LEUCIN (C„H,,N0,) Aposepidin. Leucin is a white crystalline substance frequently met with in chemical operations upon animal substances. Its composition and properties indicate that it is homo logous with sugar of gelatin [Gtvcocom.], and with ALANLN, as seen from the following formula Limprieht has, in fact, within the last few years obtained leuein by the action of hydrochloric and hydrocyanic acids npon valeride of ammonium.
Leucin is a product of the putrefaction of cheese and of gluten in the presence of water ; also of the action of sulphuric acid, or hydrate of potash upon muscular flesh, wool, white of egg, gelatin, horn, &c.
The preparation of pure leucin is a somewhat tedious operation. The simplest process is that adopted by Mulder ; it consists in boiling albumen, gelatin, or fibrin, with caustic potash until decomposition is evidently complete, evaporating the liquor to dryness, extracting the residue with alcohol, and evaporating the filtered liquid, that the leucin may crystallise out. It is finally purified by repeated recrystallisation from alcohol.
Pure leucin occurs in soft, light, colourless plates, somewhat re sembling cholesterin. It is slightly soluble in cold but readily so in hot water. In alcohol it is not very soluble, and in ether it is insoluble.
Heated to 338° Fahr., it sublimes without melting and without decom position, and condenses in beautiful silky flocks. Fused with hydrate of potash, it is decomposed into valeric acid, ammonia and hydrogen being evolved.
One equivalent of hydrogen in leucin may be replaced by copper, mercury, &c., and compounds formed soluble in water and deposited on evaporation in a granular or lamellar form. The copper compound contains (C„I1,,Cu NO,); the mercuric combination (C,,,H„Elg NO,).
Leucin is easily dissolved by the dilute acids, combining with them to form bodies that crystallise out on evaporation. The nitrate of leucin, sometimes called nitroleueic acid, has the formula (C,,H,,NO„ HO NO,); it crystallises in colourless needles. The and the sulphate are also crystalline.
L•ueic acid.—When binoxide of nitrogen is passed into a solution of leucin in nitric acid, nitrogen is evolved and an oily body obtained, to which the name of leucie acid has been given. It is very soluble in ether, gives crystallizable salts with bases, and is homologous with lactic acid.