2-(Phthalimino)ethyl Trifluoromethanesulfonate as a Highly Reactive Ultraviolet-Labeling Agent for Carboxylic Acids in High Performance Liquid Chromatography

Abstract

The use of 2-(phthalimino)ethyl trifluoromethanesulfonate in the preparation of carboxylic acid 2-(phthalimino)ethyl ester derivatives for specrophotometric detection in high performance liquid chromatography is described. The reagent is prepared in 60% yield by the reaction of N-hydroxyethylphthalimide with trifluoromethanesulfonic anhydride in the presence of pyridine in dichloromethane and is stable at least for 1 year in a refrigerator. Reactions of carboxylate potassium salts (10_-5M) with a 10-fold equivalent excess amount of the reagent in acetonitrile at room temperature proceed to completion within 10min in the presence of 18-crown-6 as a catalyst. The derivatization procedure with this reagent has been successfully applied to the determination of some carboxylic acids in mouse brain.