Reactivity differences of O‐aryl O‐(4‐nitrophenyl) thionocarbonates versus their homolog carbonates: Micellar catalysis in hydrolysis reactions

Abstract

The alkaline hydrolysis reaction of O‐(4‐cyanophenyl), O‐(4‐methylphenyl), and phenyl O‐(4‐nitrophenyl) thionocarbonates (1, 2, and 3, respectively) and O‐(4‐cyanophenyl) and phenyl O‐(4‐nitrophenyl) carbonates (4 and 5, respectively) has been spectrophotometrically studied in aqueous borate buffer media, in the presence of the cationic surfactant CTAB. The pseudophase model successfully explained the results obtained, in the presence of this cationic micelle, and various kinetic parameters were determined. Results show that the catalytic efficiency increases in carbonates and thionocarbonates. In fact, a catalytic efficiency ( kobsmax/k′w) of 485‐fold was found in the hydrolysis reaction of thionocarbonate 1, while in the carbonate homolog 4, the effect was of 146‐fold. In addition, we found that at the same experimental conditions (Borate buffer pH = 9.0 and 25°C), an increase in the concentration of the buffer led to a decrease of the hydrolysis rate.