Effect of Propanol-1 on the Reaction between Thiophenol and N,N'-Diphenyl-1,4-Benzoquinone Diimine in Chlorobenzene

Abstract

It is found that the interaction between thiophenol and N,N '-diphenyl-1,4-benzoquinone diimine proceeds by two routes, one of which is a radical chain reaction and the other is a nonchain reaction between the reagents. The kinetic patterns of the reaction depend substantially on the concentration of propanol-1 in mixtures of it and chlorobenzene. It is shown that at 343 K, replacing chlorobenzene with propanol-1 results in an almost twentyfold increase in the total rate of the reaction. Increasing the concentration of propanol-1 raises the rate of both routes of the reaction, but that of the nonchain route grows more than that of the chain route. It is concluded that increasing the concentration of propanol-1 results in a simultaneous 20–30 times rise in the rate constants of both the stage of radical generation by the reaction between the reagents as well as the rate constant of the nonchain bimolecular reaction, and the chain length of the chain reaction is shortened. When chlorobenzene is replaced with propanol-1, the rate constant of the limiting stage of chain propagation (the reaction of quinone diimine with a phenylthiyl radical) is halved, due to the formation of H complexes between the π system of quinone diimine and the proton of propanol-1.