✍ Scribed by Stephen T. Ingalls; Paul E. Minkler; Charles L. Hoppel; J. Eric Nordlander
No coin nor oath required. For personal study only.
The use of 4'-bromo-2-hydroxyacetophenone trifluoromethanesulfonate ester (4'-bromophenacyl triflate) in the preparation of carboxylic acid 4'-bromophenacyl ester derivatives for spectrophotometric detection in high-performance liquid chromatography is described. The reagent is prepared in 66% yield by the reaction of 4'-bromo-2-diazoacetophenone with trifluoromethanesulfonic acid in anhydrous sulfur dioxide and is stable for 3-6 months. Reactions of lop6 M carboxylate N,Ndiisopropylethylammonium salts with this reagent in acetonitrile at room temperature proceed to completion in l-5 min. Optimal rates of reaction are obtained with a lo-fold equivalent excess of alkylating agent and 5 equivalents of N,N-diisopropylethylamine present. The process has been applied successfully to mono-, di-and tricarboxylic and sterically hindered carboxylic acids.
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