PIPERINE I). An alkaloid contained in the different varieties of pepper. lPIPER, in NAT. IlisT. Div.] It was discovered by Oersted in 1819, and is best obtained by the following process.
White pepper, coarsely comminuted, is digested in alcohol, the latter recovered by distillation, and the residual extract treated with a small quantity of solution of potash to remove resinous matter ; the resulting impure piperine is washed with water and obtained pure by one or two recrystallisations from alcohol. Piperine occurs in colour less prisms, it is insoluble in cold water, only slightly so in hot water, tolerably soluble in ether, and readily so in alcohol, the essential oils, and acetio acid. Heated to about 212' Fahr. it melts, and at a higher temperature decomposes. Concentrated sulphuric, or hydrochloric: acids dissolve it, and nitrio acid oxidises it to a brown coloured sub stance, that dissolves in caustic potash with production of a beautiful blood-red colour.
Piperinc is but a feeble base. It absorbs hydrochloric acid gas with avidity, a stable hydrochlomte being formed. The chloroplatinale (C,11,N,0, 1101, PtCI,) forma large orange-coloured crystals, very soluble in water or alcohol.
Piperidine is obtained when one part of piperino is dis tilled with three parts of potash-lime. It is a light oily body that rises to the surface of the distillate on the addition of solid hydrate of potash. It is volatile, boiling at about 222-13* Falls, colourless when pure, has a powerful ammoniacal odour, and is very soluble in water.
Its constitution has not yet been satisfactorily ascertained ; it is usually looked upon as ammonia in which two equivalents of hydrogen are replaced by the diatomic radical piptryl (C,,11,," or Pp ). Piperyl
may however be a compound, and contain two radicals (C. Hy + CIO. each capable of taking the place of an equivalent of hydrogen in ammonia.
Piperidine forms crystalline compounds with most of the acids. The hydrochlorate HC1) occurs in long colourless needles very soloble in water. The oxalate (2 C101111N, 2 HO) also forms delicate needles.
Piperyturea, or the eyanate of piperidine (C, or N(H, Pp"), 0, CyO), is formed on boiling a solution of sulphate of piperidine with one of cyanate of potash ; it may be obtained in long white needles.
Methyl-piperyl urea (N (H, Pp") 0, CyO) and ethyl-piperyl urea (N (H, Pp") 0, CyO) are produced by acting upon piperidine with the cyanates of methyl and of ethyl respectively.
By the action of the iodides of the alcohol radicals upon excess of piperidine the following bases are produced. They are oily liquids, have fixed boiling points, and form well defined crystalline salts with acids : Methyl-piperidino N { 1 Pp" Etbyl-piperidine C.II2 1 Pp" Amyl-piperidine Pp Excess of the alcoliol iodide gives rise to iodides of the following ammoniums. By the usual oxide of silver method these iodides yield hydrated oxides : DImethyl-piperyl-ammonium . . . Diethyl-piperyl-ammonium . . . l'iperyl-sulphoearbamic add. Bisulphide of carbon combines ener getically with piperidine (Cahours) : + ,N = Gerhardt thinks the product may be piperyl-su/phocarbamate of piperdine, viz. :