Sodium Hydroxide → Crystal Violet lactone

Participants

Reaction Conditions

Reaction Steps

To a 500 ml reaction vessel, 21.5 g of 2-[4,4'-bis(dimethylamino) benzhydryl]-5-dimethylaminobenzoic acid having a purity of 97.0% was charged and 250 g of water was added. To the dispersion thus obtained, 21.5 g of activated carbon; SHIRASAGI-C (manufactured by Takeda Chemical Ind. Co.) and 2.0 g of a 49% aqueous NaOH solution were added and stirred at 90 to 95° C. Through the reaction system thus obtained air was blown for 9 hours at a rate of 400 ml/min. After finishing the reaction, the reaction mass was filtered and the obtained cake was slurried in water, and completely dissolved by adding 19.5 g of a 36% aqueous HCl solution. Thereafter, the activated carbon was filtered. The filtrate was neutralized to pH7.0 with a 49% aqueous NaOH solution. The precipitated crystals were filtered, washed and dried to obtain 20.1 g of 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide. The yield was 95.4%. Formation of by-product in the reaction was 1.5%. Selectivity of reaction was 98.4%.

Provenance & Evidence