Sulfuric Acid → Methyl 3-hydroxy-4-phenylthiobenzoate

Participants

Reaction Conditions

Reaction Steps

Adding 110.27 g of 3-amino-4-phenylthiobenzoic acid to 400 ml heated water solution of concentrated sulfuric acid (81 ml), the mixture was heated and stirred for 2 hours, and cooled with ice-salt bath to -5° C. To this solution, a 80 ml water solution of 36.25 g of sodium nitride which was ice-cooled was added in about 1 hour. Further stirring for 30 minutes at 0 ° to 5° C., 2 g of urea was added and stirred for 30 minutes, and the unreacted nitrous acid was decomposed, the obtained mixture was gradually added to a mixture of 121 ml of concentrated sulfuric acid, 168 g of anhydrous sodium sulfate and 112 ml of water, while stirring, in 75 minutes at 100° to 110° C. After addition, the mixture was further stirred for 1 hour at the same temperature. The reaction mixture was cooled, and precipitating brown granules were filtered, washed with water, and dried overnight at 50° C. The obtained product was added to the mixture of 1.4 liters of methanol and 70 ml of concentrated sulfuric acid, and the mixture was refluxed for 2 hours while stirring. After termination of reaction, the reaction mixture was concentrated in vacuo, and 1.5 liters of water was added to the residue, and the product was extracted with ethyl acetate (500 ml×3). The extract was dried in anhydrous sodium sulfate, and concentrated in vacuo. The residue was extracted in 4.2 liters of hot hexane, and cooled, and precipitating yellow matter was filtered, and 49.37 g of methyl 3-hydroxy-4-phenylthiobenzoate was obtained.

Provenance & Evidence