Perylene 3,4,9,10-tetra:carboxylic acid N,N'-di:methyl-imide prepn. - in pigment form by direct methylation of the di:imide

摘要

Perylene, 3,4,9,10-tetracarboxylic acid N,N'-dimethylimide is made by methylation of the diimide in aq. alkaline medium at 80-180 degrees C in presence of a surfactant, pref. of cationic type. Used as a maroon pigment for use in plastics, paints, lacquers, etc. The dimethylimide is obtd. directly in pigment form without need for pptn. from H2SO4, salt-milling or solvent recrystallisation. It is easily dispersed and gives purer, yellower shades with increased transparency and around 15% greater intensity than known pigments of this material.