Free-radical substitution in aliphatic compounds. Part XXV. The gas-phase chlorination of chlorocyclobutane and methylcyclobutane

Abstract

The chlorination of chlorocyclobutane and methylcyclobutane has been studied in the gas phase over a wide temperature range. Competitive experiments with 1-chlorobutane have shown that unlike unsubstituted cyclobutane, chloro- and methyl-cyclobutane are more reactive than the corresponding cyclopentyl and cyclohexyl derivatives. This difference between substituted and unsubstituted cyclobutanes is attributed to release of strain in the formation of the substituted cyclobutyl radical. The trans to cis ratio of the 1,2-dichlorocyclobutane and the 2-chloro-1-methylcyclobutane products at 100° were 6·8:1 and 1·2:1 respectively. These results are consistent with ideas concerning the trans:cis ratios discussed in previous papers.