Hydrogen Bromide → 2-Bromo-m-xylene

Participants

Reaction Conditions

Reaction Steps

To an initial charge of 125 ml of 48% aqueous HBr are added, in portions, 24.24 g [0.2 mol] of 2,6-dimethylaniline. The resulting thick suspension is stirred at 80° C. for 15 minutes. It is then cooled to −10° C., and a solution of 16 g [0.232 mol] of NaNO2 in 70 ml of water is added dropwise within approx. 1 h at such a rate that the temperature does not exceed −5° C. 160 mg of sulphamic acid are added. Then the suspension of the diazonium salt, cooled to −10° C., is metered within about 45 minutes into a solution, heated to 60° C., of 31.6 g [0.22 mol] of Cu(I)Br in 130 ml of 62% aqueous HBr. The reaction mixture is then stirred at 80° C. for another 1 hour, allowed to cool to room temperature and admixed with 250 ml of water, the phases are separated and the aqueous phase is extracted three times with 100 ml each time of methylene chloride. The combined organic phases are washed with 50 ml each of water and saturated aqueous NaCl solution, dried and concentrated under reduced pressure. This gives 33.3 g of an oil which, according to GC, contains 75.6% of 2,6-dimethylbromobenzene (68% of theory).

Provenance & Evidence