D-Mannose phenylhydrazone

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). 

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. 

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). 

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. ... 

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. 

Treatment of methyl sulfoxide solutions of D-mannose or other sugar phenylhydrazones or melibiose phenylosazone with potassium tert-butoxide and a trace of oxygen at room temperature showed no evidence of the paramagnetic species characteristic of glyoxal bis(phenylhydra-... 

Conversion of sugar phenylhydrazones into olefinic azo-sugars on treatment with acetic anhydride and pyridine was shown by Wolfrom and co-workers (28) (The acetylated forms of the acyclic phenylhydrazones of D-glucose, D-mannose, and D-galactose readily lose the elements of acetic acid to yield 1-phenylazo-frans-l-hexenetetrol tetraacetate when treated with warm aqueous ethanol (28, 30). It is assumed that atmospheric oxygen partakes in this elimination reaction.) This is a special case of base catalyzed -elimination reactions of the type proposed by Isbell in 1943 ( 31), involving consecutive electron displacement (which actu-... 

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 precipitation from molasses of D-mannose as its phenylhydrazone was reported over 50 years ago.91 Recent investigation of the phenylhydrazone from Cuban molasses did not reveal any D-mannose phenylhydrazone92 the presence of this sugar in cane molasses cannot be considered as demonstrated. 

The treatment of free D-glucal (III) in water with perbenzoic acid in ethyl acetate produces D-mannose (XXI) as the main product 7 under these conditions the product with a ct s relationship at carbon atoms 2 and 3 thus predominates. The D-mannose can be separated in good yield as its crystalline phenylhydrazone. This procedure provides an important... 

The conversion of the synthetic 4-(/3-D-galactopyranosyl)-D-mannose (epilactose) through the hexaacetyllactal to lactose forms the keystone in the total synthesis of this sugar.61-62 Proof of the structure of 4-(/3-D-gal-actopyranosyl)-D-mannose was accomplished by hydrolyzing it with hydrochloric acid, and also with emulsin, to D-galactose (identified by oxidation to mucic acid) and D-mannose (identified as its phenylhydrazone).18... 

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. 

Enzymic degradation experiments on the polysaccharide were unsuccessful, Hydrolysis was carried out with 2.5% sulfuric acid, and in the hydrolyzate, D-mannose was identified as the phenylhydrazone, D-arabin-ose as the benzylphenylhydrazone and D-galactose as the methylphenyl-hydrazone.,. The acidic components gave a negative naphthoresorcinol test for hexbronic acids, though indications of the presence of glycolic acid were claimed. 

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