4-Chlorobenzaldehyde → 1,2-Bis(4-chlorophenyl)-2-hydroxyethanone

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Reaction Steps

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.

Provenance & Evidence