Synthesis, characterisation and polar effect of the substituent on the reaction mechanism of 3-aminophenyl phosphate esters

Abstract

The kinetics and mechanism of the acid hydrolysis of 3-aminophenyl phosphate esters have been studied in 0.1 to 6.0 mol dm -3 HCl at 90 ± 0.5 °C. The effects of temperature, solvent and substrate concentration on the rate of hydrolysis have been studied and the results suggest that the hydrolysis of monoester occurs by the cleavage of P-O bond fission. The rate coefficients estimated are fairly in good agreement with the experimentally observed ones. Bond fission, molecularity and order of reaction have been supported by Arrhenius parameters, Zucker-Hammett hypothesis, concentration, solvent effect etc. A study of the reaction in dioxane water mixture suggested the nature of transition state in which charges are developed due to the bimolecular attack of water molecule. Comparative isokinetic rate data of similarly substituted phenyl phosphate monoesters, whose mechanism is known, supported P-O bond fission.