O-Phenylenediamine → 4-Bromobenzene-1,2-diamine

Participants

Reaction Conditions

Reaction Steps

In 64 ml of acetic acid, 8.0 g of o-phenylene diamine was dissolved, to which 15.3 ml of acetic anhydride was added drop-wise under cooling. Then the mixture was heated for 30 minutes in an oil bath at 65° C. After cooling to room temperature, a solution of bromine (4.6 ml bromine in 16 ml acetic acid) was quickly added, followed by heating for 40 minutes in an oil bath at 50° C. About 10 minutes after adding bromine, crystals started to precipitate. The reaction mixture was cooled to room temperature, and poured into 300 ml ice water containing 4.0 g sodium hydrogen sulfite. The resulting white precipitates were collected by filtration, washed with water and dried under reduced pressure (14.0 g; yield 70%). Into a 150 ml solution of water:methanol (2:1) containing 33.6 g potassium hydroxide, the white solid was dissolved and heated with stirring for 12 hours in an oil bath at 75°-80° C. After cooling the reaction mixture, and adding 400 ml water thereto, the mixture was extracted with 100 ml ether five times. The ether phase was washed with 200 ml of saturated salt water two times, and dried with anhydrous sodium sulfate. The solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:1 to 1:1) so as to obtain compound 13 as colorless crystals (5.5 g, total yield 40%).

Provenance & Evidence