PROCESS FOR THE PREPARATION OF 5-/6-NITROFLUORESCEIN

摘要

A process for the preparation of a mixture of 3',6'-dihydroxy-6-nitrospiro[2-benzofuran-3,9'-xanthene]-1-one and 3',6'-dihydroxy-5-nitrospiro[2-benzofuran-3,9'- xanthene]-1-one comprising the steps of:- (a) reacting 4-nitrophthalic acid or 4-nitrophthalic anhydride with benzene-1,3- diol in methanesulphonic acid; (b) quenching the reaction in step (a) with a solvent to precipitate product; (c) isolating the precipitate; (d) heating the precipitate in water in order to hydrolyse any methansulphonic acid ester present.