title: Resolution of beta-blockers on a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid: unusual temperature effect.
abstract: A chiral stationary phase (CSP) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid has been successfully employed in the liquid chromatographic resolution of eleven beta-blockers containing a secondary amino functional group. As the result of an effort to find out the optimal mobile phase condition, the mixture of trifluoroacetic acid-triethylamine-ethanol-acetonitrile with the ratio of 0.1/0.5/20/80 (v/v/v/v) was concluded to be the best mobile phase condition, the separation (alpha) and the resolution factors (Rs) for the resolution of 11 beta-blockers being in the range of 1.13-1.85 and 1.36-5.79, respectively. Surprisingly, in contrast to the resolution of other racemic compounds containing a primary amino functional group, the separation factors (alpha) for the resolution of beta-blockers were observed to improve as the column temperature increased and these unusual chromatographic behaviors were rationalized as the entropically controlled enantioselectivity.
authors.affiliation: Department of Analytical Chemistry, Shenyang Pharmaceutical University, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhang
authors.forename: Famei
authors.initials: F
authors.lastname: Li
authors.forename: Do Hun
authors.initials: DH
authors.lastname: Kim
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Choi
authors.forename: Myung Ho
authors.initials: MH
authors.lastname: Hyun
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D043844:Crown Ethers / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000319:Adrenergic beta-Antagonists; D043844:Crown Ethers; C090732:18-crown-6 2,3,11,12-tetracarboxylic acid