Über die SiN-bindung: XLIII. Kinetische untersuchungen zur hydrolyse von silylurethanen des typs (p-XC6H4)Me2SiN(Ph)COOEt

Hydrolysis reactions of silylurethanes (p-XC₆H₄)Me₂SiN(Ph)COOEt with X = MeO, Me, H or Cl in aqueous buffer solutions, with pH values from 1.73 to 10.00 and at temperatures of 20, 30, and 40°C were studied.The catalytic rate constants for the acid- and base-catalysed reactions and for the “non-catalysed” reaction k(H₃O⁺), k(CH₃COO^?), k(NH₃), k(OH^?), and k₀ and the Brönsted coefficients for the general base-catalysed reactions were evaluated from the pseudo first-order rate constants k_exp, determined by UV spectroscopy.The ? values of the reactions can be derived from the σ constants given by Jaffé. Activation parameters can be obtained by means of the Arrhenius or Eyring equation.From the catalytic constants, Brönsted coefficients, ? values and activation parameters we derive mechanisms for the acid- and general base-catalysed reactions.Conclusions about these mechanisms are compared with the results obtained with the silylurethanes Me₃Si(p-XC₆H₄)NCOOEt.