Comparative Study of Solvent Effect for Mandelic acid Oxidation by Different Oxidants

Abstract

The mandelic acid oxidation has been carried out by benzimidazolium fluorochromate (BIFC), morpholinium fluorochromate (MFC), benzimidazolium dichromate (BIDC), morpholinium chlorochromate (MCC) and tetraethylammonium chlorochromate (TEACC) using different solvents as dimethyl sulphoxide (DMSO), dimethyl formamide (DMF), chloroform (CF), acetone, dichloromethane (DCM) and 1,2-dichloroethane (DCE) at 308K, which results in the corresponding oxoacids formation. By using the TOPSIS method, we analysed the solvent effect and found the order by the solvent’s performance score for the reaction as DMSO>DMF>DCE>ACETONE>DCM>CF. The oxidation with all the oxidants resulted in the formation of corresponding oxo acid. The mechanism involved the construction of a cyclic chromate ester in a fast pre-equilibrium and then the decomposition of the ester in a subsequent slow step via a cyclic concerted symmetrical transition state leading to the formation of corresponding oxo acid in all the cases.