Mannose phenylhydrazone

It was observed in those cases in which the oxidation was arrested too soon that an appreciable amount of silver chloride was deposited when the solution was concentrated. Furthermore, the mother liquor, when treated with phenyl-hydrazine in acetic acid, deposited some yellow crystalline D,L-mannose phenylhydrazone, m. p. 195-200° (Maquenne block). It is apparent that too vigorous oxidation results in the formation of hexoses. 

Bacillus krzemieniewski(f). This soil bacillus forms thick, gelatinous capsules on carbohydrate media and yields a polysaccharide which on hydrolysis is stated to produce L-mannose.660 This claim is based upon the melting point of the isolated mannose phenylhydrazone and upon the rotation of the hydrolyzed reaction mixture. It requires further confirmation. 

Since neither the 2V-methyl nor the 2V-benzyl derivative of D-mannose phenylhydrazone showed a color change or the presence of paramagnetic species following treatment with base, it was concluded that the colored radical anion from D-mannose phenylhydrazone must arise following the abstraction of the acidic imino proton by base. Thus, this must be a first reaction step before fission of the phenylhydrazine moiety can occur. 

A) from D-mannose phenylhydrazone (B and C) a rearranged radical from (A) (D) from D-mannose phenylhydrazone [(CHsCO)20-C5H5-1% K-tert-BuO] (2.5 mM to 3.5 mM, in Me2SO-l% K-tert-BuO)... 

Figure 4 (A to C) shows changes in the ESR spectra obtained with D-mannose phenylhydrazone treated with 1% potassium terf-butoxide in methyl sulfoxide. The original three-line pattern (spectrum A), ascribed to the nitroxide radical, rearranges to a new pattern in about 15 minutes (spectrum B) this pattern remains steady for hours if the solution is kept in the absence of oxygen (spectrum C).

The base-catalyzed, / -elimination reaction of D-mannose phenyl-hydrazone is consistent with the acyclic structure for the phenylhydra-zone in solution. However, the small proportion of a nitroxide radical observed on treatment of the phenylhydrazone with a strong base may indicate the existence also of a fractional proportion in a cyclic structure in equilibrium with the open-ring structure, as was suggested by Blair and Roberts (43). The hydrazino moiety required for nitroxide-radical formation could be derived from the cyclic form of D-mannose phenylhydrazone in solution. 

The formulas depicted may reflect radicals observed in the ESR spectra of the D-mannose phenylhydrazone in an alkaline solution (A and B, Figure 4) they show a possible path for the formation of the nitroxide radical and its rearrangement. The major steps in this pathway are ... 

Attempted Acetylation of D-Mannose Phenylhydrazone. Five grams of D-mannose phenylhydrazone was acetylated as described for myo-inosose-2-phenylhydrazone. Work-up of the reaction mixture (after 24 hours) gave a yellow syrup (3.6 grams) which failed to crystallize. TLC analysis of this syrup showed only a small proportion of an olefinic... 

D-Mannose Phenylhydrazone. This was prepared by the method Of Blair and Roberts (43), mp 199°-200°C (from aqueous pyridine). 

To 4 gms. (1 mol.) of mannitol dissolved in 20 c.cs. of water, a solution of 1 gm. of ferrous sulphate in cold water is added, and then gradually 12 c.cs. (1 atom of 0) of hydrogen peroxide solution (20 vols.), or more if solution is weaker, are dropped in. The solution must be well cooled throughout. Sodium carbonate solution is added till just alkaline, the whole filtered, and portions of the filtrate tested for mannose by Fehling s solution, and by ammoniacal silver nitrate. To the bulk of the filtrate 1 c.c (excess) of phenylhydrazine dissolved in a slight excess of dilute acetic acid is added, the solution allowed to stand, and the precipitate of mannose phenylhydrazone filtered off. It is recrystallised from dilute alcohol. 

Most of the compounds are readily soluble in water and in pyridine, slightly soluble.in methanol and in ethanol (which are the usual recrystallizing solvents), and sparingly soluble in ether, acetone, light petroleum, chloroform, benzene, and ethyl acetate. AT-Phenyl- and W-p-tolyl-D-manno-sylamine, like n-mannose phenylhydrazone, have unusually low solubilities. 

Except in a few cases such as D-mannose phenylhydrazone and D-galactose methylphenylhydrazone, the hydrazones are more difficult to isolate and are more unstable than the corresponding osazones. For these reasons, apart from the search for substituted hydrazones for identification purposes, the volume of published work on this subject is not great. 

Wolfrom and Blair" have reported a crystalline product obtained by the acetylation of D-mannose phenylhydrazone with acetic anhydride and pyridine. Four easily saponifiable groups led to their allocation by these workers as 0-acetyl. " While no definitive structure could be assigned on the evidence available, the analytical data inclined the authors to favor a pyrazoline structure (XXXIVa) other possibilities obviously exist. 

Fig. 7.—Upper Curve Mutarotation of n-Mannose Phenylhydrazone [c 0.9, pyridine-ethanol (9 1 by vol.)] Lower Curve n-Mannose Diphenylformazan Formation.

The method has also been applied to the two D-mannose phenylhydrazone acetates described in the literature. The fact that anhydro-n-man-... 

On the other hand, the amorphous D-mannose phenylhydrazone acetate described by Hofmann,and more recently by Stepanenko and coworker underwent reaction but failed to produce the readily crystalline D-mannose diphenylformazan pentaacetate obtained by the acetylation of D-mannose diphenylformazan. The amorphous, acetylated D-mannose phenylhydrazone has a wide melting-point range and appears to be a mixture of partially acetylated phenylhydrazones in which the presence of the aldehydo form can be readily demonstrated by the formazan reaction. 

Acetylation of D-Mannose Phenylhydrazone," M. L. Wolfrom and Mary Grace Blair, /. Amer. Chem. Soc., 68, 2110 (1946). 

Hydrazones. When one mole each of phenylhydrazine and sugar react, phenylhydrazones are formed. Most hydrazones are water soluble, but the mannose phenylhydrazone is so insoluble that it may be used for the quantitative estimation of mannose. The hydrazones are often of value for the separation of sugars, for they may be converted to the original sugars by... 

An acetylated monoanhydro derivative of mannose phenylhydrazone serves for the confirmation of the identity of mannose, which is customarily isolated as the phenylhydrazone (see Chapter II). 

The diazo-diene (80) was obtained on acetylation (Ac20-py) of D-mannose phenylhydrazone and underwent [4+2]cycloadditions with diethyl azodicarboxylate to give (81) or hydroquinone to give (82) as epimeric mixtures. ... 

As might be expected, the carbonyl function in aldoses and ketoses undergoes condensation reactions with amine derivatives (Section 17-9). For example, treatment of o-mannose with phenylhydrazine gives the corresponding hydrazone, o-mannose phenylhydrazone. Surprisingly, the reaction does not stop at this stage but can be induced to continue with additional phenylhydrazine (two extra equivalents). The final product is a double phenylhydrazone, also called an osazone (here, phenylosazone). In addition, one equivalent each of benze-namine (aniline), ammonia, and water is generated. 

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