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

摘要

The gas-phase elimination kinetics of 2,2-diethoxyethyl amine and 2,2-diethoxy-N,N-diethylethanamine (320-380 degrees 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 alpha-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)) (s(-1)) = (11.88 +/- 10.09) - (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) ((CH2 = CH2)) (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 (C) 2008 John Wiley & Sons, Ltd.