Naslov
A computational study of the chlorination and hydroxylation of amines by hypochlorous acid

Autori
Šakić, Davor ; Hanževački, Marko ; Smith, David Matthew ; Vrček, Valerije

Izvornik
Organic & biomolecular chemistry (1477-0520) 13 (2015), 48; 11740-11752

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
MD simulation; DFT; reaction mechanism; HOCl; amines

Sažetak
Reactions of hypochlorous acid (HOCl) with ammonia, (di)methylamine, and heterocyclic amines have been studied computationally using double-hybrid DFT methods (B2PLYP-D and BK-PLYP) and a G3B3 composite scheme. In the gas phase the calculated energy barriers for N- and/or C-hydroxylation are ca. 100 kJ/mol lower the barrier for N-chlorination of amines. In the model solvent, however, the latter process becomes kinetically more favored. The explicit solvent effects are crucial for determination of the reaction mechanism. The N-chlorination is extremely susceptible to the presence of explicit water molecules, while no beneficial solvation effect has been found for the N- or C-hydroxylation of amines. The origin of the observed solvent effects arises from differential solvation of the respective transition states for chlorine- and oxygen-transfer, respectively. The nature of solvation of transition state structures has been explored in more details by classical molecular dynamics (MD) simulation. In agreement with quantum mechanical approach, the most stable structural motif, which includes the amine, HOCl, and two reactive waters, has been identified during the MD simulation. The inclusion of 5 or 6 explicit water molecules is required to reproduce experimental barriers for HOCl-induced formation of N-chloramines in aqueous environment.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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