Preparation of 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide
AssigneeBASF SE
InventorWalter Seibert
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Abstract
Crystal violet lactone is prepared by oxidizing 2-(4,4'-bis-dimethylaminobenzhydryl)-5-dimethylaminobenzoic acid in aqueous alkaline solution by means of a water-soluble ferricyanide salt or in the presence of a ferricyanide. A very pure crystal violet lactone is obtained in high yield.
Claims8
In a process for the preparation of 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone) by oxidizing 2-(4,4'-bis-dimethylaminobenzhydryl)-5-dimethylaminobenzoic acid in aqueous alkaline solution at from 0.degree. to 100.degree. C. and at a pH of from 8 to 12, the improvement that the oxidation is carried out with a water-soluble ferricyanide salt or in the presence of a ferricyanide.
Dependencies are inferred from the claim text.