Diallyl Sulfide (Funny how tasty compounds come in bottles labeled "STENCH" when it's the pure chemical)

The lablels on bottles of chemicals with warnings always make me smile. One often-joked about example is the bottles of chemicals labeled "Flammable (US) / Highly Flammable (Europe)," which makes you feel smug if you're on my side of the pond. Another is "STENCH!". There's really no other way to say it, and it's definitely something you want to know before you open one of these chemicals, forcing the regulatory/safety people to come out and say "Uh, this smells bad. I mean really bad." Seeing this next to "LACHRYMATOR! TOXIC! RISK OF IRREVERSIBLE EFFECTS!" always made me smile. (That irreversible effects one has retained some scare-power, though, even after seeing it literal thousands of times...)

Diallyl sulfide is a chemical that you would like to avoid neat. However, in small quantities, it's responsible for a fair bit of the aroma of garlic. It's a great example of how different smells can be at dilution.

Diallyl sulfide has also received some attention as being a major contributor to the health benefits attributed to garlic, particularly on the anticancer front.

Fun thiol fact: in the lab, when we work with volatile thiols, we use them in the fume hood to avoid inhaling them. Afterwards, though, you're left with a bunch of dirty glassware that stinks of thiol. What to do? Bleach! Bleach oxidizes thiols to disulfide-linked dimers, and finally, to sulfonic acids, which are nonvolatile and, therefore, nonsmelly. I'm told this will work with most oxidants (i.e., hydrogen peroxide will work, too), and just about any thiol (hence the bleach or hydrogen peroxide treatment for skunk spray).

See you tomorrow.