Study on the Thermal Decomposition Mechanism of Azetidine Using Low Pressure Pyrolysis Method

The thermal decomposition of aietidine was studied below HOOK and under the pressure of 10^-3 Pa using a low pressure pyrolysis method (Table 1). Ethylene and methanimine were found to be main products (Fig. 1). The stoichiometry of (CH₂)₈NH →C₂H₄ + CH₂NH was established on the basis of mass balance of ethylene (Table 2). First order rate constants at various temperature were determined from conversion (Table 3). The three cases of biradical mechanism, k₂ ≫k_-1 k₂=k_-1, k₂≪k_-1 were examined according to general procedure of RRKM calculation. In the first two cases, A factor was obtained by analogy with the decomposition of the oxetane (Table 4). In the third case, A factor was estimated from the entropy deference between the biradical and azetidine (Table 5) and activation entropy for the decomposition of the biradical (Table 6). High pressure Arrhenius parameters were given as follows (Fig. 2), (Tables 7, 8). k=10^15.4±o.4exp(-233±6/RT) It can be concluded that azetidine decomposes via biradical mechanism, and the heat of formation of the aminomethyl radicals, H_f298(H₂NCH₂·) = 122±15kJ·mol^-1, is derived from the kinetic data.