Glyoxal dioxime

Oxadiazole has been prepared by heating glyoxal dioxime with succinic acid anhydride at 150-170°C. For the synthesis of substituted compounds, mere heating is sufficient in some cases, whereas the action of thionyl chloride in 1,2-dichloroethane gives good results in others. 

The extent of oxidation, when determined by the reaction of the product with phenylhydrazine, is 85%. Hydrolysis of the oxidized xylan should produce approximately equimolar quantities of D-glyceraldehyde and glyoxal. Experimental determination of glyceraldehyde indicates 67 % of the theoretical when the oxidized xylan is distilled with sulfuric acid and the evolved methylglyoxal measured as the phenylosazone. Glyoxal is isolated in 63% yield, when separated as the phenylosazone or as the dioxime. Aldehyde groups in the oxidized xylan may be further... 

In the ozonolysis of 2,5-dimethylpyrrole (IV), methylglyoxal and glyoxal are formed in addition to ammonia (83%), formic acid, and acetic acid. The yield of the dioximes is about 24% and of p-nitrophenylosazones, 29 to 33%. For the molecular ratio, methylglyoxal to glyoxal, values of about 5 to 7 are found by analysis of the mixture of oximes a value of 7 has been found by analysis of the mixture of p-nitrophenylosazones. The dioximes and the p-nitrophenylosazones of both dicarbonyl compounds have been isolated in a pure form and were identified by mixed melting points with authentic samples. 

Mp 15°. Bp 51°. ng 1.3826. Vapour has green colour and burns with violet flame. Polym. readily to form complex polymeric structs. Reacts with H2O to give a complex mixt. of linear and cyclic oligomers. Aq. solns. behave chemically as the monomer. Violent reaction with some materials. Eye, skin and mucous membrane irritant. LD50 (rat, orl) 1100 mg/kg. MD2625000 Sodium bisulfite addn. compd [517-21-5] Convenient, non-aqueous form of glyoxal. Mp 193° dec. (as hydrate). Dioxime See Glyoxime in The Combined Chemical Dictionary. 

---