Free radical substitution in aliphatic compounds. Part XXII. The gasphase chlorination of chlorocyclopentane and methylcyclopentane

Abstract

The chlorination of chlorocyclopentane and methylcyclopentane has been studied in the gas phase over the temperature range 70–200°. The trans to cis ratio of the products derived from chlorine atom attack at the 2-position was 16:1 for 1,2-dichlorocyclopentane but only 1·5:1 for 1-methyl-2-chlorocyclopentane. This different trans/cis ratio is consistent with the idea of an interaction between the half-filled π-orbital of the 2-chlorocyclo-pentylradical and the 3p_z orbital of its substituent chlorine atom. Alternative explanations are considered and found to be less satisfactory.