Synthesis
2-Bromo-m-xylene is a bromoaromatic hydrocarbon that can be prepared from 2,6-dimethylaniline via a diazotization reaction.
12.12 g [0.1 mol] of 2,6-dimethylaniline was added in portions to an initial feed of 65 ml of 48% HBr aqueous solution. The resulting concentrated suspension was stirred at 80 °C for 15 min. It was then cooled to -10 °C, and a solution of 8 g [0.116 mol] NaNO2 in 35 ml of water was added dropwise over approximately 1 h at a temperature not exceeding -5 °C. 80 mg of aminosulfonic acid was then added. The diazonium salt suspension, cooled to -10°C, was then metered over approximately 30 minutes into a solution formed by heating 13.9 g [0.05 mol] FeSO4·7H2O in 65 ml of 62% HBr aqueous solution to 80°C. The reaction mixture was then stirred at 80°C for 1 h, cooled to room temperature, and mixed with 125 ml of water. The phases were separated, and the aqueous phase was extracted three times with 50 ml of dichloromethane each time. The combined organic phases were washed twice with 25 ml of water each time, dried, and concentrated under reduced pressure. 17.4 g of an oil was obtained, which, according to GC, contained 83% 2-Bromo-m-xylene (78% of the theoretical value).
Uses
2-Bromo-m-xylene has been used to prepare 2,2,4,6,6-pentamethylbiphenyl. It is used as an intermediate in organic synthesis.
