DFT computations have been performed to study the mechanism of the reactions of sulfides with hypochlorous acid and N-chlorosulfonamides. Sulfides can attack HOCl both at chlorine and oxygen atoms. The attack at chlorine results in the formation of chlorosulfonium cation (R2SCl+) and OH− intermediates, which transform to sulfoxide product. The high free energy of activation (ΔG‡), which is needed for the formation of ionic intermediates, is decreased considerably by solvation in protic solvents. Since the attack of sulfides at the oxygen atom of HOCl has low ΔG‡ value, the chlorination of sulfides can compete with the attack at the oxygen atom only in protic solvents. Kinetic studies showed that the reactivity of species, formed from N-chlorosulfonamides in protic solvents, increases in the course: RSO2NCl− << RSO2NHCl < < RSO2NCl2. The chlorination of sulfides with RSO2NHCl or RSO2NCl2 results in the formation of R2SCl+ and RSO2NH− or RSO2NCl− intermediates, respectively, and the computed and experimentally derived ΔG‡ data agree in these cases. Sulfilimine (R2S═NSO2R) and sulfoxide products are formed in the reaction of R2SCl+ with RSO2NH− and water, respectively. Acyloxy-chloro-λ4-sulfane intermediates are produced in the reactions of N-chlorosulfonamides and sulfides, bearing 2-carboxy-phenyl group, without the intermediacy of chlorosulfonium cations. Explicit water molecules must also be included in computations for reactions proceeding with formation or destruction of ions, to get ΔG‡ values, comparable with experimental data. Supporting information may be found in the online version of this paper.
- DFT calculations
- hypochlorous acid
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry