Kinetics and mechanisms of gas-phase elimination of 2,2-diethoxyethyl amine and 2,2-diethoxy-N,N-diethylethanamine

The gas‐phase elimination kinetics of 2,2‐diethoxyethyl amine and 2,2‐diethoxy‐N,N‐diethylethanamine (320–380 °C; 40–150 Torr) in a seasoned reaction vessel are homogeneous, unimolecular and obey a first‐order rate law. These elimination processes involve two parallel reactions. The first gives ethanol and the corresponding 2‐ethoxyethenamine. The latter compound further decomposes to ethylene, CO and the corresponding amine. The second parallel reaction produce ethane and the corresponding ethyl ester of an α‐amino acid. The following Arrhenius expressions are given as: For 2,2‐diethoxyethyl amine $${\rm log} \,k_{{\rm I}\;{\rm (EtOH)}} \,({\rm s}^{ - 1} ) = (13.99 \pm 0.27) - (201.1 \pm 3.2)\;{\rm kJ}\;{\rm mol}^{ - 1} \quad (2.303\,{\rm RT})^{ - 1} ,\;r = 0.9995$$ $${\rm log}\,k_{{\rm II}\;{\rm (EtH)}} ({\rm s}^{ - 1} ) = (13.77 \pm 0.18) - (203.8 \pm 2.1)\;{\rm kJ}\;{\rm mol}^{ - 1} \quad (2.303\;{\rm RT})^{ - 1} ,\;r = 0.9996$$ $${\rm log}\,k_{{\rm III}} \,_{({\rm CH}_2 = {\rm CH}_2 )} ({\rm s}^{ - 1} ) = (11.88 \pm 0.09) - (172.2 \pm 1.0)\;{\rm kJ}\;{\rm mol}^{ - 1} \quad (2.303\;{\rm RT})^{ - 1} ,\;r = 0.9996$$ For 2,2‐diethoxy‐N,N‐diethylethanamine $${\rm log}\,k_{{\rm I}\,({\rm EtOH})} \,({\rm s}^{ - 1} ) = (13.94 \pm 0.20) - (202.3 \pm 2.4)\;{\rm kJ}\;{\rm mol}^{ - 1} \quad (2.303\;{\rm RT})^{ - 1} ,\;r = 0.9995$$ $${\rm log}\,k_{{\rm II}\,{\rm (EtH)}} \,({\rm s}^{ - 1} ) = (14.03 \pm 0.22) - (203.9 \pm 2.6)\;{\rm kJ}\;{\rm mol}^{ - 1} \quad (2.303\,{\rm RT})^{ - 1} ,\;r = 0.9996$$ $${\rm log}\,k_{{\rm III}\,{\rm (CH}_{\rm 2} {\rm = CH}_{\rm 2} {\rm )}} \,({\rm s}^{ - 1} ) = (12.02 \pm 0.19) - (178.1 \pm 2.3)\;{\rm kJ}\;{\rm mol}^{ - 1} \quad (2.303\,{\rm RT})^{ - 1} ,\;r = 0.9996$$ Comparative kinetic and thermodynamic parameters of the overall, the parallel and the consecutive reactions lead to consider two types of mechanisms in terms of a concerted polar cyclic transition state structures. Copyright © 2008 John Wiley & Sons, Ltd. The gas phase elimination kinetics of 2,2‐diethoxyethyl amine and 2,2‐diethoxy‐N,N‐diethylethanamine (320–380°C; 40–150 Torr) in a seasoned reaction vessel, are homogeneous, unimolecular and obey a first‐order rate law.