Why is Benzene poisonous? How could such an elegant ring of carbon and hydrogen atoms be so dangerous?
In: Chemistry
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The other answer is just wrong, benzene is extremely stable which is probably why you’re asking this. In the mitochondria (and I think ER) of your cells, there is a group of enzymes called cytochrome P450. They catalyze a reaction that oxidizes – adds an oxygen atom – onto organic molecules. It just so happens that they form a stable complex with benzene, and will oxidize it – add an oxygen to one of the carbons in the ring – to form a molecule called benzene oxide that’s now very unstable (it’s an epoxide if you have any organic chemistry knowledge). The benzene oxide will almost immediately break down into phenols and quinones that are extremely toxic.
Don’t mistake structure and “elegance” for benevolence; that’s just your human pareidolia playing up. In reality, structure doesn’t inherently “mean” anything other than relative order, and our psyche seems to have an inborn preference for ordered systems, but that preference doesn’t mean much of anything when applied universally. It’s no more meaningful or useful than your tailbone or your appendix.
The primary reason benzene is such an issue is that those hydrogen atoms in the “outer” ring of the structure are somewhat weakly bonded to the carbon ring (which is *extremely* stable), meaning they’re easily swapped in and out for other molecules. In some substances, the ability of the benzene ring to soak up other hydrocarbons can be very useful in slowing degradation (i.e. increasing shelf-life of chemicals), but in other situations that means the benzene ring can promote reactions that you don’t want, like damaging cellular material, which can then go on to cause mutation and cancer.
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