Diamines

DIAMINES, hydrocarbons in which two hydrogen atoms are replaced by NH₂ groups. Only compounds in which both amino groups are linked to different carbon atoms are stable. Diamines are obtained by the reduction of dinitro compounds, dicyano compounds, dioximes, etc. Diamines form salts with two equivalents of acids. The number of diamines found in nature is very small. In addition to tetramethylenediamine (putrescine) and pentamethylenediamine (cadaverine), which are found during the putrefaction of protein substances, only hexamethylenediamine, found during the putrefaction of meat, tetramethylputrescine, isolated from the plant Hyoscyamus muticus by Willstätter, and trimethylenediamine, formed during the cleavage of spermine, are known. The scarcity of natural diamines is due to the insignificance of the number of diamino acids contained in proteins, which serve as material for the formation of diamines through decarboxylation (the splitting off of CO₂); cadaverine is formed from lysine, and putrescine is formed from ornithine, which is part of the arginine molecule. Various types of bacteria, both pathogenic and non-pathogenic, possess the ability to decarboxylate diamino acids (the presence of diamines in certain types of cheese). Characteristic is the formation of diamines under the influence of cultures of tetanus, cholera, the Finkler-Prior vibrio, Bac. mesentericus vulgatus, and putrefactive bacteria. But some higher plants are also capable of producing diamines. In some cases, with cystinuria, the excretion of diamines with urine and feces is observed. Diamines easily convert into heterocyclic compounds, which are the simplest alkaloids (pyrrolidine, piperidine, and their homologs):

H₂C-CH₂ / \ H₂C CH₂ H₂N NH₂ putrescine CH₂ / \ H₂C CH₂ H₂N NH₂ cadaverine H₂C CH₂ + NH₃; \/ NH pyrrolidine CH₂ / \ H₂C CH₂ + NH₃. H₂C CH₂ \/ NH piperidine This may serve as an explanation for the formation of certain alkaloids in plants from proteins through the stage of diamines. Diamines are relatively low in toxicity. When separating amines found in the organism by the method of Kossel and Kutscher, diamines are found together with lysine, choline, and betaines in the lysine fraction, i.e., the fraction of substances that are precipitated by phosphotungstic acid and are not precipitated by silver nitrate in the presence of barium hydroxide.