Osone derivatives crystalline

Hepta-0-acetyl-(2-hydroxygentiobial) gave with chlorine a mixture of non-crystalline dichlorides which, on treatment with silver carbonate, formed an acetylated osone derivative. With pyridine and acetic anhydride, this was converted into an acetate of 6-0-/3-D-glucosylkojic acid.140... 

Of unpredictable potentialities are the halogen addition compounds. Although their production and use is complicated by the existence of several isomers, they have been intermediates in the production of crystalline osone derivatives and of kojic acid. The osone derivatives, in turn, have been converted to ascorbic acid analogs through 2-ketoacids not actually isolated. 

LaForge and Hudson194 prepared an osone from the phenylosazone obtained from sedoheptulose (D-aZ(ro-heptulose). The osone reduced Fehling solution strongly, formed the original osazone with phenylhydrazine, and gave a crystalline derivative with o-phenylenediamine. 

The acetylated 2-hydroxyglycals derived from D-galactose9 and gentiobiose13 have also been chlorinated but without isolation of crystalline dichlorides. Conversion of the sirups to the respective osone hydrates was made without isolation of the intermediates. The osone hydrate from gentiobiose failed to crystallize, but the strong reducing power of the sirup indicated its presence. 

Osone hydrates have been prepared from 2,3,4,6-tetra-0-acetyl-(2-hydroxy-D-glucal)1 and from the corresponding derivatives of 2-hydroxy-D-galactal,9 2-hydroxyceIlobial13 and 2-hydroxygentiobial.13 Hydrolysis of the dichloride may be effected simply by the addition of a little water to its solution in ether or benzene, but more often silver carbonate or sodium bicarbonate is added to neutralize the hydrogen chloride produced. Sodium and potassium carbonate are too alkaline and result in yellowing of the reaction mixture. A yield of 90% of the theoretical amount of osone hydrate was obtained from the crystalline dichloride derived from D-glu-cose. However, the crystalline dichloride derived from cellobiose resisted hydrolysis (see the previous Section). Nevertheless, the cellobiosone hydrate was prepared from the sirupy mother liquor. In any case, yields on the basis of the entire, chlorinated substances were low.1613... 

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