Enantioseparation of 1,1′-bi-2-naphthol benzoates using high performance liquid chromatography

Abstract

The enantioseparations of 2'-hydroxy-1,1'-binaphthyl-2-yl benzoate (HBNB), 1,1'-binaphthyl-2,2'-diyl dibenzoate (BNDB) and 2'-methoxy-1,1'-binaphthyl-2-yl benzoate (MBNB) were studied on Chirex (S)-LEU & (S)-NEA, cellulose tris (3,5-dimethylphenylcarbamate) (Chiralcel OD-H) and amylose tris (3,5-dimethylphenyl-carbamate) (Chiralpak AD-H) columns, respectively, using high performance liquid chromatography. The effects of mobile phase, column temperature and compound structures on the enantioseparations were discussed. The Chiralpak AD-H exhibited stronger capability of enantioseparation in comparison with those of Chirex (S)-LEU & (S)-NEA and Chiralcel OD-H for 1,1'-bi-2-naphthol benzoates. When using the mobile phase of n-hexane/2-propanol (40/60, v/v), the chiral selectivities of HBNB, BNDB and MBNB were 1.76, 1.74, and 1.40, respectively. Moreover, in comparison with that of 1,1'-bi-2-naphthol (BN), the mechanisms of the enantioseparation of 1,1'-bi-2-naphthol benzoates, related to the substituted groups at 2-position, the elution orders and thermodynamic parameters were also discussed.