Benzil, preparation from diphenylacetylene

In the preparation of diphenylacetylene from benzil dihydrazone, this derivative is suspended in benzene in a flask fitted with a stirrer and reflux condenser, and mercuric oxide is added in portions at a rate sufficient to maintain gentle refluxing... 

Diphenylacetylene has been prepared by the present method 1 by the action of sodium amide on monochlorostilbene 2 by the action of potassium amide on stilbene dichloride 3 by heating 1,1-diphenyl-2-chloroethane with sodium ethoxide in a sealed tube 4 and from benzil via the hydrazone.5... 

Curtius et ah206 showed that acetylenes can also be prepared by oxidizing vicinal dihydrazones with yellow mercuric oxide. Diphenylacetylene, for example, is thus obtained in 75% yield from benzil dihydrazone.207 In a variant of the Curtius procedure diacetylenes can be prepared in 80-85% yield by oxi-... 

Dimethyl sulphoxide acts as a nucleophile, rather than an oxidant, in the conversion of epoxides into glycols, in the presence of BF3 or tri-nitrobenzenesulphonic add, but the conversion of cyclohexane 1,4-dioxide into pyrocatechol with DMS0-BF8,Et20 implies oxidation. Lead tetra-acetate in DMSO oxidizes JV-amino-pyridones and -phen-anthridones to nitrenes, which can be trapped as sulphoximides R2N-N=S(0)Me2. Diphenylacetylene gives benzil, Ph CO CO Ph, on treatment with JV-bromosuccinimide (more than 2 equiv.) in anhydrous DMSO, while stilbene gives the dibromo-adduct under the same conditions further studies may show this to be a very useful method for preparing 1,2-diketones from acetylenes. 

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See also in sourсe #XX -- [ ]

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