Neighboring group participation in the gas phase. The homogeneous elimination kinetics of 5‐(N‐phenylamino)‐1‐pentyl acetate and 5‐(N‐methyl‐N‐phenylamino)‐1‐pentyl acetate

Abstract

AbstractThe elimination kinetics of the title compounds were determined over the temperature range 370–420 °C and pressure range of 36–91 Torr (1 Torr = 133.3 Pa). The reactions carried out in seasoned vessels with the free radical suppressor toluene always present are homogeneous, unimolecular and obey a first‐order rate law. The overall rate coefficient is expressed by the following Arrhenius equations: for 5‐(N‐phenylamino)‐1‐pentyl acetate, log k1 (s−1) = (13.56 ± 0.19) − (211.8 ± 2.2) kJ mol−1 (2.303RT)−1 and for 5‐(N‐methyl‐N‐phenylamino)‐1‐pentyl acetate, log k1 (s−1) = (12.29 ± 0.41) − (182.9 ± 5.2) kJ mol−1 (2.303RT)−1. The formation of N‐phenylpiperidine in both reactions suggests the anchimeric assistance of the PhNH and Ph(CH3)N groups for a backside displacement. An intimate ion‐pair type of mechanism is assumed in the pyrolytic elimination of these phenylaminoalkyl acetates. Copyright © 2001 John Wiley & Sons, Ltd.