The Chemistry of Skunk Spray

Why does skunk spray make you want to tear off your own face? The answer lies in two simple atoms which pull together and hitch a ride on other molecules. We'll tell you what they are, and how you can neutralize them.

Personally, I find the faint odor of skunk quite pleasant. I never knew what was the big deal with skunk spray until a scientist friend let me smell a collection of it in a small vial and I jerked back so fast that I cracked my head on a cabinet behind me. The smell made my eyes water - something that's not surprising as the organic compounds that make skunk spray smell are also found in garlic and onions. They're called thiols, and they're very simple. Just hook one sulfur atom to one hydrogen atom.

The Chemistry of Skunk Spray

The best way to understand thiols as a group is to compare them to the alcohols. Alcohols are fairly simple compounds that change their function depending on what molecules they're attached to. Ethanol gets you drunk, but methanol makes you go blind, and there are hidden alcohol groups in things like sucrose that we don't really notice. So while thiols make skunk spray the vile thing that it is, they also make garlic tasty, and form parts of the keratin in hair. (When you perm your hair, you're rearranging the thiol groups.)

The two leg-breakers in the family of chemicals that a skunk sprays are (E )-2-butene-1-thiol and 3-methyl-1-butanethiol. These are chains of carbon and hydrogen with the sulfur and hydrogen thiol group attached to one end. They're volatile, which means they disperse easily in the air, and they're easily picked up by the human nose. The back-up squad of skunk spray consists of thioacetates, other groupings of carbon and hydrogen that are, at first, not particularly smelly. When water hits them, it rearranges them into more potent configurations. A dog - or human - that's been sprayed by a skunk will sometimes get smellier after being bathed in water. These compounds also linger, so when an area of a house that's been sprayed by a skunk gets rained on, we get a delayed reminder never to make a skunk mad.

How to get the stench out? Tomato juice won't do it. It's just a strong smell that attempts to cover up the smell of skunk. What you need is a chemical that will change the composition of the thiol group. Fortunately, baking soda and hydrogen peroxide are cheap, mild, and will do the job. They are oxidizing agents, meaning they will attach oxygen atoms to the sulfur atom in the thiol pairing, and take away its ability to stink.

And if you're feeling glum about being sprayed by a skunk, cheer up. It could be worse. The chemicals are flammable, so under the right conditions, we could have had little striped flame throwers running around the woods.

Image: Dan & Lin Dzurisin

[Via Invitation to Organic Chemistry,The Chemistry of Skunk Spray, Is That Skunk?]