Effect of 4-t-butyl and other 4-substituents on rate constants for reactions of 1,1-disubstituted cyclohexanes and piperidines. 4-t-Butyl derivatives as valid reactivity models in the kinetic method of conformational analysis of cyclohexanes

Abstract

A 4-t-butyl group (or a 4-methyl group) has no effect on the rate constant for ethoxy-exchange in diethyl cyclohexane-1,1-dicarboxylates; a 4-phenyl group, however, increases the rate constant by more than 50%. By contrast, both 4-alkyl and 4-phenyl groups increase the overall rate constants for nucleophilic displacement by thiopholate anion at the benzyl methylene groups in 1-benzylpiperidine benzobromides, a 4-t-butyl group approximately doubling the value. The significance of these results in relation to the validity of the usual kinetic method for conformational analysis of cyclohexanes is discussed.