A white, non-toxic solid, Bitrex is according to the Guinness Book Of World Records the bitterest substance known. It is the trade name for denatonium benzoate, and it's primary use is stop young children drinking harmful household and garden chemicals. Only 10mgs per litre (10 parts per million) is needed to make industrial alcohol undrinkable, or denatured.
It is also similar in structure to lidocaine, only an addition of a benzyl group turns it into a local anesthetic.
The molecule is a very good fit for the chemical receptors on our tongues responsible for sensing 'bitterness', and any changes to the structure of the molecule will affect its activity. For instance if the
ethyl (-CH2CH3) groups are replaced with
methyl (-CH3) groups it tastes
100,000 times less bitter.
It has the following chemical structure :-
___ ___
| CH3 |
| ___/ CH2CH3 ___ |
| / \ | / \ |
| / _ \ |+ / _ \ |
| / / \ \---NH--CO--CH2--N--CH2---/ / \ \ |
| \ \_/ / | \ \_/ / |
| \ / | \ / |
| \___/ CH2CH3 \___/ |
| \ |
|__ CH3 ___|
___
/ \
/ _ \
/ / \ \---CO2-
\ \_/ /
\ /
\___/