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

The 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 k 1 (s −1 ) = (13.56 ± 0.19) − (211.8 ± 2.2) kJ mol −1 (2.303 RT ) −1 and for 5‐( N ‐methyl‐ N ‐phenylamino)‐1‐pentyl acetate, log k 1 (s −1 ) = (12.29 ± 0.41) − (182.9 ± 5.2) kJ mol −1 (2.303 RT ) −1 . The formation of N ‐phenylpiperidine in both reactions suggests the anchimeric assistance of the PhNH and Ph(CH 3 )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.