Lactose osazone

Lactose Osazone. This was prepared as reported by Fischer (64), mp 211°-212°C. 

Both maltose and lactose, being reducing sugars, give osazones which differ from one another and from glucosazone in crystalline form. Sucrose (G-r-r-F), having no potential aldehyde or ketone grouping, does not form an osazone. 

The approximate times of osazone formation in minutes are given in Table 111,139. The product from mannose is the simple hydrazone and is practically white. Arabinose osazone separates first as an oil, whilst that from galactose is highly crystalline. Lactose and maltose give no precipitate from hot solution. 

Lactosone was first prepared by the hydrochloric acid decomposition of the phenylosazone,1 although it had been noted that, in acid solutions, lactose phenylosazone forms an anhydride.197 Since its discovery,17 the benzaldehyde method has usually been employed,6-10-28 because it avoids the risks of osone hydrolysis and of alteration to the osazone. Lactosone is hydrolyzed by hot, dilute, mineral acid to D-glucosone and D-galactose.1-6 It reacts with cyanide to form an analog of iminoascorbic acid which, on acid treatment, is converted into a mixture of D-glucoascorbic acid and D-galactose.10... 

Problem 22.38 Use shorthand formulas to show how osazone formation establishes the glucose unit of lactose to have the hemiacetal linkage (Problem 22.37). ... 

Addition of specific compounds to milk has been used to allow spec-trophotometric measurement of lactose as the osazone (Wahba 1965) and fat by fluorescence (Bakhiren and Butov 1968 Konev and Kozlova 1970). The dye-binding method for measuring protein in milk is based on the ability of sulfonic acid dyes to complex with the basic amino acid residues of milk proteins at low pH (Fraenkel-Conrat and Cooper 1944). Dye binding correlates well with Kjeldahl (Sherbon 1970) and infrared (Mogot et al. 1982 Grappin et al. 1980) results, but variations are caused by the different compositions of the different milk proteins (Ashworth 1966 Vanderzant and Tennison 1961). 

Although Fischer described a lactose phenylosazone anhydride in 1887, little attention was paid to substances of this type until 1935 when Diels and Meyer reported the isolation of monoanhydrides of D-glucose phenylosazone, D-galactose phenylosazone, D-xylose phenylosazone, L-arabinose phenylosazone, lactose phenylosazone, and cellobiose phenylosazone, as well as a dianhydride of maltose phenylosazone, by boiling the corresponding osazones in alcoholic solution with a little sulfuric acid. Because of the apparent identity of the D-glucose phenylosazone anhydride with the 3,6-anhydro-D-glucose phenylosazone of Fischer and Zach, Diels and Meyer formulated these compounds as 3,6-anhydrides. 

Maltose reduces Fehling s solution and therefore probably contains an aldehyde group. The constitutional formula is probably the same as that given for lactose. It yields an osazone which crystallizes in tufts of needles which are more blunt than the crystals of glucosazone. Maltose, like the other di-saccharoses does not ferment with yeast zymase. 

Put 1-mL portions of phenylhydrazine reagent into each of four cleaned, numbered test tubes. Add 3.3-mL portions of 0.1 M solutions of glucose, fructose, lactose, and maltose and heat the tubes in the beaker of hot water for 20 min. Shake the tubes occasionally to relieve supersaturation and note the times at which osazones separate. If after 20 min no product has separated, cool and scratch the test tube to induce crystallization. 

By the catalytic reduction of the phenylosazone from lactose, Kuhn and Kirschenlohr obtained both /3-n-gaIactopyranosyl-(l— 4)-l-amino-l-deoxy-D-fructose and /S-n-galactopyranosyl- (1- -4) -2-amino-2-deoxy-D-glu-cose. The A -acetyl derivative of the latter was found to be identical with a disaccharide obtained from the partial hydrolysis of a blood-group substance. The structure of a disaccharide obtained from the partial hydrolysis of heparin was likewise confirmed by comparison of the disaccharide with a synthetic product obtained by catalytic hydrogenation of the osazone from maltose. - Here, too, both the 1-amino-l-deoxy and the 2-amino-2-deoxy compounds were obtained. 

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