Science Fair Project Encyclopedia
Coniine or 2-propylpiperidine is a poisonous alkaloid found in poison hemlock. It is a [neurotoxin] which disrupts the central nervous system. It is toxic to all classes of livestock and humans. Socrates was put to death by way of this poison in 399 B.C.
Coniine was the first of the alkaloids ever synthesised by Albert Ladenburg in 1886.
The original synthesis of this piperidine by Ladenburg started by heating methylpyridinium iodide at 300°C (not shown)to obtain 2-methyl pyridine. 2-methyl pyridine (alpha-Picoline) reacts with Acetaldehyde in presence of a base to 2-Propenylpyridine in a Knoevenagel condensation . This intermediate was reduced with metallic sodium in ethanol to racemic (+-) Coniine (reduction by hydrogen gas is also possible). Enantiopure Coniine was obtained by fractional crystallisation of the diastereoisomers of the salt obtained with (+)-tartaric acid.
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