4,5-DIBROMO-O-XYLENE

White solid

General procedure: 1-Methoxy-3, 5-dimethylbenzene(100mg, 0.73 mmol), N-Bromosuccinimide (NBS, 260 mg, 1.46 mmol) and one ball (5 mmdiameter, stainless steel) were transferred to a milling jar (10 mL, stainlesssteel). The ball-milling operation was performed and the progress of reaction was monitored by TLC/General procedure: 1-Methoxy-3, 5-dimethylbenzene (100mg, 0.73 mmol), N-Bromosuccinimide (NBS, 260 mg, 1.46 mmol) and one ball (5 mmdiameter, stainless steel) were transferred to a milling jar (10 mL, stainlesssteel). The ball-milling operation was performed and the progress of reactionwas monitored by TLC/4 mL Br2 was added dropwise to a solution of I2 (20 mg) in o-xylene (4.6 mL, 38mmol) at 0oC within 30 min. The resultant was left overnight at room temperature, followed by dissolving in Et2O (20 mL), washing with 2 N NaOH (2 X 10 mL), H2O(2 X 10 mL) and dring over MgSO4. The organic solvents were then concentrated invacuo to afford a faintly pink colored oil, which was further purified byrecrystallization in methanol to give 6.8 g pure 4, 5-dibromo-o-xylene in 67percent yield.1H NMR (400 MHz, CDCl3) δ 7.37 (s, 2H), 2.18 (s, 6H).Iodine (1.6g, 6.3mmol) was added to o-xylene (40g, 0.38mol) and stirred under ice-water mixture, then bromine (124g, 0.77mol) was dropped slowly to keep the temperature at −5 to 0°C. After stirring for 20h, the mixture was dissolved in ether, washed with aqueous potassium hydroxide and fresh water for three times, dried with anhydrous MgSOWill be o-Xylene 24 ml (0.2 mol)Dissolved in 30mlIn dry methylene chloride, Iodine was added to the solution while stirring2.5 g (10 mmol) and reduced iron powder(10 mmol).The mixture was cooled to zero degrees with an ice bath.Another liquid bromine 20.5 ml (0.4 mol)Was dissolved in 10 ml of dry methylene chloride, The solution was slowly added dropwise over a period of six hours using a dropping funnelThe reaction mixture, The released hydrogen bromide gas was absorbed in a funnel inverted in a 10percent sodium hydroxide solution.The reaction was stirred continuously at 0 ° C for 38 hours, Followed by stirring at room temperature for 6 hours.The reaction mixture was washed with 5percent sodium hydroxide solution until colorless, Separating the organic layer;And then washed with 5percent sodium bisulfite solution to neutral, The organic layer was separated, And dried over anhydrous sodium sulfate.After standing overnight, the filtrate was evaporated under reduced pressure on a rotary evaporator to give a light brown oily liquid.To the liquid was added 8-10 times the volume of methanol, Stirring heated to boiling, and then stop stirring, Cooled to zero degrees recrystallization.32.7 g of a transparent acicular crystal was obtained in a yield of 62percent.

Molecular Weight:263.96
XLogP3:4
Exact Mass:263.89723
Monoisotopic Mass:261.89928
Heavy Atom Count:10
Complexity:99.8
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes