Interaction of thiourea and urea with maleimide: comparative theoretical DFT study
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Updated: Jan 4, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Nabila Achoui1, Karima Zaioua1, Dalila Hammoutène1
1USTHB, Faculty of Chemistry, Laboratory of Thermodynamics and Molecular Modeling, BP 32, Al Alia, 16111, Bab Ezzouar, Algiers, Algeria.
Abstract:
A gas-phase mechanism reaction of maleimide with urea or thiourea was studied by DFT method. A comparison between atomic charges, Fukui index evaluation and Frontier orbitals theory was carried out. The involvement of pre- and post-reactive complexes was examined as the reaction profiles are modelled. For each mechanism, two approaches have been proposed through nitrogen and sulfur (for thiourea), or oxygen and nitrogen (for urea) attack. The results indicate that the carbon double bonded of maleimide is the electophilic site and chalcogen atom of chalcogenourea is the nucleophilic one. The obtained activation free energies predict suitable specie that could be generated after an opening-cycle and new bonds formation. Consequently, the sulfur attack of thiourea was promoted on oxygen (urea) which is in accordance with the experiments.
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