C Benzoin

C 6 H BENZOIN 5 [[Choh Co. C 6 H]] 5, a ketone-alcohol, which may be prepared by boiling an alcoholic solution of benzaldehyde with potassium cyanide; by reducing benzil (C6H5CO CO C6H5) with zinc and acetic acid; or by the oxidation of hydrobenzoin (C 6 H 5. [[Choh Choh C 6 H]] 5). It is a colourless, crystalline solid, readily soluble in alcohol and ether, melting at 137° C. and boiling at 343-344°C. On passing the vapour of benzoin over heated lead oxide, it is converted into benzil and benzophenone. Owing to the readiness with which it is oxidized, it acts as a reducing agent, giving a red precipitate of cuprous oxide with Fehling's solution in the cold. Chlorine and nitric acid oxidize it to benzil; chromic acid mixture and potassium permanganate, to benzoic acid and benzaldehyde. On heating with zinc dust, desoxybenzoin (C 6 H 5 CO CH 2 C 6 H 5) is obtained; sodium amalgam converts it into hydrobenzoin; and fuming hydriodic acid at 130° C. gives dibenzyl (C 6 H 5 CH 2 CH 2 C 6 H 5). By fusion with alkali it is converted into benzil; and with an alcoholic solution of benzaldehyde in presence of ammonia it forms amarine (triphenyl dihydro-glyoxaline). In the presence of sulphuric acid it condenses with nitriles to oxazoles.

Categories: BEF-BEN | Biography