Galactose phenylhydrazone

D-Galactose Phenylhydrazone. This was prepared by the method of Mester (56), mp 159°-160°C. 

D-Galactose oxime, IV, 122, 124 —, hexaacetyl-, IV, 123, 160 D-Galactose phenylhydrazones, and their pentaacetates, III, 26 D-Galactose phenylosazone, III, 29, 34 D-Galactose phenylosazone anhydride, III, 31, 39... 

Both tetraacetyl-D- -galactose phenylhydrazones on mild acetylation... 

As has been pointed out in Section I, 2, when R and R" differ, the two isomers (A and B) permitted by the classical formulation cannot be isolated (because of the chelated structure of the formazans). This phenomenon, so very characteristic of the formazans, is also encountered in the formazans of sugars. The mono-p-bromo derivative of n-galactose diphenylformazan was prepared by two routes one was by causing n-galactose p-bromo-phenylhydrazone to react with diazotized aniline the other, by coupling D-galactose phenylhydrazone with diazotized p-bromoaniline as follows. 

Scheme 11. Formation of iV-phenyl-aldonohydrazono-1,4-lactones by the action of air on D-galactose phenylhydrazone in dilute alkali.

Pentahydroxypentylpyrazoles, e.a.. diphenyl-derivative (47), have been prepared by condensation of D-galactose phenylhydrazones with various j9-nitrostyrenes, and were converted to pyrazole-3-carboxylic acids. Cyclization (by use of ACaO) of per-Q-... 

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-... 

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... 

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. 

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. 

D-Sorbose potassium hydroxide D-galactose iV -methyl-iV -phenylhydrazone 3... 

Fig. 9.—Upper Curve Mutarotation of o-Galaotose Phenylhydrazone (c 5.4 pyridine) Lower Curve n-Galactose Diphenylformazan Formation.

Under analogous conditions, galactitol is converted to DL-galactose, isolated as the phenylhydrazone in 30% yield. In the presence of 2 moles of sodium hydrogen carbonate per mole and a platinum-on-carbon catalyst at 61°, galactitol is readily oxidized to galactaric acid. ... 

Lactose forms a phenylhydrazone, osazone, and osone. The composition of these substances indicates that lactose contains one free carbonyl group. It is an anhydride of dextrose and galactose, in which one carbonyl group is involved in the union of the molecules, and one is free. The structure of the products formed on oxidizing lactose indicates that the free carbonyl group is in that part of the molecule which yields dextrose on hydrolysis. 

The similar polarographic behavior of semicarbazones, hydrazones, phenylhydrazones, and oximes of D-glucose, D-galactose, and n-mannose was described in another paper. For the aldoses studied, the equilibrium and rate constants for the formation of their oximes, semicarbazones, and hydrazones were determined at several different pH values, and it was found that their reactivity increases in the order D-glucose < D-galactose < D-mannose < D-xylose < n-arabinose < D-ribose < D-lyxose. ... 

The synthesis of oct-2-ulosono-1,4-lactone phenylhydrazones from D-gluconic acid is covered in Chapter 16, while the formation of a 1-C-substituted 1,5-dideoxy-l,5-iminopentitol by reduction of 6-azido-6-deoxy-D-galactose diphenyl-formazan with triphenylphosphine is detailed in Chapter 18. 

Sugars differ in their tendency to combine with silica. Holzapfel (173, 276) found that galactose was adsorbed on quartz and reacted with phenylhydrazOne and formed osazones, but arabinose did not. The amount of adsorbed galactose was twice that of lactose and four times that of glucose. 

Preparation 42, 106). Seaweed Fvcus species or Ascophyllum nodosum) is hydrolyzed by acids and the neutralized hydrolyzate fermented by galactose-acclimatized yeasts. The solution after evaporation is extracted with alcohol after removal of the alcohol, the extracted material is converted to the difficulty soluble phenylhydrazone. The hydrazine groups are then removed by reaction with benzaldehyde and the sugar is crystallized from the liquid. The fermentation removes the mannose and galactose which often accompany the L-fucose in seaweeds. The mannose is particularly objectionable since it also forms a difficultly soluble phenylhydrazone. 

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