Temperature dependence of activation parameters in the neutral ester hydrolysis in t-butyl alcohol–water solutions

Abstract

The kinetic behaviour of the neutral hydrolyses of methyl trifluoroacetate and chloromethyl dichloroacetate in t-butyl alcohol–water solutions, rich in water, has been studied. In these hydrolyses at x_w close to 0.95, ΔC_p^‡ depends on temperature, d ΔC_p^‡/dT being + 23 ± 1 (x_w 0.951) and + 21 ± 2 (x_w 0.957) J mol^–1 K^–2 for the hydrolysis of methyl trifluoroacetate and chloromethyl dichloroacetate, respectively. The temperature dependence of ΔC_p^‡ found has been explained by the formation of ‘moving units’ so that at x_wca. 0.95 there are two pseudo-phases representing the transition from the aggregates of the form (H₂O)₂₀(Bu^tOH) into the aggregates of the form 4[(H₂O)₂₀(Bu^tOH)].