N([O-])=O.[Na+].[CH3:5][C:6]1[CH:12]=[CH:11][C:9](N)=[CH:8][C:7]=1[S:13][CH3:14].[BrH:15]>S(=O)(=O)(O)O.C(O)(=O)C.O.[Cu]Br>[Br:15][C:9]1[CH:11]=[CH:12][C:6]([CH3:5])=[C:7]([S:13][CH3:14])[CH:8]=1
A cooled solution of sodium nitrite (5.8 g) in concentrated sulphuric acid (50 ml) was added dropwise to a stirred solution of 4-methyl-3-methylsulphenylaniline (12.8 g) in glacial acetic acid at 20° C. The resulting suspension was added to a mixture of copper (I) bromide (12 g), aqueous hydrobromic acid (48-50%) and ice. The mixture was stirred at room temperature for 3 hours then diluted with water and extracted with ethyl acetate. The organic layer was washed with water, aqueous sodium hydroxide (2M), dried (anhydrous magnesium sulphate) and filtered. The filtrate was evaporated to dryness. The residue was triturated with hot cyclohexane and filtered. The filtrate was evaporated to dryness to give 4-bromo-2-methylsulphenyltoluene (8.6 g) as a brown oil, NMR (CDCl3): 2.15(s,3H), 2.2(s,3H), 6.5-7.1 (m,3H).
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