Glycolic acid oxidative cleavage

Fatty acids, both saturated and unsaturated, have found a variety of applications. Brassilic acid (1,11-un-decanedicarboxylic acid [BA]), an important monomer used in many polymer applications, is prepared from erucic acid (Scheme 2), obtained from rapeseed and crambe abyssinica oils by ozonolysis and oxidative cleavage [127]. For example, an oligomer of BA with 1,3-butane diol-lauric acid system is an effective plasticizer for polyvinylchloride. Polyester-based polyurethane elastomers are prepared from BA by condensing with ethylene glycol-propylene glycol. Polyamides based on BA are known to impart moisture resistance. 

Desilylation of the major jjw-isomer, followed by oxidative cleavage with sodium metaperiodate, liberates the 3-hydroxy-2-methyl carboxylic acids. The immolative character of this method, i.e., the destruction of the chiral auxiliary reagent in the final glycol cleavage, is a drawback. 

Some of the earliest work in the oxidation of alkenes was performed by oxidation with potassium permanganate. Under acidic and neutral conditions the intermediately formed glycols are oxidized, generally leading to cleavage of the carbon-carbon bond. Thus, such procedures have seldom been synthetically applied to diene oxidation. One notable... 

Cyelobutanone has been prepared by (1) reaction of diazomethane with ketene,4 (2) treatment of methylenecyclobutane with performic acid, followed by cleavage of the resulting glycol with lead tetraacetate,s (3) ozonolysis of methylenecyclobutane, (4) epoxidation of methylene-cyclopropane followed by acid-catalyzed ring expansion,7 and (5) oxidative cleavage of cyclobutane trimethylene thioketal, which in turn is prepared from 2-(co-chloropropyl)-l,3-dithiane.8... 

Oxidative degradation of a ketose may proceed by two pathways (Scheme IX). Hexuloses by addition of a peroxide anion form a ketose peroxide (13). Cleavage of this intermediate at the C-2-C-3 bond gives glycolic acid and an aldo-tetrose. The aldo-tetrose is smoothly converted to four moles of formic acid. Alternatively, the ketose peroxide (13)... 

With a molar ratio of propylene glycol to H2O2 of 2.5, the selectivity to hydroxyacetone at 32% conversion of the glycol was 94%, and the selectivity based on H202 was 85%. Small amounts of acetic acid and formic acid were detected. The initial oxidation proceeds with high selectivity for the secondary alcohol group. Further oxidation affords oxidative cleavage products rather than pyruvic acid, as is observed when the oxidation of hydroxyacetone is carried out with 02 and noble metal catalysts. 

The Au-catalyzed glycerol oxidation was influenced by the kind of support, the size of Au particles and the reaction conditions such as concentration of glycerol, p02 and molar ratio of NaOH to glycerol. As metal oxide supports showed inferior selectivity to glyceric acid compared to carbons, due to successive oxidation and C—C bond cleavage to form di-adds such as tartronic acid and glycolic acid, research has focused on Au NPs supported on carbon, as in the case of ethylene glycol oxidation [182]. Indeed, the catalytic activity was influenced by the kind of carbon support in terms of porous texture [183]. 

The reagent is effective for oxidative cleavage of a-glycols to aldehydes, of a-hydroxy ketones to an aldehyde and a carboxylic acid, and of a-diketones and a-keto iicids to acids.3... 

At higher temperatures, carbon dioxide, formic acid, oxalic acid, glycolic acid, hydroxymalonic acid, glyceric acid, and other acids were shown to be formed. The formation of carbon dioxide is ascribed to decarboxylation of 38 oxalic acid and D-erythronic acid arise from cleavage of the C-2-C-3 bond compound 39 is cleaved to glyoxylic acid plus D-erythronic acid. Compound 40 is oxidized further to D-g7ycero-2,3-pentodiulosonic acid and is subsequently cleaved to oxalic and glyceric acids. 

There are three known metabolic pathways to 3-deoxyulosonic acids. In the first, aldonic acids, formed by oxidation of aldopyranoses to the corresponding lactones, are dehydrated to the ulosonic acids (see Fig. 6). Thus, D-arabinose is converted by way of D-arabinonic acid to 3-deoxy-o-ffZj/cero-pentulosonic acid. The latter is then subjected to oxidative cleavage, yielding pyruvic and glycolic acids. L-Arabinose is oxidized and dehydrated to the 3-deoxy-L-g Z2/cero-pentulosonic acid, which is further oxidized to... 

Periodic acid is a versatile oxidant since, depending on pH, the redox potential for the periodate-iodate couple varies from 0.7 V in aqueous basic media to 1.6 V in aqueous acidic media. Based on this observation, Villemin and Ricard devised an oxidative cleavage of glycols, in which /nc50-l,2-diphenyl-... 

Periodic acid is a versatile oxidant since, depending on pH, the redox potential for the periodate-iodate couple varies from 0.7 V in aqueous basic media to 1.6 V in aqueous acidic media.Based on this observation, Villemin and Ricard devised an oxidative cleavage of glycols, in which mcjo-l,2-diphenyl-1,2-ethanediol was oxidized by periodic acid on alumina to benzaldehyde in 82% yield in aqueous ethanol (90% ethanol) at room temperature in 26 h. The same supported oxidant converted aromatics into quinones. In the presence of transition metal complexes (Mn ), a-arylalkenes suffer oxidative cleavage to aldehydes. For example, tran.r-stilbene gives benzaldehyde at room temperature. 

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