| abstract |
The present invention relates to a process for preparing a compound of the formula [Chem I]n n n this process being characterized in that it comprises at least one step of oxidation of the sulfonated triphenylmethane of formula [Chem V] by a quinone chosen from 1,4-benzoquinone, 1,2-benzoquinone, a dialkyl (C1- C4) 1,4-benzoquinone, a dialkyl (C1-C4) 1,2-benzoquinone, a monoalkyl (C1-C4) 1,4-benzoquinone, a monoalkyl (C1-C4) 1,2-benzoquinone. |