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Experimental and theoretical study of the mechanism for the kinetic of elimination of methyl carbazate in the gas phase

Abstract:

The elimination kinetic of methyl carbazate in the gas phase was determined in a static system over the temperature range of 340-390°C and pressure range of 47-118 Torr. The reaction is homogeneous, unimolecular, and obeys a first order rate law. The decomposition products are methyl amine, nitrous acid, and CO gas. The variation of the rate coefficients with temperatures is given by the Arrhenius expression: log k1 (s-1) = (11.56 ± 0.34)-(180.7 ± 4.1) kJ mol-1 (2.303 RT)-1. The estimated kinetics and thermodynamics parameters are in good agreement to the experimental values using B3LYP/6-31G (d,p), and MP2/6-31G (d,p) levels of theory. These calculations imply a molecular mechanism involving a concerted non-synchronous quasi three-membered ring cyclic transition state to give an unstable intermediate, 1,2-oxaziridin-3-one. Bond order analysis and natural charges implies that polarization of O (alkyl) - C (alkyl) bond of the ester is rate determining In this reaction. Copyright © 2008 John Wiley & Sons, Ltd.