HYDROLYSE BASIQUE ET DECARBOXYLATION D'ESTERS ALLOPHANIQUES EN MILIEU MIXTE ACETONITRILE-EAU: CATALYSE BIFONCTIONNELLE PAR UNE ENTITE FORMEE ENTRE BASE ET SOLVANT

Article abstract of DOI:10.1016/S0040-4039(00)88097-1

Base catalysed hydrolysis of allophanic esters-models of carboxybiotine- in acetonitrile/water mixture, shows a sharp increase in rate constant in the range of 0.1-0.3 M in water, with a maximum which is interpreted as a balance between two desolvation terms, one concerning the nucleophile, the other the anionic transition state.Moreover, in acetonitrile/water mixtures at low water content (2.10^-2 M), a fast hydrolysis (k_expca.0.5 s^-1 at 20 deg C) of allophanic esters (carboxy-biotin models) is observed due to catalysis by the enolate of acetamide.This speciesalso catalyses the decarboxylation step, likely behaving as a bifunctional catalyst.