I mentioned going through the scientific literature yesterday - it's only when you start on a deep search that you realize what huge swaths of chemical space are covered by patent claims. Of course, just about every word in that sentence needs some clarification.

"Chemical space", the universe of possible structures, is of course gigantic. Even if you confine yourself to the basic elements of organic chemistry - carbon, hydrogen, nitrogen, oxygen and sulfur - you still end up with insane numbers, with ten-to-the-sixtieth-power being one of the orders of magnitude being tossed around. Clearly, in a number that size you could lose all the chemical compounds prepared so far in human history and never see them again.

Plenty of those compounds are found (only) in the patent literature. But chemical patents typically claim much, much more territory than they ever exemplify. I spoke about this last spring.) As I mentioned then, those huge claims don't mean all that much when it comes to spraying down the area against competitor patents. If you want to know more, heaps more, about patentability in these situations, try this section of the US Patent Office's Manual of Patent Examining Procedure. It's an illustration in prose of what the phrase "grind to a halt" is supposed to convey, but I regret to admit that I've read the whole thing.

Back to the outer reaches of chemical space: I'd be in violation of my medicinal chemistry club pledge if I didn't point out that big swaths of it are a priorialmost certainly useless for drug discovery. Molecules can be too big, too polar, too greasy, or too rock-like to ever be of any medicinal use. That much everyone agrees on, but when you start to apply numerical cutoffs to those ideas, the arguing starts. More on this next week.