Patent ID: 7524979
Filing Date: 2009-04-28
Classification: C09B

Abstract:
1. A process for preparing a colorant of the formula wherein Y is a hydrogen atom or a bromine atom, n is an integer of 0, 1, 2, 3, or 4, R 1 is an alkylene group or an arylalkylene group, R 2 is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, and R 4 is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, which comprises (a) preparing a first reaction mixture by admixing (1) leucoquinizarin and, optionally, quinizarin, (2) an aminobenzene substituted with an alcohol group of the formula —R 1 —OH, (3) boric acid, and (4) an optional solvent, and heating the first reaction mixture to prepare an alcohol-substituted colorant of the formula followed by (b) converting the colorant thus prepared to either (i) an ester-substituted colorant by reaction with an esterification compound which is either (A) an anhydride of the formula or (B) an acid of the formula R 2 COOH in the presence of an optional esterification catalyst, or (ii) a urethane-substituted colorant by reaction with an isocyanate compound of the formula and (c) brominating the colorant thus prepared, wherein either conversion to ester or urethane can be performed before bromination or bromination can be performed before conversion to ester or urethane.