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 te mperature range 370-420 degreesC and pressure range of 36-91 Torr (1 Torr = 133.3 Pa). The reactions carried out in seasoned vessels with the free rad ical suppressor toluene always present are homogeneous, unimolecular and ob ey 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) (2.303RT)(-1) and for 5-(N-methyl-N-phenylamino)-1-pentyl acetate, log k(1) (s(-1)) = (1 2.29 +/- 0.31) - (18.9 +/- 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-p air type of mechanism is assumed in the pyrolytic elimination of these phen ylaminoalkyl acetates. Copyright (C) 2001 John Wiley & Sons, Ltd.