Coniine and the Hemlock Alkaloids
The hemlock alkaloids are (+)-coniine, N-methylconiine, (+)-conhydrine, psuedoconhydrine and g-coniceïne. They are all monocyclic alkaloids. Of these coniine is the most important and most toxic.
(+)-Coniine is a liquid, boiling point 166o - 187oC, [a]D +15.7o, and is the main constituent of oil of hemlock. Socrates drunk this liquid when he was condemned to death in 399 B.C. and it is this which gives rise to the material's notoriety. It was also the first alkaloid to be synthesised. The structure of coniine, 2-propylpiperidine, is shown below:
The four remaining hemlock alkaloids are less important. They are Conhydrine, 1-piperidin-2-yl-propan-1-ol, g-coniceïne, 2-propyl-2,3,4,5- tetrahydropyridine, N-methylconiine and psuedoconhydrine. Their structures are shown below:
