Coniine
603468
220978497
2008-06-22T14:16:43Z
Rifleman 82
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move history to lede
{{Chembox new
| Name = '''Coniine'''
| ImageFile = Coniin - Coniine.svg
| ImageSize = 131px
| ImageName = Coniine
| ImageFile1 = Coniine3d.png
| ImageSize1 = 200px
| ImageName1 = Coniine
| IUPACName = (''2S'')-2-propylpiperidine
| Section1 = {{Chembox Identifiers
| CASNo = 458-88-8
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>8</sub>H<sub>17</sub>N
| MolarMass = 127.227 g/mol
}}
}}
'''Coniine''' is a poisonous [[alkaloid]] found in [[Conium|poison hemlock]] and the [[Sarracenia flava|Yellow Pitcher Plant]], and contributes to hemlock's fetid smell. It is a [[neurotoxin]] which disrupts the peripheral nervous system. It is toxic to humans and all classes of livestock; less than 0.2g (0.007oz) is fatal to humans, with death caused by respiratory paralysis. [[Socrates]] was put to death by way of this poison in [[399 BC]]. Coniine has two [[stereoisomer]]s: (''S'')-(+)-coniine (CAS 458-88-8), which is the natural isomer present in hemlock and (''R'')-(-)-coniine (CAS 5985-99-9). Coniine was first synthesized by [[Albert Ladenburg]] in 1886; it was the first of the alkaloids ever synthesized as well.
==Synthesis==
:[[Image:Coniinsynthese.png|450px]]
In the original synthesis of this [[piperidine]] by Ladenburg, he heated [[methylpyridinium iodide]] at 300 °C to obtain [[2-methylpyridine]] (α-picoline). 2-Methylpyridine was reacted with [[acetaldehyde]] in the presence of a [[base (chemistry)|base]] to 2-propenyl[[pyridine]] in a [[Knoevenagel condensation]]. This intermediate was [[Reducing agent|reduced]] with metallic [[sodium]] in [[ethanol]] to [[racemate|racemic]] (±) coniine (reduction by hydrogen gas is also possible). [[Enantiomer|Enantiopure]] Coniine was obtained by[[chiral resolution]] — [[fractional crystallisation]] of the [[diastereoisomer]]s of the salt obtained with (+)-[[tartaric acid]].
==Pharmacology==
Coniine paralyzes muscles by blocking the nicotinic receptor on the post-synaptic membrane of the [[neuromuscular junction]] causing a flaccid paralysis. This action is similar to that of [[curare]]. Symptoms of paralysis occur within a half hour, and death may take several hours. As the central nervous system is not affected the person remains conscious and aware until respiratory paralysis results in cessation of breathing. The muscular paralysis is an ascending flaccid paralysis as the lower limbs are affected first. The person may have an hypoxic convulsion just prior to death but this is greatly disguised by the muscular paralysis and the person may just weakly shudder. The cause of death is lack of oxygen to the brain and heart as a consequence of respiratory paralysis. A poisoned person will recover if artificial ventilation (breathing) is maintained until the toxin is removed from the receptor.
There have been a number of cases of poisoning in certain regions of Italy due to the consumption of larks and chaffinches, which eat the buds of [[Conium|poison hemlock]] during April and May. Also, the alkaloid appears to have an addictive effect: goats, cows and pigs have all shown a preference for conium-containing foliage (up to the point of eventual death) if they survive initial exposure.
==Coniine in Literature==
Coniine is the poison used to kill Amyas Crale in ''[[Five Little Pigs]]'' (published in 1943), also known as ''Murder in Retrospect'', one of Agatha Christie's [[Hercule Poirot]] mysteries.
==References==
{{unreferenced|date=January 2008}}
<references/>
==External links==
* [http://www.chm.bris.ac.uk/motm/hemlock/intro.htm Information on hemlock] from the [[University of Bristol]]
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[[Category:Nitrogen heterocycles]]
[[Category:Alkaloids]]
[[Category:Neurotoxins]]
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