$^1$H-NMR Studies of Chiral Solvating Agent Induced - Chemical Shift Differences of Ibuprofen Enantiomers

Chiral discrimination of ibuprofen by $^1$H-NMR using several chiral solvating agents such as (-)-brucine, (-)-cinchonidine, (1R, 2S)-(-)-ephedrine, (S)-(-)-${\alpha}$- methylbenzylamine, (-)-strychnine and L-(-)-tryptophane was investigated. Racemic ibuprofen treated with one equivalent of chiral solvating agent was preferentially crystallized. Chiral purity of each precipitates was measured by chiral HPLC and chemical shift differences(ΔΔ$\delta$) was calculated. Eventhough (S)-(-)-${\alpha}$-methylbenzylamine was most effective for the preferential recrystalization of (S)-(+)-ibuprofen, chemical shift differentiation ability was weak. (omitted)