Effect of temperature on the alkaline (\(p\)H 10.0) hydrolyses of some para- and \(ortho\)-substituted 5-phenylazorhodanines are reported. For the \(para\)-substituted compounds, observed rates are well correlated by \(\sigma\)+\(p\) relation (\(p\) = 0·468) but sign and magnitude of \(p\) are unaffected by temperature variation. Calculated activation parameters suggest that ∆G* is nearly invariant, and ∆H* and ∆S* show isokinetic relation ship. Results strongly indicate water attack on the

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... ated anion. For the \(ortho\)-derivatives, internal strain causes steric assistance in hydrolyses.