1,2-dichloroethane, commercial, 98%

Aluminium chloride, Lab reagent, 98%

Benzaldehyde, commercial, 97.5%

Sodium carbonate, Lab grade

Bromine- 98%, commercial

To a clean 2 l 4 necked flask carrying calcium chloride guard tube, thermometer pocket and a mechanical stirrer, was charged Dichloroethane (500 mL) followed by anhydrous aluminium chloride (177 g, 1.32 mol) under stirring. To this benzaldehyde (104 g, 1 mol) was added over a period of 1 h at 38-40 oC. After this bromine (176 g, 56.8 mL, 1.1 mol) was added over a period of 2 h at about 40 oC and further the mixture was stirred at the same temperature for 2 h. The reaction mass was quenched to approximately 1 kg crushed ice and stirred for 10 min. The organic layer separated was removed and washed with water ( 1000 mL) and 300 mL sodium carbonate solution(5%) followed by water (750 mL). The organic layer thus obtained was concentrated to get about 200 g residue. This residue was distilled under vacuum to get 160 g of pure 3-bromo benzaldehyde (Yield: 87%).

1H NMR (90 MHz): δ 9.95 (1H), 8.20-7.15 (3 multiplets, 4H)

13C NMR ( 75 MHz): δ 190.50, 137.96, 137.15, 12.13, 130.58, 128.30, 123.27.

FTIR (neat): 1708, 1191, 676 cm -1

 

Shinichi Matsuura, Osamu Miyano, USPatent No: 4,945,186 (1990)