ChemicalBook CAS DataBase List 4'-Bromo-3'-methylacetophenone

4'-Bromo-3'-methylacetophenone synthesis

14synthesis methods

Product Name:4'-Bromo-3'-methylacetophenone
CAS Number:37074-40-1
Molecular formula:C9H9BrO
Molecular Weight:213.07

A solution of 4-bromo-3-methylbenzaldehyde (4 g, 20 mmol) in dry tetrahydrofuran (40 mL) was cooled to 0°C under nitrogen atmosphere, and then methyl magnesium bromide (20 mL, 1N in tetrahydrofuran) was added dropwise. The ice bath was removed, and the mixture was stirred for 2 hours. Ammonium chloride aqueous (40 mL) was added and the mixture was extracted with dichloromethane (20 mL * 3). The organic phase was dried by sodium sulphate, filtered and concentrated to give a residue. The residue was purified by column chromatography (silica gel, petroleum ether/ethyl acetate = 5:1) to give 1-(4-bromo-3-methylphenyl)ethanol. Colorless oil, yield 4.0 g, 93%. Pyridinium chlorochromate (48 g, 223 mmol) was added to a solution of 1-(4-bromo-3-methylphenyl)ethanol (31.9 g, 148 mmol) in dichloromethane (800 mL). The mixture was stirred at room temperature for 2 hours. The mixture was concentrated to give a residue. The residue was purified by column chromatography (silica gel, petroleum ether/ethyl acetate = 25:1) to give 4'-Bromo-3'-methylacetophenone. Yield 27.3 g, 87%.

Figure Synthesis of 4'-Bromo-3'-methylacetophenone

43230-11-1 Synthesis

Ethanone, 1-(4-amino-3-methylphenyl)- (9CI)

43230-11-1
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37074-40-1
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Yield: 84%

Reaction Conditions:

Stage #1:4'-amino-3'-methyl-acetophenone with sulfuric acid;sodium nitrite in acetonitrile at 0;
Stage #2: with urea in water;acetonitrile
Stage #3: with hydrogen bromide;copper(I) bromide in water;acetonitrile at 50; for 2 h;

Steps:

Step 2: Synthesis of 4'-bromo-3'-methylacetophenone 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%).

References:

Nissan Chemical Industries, Ltd. EP2172462, 2010, A1 Location in patent:Page/Page column 73-74