Twenty chiral catalysts, among which twelve were prepared or purified in this work, have been used in the asym. synthesis of cyanohydrins from benzaldehyde. The activity and enantioselectivity of these catalysts in the reaction have been observed The optical yields of these asym. reaction varied from zero to about 60%. The investigation on the stability of the cyanohydrins showed that the purified cyanohydrins could be optically stable within a week without apparent decrease of their optical rotation and chem. stable over 5 mo. The mechanism of the reaction and the evaluation of enantioselectivity of the catalysts have also been discussed.

Key words: REACTION MECHANISM, STABILITY, INFRARED SPECTROPHOTOMETRY, ALCOHOL, CYANOGEN COMPOUNDS, NMR SPECTROMETRY, ELEMENTAL ANALYSIS, AROMATIC COMPOUNDS, RACEMIZATION