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Autori: Sergiu Coseri
Editorial: Sage Publications, High Performance Polymers, 19, p.520-530, 2007.
The kinetic and mechanism of the reaction between phenylisocyanate and ethanol, in the presence of various additives, able to inhibit or to activate the urethane formation, have been evaluated. An alternative reaction mechanism, as a special case of second-order reaction for the reactions performed in unpolar media is proposed. In the first step of the reaction, the isocyanate group is activated through a rapid and reversible process by the “mobile” and polarized form of the hydroxyl hydrogen from the alcohol—alcohol and/or alcohol—urethane hydrogen bond associates. The final products appear in the next step, through a second order reaction as a result of the nucleophile attack of the hydroxyl oxygen to the activated isocyanate group.
Cuvinte cheie: Urethane formation • phenylisocyanate • reaction mechanism • hydrogen bond • alcohol association