title: Practical method for the multigram separation of the 5- and 6-isomers of carboxyfluorescein.
abstract: An efficient preparative method for separating 5- and 6-carboxyfluorescein is presented. 6-Carboxyfluorescein dipivalate is isolated as its diisopropylamine salt, which can be converted to the free acid or used directly in coupling reactions. The 5-isomer is isolated from the acidified mother liquor. Isomerically pure carboxyfluoresceins are prepared by hydrolysis of the corresponding dipivalates.
authors.affiliation: Medical Biotechnology Center, School of Medicine, University of Maryland, Baltimore 21201, USA. frossi@scuacc.scu.edu
authors.forename: F M
authors.initials: FM
authors.lastname: Rossi
authors.forename: J P
authors.initials: JP
authors.lastname: Kao
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005452:Fluoresceins / Q000737:chemistry / Q000302:isolation & purification*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry / Q000379:methods
chemical_list: D005452:Fluoresceins; C024098:6-carboxyfluorescein; C045132:4-carboxyfluorescein