反应详情

温度

-30 °C

Twenty milliliters (ml) of methylene chloride are added to a 100 ml, 3-neck roundbottom flask fitted with a thermometer, pressure equalizing dropping funnel and nitrogen inlet. The flask is cooled in a bath of dry ice and ethylene glycol until the methylene chloride reaches a temperature of -30° C. Cyanogen bromide (4.32 grams (g), 0.0408 moles) is added to the flask. A solution of 2,4,6-trimethyl-3,5-dibromophenol (10.0 g, 0.034 mole), triethylamine (3.96 g, 0.0391 mole), and 20 ml of methylene chloride is added dropwise through the dropping funnel over a 1-hour period. The reaction temperature is maintained between -25° C. and -30° C. After about 2/3 of the phenol solution is added, a solid begins to precipitate. When the addition of the phenol solution is complete, the dropping funnel is rinsed with an additional 5 ml of methylene chloride. The reaction mixture is stirred at -30° C. for 45 minutes and then is allowed to warm to room temperature over an additional 45 minutes. 0.1N aqueous HCl is added to the reaction mixture to neutralize excess cyanogen bromide and the mixture is then stirred for 5 minutes. The neutralized mixture is transferred to a separatory funnel and the organic layer is removed. The organic layer is washed with water and is dried over magnesium sulfate. The solvent is removed from the treated organic layer in vacuo to give 10.9 g of a white solid (100 percent crude yield). This material is heated to 75° C. under vacuum to remove volatiles. The material is then bulb to bulb distilled at 150° C. and 0.1 millimeters (mm) mercury to give a white solid (7.46 g, 69 percent yield) with a melting point between 126.5° and 127.5° C.

1. customfitted with a thermometer, pressure
2. customa temperature of -30° C
3. temperatureThe reaction temperature is maintained between -25° C. and -30° C
4. customto precipitate
5. additionWhen the addition of the phenol solution
6. washthe dropping funnel is rinsed with an additional 5 ml of methylene chloride
7. temperatureto warm to room temperature over an additional 45 minutes
8. addition0.1N aqueous HCl is added to the reaction mixture
9. stirringthe mixture is then stirred for 5 minutes
10. customThe neutralized mixture is transferred to a separatory funnel
11. customthe organic layer is removed
12. washThe organic layer is washed with water
13. dry with materialis dried over magnesium sulfate
14. customThe solvent is removed from the treated organic layer in vacuo