Some studies on the solvolysis of 1-chloro-1-alkyl cycloalkanes

The effect of the bulk of the sidechain on the rate of solvolysis of 1-alkyl cyclopentyl, cyclohexyl, and cycloheptyl chlorides has been studied. With the exception of the t-butyl systems, the ratio of solvolysis rates for the three ring systems falls in a given series. The slower rate of solvolysis in the six-membered ring system may be due to an extra activation energy contribution caused by the conversion of a neutral chair form to the twist boat or half chair conformation, prior to the actual solvolysis. In the case of five- and seven-membered ring systems the formation of an intermediate carbonium ion is sterically favoured (I-strain or eclipsing interaction) consistent with earlier findings. The faster rate of solvolysis of 1-t-butylcycloalkyl chlorides is likely due to a rearrangement reaction where alkyl participation enhances the rate of solvolysis.