mixture melting point with authentic trans-1,4dichlorocyclohexane showed no depression and the infrared spectra were superimposable.
A Novel Telomerization Process DONALD R. NAPIER Petrochemical Research Division, Continental Oil Company, Ponca Czty, Oklahoma Received October 13, 1964
Reaction of oxalyl chloride with olefins is reported to occur only in the case of certain di- and trisubstituted ethylenes. ln2 These particular reactions result in replacement of an ethylenic hydrogen with the chloroformyl group and apparently occur by an ionic mechanism. Although oxalyl chloride undergoes homolytic decomposition under relatively mild condition^,^ there are no reports of a free-radical addition to the carboncarbon double bond. A Co60-catalyzed reaction between ethylene and oxalyl chloride was discovered in these laboratories during the course of a general investigation of radiation promoted telomerizations. I n the first of several preliminary experiments, an equimolar mixture of oxalyl chloride and ethylene (500 p s i . ) was irradiated 41 hr. a t lo5 rep/hr. and 25". Analysis (g.1.p.c.) indicated two major products: the 1 : l (G = 20) and 2:1 (G = 70) telomers C1(C2H4).COCl; other products including the 3 : 1 telomer were formed, but these totaled less than 1% of the combined 1: 1 and 2:1 telomer yields. Surprisingly, and in contrast to the broad distribution of products predicted for a "normal" telomeri~ation,~ the 2 : l telomer was the sole major product a t low (e.g., 99 wt. % pure by g.l.p.c., were obtained from commercial sources. Pure 2: 1 and 3: 1 ethylenecarbon tetrachloride telomers were hydrolyzed with aqueous SUIfuric acid and after purification the resulting a-chloro acids were treated with oxalyl chloride to give 5-chloropentanoyl chloride, (9) C / . ref. 4; also F. W. Mellows and M. Burton, J. P h w . Chem., 6 6 , 2164 (1962). (IO) Mixtures of liquid and solid products which are presumably high molecular weight telomers [see Japanese Patent 7880 (1963) ; Chem. Abstr., 59, 13828 (196411 uere obtained on irradiation of dense 0.5-1.5:1 phosgeneethylene mixtures. Only trace amounts of the 1 : 1 (0
