Kinetics and mechanisms of the gas‐phase elimination of N ‐phenylglycine and its ethyl ester

The elimination kinetics of the title compounds were determined over the temperature range 290.4–420.3°C and pressure range 14.5–44.0 Torr. The reactions, carried out in seasoned vessels and in the presence of the free radical inhibitor toluene, are homogeneous, unimolecular and follow a first‐order rate law. The rate coefficient is expressed by the following Arrhenius equation: for N ‐phenylglycine ethyl ester, log [ I 1 (s −1 )]=(12.13±0.38)− (193.6±4.9) kJ mol −1 (2.303 RT ) −1 ; and for N ‐phenylglycine, log [ k 1 (s −1 )]=(12.95±0.52)−(177.4±5.8) kJ mol −1 (2.303 RT ) −1 . Both substrates yield mainly N ‐methylaniline and a small amount of aniline. N ‐Phenylglycine as a neutral amino acid decomposes 130 times faster than its ethyl ester at 380°C. The mechanisms of these elimination reactions are presented and discussed. Copyright © 2003 John Wiley & Sons, Ltd.