Hydrazones and osazones

The sugars are occasionally identified by conversion to the crystalline hydrazones or osazones which are characterized in turn by their melting points and infrared spectra. Chromatography on columns of calcium carbonate [61] and alumina [62] resolves mixtures of the osazones and some success has attended paper chromatographic methods [62]. 

Thin-layer chromatography of the osazones can be effected on a variety of adsorbents. Tore [63] reported the chromatography of the phenylosazones on unbound Silene E. F. plates (activated at 110° for 24 hours) with solvent systems containing mixtures of chloroform, acetone, ethanol and water (solvents XXXII and XXXIII). The hRf values increase rapidly with an increase in the water content of the solvent as shown in Table 211. 

Haas and Sbeuger [64] investigated the resolution of phenylosazones on polyamide (Firm 153). The hMf values are primarily dependent on the molecular weight (pentoses hexoses) and little differentiation between stereoisomers was obtained. With pyridine and water (15 + 85), a reversal 

BiOjrcHBB et al. [47], in an extensive study of TLC of the sugars and derivatives on silica gel G, observed that benzene-acetone (45 + 55) afforded an excellent resolution of the phenylosazones of the sugars 

W mended that the sugars in urine be identi-- fied by chromatography of their phenylosa- 

Ar = Phor p-C C i Reagents i, PhNHNHj ii, CuClj-EtOH iii, NaOH iv, H+ 

D-Glucose, D-mannose, D-galactose, and D-arabinose yielded the corresponding osazones on treatment with 8-hydrazinotheobromine,  

Dursun, M. Hadzic, and A. Hadzic, Glas. Hem. Tehnol. Bosne Hercegovine, 1974, 21-22, 63 Chem. Abs., 1976, 85, 78 288z). 

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The saccharide derivatives best suited for cyclization to pyrazolines and pyrazoles are the hydrazones and osazones, which possess the two adjacent nitrogen atoms required. 

Peat, Stanley, The Chemistry of An-hydro Sugars, 2, 37-77 Peat, Stanley. See also, Bourne, E. J. Percival, E. G. V., The Structure and Reactivity of the Hydrazone and Osazone Derivatives of the Sugars, 3, 23-44... 

Several hydrazones and osazones of D-fructose have been prepared. Their structures have already been discussed by Percival.148... 

E. S. El Ashry Carbohydrate hydrazones and osazones as organic raw materials for nucleosides and heterocycles 2000COR609... 

THE STRUCTURE AND REACTIVITY OF THE HYDRAZONE AND OSAZONE DERIVATIVES OF THE SUGARS... 

Fischer represented the hydrazones and osazones as open chain structures one sees at once, however, other structural possibilities since mutarotation occurs in solution in many cases. Unless this is due to decomposition, some form of tautomeric equilibrium must be postulated, and Haworth pointed out that cyclic structures must be considered Behrend and Lohr recognized the possibility of the existence of syn and anti forms, and it has also been suggested that there may be an equilibrium between hydrazone and azo structures in the osazones. 

Information on these points has been sought by a study of rotation changes in solution, by the examination of derivatives and transformation products of the sugar hydrazones and osazones, and by synthetic experiments. While the conclusions drawn are not always in harmony with one another and the assignment of a particular structure to a derivative does not necessarily decide the constitution of the parent substance, many interesting observations have been made. 

Norman has tabulated the constants for various derivatives of the uronic acids and has summarized previous work on their identification. The free acids or their lactones have been used for the purpose of identification. The quinine, brucine, and cinchonine salts" have also been used for this purpose, although their isolation in pure form is hindered by the presence of the corresponding alkaloidal salts of the low polymers of the acid. Some of the complex hydrazines have been used to identify the acids. p-Bromophenylhydrazine has been frequently used for this purpose. One difficulty in the use of hydrazines is that they may form numerous types of derivatives such as salts, hydrazides, hydrazones and osazones. 

At a temperature of —20° C. and in chloroform solution, the y-pyrones take up 2 molecules of ozone. This means that only the C=C bonds react with ozone, which was also found when ozone reacted with other heterocyclic rings, such as pyridine, pyrrole, and furan. The ozonides were decomposed by reduction with hydriodic acid, whereby carbonyl compounds are formed, as well as acetic acid and in some cases formic acid. By reacting the carbonyl compounds with p-nitrophenylhydrazine, the corresponding nitrophenylhydrazones or p-nitrophenylosazones are formed. The separation of the mixture of hydrazones and osazones is carried out by a chromatographic method. The quantitative determination of the separated nitrophenylosazones (or hydrazones) is carried out by means of spectrographic measurements. 

First of all, new (substituted) hydrazones and osazones will be described these have been characteristic derivatives in sugar chemistry for a long time, but are now, to a certain degree, replaced by the osotriazoles. The common substituted hydrazones have been reviewed, but during the past decade a great deal of work has been done in this field, not only to resolve the last remaining doubts about osazone formation, but especially in a study of the... 

Among the many reaction products obtained from hydrazones and osazones that offer promise to synthetic chemists are the carbenes generated from azirines and sulfonylhydrazono-1,5-lactones by irradiation.299 300... 

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