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 [I1 (s−1)]=(12.13±0.38)− (193.6±4.9) kJ mol−1 (2.303 RT)−1; and for N-phenylglycine, log [k1 (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.

[1]  G. Chuchani,et al.  Mechanism of elimination of amino acid derivatives in the gas phase. Pyrolysis kinetics of ethyl picolinate, ethyl 1‐methylpipecolinate and picolinic acid , 2003 .

[2]  G. Chuchani,et al.  The mechanism of neutral amino acid decomposition in the gas phase. The elimination kinetics of N,N-dimethylglycine ethyl ester, ethyl 1-piperidineacetate, and N,N-dimethylglycine , 2001 .

[3]  G. Chuchani,et al.  Kinetics and mechanism of the gas-phase elimination of primary, secondary and tertiary 2-acetoxycarboxylic acids , 2000 .

[4]  G. Chuchani,et al.  Pyrolysis kinetics of 2-phenoxycarboxylic acids in the gas phase , 1999 .

[5]  L. Domingo,et al.  A combined experimental and theoretical study of the unimolecular elimination kinetics of 2-alkoxypropionic acids in the gas phase , 1999 .

[6]  Juan Andrés,et al.  Theoretical Study of the Mechanisms for the Alkoxyacetic Acids Decomposition , 1999 .

[7]  L. Domingo,et al.  Potential energy surface for the decomposition of mandelic acid , 1997 .

[8]  V. Moliner,et al.  Theoretical Study of the Gas Phase Decomposition of Glycolic, Lactic, and 2-Hydroxyisobutyric Acids , 1997 .

[9]  V. Moliner,et al.  Theoretical Study of the Elimination Kinetics of Carboxylic Acid Derivatives in the Gas Phase. Decomposition of 2-Chloropropionic Acid , 1997 .

[10]  E. Swinbourne.  The kinetics of the pyrolysis of Cyclohexyl chloride. , 1958 .

[11]  A. Maccoll.  Studies in the pyrolysis of organic bromides. Part I. The kinetics of the decomposition of allyl bromide , 1955 .