Diazobenzene Sulfonic Acid and Derivatives

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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