MP2 study of the gas phase elimination mechanism of some neutral amino acids and their ethyl esters

The mechanisms of the gas phase elimination of N,N‐dimethylglycine, picolinic acid, and N‐phenylglycine and their ethyl esters have been examined at Möller–Plesset MP2/6‐31G (d, p) level of theory. The ethyl esters of these 2‐amino carboxylic acids produce the corresponding amino carboxylic acid and ethylene in a rate‐determining step. However, the unstable intermediate amino carboxylic acid rapidly decarboxylate to give the corresponding amino compound. These calculations imply a concerted, semi‐polar six‐membered cyclic transition state type of mechanism for the ethyl esters, and a non‐synchronous five‐membered cyclic transition state for the amino acids decarboxylation. The present results support previous mechanistic consideration of the elimination of the above‐mentioned compounds in the gas phase. Copyright © 2008 John Wiley & Sons, Ltd. The mechanisms of the elimination kinetics of N,N‐dimethylglycine, picolinic acid, N‐phenyl glycine and their ethyl ester have been examined at the MP2/6‐31(d, p) level of theory. Results of the kinetics and thermodynamic parameters are presented and discussed.