The Use of MM/QM Calculations of 13C Chemical Shifts in the Analysis of Edaravone Tautomers

Abstract The 13 C NMR chemical shifts of the three Edaravone tautomers (keto, enol, and amine) were calculated using a combined molecular mechanics (Pcmod 9.1/MMFF94) ab initio (GIAO (B3LYP/DFT, 6–31 + G(d)) model. This method gave such good agreement with experiment that assignment complex spectrum in solution, which is mixture could be made. has been attempted previously by various methods diverse results. In CDCl 3 observed spectra show only one form, keto tautomer, this also case acetonitrile solvent. Acetone solvent reacts Edavarone tube. other solvents studied, methanol, pyridine, DMSO, trifluoroethanol (TFE), there populations vary application shift predictions allows to from proportions solution. results at times differ significantly previous studies, discussed.