Sulfuric Acid → 4-Acetyl-2-methylbenzenediazonium sulfate

Participants

Reaction Conditions

Reaction Steps

27.0 g of acetonitrile was added to a sulfuric acid solution of 27.0 g (181 mmol) of 4-acetyl-2-methylaniline, and the mixture was cooled to 0° C. An aqueous solution in which 13.1 g (190 mmol) of sodium nitrite was dissolved into 26.2 g of water was added in dropwise to the mixture. After reacting the resultant mixture for 1 hour at 0° C., an aqueous solution in which 1.1 g (18 mmol) of urea was dissolved into 2.2 g of water was added in dropwise, and the mixture was further stirred for 30 minutes to obtain an aqueous solution of 4-acetyl-2-methylbenzenediazonium sulfate. 5.18 g (36 mmol) of copper bromide, 62.2 g (362 mmol) of 47% hydrobromic acid and 81.0 g of acetonitrile were fed into another reactor. The aqueous solution of 4-acetyl-2-methylbenzenediazonium sulfate was added to this mixture in dropwise over 1 hour with stirring at 50° C. After adding in dropwise, the mixture was reacted for 1 hour at 50° C. Then, 81 g of toluene was added and the mixture was stirred for 30 minutes, and the water phase was separated. 54 g of toluene was added to the water phase and extracted again. The combined toluene solution was washed twice with 54 g of 14% aqueous ammonia and once with 54 g of water to obtain a toluene solution of 4′-bromo-3′-methylacetophenone. After removing the solvent by distilling under reduced pressure, the residue was distilled under reduced pressure of 1.5 kPa. 32.8 g of the obtained fraction which was collected in the range of outflow gas temperature from 130° C. to 137° C. was analyzed by HPLC. A percentage of relative area of 4′-bromo-3′-methylacetophenone was 99.1% (yield 84%).

Provenance & Evidence