Gas-phase thermolysis of N-substituted diallyl- and allylpropargylamines

Various diallyl- and allylpropargylamines were pyrolyzed in a stirred-flow reactor at temperatures in the range of 330–500°C, pressures of 8–16 Torr and residence times of 0·4–2·4 s using toluene as carrier gas. The reaction products were propene, allene and aldimines. The allene to propene ratio changed considerably with the third substituent on the N atom. At conversions in the range 13–55%, the consumption of the amines showed first-order kinetics. The following Arrhenius parameters [A (s−1) and Ea (kJ mol−1)] were obtained from the rate coefficients: diallyl-tert-butylamine, log  A = 10·32 ± 0·12, Ea = 139 ± 2; diallylneopentylamine, log A = 12·87 ± 0·26, Ea = 168 ± 3; allylpropargyl-tert-butylamine, log A = 10·23 ± 0·18, Ea = 126 ± 2; allylpropargyltosylamine, log A = 13·05 ± 0.36, Ea = 197 ± 5; and allylpropargylphenylamine, log A = 12·10 ± 0·35, Ea = 162 ± 4. Polar, six-center cyclic transition states are suggested for the elimination of propene and allene, via non-concerted bond breaking-bond forming mechanisms. © 1997 John Wiley & Sons, Ltd.