Benzaldehyde → HCID 11346195, compound

Participants

Reaction Steps

A portion of ZnCl2 (23 kg, 171 mol) was placed into a reactor, taking measures to exclude moisture. Benzaldehyde (70 L, 680 mol) was poured into the reactor, and the mixture was stirred for about 30 minutes using a powerful mechanical stirrer. After initial dissolution of zinc chloride, a thick slurry of a benzaldehyde-ZnCl2 complex forms. Anhydrous D-galactose (30 kg, 164 mol) and more benzaldehyde (60 L, 570 mol) were added to the warm slurry, and the mixture was allowed to react at RT for 24 hours with vigorous stirring. The precipitate was filtered off and washed portionwise with benzaldehyde (10-15 L total) and then with acetone, to give, after air-drying, 6-7 kg of unreacted D-galactose, probably as the monohydrate. The combined filtrate and benzaldehyde washings were diluted with ether (70 L) and petroleum ether (80 L), and the mixture was extracted with ice-cold water (140 L) . The organic layer was washed 3 times with ice water (70 L each time), and the combined aqueous layers were neutralized by rapid addition of a solution of potassium carbonate (38 kg of anhydrous carbonate in approximately 45-50 L of water). The resulting thick suspension of zinc salts was filtered, and the precipitate was washed thoroughly with water until 500-600 L of filtrate were collected. After extraction with chloroform (70 L) and with petroleum ether (70 L), the filtrate, containing 4,6-O-benzylidene-D-galactose (2) and a mixture of KCl and KHCO3, and having a pH of about 8.7, was used directly for the following oxidation.

Provenance & Evidence