Method for preparation of 4-halogenonaphthalic acid anhydrides

摘要

A method for the preparation of 4-halogenonaphthalic acid anhydrides by halogenation of an aqueous solution of an alkali salt of the naphthalic acid with halogen or alkali metal hypohalogenite wherein a solution of the alkali metal salt of the naphthalic acid is treated with a water soluble magnesium salt and at least an equal molar amount of an alkakli metal hydroxide, halogenating this reaction mixture at a temperature in the range of 10 DEG to 25 DEG C. and subsequently acidifying the reaction mixture. In a second embodiment of the invention, an aqueous solution of alkali metal carbonate is used in place of the magnesium salt and alkali metal hydroxide.