Who doesn’t love a good murder mystery? There are clues to find, people to suspect and of course the all important, big reveal. One of the all time classic murder mystery plots involves a good old poisoning. This usually involves slipping a few drops or pieces of something very poisonous into someone’s food or drink. Let’s introduce a character to this murder mystery – Coniine.

Hemlock and Key

One of the most famous and oldest poisons exists in the plant Hemlock. Hemlock was responsible for the death of the Greek philosopher Socrates! There are several different molecules that contribute to Hemlock’s poisonous nature, but one of the main ones is coniine! 

a drawing of a statue of socrates who was poisoned with hemlock
Socrates was a brilliant speaker and philosopher which is lucky since he was a floating stone head (according to archaeological evidence) so professional footballer was probably not an option for him.

Simple, But Deadly!

You might expect a poisonous molecule to have a very complicated or nasty looking chemical structure. However, coniine is a fairly, straightforward molecule with only hydrogen, nitrogen, and carbon atoms in it.

three atoms labelled N, C and H
Wait, you mean the illustrator only needs to draw three different elements this month? Result!

It is made from a 6-membered ring, containing five carbon and one nitrogen atom, to which is attached a chain of three carbon atoms. Add in some hydrogen atoms and we have our molecule of coniine. 

the structure of coniine


The presence of a single nitrogen atom means coniine belongs to a family of molecules called alkaloids. Other well-known alkaloids include nicotine, morphine and cocaine!

Coniine exists as two mirror images of each other, depending on how the chain or carbon atoms is attached to the ring. You might be thinking that it’s a flip of the coin whether you get the poisonous, molecule or the totally safe mirror-image enantiomer… However, both are toxic so it doesn’t matter which one you consume! The proper chemical name for this molecule is (2S)-2-Propylpiperidine.

You can see why we’ve gone with coniine instead.

Toxic Liquid

Under normal conditions, coniine is a colourless liquid with a strong odour. It it slightly soluble in water, but dissolves much better in alcohol and ether. Below -2 ℃ the liquid turns into a soft solid.

An Ancient Poison

The early history of coniine is mostly through the plant hemlock. Hemlock juice was responsible for many accidental and deliberate poisonings, as well as a form of punishment.

A Modern Extraction

However, coniine itself was first isolated from hemlock in 1826 by Giseke. However, it took nearly another 60 years before its structure was determined by Hofmann in 1881.

In 1886, Ladenberg became the first person to make coniine in a laboratory!

On My Nerves

So how does coniine poison the body? Well, it mainly affects our nervous system.  In the body, information and signals moved through our body through nerve cells. Between each nerve cell is a synapse. Normally, when a signal moves through our nervous system, the neurones turn on, transfer the information, and then turn off. 

On and On and On

However, coniine attaches to a receptor on neurones, which are cells that help send signals throughout the body. This attachment prevents the neurones from turning off and so are constantly on. As a result, no information can get through the body and leads to loss of muscle control and paralysis.

Take My Breath Away

Unfortunately, the central nervous system is unaffected, so you’re awake and consciousness as you’re slowly paralyzed. Horrible! Eventually, the paralysis stops you breathing and death follows pretty quickly after that!

Luckily, modern technology can keep someone breathing until the poison leaves the body, and so people can recover from coniine poisoning! 

Look, Don’t Touch

Hemlock and coniine may sound like something difficult to find, but this plant is native to the UK. It can grow up to 2 m tall and produces clusters of white flowers. It usually grows in damp places such as river banks, ditches and wasteland, but does occur alongside roads.

ferris wheel beside body of water
There’s an extra i in this molecule’s name, and here’s an extra i in London. (Photo by Chait Goli on Pexels.com)

The safest way to avoid this poisonous plant is by doing exactly that – avoiding it. However, it you do find yourself near some or may have touched some, another way to tell is from the horrible smell.

The best advice is always to wash your hands and avoid putting fingers, hands or anything else in your mouth!

The Final Solution

Coniine is a poison that has been in use for thousands of years. For the Ancient Greeks it was a form of capital punishment, but nowadays its use is mainly in fiction. Nevertheless, this poison is still all around us, one of a number of toxic molecules found in hemlock.

You never know where poisons may turn up, so best to avoid touching unknown plants and definitely wash those hands! Otherwise, you might end up in a very short, but very sad, mystery story!



No responses yet

Leave a Reply

%d bloggers like this: