NH2 OC  .R' ~N : C•R' In a similar manner, diamino derivatives are formed when cyanogen is condensed with ortho-diamines, and these amino compounds readily pass into the corresponding dioxy derivatives when acted upon with dilute hydrochloric acid . The quinoxalines are weak bases, and are stable towards oxidizing agents but are readily reduced to hydro derivatives . The tetrahydroquinoxalines are formed by condensing ortho-diamines with ortho-dihydroxy benzenes, and the keto-dihydro derivatives arise similarly by condensing mono-alkyl diamines with ketonic acids (Kehrmann and Messinger, Ber., 1892, 25, pp . 1628 et seq.) . The azonium bases (formula II.) of this series are produced when the dihydroquinoxalines (obtained by similar condensations from the mono-alkyl-ortho-diamines) are oxidized with ferric chloride . N: C•R' N: />13, II . Azonium bases .