Kinetic studies on alkyl radical additions onto C=N bonds

Abstract

Kinetic studies were carried out to determine the rate constants for the 5-exo and the 6-exo cyclizations of primary alkyl radicals onto the hydrazones and the rate constant for intermolecular additions of alkyl radicals onto the bis-methanesulfonyl oxime ether. The approximate rate constant $k(C=N-NMe_2)^{5}$ obtained from competition studies was $7.6×10^{7}M^{-1}s^{-1}$ at 80℃. The approximate rate constant $k(C=N-NMe_2)^{6}$ was obtained as $2.2×10^{6}M^{-1}s^{-1}$ at 80℃ from kinetic studies and as $3.1×10^{6}M^{-1}s^{-1}$ at 80℃ from competition studies. Kinetic studies for intermolecular additions of alkyl radicals onto the bis-methanesulfonyl oxime ether gave the rate constant $(k_a=1.7×10^{6}M^{-1}s^{-1} at 80℃)$ Which was confirmed by four competition experiments.