反应详情

To a solution of 4-chlorobenzaldehyde (240 g, 1.707 mol) in 144 mL of methanol was added 2.40 g of potassium cyanide in 4.8 mL water over 6 min. The mixture was refluxed for another 50 min (mixture became deep red), cooled, then concentrated under reduced pressure. The red residue was taken up in 1500 mL of hexane-ethyl acetate (1:1), and washed successively with water (1×150 mL), 20% sodium bisulfite (6×150 mL), brine (1×150 mL) and dried over anhydrous sodium sulfate. After filtration and concentration under reduced pressure, the product was boiled in 400 mL of hexane to remove small amounts of 4-chlorobenzaldehyde. The mixture was cooled and the white solid was collected by suction filtration to give 183.94 g of 4,4′-dichlorobenzoin (76%). This procedure was adapted from Lutz et al. J. Am. Chem. Soc. 1949, 71, 478.

1. temperatureThe mixture was refluxed for another 50 min (mixture became deep red)
2. temperaturecooled
3. concentrationconcentrated under reduced pressure
4. washwashed successively with water (1×150 mL), 20% sodium bisulfite (6×150 mL), brine (1×150 mL)
5. dry with materialdried over anhydrous sodium sulfate
6. filtrationAfter filtration and concentration under reduced pressure
7. customto remove small amounts of 4-chlorobenzaldehyde
8. temperatureThe mixture was cooled
9. filtrationthe white solid was collected by suction filtration