The elimination kinetics and mechanisms of ethyl piperidine‐3‐carboxylate, ethyl 1‐methylpiperidine‐3‐carboxylate, and ethyl 3‐(piperidin‐1‐yl)propionate in the gas phase

Abstract

The gas-phase elimination kinetics of the above-mentioned compounds were determined in a static reaction system over the temperature range of 369-450.3• C and pressure range of 29-103.5 Torr. The reactions are homogeneous, unimolecular, and obey a first-order rate law. The rate coefficients are given by the following Arrhenius expressions: ethyl 3-(piperidin-1-yl) propionate, log k 1 (s −1 ) = (12.79 ± 0.16) − (199.7 ± 2.0) kJ mol −1 (2.303 RT) −1 ; ethyl 1-methylpiperidine-3-carboxylate, log k 1 (s −1 ) = (13.07 ± 0.12)-(212.8 ± 1.6) kJ mol −1 (2.303 RT) −1 ; ethyl piperidine-3-carboxylate, log k 1 (s −1 ) = (13.12 ± 0.13) − (210.4 ± 1.7) kJ mol −1 (2.303 RT) −1 ; and 3-piperidine carboxylic acid, log k 1 (s −1 ) = (14.24 ± 0.17) − (234.4 ± 2.2) kJ mol −1 (2.303 RT) −1 . The first step of decomposition of these esters is the formation of the corresponding carboxylic acids and ethylene through a concerted six-membered cyclic transition

Elimination Reactions

“…Gas-phase elimination reactions of ethyl esters of α-and β-amino acids have been investigated in a static reaction system. 20,21 The first step of decomposition of these esters is formation of the corresponding carboxylic acids and ethylene through a concerted six-membered cyclic transition state. The intermediate β-amino acids decarboxylate via a semipolar six-membered cyclic transition state.…”