| 42% |
With N-Bromosuccinimide; 2,2'-azobis(isobutyronitrile); In tetrachloromethane; at 70℃; |
To a solution of compound 9b (300 mg, 1.43 mmol) in 20 mL of CC14 was added NBS (584 mg, 3.30 mmol) and AIBN (18 mg, 0.10 mmol). The resultant solution was stirred overnight at 70 C, then filtered and the filtrate was washed with hot water and brine and dried (MgS04). After evaporation of the solvent, the product was recrystallized from acetonitrile yielding 220 mg (42%) of an orange solid. Mp. 183-185 C. -NMR (400 MHz, CDCI3): delta 7.89 (d, J=8.4 Hz, 4H), 7.54 (d, J=8.4 Hz, 4H), 4.56 (s, 4H). -NMR spectrum in agreement with published data.35 |
|
With N-Bromosuccinimide; dibenzoyl peroxide; In acetonitrile; for 4h;Reflux; |
In a 250 ml round bottom flask, 6.86 g (0.050 mol) of p-nitrotoluene, 110 ml of methanol, 1.5 g (0.063piomicron1) of magnesium shoulder and a small amount of iodine were added, and the reaction was initiated by warming, and the reaction was started to exotherm, and an ice water bath was available. Keep the flow back.When the magnesium shoulder reacted substantially, it was cooled, and then 1.5 g (0.063 mol) of magnesium shoulder was added, and then it was refluxed on a hot water bath at 70-80 C until the magnesium shoulder substantially disappeared. After cooling, the mixture was poured into a beaker containing 200 ml of water, and glacial acetic acid was slowly added thereto under stirring to weakly acidify, and a pale yellow solid was precipitated. The mixture was filtered under reduced pressure, and the filter cake was washed with water, and recrystallized three times from anhydrous ethanol to obtain crystals twice. The type does not meet the requirements, and a golden solid is obtained after three times. In a 250 ml beaker, add 2.8 g (0.013 mol) of 4,4'-dimethylazobenzene, 5.2 g (0.029 mol) of NBS, benzoyl peroxide and a sufficient amount of acetonitrile, first dissolve with acetonitrile, then add half NBS and a sufficient amount of catalyst benzoyl peroxide, completely dissolved and then added to the other half of the NBS, heated under reflux for 4 h, cooled and filtered. The residue was taken up, dissolved in ethanol and then added with a solution of 1.33 g (0.029 mol) of trimethylamine, heated under reflux for 5 h, and evaporated to remove ethanol.The remaining solid was dissolved in ethanol, and then ethyl acetate was added until a trace amount of product was precipitated, which was cooled and precipitated, and recrystallized. The solid was obtained by suction filtration, and the above procedure was repeated three times to obtain a yellow solid product. Yield 60.5 % (yield = molar amount of p-nitrotoluene / 1,1 '-(diazene-1,2-diylbis(4,1-phenylene))di(N,N,N- Trimethylammonium) molar amount). |
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