I don't know if everyone has been following the comments that are starting to accumulate around here after my posts, but there are some interesting ones. In response to "By Any Other Name", below, I had a report that "a well-known organic chemistry professor" continues to taste various small molecules from his lab.
The person leaving the comment was clearly referring to Nobel-winning professor Barry Sharpless, a famous and very imaginative chemist indeed. I have some points of contact with people from his lab, so I investigated. And by gosh, it's true: Sharpless apparently does taste many newly synthesized compounds, a habit that's been remarked on before: "I taste many chemicals that I make today still. That's not normal. But I'll smell almost everything, even if it's dangerous.''
In sampling compounds, Sharpless seems to observe a rule that (as one witness told me) "anything without a nitrogen in it is probably safe." Before anyone writes to point it out, it's true that mustard gas doesn't have a nitrogen in it, but we can assume that Sharpless is sharp enough to avoid such reactive compounds!
It's not a bad distinction, overall. It's not good enough to make me extend my own tongue, but if you were forced to taste compounds based on one simple rule, you could do a lot worse. You avoid sampling all the alkaloids that way, which is sound advice. Almost all compounds active in the central nervous system have a nitrogen in them somewhere, too, and that's another class of unknowns I'd step aside for.
But the no-nitrogen rule isn't foolproof. There are some mighty foul terpenoids out there, put together with nothing but good old carbon, hydrogen, and oxygen. I'd offer up the carcinogenic phorbol esters as an example. Just looking at the structures, you wouldn't guess that they're as bad as they are. There are plenty of marine natural products that will degrade you, too: the brevetoxins and aplysiatoxins are a real sensation on the tongue, no doubt. And fungi can take you out without nitrogens, no problem at all, as witness the aflatoxins and the hideous trichothecenes.
Granted, Prof. Sharpless probably doesn't take in much of a compound when he gives it his taste test. But I still think I'll leave him to it; he can tell us if he comes across anything interesting. De gustibus non disputandum est. I certainly hope he doesn't poison himself, not least because I find his current work quite interesting. . .