A KINETIC-STUDY OF THE 1,3-DIPOLAR CYCLOADDITION REACTION BETWEEN N-P-METHOXYBENZYLIDEN-ALPHA-PHENYLGLYCINE METHYL-ESTER AND NITROSOBENZENE

The kinetics of the reaction between N-p-methoxybenzyliden-alpha-pheny lglycine methyl ester and nitrosobenzene, using benzene as the solvent and both acetic and chloroacetic acid as catalysts, was studied by me ans of UV-VIS spectroscopy. The results obtained show clearly that the product formation rate is determined by the formation of the imine 1, 3-dipole, a process that is catalyzed by Bronsted acids. From kinetic experiments it was found that the reaction rate is independent of nitr obenzene concentration and first order in imine and monomeric carboxyl ic acid concentrations. Catalytic rate constants take the values 8.9 x 10(-3) and 48.2 x 10(-3) M-1 s(-1) when acetic and chloroacetic acids , respectively, are used as the catalyst. Kinetic and H-1-NMR studies provide evidence that the catalysis occurs through a bifunctional cata lytic mechanism.