Premium
Kinetics and mechanisms of gas phase elimination of ethyl 1‐piperidine carboxylate, ethyl pipecolinate, and (revisited) ethyl 1‐methyl pipecolinate
Author(s) -
Rosas Felix,
Monsalve Angiebelk,
Tosta María,
Herize Armando,
Domínguez Rosa M.,
Brusco Doris,
Chuchani Gabriel
Publication year - 2005
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20084
Subject(s) - chemistry , piperidine , arrhenius equation , kinetics , decarboxylation , torr , atmospheric temperature range , reaction rate constant , carboxylate , gas phase , decomposition , thermal decomposition , organic chemistry , ethylene , medicinal chemistry , computational chemistry , thermodynamics , activation energy , catalysis , physics , quantum mechanics
The kinetics of the gas‐phase elimination of the title compounds has been determined in a static reaction system over the temperature range of 340–420°C and pressure range of 45–96 Torr. The reactions proved to be homogeneous, unimolecular, and obey a first‐order rate law. The estimated rate coefficients are represented by the following Arrhenius expressions: Ethyl 1‐piperidine carboxylate\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{1}({\rm s}^{-1}) = (12.61 \pm 0.11) - (191.1 \pm 1.4)\,{\rm kJ}\ {\rm mol}^{-1}(2.303\ \hbox{\bfseries\itshape{RT}})^{-1}, r = 0.9999 $$\end{document}Ethyl pipecolinate\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{1}({\rm s}^{-1}) = (12.87 \pm 0.16) - (204.3 \pm 2.1)\, {\rm kJ}\ {\rm mol}^{-1}(2.303\ \hbox{\bfseries\itshape{RT}})^{-1}, r = 0.9998 $$\end{document}Ethyl 1‐methyl pipecolinate\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{1}({\rm s}^{-1}) = (13.34 \pm 0.32) - (209.4 \pm 4.0)\, {\rm kJ} {\rm mol}^{-1}(2.303\ \hbox{\bfseries\itshape{RT}})^{-1}, r = 0.9992 $$\end{document}The first step of decomposition of these esters is the formation of the corresponding carboxylic acids and ethylene. The acid intermediate undergoes a very fast decarboxylation process. The mechanism of this elimination reactions is suggested on the basis of the kinetic and thermodynamic parameters. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 383–389, 2005