The solvolysis of silicon substituted 2-silylpyridines by alcohols and by water

Abstract

2-Dimethyl-, 2-triethyl-, and 2-triphenyl-silylpyridine react with hydroxylic solvents in a similar manner to 2-tri-methylsilylpyridine. The rates of methanolysis are in the order dimethyl- > trimethyl- > triphenyl- > triethyl-silylpyridine. For the alkyl substituents, steric or electronic effects could be the dominant factor. The triphenyl compound is less reactive in this than in other nucleophilic substitutions, probably because the cyclic activated complex for this reaction will involve crowding of the phenyl groups. Formation of a cyclic activated complex is supported by the enthalpies and entropies of activation.