Pyruvic acid, from decomposition

Cysteine and cystine are unstable towards hot base. The reaction rate and the decomposition products are very much dependent on the presence or absence of oxygen. Presumably, cysteine is more stable than cystine but as with the stability in acid this fact is of minor importance when considering the reaction of cysteine in plant extracts. The production of alanine from cysteine has been demonstrated (Wieland and Wirth, 1949), but again this formation is probably due to secondary transamination with pyruvic acid formed initially. The formation of ammonia, hydrogen sulfide, and pyruvic acid from both cysteine and cystine has been demonstrated. With cysteine the decomposition probably follows a route parallel to that for serine described above ... 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

Since formation of citraconic anhydride from pyruvic acid is one of "acid to acid type" transformations, such as reactions from isobutyric acid to methacrylic acid and from lactic acid to pyruvic acid, the required catalysts must be acidic [11). If the catalysts are basic, it may be impossible to obtained acidic products, because basic catalysts activate selectively acidic molecules and, as a result, they show a very high activity for the decomposition of acidic products [11]. 

Benzylidene-o-arsanilic acid, Cgjr5.CH=N.C6ir4.AsO(OH)2, obtained from e-arsanilic acid, benzaldehyde and pyruvic acid, or the aldehyde in alcohol, melts with decomposition at 227° to 229° C. ... 

AH = 34.7+0.1 kcal.mole and AS = 10.5 0.2 eu, which are similar to homolysis of the peroxide bond in di-t-butyl peroxide (see the section on peroxides). Furthermore, pyruvic acid (CH3COCO2H) is a product of the reaction, which is an expected product from homolysis of the peroxide bond. Apparently decomposition via (X) is of minor importance compared to free radical decomposition of the peroxide linkage. 

Interestingly, the Fischer indole synthesis does not readily proceed from acetaldehyde to afford indole. Usually, indole-2-carboxylic acid is prepared from phenylhydrazine with pyruvic acid or with a pyruvate ester, followed by hydrolysis. Traditional methods for decarboxylation of indole-2-carboxylic acid to form indole are not environmentally benign. They include pyrolysis or heating with copper-bronze powder, copper(I) chloride, copper chromite, copper acetate, orcopper(II) oxide in, for example, heat-transfer oils, glycerol, quinoline, or 2-benzylpyridine. Decomposition of the product during lengthy thermolysis or purification affects the yields. 

GSH. From alkaline desulfurization there results among other products pyruvic acid, as Clarke and Inouye have shown (61). They also found NHs and H2S. Later Lindstroem and Sandstroem suspected the presence of alanine among the products of decomposition (62). Reproducing their results by means of paper chromatography we were able to show in 1949... 

Pyridoxal phosphate has been established as a coenzyme in two reactions involving tryptophan. An enzyme has been isolated from Neurospora which catalyzes a synthesis of tryptophane from serine and indole. This reaction requires pyridoxal phosphate. An enzyme has been isolated from E. coli which causes the decomposition of tryptophan to pyruvic acid, indole, and ammonia here too pyridoxal phosphate is a necessary cofactor. 

Very little information is available about the species which react in the further decomposition of ascorbic add. Apparently, both dehydroascorbic acid and 2,3-diketogulonic acid can be oxidized directly, since both oxalylthreonic acid and the same two free acids have been identified. The former would result from oxidative fission of the chain while the lactone ring was intact. Even less is known of the oxidation mechanism. The oxidation occurs with iodine and with acid permanganate (H12) and also with oxygen or peroxide (R23). Recent studies on the similar decomposition of the enols of aryl pyruvates to aryl aldehydes plus oxalic acid identified these reactions as examples of the direct attack... 

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