Enantiomer separation of some barbiturates on a cellulose tris(4-methylbenzoate) chiral stationary phase under reversed phase conditions

The enantiomeric separation of ten racemic barbiturates with various substitutions at C-5 was investigated using a newly developed cellulose tris(4-methylbenzoate) chiral stationary phase known as Chiralcel OJ-R-CSP under reversed phase conditions. The results revealed that better resolution was achieved for barbiturates with one cyclic substituent at C-5 while poor resolution or no separation was achieved with analogs having two aliphatic chain substituents at C-5. The results obtained in this study are comparable to the data obtained using cellulose tris(4-methylbenzoate) CSP under normal phase conditions. A possible chiral recognition mechanism for these barbiturates and the newly developed CSP is discussed.