Studies in decarboxylation. Part IV. The effect of alkyl substituents on the rate of gas-phase decarboxylation of some βγ-unsaturated acids

Rates of gas-phase decarboxylation of seven α-dimethylated βγ-unsaturated acids have been measured at a series of temperatures. Simple changes in alkylation alter the rate by up to 200-fold. The activation parameters for these reactions suggest that the reaction is only slightly affected by the electric effect of the alkyl groups; these groups exert a much larger effect by straining the double bond.