Oxalic acid from glycol

Glycolic acid slowly gives formic acid, oxalic acid, and carbon dioxide, through the intermediate glyoxylic acid. However, Spoehr could not isolate oxalic acid from glycolic acid under these conditions. Glycos-uloses " and dihydroxymaleic acid are also oxidized. 

Fig. 4.11 Formation of oxalic acid from ethylene glycol.

Summary The syntheses and properties of derivatives of a new class of zwitterionic monocyclic 5i-silicates with an Si02C2F framework are reported. These molecular pentacoordinate silicon compounds contain bidentate diolato(2-) ligands that derive from benzohydroximic acid, oxalic acid, or glycolic acid. In addition, the crystal structures of these compounds are described. 

The zwitterionic monocyclic X S/-silicates 3a-5a were synthesized according to Scheme 2 by reaction of [(dimethylammonio)methyl]trifluoro(methyl)silicate (6a) with one molar equivalent of the 0,0 -bis(trimethylsilyl) derivatives of benzohydroximic acid, oxalic acid or glycolic acid (formation of two molar equivalents of MesSiF). Compounds 3b-5b were prepared analogously starting from trifluoro(methyl)[(2,2,6,6-tetramethylpiperidinio)methyl]silicate (6b) (Scheme 2). 

Oxalic acid produced from syngas can be esteiified (eq. 20) and reduced with hydrogen to form ethylene glycol with recovery of the esterification alcohol (eq. 21). Hydrogenation requires a copper catalyst giving 100% conversion with selectivities to ethylene glycol of 95% (15). 

This dioxolane is readily formed from the glycol (TsOH, benzene, reflux, 70-95% yield) it is cleaved by irradiation (350 nm, benzene, 25°, 6 h, 75-90% yield). This group is stable to 5% HCl/THF 10% AcOH/THF 2% oxalic acid/THF 10% aq. H2SO4/THF 3% aq. TsOH/THF. ... 

A rather simple polymer can be made from ethylene glycol, HO—CH2—CH2—OH, and oxalic acid, HO—C—C—OH. 

Furthermore, a base-catalyzed transformation by OH from the reaction medium between glycerate and hydroxypyruvate aldehyde (or hydroxypyruvic acid) could be excluded, while hydroxyacetone and glyceraldehyde interconversion was possible (Scheme 11.11). The existence of two major routes, of which hydroxyacetone and glyceric aldehyde are the primary oxidation products and glycolic and oxalic acid are the end-members, respectively, is now firmly established. Clearly, rapid oxidation of glyceraldehydes favors glyceric acid rather than hydroxyacetone formation. 

The pentacoordinate silicon compounds 94,23 95,23 96-98,60 99,60,61100,61,62 101-103,60 104,61,62 105,62 106,62 and 10761,63 are monocyclic zwitterionic A5S7-silicates with an Si02FC2 skeleton. The chiral zwitterions each contain one bidentate diolato(2-) ligand that formally derives from 1,2-dihydroxy-benzene, salicylic acid, glycolic acid, oxalic acid, benzohydroximic acid (tautomer of benzohydroxamic acid), 2-methyllactic acid, or (S)-mande-lic acid. 

The peak at 17.34 min is 50 pg ml mesaconic acid which was added as a possible internal standard, but it proved unsuitable because of an unknown peak eluting at 16.78 minutes seen when analysing silage juice without added internal standard oxalic acid suffered from the same problem. We still need a suitable internal standard for this column, thus further use was suspended. Other failed compounds included adipic acid, fumaric acid, D-glucuronic acid, glutaric acid, glycolic acid, 3-hydroxybutanone, itaconic acid, malic acid, maleic acid, malonic acid, pimelic acid and succinic acid. 

The formation and decomposition of Crv in aqueous and non-aqueous media during the oxidation of organic substrates such as oxalic acid and ethylene glycol by potassium dichromate has been recognized for some time. No study resulted in the isolation of a stable, well-characterized chromium(V) complex until 1978 when potassium bis(2-hydroxy-2-methylbutyrato)oxochromate(V) monohydrate was prepared from chromium trioxide and the tertiary a-hydroxy acid in dilute perchloric acid according to equation (91). The Crv, which is... 

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. 

Carnahan et al. obtained good yields of alcohols and glycols by hydrogenation of lower mono- and dicarboxylic acids over ruthenium dioxide or Ru-C at 135-225°C and 34-69 MPa H2 (eqs. 10.1 and 10.2).8 In general, the optimum temperature was about 150°C. The chief side reaction was hydrogenolysis of the alcohols, as exemplified in the formation of ethanol from oxalic acid and of butanol and propanol from succinic acid (see eq. 10.2). Platinum and palladium catalysts were ineffective under similar or even more severe conditions. 

Disposition in the Body. Less than 5% of ingested oxalic acid is absorbed in healthy adults. About 8 to 40 mg of oxalic acid is normally excreted in the urine daily this is derived mainly from the metabolism of dietary ascorbic acid and glycine with small amounts from dietary oxalic acid and other minor metabolic sources. Calcium oxalate is a major constituent of kidney stones and is frequently found as crystals in freshly-voided urine. In normal subjects concentrations of oxalic acid in blood range from about 1 to 3 pg/ml. Small amounts of oxalate are produced as a metabolite of ethylene glycol. 

The ethylene glycol and methyl alcohol (see below), which is also sometimes found in antifreeze, are poisonous because they are converted into more toxic products. Once inside the body, the ethylene glycol in the antifreeze is changed by metabolism into first one, and then several other chemicals. This requires the same enzyme that metabolizes the alcohol we consume in alcoholic drinks (ethyl alcohol). The ethylene glycol is converted into oxalic acid which is poisonous, and other poisonous products are also produced. Oxalic acid is also found in rhubarb leaves, which is what makes them poisonous. The result of these metabolic conversions is that the acidity of the blood increases (the pH decreases) and normal metabolic processes are inhibited. The oxalic acid formed can crystallize in the brain and the kidneys, causing damage. The oxalic acid also reacts with calcium and removes it from the body. The reduction of calcium... 

From Glycol.—A second synthesis which proves the constitution of oxalic acid is that from ethylene glycol, HO—CH2—CH2—OH. On the complete oxidation of glycol with nitric acid oxalic acid is obtained. This is plainly the oxidation of each of the primary alcohol groups to carboxyl, and may be represented as follows,... 

As oxalic acid is derived from ethan-di-ol, ethylene glycol, and malonic acid is derived from 1-3-propan-di-ol, so the next member in such a series will be derived from i- -hiitan-di-ol, as follows ... 

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