Sulfur usually stinks. Previously, I’ve covered ammonium thioglycolate, mercaptoethanol, and dithiothreitol, all of which are used to break up S-S bonds in biomolecules. The S-H group is what does the job here, and where this functional group is found, stink is usually nearby. The above thiols all have some degree of stink.
Methanethiol is not one of the nice-smelling thiols. With a smell most often described as rotten cabbage or rotten eggs, you’d think it was useless. You’d be wrong.
Because it smells so terrible, it’s a great warning indicator for something that shouldn’t be escaping into the atmosphere – such as natural gas. You can smell methanethiol down to the parts per billion level – that is, micrograms per liter. We add it to natural gas (which is mostly odorless methane) for just this reason.
Interestingly, farts often contain methane and hydrogen – flammable natural gas components, as any frat boy with a lighter can tell you. Additionally, their odor is partly caused by methanethiol (as well as other stinkies like hydrogen sulfide and indole). One quasi-renewable energy source is so-called “landfill gas” – essentially a landfill fart:
Municipal solid waste contains significant portions of organic materials that produce a variety of gaseous products when dumped, compacted, and covered in landfills. Anaerobic bacteria thrives in the oxygen-free environment, resulting in the decomposition of the organic materials and the production of primarily carbon dioxide and methane.
In a related vein, here is a video of Prof. Dr. Ross Eustace Geller explaining methanethiol doping of natural gas.
Of course, he messes it up by contending methane is not natural gas, but a different, smelly gas, which is false. But what do you expect from a sitcom professor who you’ve never seen working on a grant proposal?