Preparation and evaluation of a doubly tethered chiral stationary phase based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid

A new doubly tethered chiral stationary phase (CSP) was prepared to enhance CSP stability as well as to take advantage of the tertiary amide linkage by bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to bis(3-aminopropyl)silica gel. The new CSP was quite effective in the resolution of alpha-amino acids, beta-amino acids, amino alcohols, and amines and the chromatographic resolution behaviors of the new CSP were exactly consistent with those of the corresponding singly tethered CSP containing N-CH3 tertiary amide linkage. Direct comparison between the stabilities of the new CSP and the corresponding singly tethered CSP containing N-CH3 tertiary amide linkage under harsh chromatographic conditions reveals that the new CSP is more stable than the latter.