G. Olah, J. Bollinger, C. A. Cupas
May 1, 1967
Citations
0
Influential Citations
44
Citations
Journal
Journal of the American Chemical Society
Abstract
1-Methyl-1-chlorocyclopentane, cyclopentylcarbinyl chloride, a n d cyclohexyl fluoride (chloride, bromide) i n SbF5-S02 solutions at -60’ gave a stable solution of the 1-methylcyclopentyl cation. T h e same ion is also formed when 1-methylcyclopentanol or cyclohexanol were dissolved in FSO3H-SbF6 solutions. I-Methylcyclopenteneandcyclohexene are protonated i n HF-SbFs-SO2 or FSOaH-SbF5-S02 solut ionto the 1-methylcyclopentyl cation, which is a lso formed by hydride abstraction from methylcyclopentane and cyclohexane i n FSOSH-SbFs solution. T h e structure of the 1-methylcyclopentyl cation was investigated based on its nmr spectrum. he acid-catalyzed isomerization of methylcycloT pentane and cyclohexane has long been recognized and studied and has provided much useful information concerning the carbonium ion chain mechanism f o r hydrocarbon isomerization. 4 , 5 In terms of product (1) Part XXXIII: G. A. Olah and J. M. Bollingrr, J . Am. Chem. Soc., in press. (2) For a preliminary report see G. A. Olah and M. W. Meyer in “Friedel-Crafts and Related Reactions,” Vol. I, G. A. Olah, Ed., Interscience Publishers, Inc., New York, N. Y., 1963, p 645. (3) (a) National Science Foundation Postdoctoral Research Investigator, 19661967. (b) National Institutes of Health Postdoctoral Research Investigator, 1966-1 967. (4) C. D. Nenitzescu and I. P. Cantuniari, Ber., 66, 1097 (1933). ( 5 ) For reviews see (a) H. Pines and N. E. Hoffman, “Friedel-Crafts and Related Reactions,” Vol. 11, Part 2, G. A. Olah, Ed., Interscience Publishers, Inc., New York, N. Y., 1964, Chapter 28; (b) F. E. Condon stability, cyclohexane is favored. The equilibrium mixture at 25” consists of 77% cyclohexane and 23% methylcyclopentane.6 In terms of carbonium ion stability, however, the t e r t i a r y m e t h y l c y c l o p e n t y l cation I should be favored over the secondary cyclohexyl cation 11. No good estimate is available concerning either the relative energy differences between these two and P. H. Emmett, Ed., “Catalysis,” Vol. VI, Reinhold Publishing Corp., New York, N. Y. 1958, Chapter 2. 16) A. L. Glasebrook and W. G. Lovell, J . Am. Chem. Soc., 61, 1717 (1939), reported in accordance with ref 2 that the equilibrium mixture at 25” consists of 77% cyclohexane and 23 % methylcyclopentane. D. P. Stevenson and J. H. Morgan, ibid., 70, 2773 (1948), found the equilibrium favors cyclohexane at lower temperatures, the amount of rnethylcyclopentane increasing with temperature. Journal of the American Chemical Society 89:ll May 24, 1967 D ow nl oa de d by T A R B IA T M O D A R R E S U N IV o n Ju ly 1 6, 2 00 9 Pu bl is he d on M ay 1 , 2 00 2 on h ttp :// pu bs .a cs .o rg | do i: 10 .1 02 1/ ja 00 98 7a 03 4