American Hoechst Corporation

Richard L Castenson

James R Hazen

Rex Y Tien

This invention is directed to new azoacylacetamide dispersing agents for azo pigments and azo pigment compositions made therefrom. The pigment compositions of this invention comprise a mixture of dispersing agents which are represented below by abbreviated Formula I and pigments which are represented by the abbreviated Formula II, wherein said dispersing agents are present in an amount of 1-25% and said pigments are present in an amount of 99 to 75%: ##STR1## where: A is an aromatic or heterocyclic amino group;

Azoacylacetamide dispersing agents and azo-pigment compositions

A novel method for the preparation of 4-bromo-1,8-naphthalic acid anhydride is disclosed. This method is carried out by the bromination, with alkali metal bromide or molecular bromine in the presence of a hypohalite, of a di-alkali metal salt of 1,8-naphthalic acid in aqueous solution at a pH of between 6.5 and 9.5 and at a temperature of between 0.degree. and 30.degree. C. to a di-alkali metal salt of 4-bromo-1,8-naphthalic acid and cyclizing to produce 4-bromo-1,8-naphthalic acid anhydride. This novel direct bromination method produces the desired product in good yields and high purity. 4-Bromo-1,8-naphthalic acid anhydride is a valuable intermediate for the preparation of dyestuffs, pigments and optical brighteners.

Growing community of inventors

Coventry, RI, United States of America

Richard L Castenson