Process for preparing bis(hydroxymethyl)perylenetetracarboximide

A process for the preparation of a perylene derivative of the formula (I)

• wherein X1 and X2, each independently of the other, are pigment moieties selected from the group consisting of diketopyrrolopyrrole, quinacridone, phthalocyanine, indanthrone, isoindoline, isoindolone, flavanthrone, pyranthrone, anthraquinone, thioindigo, perylene and dioxazine moieties and mixtures thereof, D is chlorine or bromine, and n is an integer from 0 to 4;
• which perylene derivative contains from 0 to 6 moles of —SO3M per mole of the perylene derivative;
• wherein M is hydrogen or a metal or ammonium cation, which process comprises reacting perylene-3,4,9,10-tetracarboximide of the formula
• in a first step with formaldehyde to yield a sulfonated or non-sulfonated form of bis(hydroxymethyl)perylene-3,4,9,10-tetracarboximide of the formula (II)
• which intermediate reacts in a second step with a precursor of the organic radicals, X1 and X2, to yield the sulfonated or non-sulfonated form of the perylene derivative of formula (I).