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

Abstract:

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 kI (EtOH (s-1) = (13 .99 ± 0.27) - (201.1 ± 3.2) kJ mol-1 (2.303 RT)-1, r = 0.9995 log kII (EtH)(s-1) = (13.77 ± 0 18) - (203.8 ± 2.1) kJ mol-1 (2.303 RT)-1, r = 0.9996 log kIII (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 kI (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. Copyright © 2008 John Wiley & Sons, Ltd.