Solid−liquid equilibria of n‑methylephedrine enantiomers and their mixtures in two chiral ionic liquids

Abstract

Solubility equilibria of the chiral N-methyl ephedrine species in two chiral ionic liquids, (S)-2- (methoxycarbonyl) pyrrolidinium is- (trifuoromethylsulfonyl) amide ([(S)-2-Pro-Me][NTF2]) and (1R , 2 S )-(−)-dimethylephedrinium is- (trifuoromethylsulfonyl) amide, have been systematically studied. Solubility measurements ere performed for [(S)-2- Pro-Me][NTF2] at temperatures between 278 and 308 K and ( 1R , 2 S )-(− )-dimethylephedrinium is- (trifuoromethylsulfonyl) amide at 308 K, both ith diferentinitial enantiomeric compositions of N-methylephedrine. Methanol as a co-solvent as used to decrease the iscosity of [(S)-2-Pro-Me][NTF2]. The solubilities in [(S)-2-Pro-Me][NTF2] increased with temperature increments. Considerable asymmetry as observed in the ternary solubility phase diagram of the chiral N-methylephedrine and (1R,2S)- (−)-dimethylephedrinium is(trifuoromethylsulfonyl) amide system. The accuracy of the solubility data for N methylephedrine in (1R,2S)-(−)-dimethylephedrinium is(trifuoromethylsulfonyl) amide at 308 K as asc ertained by evaluating the mean absolute error