Ester containing aggregates in the autocatalytic biphasic hydrolysis of ethyl alkanoate

Autocatalytic kinetics are observed during the biphasic alkaline hydrolysis of C-4, C-6 and C-8 (butanoate, hexanoate and octanaoate) ethyl eaters. Et hanol and alkanoate anions are the products of the reaction. A kinetic mode l including spontaneous dissolution of the organic phase into the aqueous p hase, aqueous hydrolysis of the ester, formation of ester containing aggreg ates and micellisation has been proposed. For C-4, taking into account salt ing-in and solvent effects is sufficient to reproduce the autocatalytic beh aviour. For C-8, the major autocatalytic process is an ester containing agg regates (ECA) mediated phase transfer. For C-6, it appears that the role of ECA is double. Small sized ECA which are formed at the beginning of the re action do not perform rapid phase transfer and trap surfactant molecules. L arger ECA which appear at the end of the reaction are the main phase transf er agent. Using an empirical formula to describe the size of the interface, the model is able to reproduce the effect of a variation of the volumic ra tio of the two phases as well as the effect of stirring rate and non-emulsi fied experiments. (C) 2000 Elsevier Science B.V. All rights reserved.