Chemical oxygen demand of some nitrogenous heterocyclic compounds

Chemical oxygen demands of fourteen nitrogenous compounds were determined by the dichromate method. Only pyridine and its derivatives were resistant to oxidation. Heterocyclic compounds containing one atom of nitrogen in a molecule, e.g. quinoline, pyrrole, proline, and indole were 90–100 per cent oxidized. Nitrogen is split off these compounds as NH₃. Heterocyclic compounds containing two or more atoms of nitrogen in a molecule are also easily oxidized. However, only a part of the nitrogen is split off as NH₃. On the basis of the results obtained it is possible to make the following generalization: nitrogen in amino groups is split off mostly as NH₃; quinoline, pyrrole, pyrrolidine, and indole nitrogen is split off as NH₃; from imidazole and pyrimidine rings, one atom of nitrogen is split off as NH₃ and one as N₂; from the purine configuration, two atoms of nitrogen are split off as NH₃ and two atoms as N₂; from isoalloxazine, three atoms of nitrogen are split off as NH₃ and one as N₂.