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 o•845 (20° C.), boiling at 166° C., almost insoluble in water, soluble in ether and in alcohol . It has a sharp burning taste 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, NH2•CH(C3H7)•(CH2)3•CHO, whilst the benzoyl derivative is oxidized by potassium permanganate to benzoyl-a-aminovaleric acid, C6H5CO•NH• 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 nitrosoconine with phosphoric anhydride to 8o-90 C . On 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's Annalen for 1888, 1894) . A . W . Hofmann had shown that conine on distillation with zinc dust gave a-propyl 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 (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 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 C3H14•N(

CH3), is synthesized from conine and an aqueous solution of potassium methyl sulphate at Too° .