反应详情

A dry 100 mL three-necked, round-bottomed flask equipped with magnetic stirring, reflux condenser, nitrogen bubbler and thermometer is charged with 0.73 g (30 mgat) of magnesium shavings and ca. 1 mL of dry ether. 4.5 g (30 mmoles) of iodomethane as a solution in ca 5 mL of ether are placed in a pressure equilibrated dropping funnel. The funnel is mounted in the central neck of the flask. A small crystal of iodine is dropped in the flask followed by about 1 mL of the iodomethane solution. When the reaction starts, the rest of the iodomethane is added dropwise, so as to maintain a gentle reflux. When the addition is complete, the solution is refluxed for 15 minutes, then cooled in an ice bath. The dropping funnel is now charged with a solution of 4.85 g (20 mmoles) of 3,3′-dimethoxybenzophenone in 10 mL of ether. The ketone is added to the Grignard reagent solution dropwise or in small portions so that the reaction is not too violent. After addition of the ketone the resulting solution is refluxed briefly (15 minutes), then cooled to room temperature. The reaction is quenched by addition of 15 g of ice. The precipitated magnesium hydroxide is dissolved by addition of 2 g of citric acid. The different layers are separated, the lower aqueous layer is extracted with 5 mL of ether. Both ethereal extracts combined are washed consecutively with water and 10% sodium carbonate, dried over anh. K2CO3 and evaporated to yield 5.28 g (quant. based on benzophenone) of 1,1-bis-(3-methoxyphenyl)ethanol. 1H NMR (CDCl3): 6.7-7.3 (m, ArH, 8H), 3.75 (s, OMe, 6H), ˜2.2 (bs, OH, 1H), 1.9 (s, C—Me, 3H).

1. customA dry 100 mL three-necked, round-bottomed flask equipped with magnetic stirring
2. temperaturereflux condenser
3. temperatureso as to maintain a gentle reflux
4. additionWhen the addition
5. temperaturethe solution is refluxed for 15 minutes
6. temperaturecooled in an ice bath
7. temperatureis refluxed briefly (15 minutes)
8. customThe reaction is quenched by addition of 15 g of ice
9. dissolutionThe precipitated magnesium hydroxide is dissolved by addition of 2 g of citric acid
10. customThe different layers are separated
11. extractionthe lower aqueous layer is extracted with 5 mL of ether
12. washBoth ethereal extracts combined are washed consecutively with water and 10% sodium carbonate
13. dry with materialdried over anh. K2CO3
14. customevaporated
15. customto yield 5.28 g (quant. based on benzophenone) of 1,1-bis-(3-methoxyphenyl)ethanol