Solvent effects in the conversion of anthraquinone to anthrahydroquinone and simultaneously hydrogen sulfide to hydrogen and sulfur

Abstract

The conversion rate of hydrogen sulfide (H₂S) and t-butylanthraquinone (TBAQ) to a sulfur atom and t-butylanthrahydroquinone (HTBAQH) is determined by the strength of three complexes. The complexes are between the reaction solvent and the TBAQ diradical, the HTBAQ radical or the HS radical. The strength of these complexes was determined by calculating the highest value of the electrostatic potential surface overlap between the solvent and a given radical. These computations used either the TINDO2 or the Zindo/1 semi empirical method. The solvent/TBAQ diradical complex was confirmed by experimental proton NMR. The width of the NMR aromatic region is directly related to the strength of the solvent/TBAQ diradical complex and to the experimental overall TBAQ conversion level.