o-Phenylenediamine and 1:2-diamino-4-nitrobenzene as reagents for α-keto acids

Abstract
A series of stable nitroquinoxalinols, new colored derivatives of alpha-keto acids, was prepared. The quinoxalinols obtained by condensation of either o-phenylenediamine or l,2-diamino-4-nitrobenzene with pyruvic, dimethylpyruvic and alpha-ketoglutaric acids, may be separated by paper chromatography. The nitroquinoxalinols may also be separated on alumina. 1,2-Diamino-4-nitrobenzene is superior to 2,4-dinitrophenylhydrazine as a reagent for alpha-keto acids in specificity, stability, separability and characterizability of the products.