Osones

The osones are known primarily in the form of their hydrazine derivatives, the osazones. These dicarbonyP sugars have achieved importance as intermediates in the synthesis of ascorbic acids. They also can be oxidized to 2-keto aldonic acids. 

The osones exist only as amorphous or sirupy materials. They are very labile and show the characteristics of enediols of the reductone type. For this reason the formula for n-glucosone, for example, might be represented best by (II) below, rather than (I). This formula is similar to a reduced  

Several methods are available for the preparation of these compounds. Osazones can be hydrolyzed by acids or by carbonyl compounds. (See 

Catalytic oxidation of sugars and alcohols is a more direct method. Hydrogen peroxide and iron salts were used originally (see under Hydrogen peroxide oxidations). However, much better yields have been obtained by the direct oxidation with cupric salts 159). The action of a limited excess of cupric acetate for a short time on methanol solutions of L-sorbose or l-xylose has given a 60 % yield of the osone. 

The simplest osone, glycerosone or hydroxypyruvic aldehyde, has been prepared by the oxidation of dihydroxyacetone. This compound is enolic in character, reducing cold Fehling solution and forming acidic aqueous solutions 160). It exists normally as the trimer. 

---

Oxidation. Acetaldehyde is readily oxidised with oxygen or air to acetic acid, acetic anhydride, and peracetic acid (see Acetic acid and derivatives). The principal product depends on the reaction conditions. Acetic acid [64-19-7] may be produced commercially by the Hquid-phase oxidation of acetaldehyde at 65°C using cobalt or manganese acetate dissolved in acetic acid as a catalyst (34). Liquid-phase oxidation in the presence of mixed acetates of copper and cobalt yields acetic anhydride [108-24-7] (35). Peroxyacetic acid or a perester is beheved to be the precursor in both syntheses. There are two commercial processes for the production of peracetic acid [79-21 -0]. Low temperature oxidation of acetaldehyde in the presence of metal salts, ultraviolet irradiation, or osone yields acetaldehyde monoperacetate, which can be decomposed to peracetic acid and acetaldehyde (36). Peracetic acid can also be formed directiy by Hquid-phase oxidation at 5—50°C with a cobalt salt catalyst (37) (see Peroxides and peroxy compounds). Nitric acid oxidation of acetaldehyde yields glyoxal [107-22-2] (38,39). Oxidations of /)-xylene to terephthaHc acid [100-21-0] and of ethanol to acetic acid are activated by acetaldehyde (40,41). 

RO—CF=CF2, are obtained by reaction with sodium salts of alcohols (26). An osone—TFE reaction is accompanied by chemiluminescence (27). Dimerization at 600°C gives perfluorocyclobutane, C Fg further heating gives hexafluoropropylene, CF2=CFCF2, and eventually perfluoroisobutylene, CF2=C(CF2)2 (28). Purity is deterrnined by both gas—Hquid and gas—soHd chromatography the in spectmm is complex and therefore of no value. 

D,L-Mannitol has been obtained by sodium amalgam reduction of D,L-mannose. The identical hexitol is formed from the formaldehyde polymer, acrose, by conversion through its osazone and osone to D,L-fmctose (a-acrose) followed by reduction (83). 

The condensation reactions of aromatic o-diamines and sugars and sugar derivatives have been studied in detail and quinoxaline derivatives have been prepared recently from osones, osonehydrazones, and dehydro-L-ascorbic acidd ... 

C H19N09-2H20 5-Acetamido-3,5-dideoxy-D-gh/eero-/ -D-galacto-nonulopyran-osonic acid, dihydrate (N-acetylneuraminic acid, dihydrate) (sialic acid, dihydrate) SIALAC 31 350... 

Addition of Hydrbgen Cyanide to Osones Followed by Hydrolysis. 80... 

Addition of hydrogen cyanide to osones followed by hydrolysis. 

In this reaction the osone (or a-keto aldehyde (VI)) is allowed to react with hydrogen cyanide or preferably with potassium cyanide in aqueous... 

The nomenclature adopted in the designation of the analogs of L-ascorbic acid is based for convenience upon the name of the sugar from which the osone was prepared. For example, D-xylose (XVIII)... 

In addition to L-ascorbic acid this method, involving the use of osones and potassium cyanide, has afforded the following analogs ... 

The 2-keto acids such as 2-keto-D-galactonic acid (XXIV) can be derived from the corresponding osone (XXIII) by oxidation with bromine.10 Oxidation of L-gulosone by the same method has provided 2-keto-L-gulonic acid. The success of this oxidation depends to a large extent upon the purity of the osone subjected to oxidation and this, as previously stated, is controlled by the purity of the osazone. 

The glyoxals, of which (hydroxymethyl) glyoxal is sometimes regarded as the simplest osone, differ from the osones in many of their properties and are not considered in this review. 

Partially methylated derivatives of D-glucosone have been prepared by decomposition of the corresponding partially methylated phenylosazones with p-nitrobenzaldehyde osones have been obtained from 5-0-methyl-D-glucose phenylosazone and from 3,4,5-tri-O-methyl-D-glucose phenylosazone in this way.22 Although 6-0-methyl-D-glucose phenylosazone is not altered by heating with benzaldehyde or piperonal in aqueous ethanolic... 

It has recently been reported21 that a mixed osazone of 3,4-di-O-methyl-D-glucose can be converted, by treatment with p-nitrobenzaldehyde, into an osone which reacts with phenylhydrazine to give 3,4-di-O-methyl-D-glucose phenylosazone. Von Lebedev29 claimed to have obtained D-glu-cosone 6-phosphate, isolated as an amorphous lead salt, by the action of hydrochloric acid on the phenylosazone prepared from D-fructose 6-phosphate. 

Yields of osones obtained by the oxidation of sugars by Fenton s reagent are low, and the osones are invariably contaminated both with starting material and with the products of further oxidation in consequence, the method has had only limited application.44... 

Evans, Nicoll, Strause and Waring46 oxidized D-glucose and D-fructose in aqueous solution with excess cupric acetate at 50° for the purpose of ascertaining whether the general principles underlying the mechanism of carbohydrate oxidation in alkaline solutions are sufficient to explain the course of such oxidations in acid solutions. D-Glucosone was claimed to be one of the first products of oxidation the osone was not isolated, and,... 

---