The influence of carbon-carbon multiple bonds on the solvolyses of tertiary alkyl halides: A Grunwald-Winstein analysis.

The influence of carbon-carbon multiple bonds on the solvolyses of 3-chloro-3-methylbutyne (1), 2-chloro-2-phenylpropane (2), 2-bromo-2-methyl-1-phenylpropane (3), 4-chloro-4-methyl-2-pentyne (4) and 2-chloro-2-methylbutane (5) is critically evaluated through the extended Grunwald-Winstein equation. Substrates 1, 3 and 5 lead to correlations with unexpected negative sensitivity, h, to changes in the aromatic ring parameter, I. It is claimed that I is not a pure parameter, reflecting also some solvent nucleophilicity, N(OTs), character. In substrates 2 and 4 the possibility of rearside solvation is reduced due to steric hindrance and/or cation stabilization and the best found correlations involve only the solvent ionizing power, Y, and I.