Reaction mechanism of the gas-phase pyrolysis of N–Acetylthiourea and N, N’–diacetylthiourea: A theoretical study based in density functional theory

Abstract:

In the present study, we propose a reaction mechanism for the decomposition of N -Acetylthiourea and N, N '-Diacetylthiourea using density functional quantum chemical calculations. For both reactions the level of theory that gave us the better agreement between theory and experiment was MPW1PW91/6-311G (d, p). Thermodynamic and kinetic parameters were evaluated at 600 K and 1 atm. For N -Acetylthiourea decomposition reaction, the products are ketene and thiourea, while for are N, N '-Diacetylthiourea, the product are ketene and N–Acetylthiourea. Our calculations suggest that the mechanism proceeds stepwise, where the rate-determining step is promoted by an intramolecular nucleophilic attack of the sulfur atom to the carbonyl carbon in the acetyl group. The kinetics of these reactions is influenced by the electron-withdrawing effect of the acetyl group. Population analysis shows that the mechanism is …

Año de publicación:

2022

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Fuente:

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