Harmon Colors Corporation

Robert Jarl North

A method is provided for the direct production of gamma quinacridone pigment comprising ring closure of 2,5-dianilinoterephthalic acid in polyphosphoric acid and diluting the mixture by addition thereof into a water-miscible alcohol containing 1-3 carbon atoms, e.g. methanol, while maintaining the temperature of the alcohol-acid at between 0.degree. and 25.degree. C.

Process for preparing gamma quinacridone from polyphosphoric acid and

A method is provided for the production of gamma quinacridone solid solutions which comprises ring-closing a mixture comprising 80-99 weight percent of dianilinoterephthalic acid and 1-20 weight percent of di(ortho-substituted) anilinoterephthalic acid, 4,11-disubstituted quinacridone, or mixtures thereof, and drowning the product into a water miscible alcohol containing from 1 to 3 carbon atoms.

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Elmwood Park, NJ, United States of America

Robert Jarl North