Phenylhydrazine sugar reaction

A study of the scope of this reaction has been performed which shows that excess phenylhydrazine will convert the disubstituted quinoxalines 19 into the pyrazolo[3,4-h]quinoxaline 20. Analogously hydroxylamine gave the isoxazolo compound 21 from these starting materials. The compounds 19 (R = Me or Ph) did not undergo cyclization with phenylhydrazine. A reaction mechanism has been suggested (see Scheme 1) which is analogous to osazone formation in sugar chemistry. 

D. Volz, P. E. Reid, C. M. Park, D. A. Owen, and W. L. Dunn, Histochemical procedures for the simultaneous visualization of neutral sugars and either sialic acid and its side chain O-acyl variants or O-sulfate ester. I. Methods based upon the selective periodate oxidation of sialic acids, Histochem. J., 19 (1987) 249-256 Histochemical procedures for the simultaneous visualization of neutral sugars and either sialic acid and its O-acyl variants or O-sulfate ester. II. Methods based upon the periodic acid-phenylhydrazine-Schiff reaction, Histochem. J., 19 (1987) 257-263. 

Another reaction that is characteristic of a-hydroxy aldehydes or ketones, which has been found of value for the characterisation of sugars, is the formation of osazones with phenylhydrazine. This reagent reacts with either an aldose... 

Simple sugars undergo reaction with phenylhydrazine, PhNHNH2, to yield crystalline derivatives called osazones. The reaction is a bit complex, however, as shown by the fact that glucose and fructose yield the same osazone. 

Reducing sugars can be detected by reaction with phenylhydrazine to yield a hydrazone product, except the result of the reaction is not what one might imagine giving the structure of aldoses and ketoses. Glucose, for example, can react with phenylhydrazine to yield the anticipated... 

Sugar lactones react readily with hydrazine to give crystalline derivatives useful for isolation and identification (127). Thus, addition of hydrazine to a reaction mixture containing an aldonolactone facilitates isolation of the product. The lactone may be regenerated from the hydrazide by treatment with nitrous acid (128). The phenylhydrazides obtained on treatment of aldonolactones with phenylhydrazine are also useful for characterization (129,130). 

Reaction (reduction) with phenylhydrazine (osazone test) The open chain form of the sugar reacts with phenylhydrazine to produce a pheny-losazone. Three moles of phenylhydrazine are used, but only two moles taken up at C-1 and C-2. 

Since the discovery of the reaction of phenylhydrazine with sugars to form osazones by Fischer,35 many investigations have utilized this reaction in the identification and separation of sugars, but the precise structures of osazones and their mode of formation are still in doubt.34 There is no doubt, however, that the initial reaction involves the formation of a hydrazone, which then reacts further to yield eventually a f)u-l,2-hydrazone or osazone. 

Very little conclusive evidence for the position of the methyl group in 2-methyl-D-mannose is available. Pacsu and Trister4 showed that the sugar reacted with phenylhydrazine in the cold to give a phenylhydrazone but not a phenylosazone. More drastic conditions were required to form the phenylosazone, during which reaction the methyl group was lost with the formation of D-glucosazone. 

The structure of this sugar was established as follows (a) reaction with phenylhydrazine yielded 4-methyl-D-glucosazone 11 (b) oxidation (HOBr) yielded a methylmannonolactone, which exhibited the properties that are characteristic of 8-lactones.7... 

The product, containing two phenylhydrazone groups, that results from reaction of a reducing sugar with phenylhydrazine. (p. 1124)... 

Fig. 9. Fischer s phenylhydrazone reaction85 and the glycoblotting method first demonstrated by using aminooxy-functionalized synthetic polymers. (A) Reaction of sugars with phenylhydrazine (B) the general concept of glycoblotting and (C) the aminooxy-functionalized synthetic polymers used in the preliminary study.84 (Original figure made by the author.)...

Fried, Walz and Wintersteiner isolated 4-desoxy-i/-glycero-tetrose phenylosazone (XLII) from the reaction of streptobiosamine hydrochloride with phenylhydrazine and thus demonstrated that streptose was configurationally an l sugar. The levorotation ([a] o —37°, water ) of streptosonic acid monolactone (XXIII) might also be adduced as contributory evidence for the l configuration of the penultimate carbon of streptose, should Hudson s lactone rule be applicable to this rather complex structure. 

---