[Separation of norephedrine enantiomers by high performance liquid chromatography (HPLC) with urea derivative as chiral stationary phase]. 1998

Z Wang, and Z Yun
Department of Chemistry, Beijing Normal University, Beijing, 100875.

By using normal-phase HPLC with urea derivative as chiral stationary phase(CSP), the direct separation of racemic norephedrine has been investigated. The resolution was optimized by varying the concentration of iso-propanol in a ternary mobile phase which consists of two other components: hexane and 1,2-dichloroethane. The lower the percent of iso-propanol, the better the resolution is. But the retention time is longer as the percent of iso-propanol decreases. In an attempt to reduce the retention time without reducing the stereoselectivity, we chose the mixture of hexane, 1,2-dichloroethane and iso-propanol as the mobile phase with a proportion of 73.5:25:1.5 in vol. We also altered the organic modifier by substituting ethanol, acetonitrile and tetrahydrofuran (THF) for iso-propanol. The addition of ethanol appears to increase the hydrogen bond interactions between the solute and solvent, which results in lower k' values and an increase in alpha and Ra. Acetonitrile is only a kind of proton-accepter and the interactions of hydrogen bonding between the solute and solvent are weaker than iso-propanol, which results in higher k' values and a reduction in alpha and Ra. These separations are in agreement with the three-point rule. When THF is used as organic modifier, a reversed elution order and a more favorable separation can be obtained. The specific behavior of THF in HPLC has not been explained satisfactorily yet.

UI MeSH Term Description Entries
D010665 Phenylpropanolamine A sympathomimetic that acts mainly by causing release of NOREPINEPHRINE but also has direct agonist activity at some adrenergic receptors. It is most commonly used as a nasal vasoconstrictor and an appetite depressant. Norephedrine,Dexatrim,Phenylpropanolamine Hydrochloride,Prolamine,Propagest,Triaminic DM,Hydrochloride, Phenylpropanolamine
D002851 Chromatography, High Pressure Liquid Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D013237 Stereoisomerism The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed) Molecular Stereochemistry,Stereoisomers,Stereochemistry, Molecular,Stereoisomer
D014508 Urea A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids. Basodexan,Carbamide,Carmol

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