Process for manufacturing crystal violet lactone
AssigneeAmerican Cyanamid Company
InventorDonald Roy Maulding
Life of this patent
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Abstract
Crystal Violet Lactone (CVL) is produced in high yield and highly pure form by a process comprising condensing Michlers hydrol with 3-dimethylaminobenzoic acid to form leuco CVL, extracting the reaction mixture containing the leuco CVL with an aromatic hydrocarbon solvent, such as toluene, or a mixture of such a solvent and a water-immiscible alkane, such as heptane, to remove impurities therefrom and treating the extracted reaction mixture with an inorganic oxidizing agent to convert the leuco CVL to CVL.
Claims8
A process for preparing 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide which comprises reacting one mole proportion of tetramethyl-4,4'-diaminobenzhydrol with from about 0.9 to about 1.2 mole proportions of 3-dimethylaminobenzoic acid in aqueous sulfuric acid at a temperature of 65.degree.-100.degree. C. to form 2-[4,4'-bis(dimethylamino)benzhydryl]-5-dimethylaminobenzoic acid, adding sodium hydroxide to the reaction mixture to form the sodium salt of the said benzoic acid therein, contacting the reaction mixture at a temperature of about 40.degree.-90.degree. C. with a solvent selected from a liquid aromatic hydrocarbon and a mixture of liquid aromatic hydrocarbon and a water-immiscible alkane, whereby impurities present in said solution are extracted therefrom;
- separating the organic extract phase from the aqueous reaction mixture phase, treating the reaction mixture phase with an inorganic oxidizing agent to oxidize the sodium salt of the 2-[4,4'-bis(dimethylamino)benzhydryl]-5-dimethylaminobenzoic acid to the 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide product and recovering said product from the reaction mixture.
Dependencies are inferred from the claim text.