Iodination pyruvic acid

Photodecarboxylation of pyruvic acid (135) in the gas phase has been examined using i.r. fluorescense spectroscopy. The reaction is thought to proceed via the intermediate hydroxycarbene (136) which undergoes isomerization to ethanal (137). An analogous five-centred mechanism has been proposed to account for photoelimination of carbon dioxide from acrylic and methacrylic acids. Photodecarboxylation of alkoxyacetic acids has been observed in the presence of mercury(u) oxide and iodine and yields alkoxyalkyl alkoxyacetates via alkoxyalkyl iodide intermediates. ... 

It is not yet known whether deiodination of thyroxine and triiodothyronine is complete or partial, or what route the degradation of the deiodi-nated products takes. Mono- and diiodotyrosine are said not to leave the thyroid as such, but are deiodinated and the iodine reutilized (320, 720). However, in liver and kidney diiodotyrosine can be converted to the corresponding pyruvic and lactic acids (873), and triiodothyronine and thyroxine give the corresponding pyruvic acids (721a). 

Boron Borsaiire Boric acid Borsaureanbydrid Boron trioxide Brenzcatechin Pyrocatediol Brenztraubensaure Pyruvic acid Brom Bromine Brom-Bromo-Bromcyan Cyanogen bromide Bromjod Iodine bromide Carbathoxylierung Carbethoxylation Carbonsaure-Carboxylic acid-Cblor Chlorine Chlor-Chloro-... 

Theoretically, the condensation of mono- and diiodotyrosine could yield four different compounds 3,3 -diiodothyronine, 3,3, 5 -triiodothyronine, 3,5,3 -triio-dothyronine, and thyroxine (see Fig. 8-4). The exact mechanism of the formation of these various iodinated derivatives is not clear, but it has been suggested that they are formed by the condensation of two molecules of iodotyrosines with loss of a side chain. In this reaction, the iodinated tyrosine is converted by the loss of two atoms of hydrogen to the quinoid form, which acts as a free radical and condenses with other molecules of iodinated tyrosine to yield a diphenyl ring. During such a reaction, an oxygen bridge is formed, and one of the side chains of tyrosine is split to yield an a-amino acrylic acid. The a-amino acrylic acid is further metabolized to yield ammonia and pyruvic acid. 

Various aryl aldehydes 196 have been cyclized with 5-aminotetrazole 197 and pyruvic acid 195 catalyzed by iodine in refluxing ethyl acetate (Scheme 13.47). 

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... 

Iodoform Test.— Addition of 1-5 ml. of I per cent, aqueous iodine and 1-2 ml. 20 per cent. NaOH to 10 ml. of a urine containing acetone produces iodoform, CHI3, which is recognisable by its smell, and its separation as a pale yellow precipitate with a characteristic microscopic appearance (hexagonal plates and stars). Pyruvic and lactic acid, which are minor constituents of normal urine, give a similar reaction, as also does alcohol, so the test is not reliable for detecting traces of acetone. 

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