1,2-DIPHENYLETHANE-1,2-DIAMINE - AN EFFECTIVE NMR CHIRAL SOLVATING AGENT FOR CHIRAL CARBOXYLIC-ACIDS

(1R,2R)-1,2-diphenylethane-1,2-diamine, 1, acts as an effective chiral solvating agent (CSA) in the H-1 NMR analysis of the enantiomeric pur ity of chiral carboxylic acids. In the 2:1 salt complexes with a range of acids including alpha-arylpropanoic, alpha-halo carboxylic acid an d primary carboxylic acids, RCH2CO2H, the diastereotopic resonances in H-1 NMR were typically more than 0.05 ppm shift non-equivalent. The e ffect of temperature, stoichiometry, acid enantiomeric purity, concent ration and solvent on the observed shift non-equivalence was studied. The structure of the CSA was varied systematically and the observed no n-equivalence with 1, may be attributed to the anisotropy of the secon d aryl ring which is proximate to the substituents alpha to the carbox ylic acid group.