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 log k_{I (EtOH} (s^-1) = (13 .99 ± 0.27) - (201.1 ± 3.2) kJ mol^-1 (2.303 RT)^-1, r = 0.9995 log k_{II (EtH)}(s^-1) = (13.77 ± 0 18) - (203.8 ± 2.1) kJ mol^-1 (2.303 RT)^-1, r = 0.9996 log k_III (CH₂-CH₂)₂ (S^-1) = (11.88 ± 0.09) - (172.2 ± 1.0) kJ mol^-1 (2.303 RT)^-1, r = 0.9996 For 2,2-diethoxy-N,N-diethylethanamine log k_{I (EtOH)}(S ^-1) = (13.94 ± 0.20) - (202.3 ± 2.4) kJ mol ^-1 (2.303 RT)^-1, r = 0.9995 log k _{II (EtH)} (S^-1) = (14.03 ± 0.22) - (203.9 ± 2.6) kJ mol ^-1 (2.303 RT)^-1, r = 0.9996 log k _III(CH2CH2)(S^-1) = (12.02 ± 0.19) - (178.1 ± 2.3) kJ mol^-1 (2.303 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.