Glycollic acid aldehyde

Lead(fV) ethanoate, Pb(02CCH3)4, (Pb(ll)ethanoate plus CI2) is a powerful oxidizing agent which will convert vicinal glycols to aldehydes or ketones and 1,2-dicarboxylic acids into alkenes. Primary amides give ketones and amines give nitriles. 

Oxidation of a glycol can lead to a variety of products. Periodic acid quantitatively cleaves 1,2-glycols to aldehydes and is used as an analysis method for glycols (12,13). The oxidation of propylene glycol over Pd/C modified with Pb, Bi, or Te forms a mixture of lactic acid, hydroxyacetone, and pymvic acid (14). Air oxidation of propylene glycol using an electrolytic crystalline silver catalyst yields pymvic aldehyde. 

Reaction of ketones such as 1-menthone 398 with silylated glycolic acid 417 in the presence of catalytic amounts of TMSOTf 20 provides an lil-mixture of the l,3-dioxolan-4-ones 418 and 419 [35, 36]. Likewise, other aldehydes and ketones [37, 38] and pivaldehyde [39] react with substituted silylated glycohc adds 420 a, b and yS-hydroxy acids 420c to give, e.g., 421 a, b and 421c as mixtures [37-40]. Reaction of pivaldehyde with the persilylated hydroxy acid 420 d and TMSOTf 20 to... 

In temperature-sensitive reactions, aryl aldehydes and ketones produce the trimethylcarbinols at ca. 0°C and the glycolic acids at ca. 56°C in competition with the base-catalysed Cannizzaro or condensation reactions [3, 5, 8]. 2- and 3-Formylpyridines produce the trichloromethylcarbinols (20-30%), whereas 4-formylpyridine undergoes the Cannizzaro reaction [9]. Formylferrocene is converted into the a-ferrocenylglycolic acid (35%) [10],... 

Lead tetraacetate is used as a highly selective oxidizing agent in organic synthesis. This includes oxidation of glycols into aldehydes, preparation of cyclohexyl acetate, production of oxahc acid, and in structural analysis of sugars. 

Figure 7.84 The metabolism of ethylene glycol. The NADH produced is used in the production of lactate, the level of which will rise dramatically in poisoning cases. Abbreviations. ADH, alcohol dehydrogenase ALDH, aldehyde dehydrogenase LDH, lactate dehydrogenase GAO, glycolic acid oxidase AO, aldehyde oxidase.

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... 

It was also shown that the ratio of oxidized alcohol to oxidized Fe2+ could be greater then one. Baxendale and Wilson (1957) showed that hydroxyl radical initiating the chain polymerization of olefins by hydrogen peroxide was the same process as the rapid oxidation of glycolic acid. Merz and Waters (1947) confirmed that simple water-soluble alcohols are oxidized rapidly by Fenton s reagent. The primary alcohols are oxidized to aldehydes, which are further oxidized at comparable rates by exactly the same mechanism. Merz and Waters proposed a mechanism of chain oxidation of alcohols and aldehydes by sodium persulfate, hydrogen peroxide, and an excess of ferrous salt as follows ... 

Figure 2.2.12 Reaction network of glycerol oxidation (GLY, glycerol DHA, dihydroxyace-tone GLA, glyceric aldehyde GLS, glyceric acid HBT, hydroxypyruvic acid MOS, mesoxalic acid TS, tartronic acid GOX, glyoxal GOS, glycolic acid GYS, glyoxylic acid OS, oxalic acid).

The next higher hydroxy acid is hydroxy acetic acid CH2(OH)— COOH, known also as glycolic acid. It may be prepared (a) from chlor acetic acid, (b) from the cyan-hydrine obtained from formic aldehyde, or (c) hy the oxidation of ethylene glycol, by reactions which have been already discussed. Its relation to ethylene glycol gives it the name of glycolic acid. It may be considered as a direct oxidation product of ethane. 

Degradative oxidation of a-hydroxy carboxylic acids furnishes aldehydes or ketones. Glycolic acid, lactic acid, and mandelic acid are converted into formaldehyde, acetaldehyde, and benzaldehyde, respectively, in 50% yields on refluxing with A -bromosuccinimide in water [745]. Periodates, with phase-transfer reagents, convert a-hydroxyhexanoic acid and mandelic acid into valeraldehyde and benzaldehyde in respective yields of 90 and 88% (equation 478) [776, 778]. 

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