| 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, R1 is an alkylene group or an arylalkylene group, R2 is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, and R4 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 —R1—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 R2COOH in the presence of an optional esterification catalyst, or (ii) a urethane-substituted colorant by reaction with an isocyanate
compound of the formula
R4—N═C═O,
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.
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