Hydrogen Bromide → 2-bromo-5-chloro-1,3-dimethylbenzene

Temperature

80 °C

To an initial charge of 75 ml of 48% aqueous HBr are added, in portions, 19.67 g [0.12 mol] of 4-chloro-2,6-dimethylaniline. The resulting thick suspension is stirred at 80° C. for 15 minutes. Then the mixture is cooled to −10° C., and a solution of 9.6 g [0.139 mol] of NaNO2 in 45 ml of water is added dropwise within approx. 1 h at such a rate that the temperature does not exceed −5° C. 100 mg of sulphamic acid are added. Then the suspension of the diazonium salt, cooled to −10° C., is metered within about 35 minutes into a solution, heated to 80° C., of 17.93 g [0.125 mol] of Cu(I)Br in 75 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 125 ml of water, the phases are separated and the aqueous phase is extracted three times with 50 ml each time of methylene chloride. The combined organic phases are washed twice with 25 ml each time of water, dried and concentrated under reduced pressure. This gives 20.2 g of an oil which, according to GC, contains 95.5% 4-chloro-2,6-dimethylbromobenzene (73% of theory).

1. temperatureThen the mixture is cooled to −10° C.
2. customdoes not exceed −5° C
3. temperaturecooled to −10° C.
4. waitis metered within about 35 minutes into a solution
5. stirringThe reaction mixture is then stirred at 80° C. for another 1 hour
6. temperatureto cool to room temperature
7. customthe phases are separated
8. extractionthe aqueous phase is extracted three times with 50 ml each time of methylene chloride
9. washThe combined organic phases are washed twice with 25 ml each time of water
10. customdried
11. concentrationconcentrated under reduced pressure

ORD record

ord-b37f9c4a220340ce8db82eabd7b5b23a

Source dataset

uspto-grants-2012_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08334417B2