Isobarbituric acid

Isay reaction, 2, 79-80 3, 259 Ismelin 7, 656 Isoalloxazine oxidation states, 1, 252 Isoaminopterin synthesis, 3, 327 Isoarsindolines, 1, 543-544 Isoarsinoline, tetrahydro-synthesis, 1, 552-553 stability, 1, 552 Isoascorbic acid structure, 4, 552 ( )-IsoavenacioIide synthesis, 1, 416 Isoazapenem synthesis, 1, 465 Isobacteriochlorin synthesis, 4, 419 Isobacteriochlorin, dimethyl-biosynthesis, 1, 105 Isobacteriochlorin, methyl-biosynthesis, 1, 105 Isobacteriochlorin, trimethyl-biosynthesis, 1, 105 Isobarbituric acid Mannich reaction, 3, 71 synthesis, 3, 133... 

Hayon447 to absorb in this UV region. Similar measurements have been made for a number derivatives of uracil (5,6-dihydro, 1-, 3-, and 6-methyl, 1,3-dimethyl-, and 5-aminouracil, orotic acid, barbituric and isobarbituric acids also see similar measurements448 on 5-bromouracil and its iV-methyl derivatives), thymine itself and its derivatives (5,6-dihydro, 2-methylthymine). In the case of cytosine, Hayon447 has very tentatively suggested that species 47 and 48 are obtained on pulse radiolysis of the solution at pH 5.5, and 49 at pH 13.3. 

Isobarbituric acid 2,4,5(3//)-Pyrimidinetrione, dihydro- Methylenimine Methanimine... 

Both 5-hydroxyuracil (isobarbituric acid, I) and 5-hydroxyuridine (II) can be prepared from the corresponding 5-bromopyrimidines by mild basic hydrolysis [5-8]. 5-Hydroxyuracil inhibits enzymatic degradation of uracil [9] and is one of three pyrimidine analogues (the other two are 5-bromouracil and 6-azauracil) that inhibit the rate of incorporation of uracil into nucleic... 

Preparation of Isovioluric Acid VI),—Six and three-tenths g. (0.05 mol.) of isobarbituric acid was dissolved in 40 cc. of 10% sodium hydroxide (0.10 mol.) together with 3.7 g. of sodium nitrite (0.055 mol.). This solution was then stirred into a mixture of 18 g. (0.3 mol.) of glacial acetic acid and 50 g. of ice. Stirring was continued for half an hour, whereupon the light yellow precipitate was filtered by suction and washed with cold water. Air drying yielded 8.2 g. (85% of theory) of analytically pine isovioluric acid dihydrate. 

The action of nitrous acid on isobarbituric acid yields isovioluric acid (alloxan-6-oxime), which is rearranged to violuric acid (alloxan-5-oxime) by means of add, but otherwise behaves much like alloxan. 

Whether the pathways of oxidation of pyrimidines by bacteria are valid for mammalian systems remains to be determined. The formation of isobarbituric acid, as suggested by Cerecedo, is not in accord with the bacterial studies discussed above. The appearance of urea, however, as a final product of pyrimidine catabolism, agrees with the early observations of Plentl and Schoenheimer and of Bendich et alM Their experiments showed that N Mabeled pyrimidines were converted to labeled urea by the rat. 

The problem of pyrimidine degradation by microorganisms has been studied primarily by enrichment culture techniques. By this method, bacterial strains were grown that utilized pyrimidines as their source of nitrogen and carbon intact cells, as well as purified enzymes obtmned from such bacteria, were investigated (296, 390-392). Pyrimidines were converted to barbituric acid by cell-free extracts of the soil bacterium, strain U-1, which indicated that the initial oxidation of the pyrimidine ring occurred at carbon 6 (392) (Kg. 23). There was no converaon of uracil to isobarbituric acid (391). Barbituric acid was also obtained as a product of uracil oxidation by strains of Corynehacterium and Mycobacterium... 

We have fotmd that isobarbituric acid (VIII) readily couples in weakly acid solution with aromatic diazonium salts to give highly colored products... 

Johnson and Jones, Am. Chem. J., 40, 538 (1908), noted the production of a red color from the action of diazobenzene-/>-sulfonic acid on isobarbituric acid in the presence of sodium bicarbonate. They neither isolated the product nor proposed a structure for it, but related it to the colors obtained by Johnson and Clapp, J. Biol. Chem., 5, 163 (1908), by the action of diazobenzene-/>-sulfonic acid on all uracil derivatives in which the 1-position was unsubstituted. [In Johnson s papers this position is munbered 3. The numbering in the present paper conforms with the system adopted by Chemical Abstracts.]... 

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