Benzoins benzilic acids

Benzilic acid may be obtained in a high state of purity by the action of an alkaline bromate solution upon benzoin at 85-90° ... 

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction... 

RecrystaUise 5 0 g. from about 40 ml. of hot rectified (or methylated) spirit upon cooling, 4-5 g. of pure benzoin (a white, crystalline solid, m.p. 137°) separate. Reserve the remainder of the preparation for benzil and benzilic acid (Sections IV,126 and IV,127 respectively). 

Benzilic acid rearrangement, 232 Benzoin condensation, 231 cyanide ion in, 231 thiazolium ylids in, 232... 

Benzilic acid has been made by the action of potassium hydroxide on benzil, either in concentrated aqueous solution 1 (described first in a paper by M. Bosler and later in papers by H. Klinger and by H. Staudinger) or in alcoholic solution2 (described by J. Liebig, N. Zinin, A. Jena and H. v. Liebig) and either one of these processes furnishes a method for producing benzilic acid cheaply and in large amounts. The other methods by which it may be made are the action of alcoholic potash upon isobenzil 3 the hydrolysis of diphenyl-bromoacetic acid 4 the action of alkalies upon benzoin 5 the action of sodium on benzo-phenone.6... 

Both benzil and benzoin are reduced by TiCl3 in an acidic medium to hydrobenzoin (95% yield) but in this case the meso-isomer is strongly favored over the d/-isomer (—80 20). 

Direct conversion of a benzoin into the corresponding benzilic acid may be accomplished conveniently and in good yield by reaction with alkaline bromate solution at 85-90 °C (see Expt 6.144, Method 2). 

A similar rearrangement occurs when a-epoxyketones are refluxed with 30% aqueous sodium hydroxide. Best directions ate those for benzilic acid (90%) from benzoin, sodium bromate, and sodium hydroxide. Oxidation of the benzoin to benzil and rearrangement of benzil to benzilic acid are accomplished in one step. a-Ketoaldehydes and potential a-ketoalde-hydes undergo a similar internal oxidation-reduction reaction in excellent yields, viz.,... 

Chapter 55 Nitric Acid Oxidation. Preparation of Benzil from Benzoin. 

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