CONINE

This article appears in Volume V06, Page 942 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: COM-COR

CONINE , or CoNIINE (a-propyl piperidine), CRH17N, an alkaloid occurring, associated with y-coniceine, conhydrine, pseudoconhydrine and methyl conine, in hemlock (Conium maculatum). It is a colourless oily liquid of specific gravity o845 (20 C.), boiling at 166 C., almost insoluble in water, soluble in ether and in alcohol. It has a

sharp

SHARP,
GRANVILLE
- GRANVILLE
- GRANVILLE, GRANVILLE
- GRANVILLE, JOHN
  CARTERET
  - CARTERET, SIR GEORGE (c. 1610-1680)
  , EARL (1690-1763)
(1735-1813)
SHARP, JAMES (1618-1679)
SHARP, JOHN (1645-1714)
SHARP, RICHARD (1759-1835)
SHARP, WILLIAM (1749-1824)
SHARP, WILLIAM (1856-1905)

burning

taste

TASTE (from Lat. taxare, to touch sharply; tangere, to touch)

and a penetrating smell, and acts as a violent poison. It is dextro-rotatory. The alkaloid is a strong base and is very readily oxidized; chromic acid converts it into normal butyric acid and ammonia; hydrogen peroxide gives aminopropylvalerylaldehyde, NH2CH(C3H7)(CH2)3CHO, whilst the benzoyl derivative is oxidized by potassium permanganate to benzoyl-a-aminovaleric acid, C6H5CONH CH(C3H7) (CH2)3 COOH. It combines directly with methyl iodide to form dimethyl coninium iodide, C1oH22NI, which by the destructive methylation process of A. W. Hofmann (Berichte, 1881, 14, pp. 494, 659) is converted into the hydrocarbon conylene C8H14, a compound that can also be obtained by

heating

HEATING

nitrosoconine with phosphoric anhydride to 8o-90 C. On

heating

HEATING

conine with concentrated hydriodic acid and phosphorus it is decomposed into ammonia and normal octane C8H18. Conine is a secondary base, forming a nitroso derivative with nitrous acid, a urethane with chlorcarbonic ester and a tertiary base (methyl conine) with methyl iodide; reactions which point to the presence of the = NH group in the molecule.
It was the first alkaloid to be synthesized, a result due to A. Ladenburg (see various papers in the Bericlate for the years 1881, 1884, 1885, 1886, 1889, 1893, 1894, 1895, and

Liebig

LIEBIG, JUSTUS VON, BARON (1803-1873)

's Annalen for 1888, 1894). A. W. Hofmann had shown that conine on

distillation

DISTILLATION (from the Lat. distillare, more correctly destillare, to drop or trickle down)

with zinc dust gave a-propyl

pyridine

PYRIDINE

(conyrine). This substance when heated with hydriodic acid to 3oc C. is converted into a-propyl piperidine, which can also be obtained by the reduction of a-allyl

pyridine

PYRIDINE

(formed from a-methyl pyridine and paraldehyde). The a-propyl piperidine so obtained is the inactive (racemic) form of conine, and it can be resolved into the dextro- and laevo-varieties by means of dextro-tartaric acid, the d-conine d-tartrate with

caustic

CAUSTIC (Gr. rcavvraubs, burning)

soda giving d-conine closely resembling the naturally occurring alkaloid. A. Laden-burg (Ber. 1906, 39, p. 2486) showed that the difference in the rotations of the natural and synthetic d-conine is not due to another substance, iso-conine, as was originally supposed, but that the artificial product is a stereo-isomer, which yields natural conine on heating for some time to 290-300, and then distilling.
y-Coniceine, CsH15N, is a tetrahydro conyrine, i.e. a tetra-hydro propyl pyridine. It may be obtained by brominating conine, and then removing the elements of hydrobromic acid with alkalis. Other coniceines have been prepared. Conhydrine, C8H17NO, and pseudoconhydrine are probably stereo-isomers, the latter being converted into the former when boiled with ligroin. Since conhydrine is dehydrated by phosphorus pentoxide into a mixture of a and (3 coniceines, it may be considered an oxyconine. Methyl conine, C5H18N or C3H14N(CH3), is synthesized from conine and an aqueous solution of potassium methyl sulphate at Too.

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