Preparation of DI- or triarylmethane dyes by oxidation
AssigneeBASF SE
InventorsThomas Gessner, Udo Mayer
Life of this patent
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Abstract
A process for preparing di- or triarylmethane dyes by oxidation of di- or triarylmethanes in the presence of a diluent and of an oxygen transfer catalyst that contains a complexed heavy metal ion or of a catalyst based on molybdenic acid and vanadium compounds comprises using as oxidizing agent peroxomonosulfuric acid or a salt thereof.
Claims6
A process for preparing dyes of the formula I ##STR12## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently of one another C.sub.1 -C.sub.8 -alkyl which may be substituted and may be interrupted by from 1 to 3 oxygen atoms in the ether function, phenyl or C.sub.1 -C.sub.4 -alkylphenyl, and
- R.sup.5 and R.sup.6 are independently of one another hydrogen or methyl,
- X is hydrogen, substituted or unsubstituted phenyl or substituted or unsubstituted naphthyl, and
- An.sup..crclbar. is an anion, by oxidation of a leuco compound of the formula II ##STR13## where R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and X are each as defined above, in the presence of a diluent, peroxomonosulfuric acid or a salt thereof as oxidizing agent, and a catalyst consisting essentially of an oxygen transfer catalyst which contains a complexed heavy metal ion;
- or molybdenic acid in admixture with vanadium in the form of VO.sup.2.sym. ions or pentavalent vanadium compounds.
Dependencies are inferred from the claim text.