Abstract: | The velocity of the hydrogen ion catalysed hydrolysis of p-nitrophenyl-diazo-methane (I) has been measured in H2O? D2O mixtures, giving an isotopic αi = 0.49. The product isotope effect r = 5.1, determined from product analyses, combined with the (overall) solvent isotope effect kH/kD = 2.81, yields the primary kinetic isotope effect (kH/kD)I = 3.8, and the secondary kinetic isotope effect (kH/kD)II = 0.75. The CICH2COOH-catalysed hydrolysis of I in H2O? D2O mixtures gave a straight-line plot of kn/kH versus the atomic fraction n of deuterium. With four carboxylic acids, as catalysts, values of about 4.3 for the kinetic (overall) isotope effects were observed. |