Now here’s a news item that I’m pretty sure you haven’t heard about unless you work in or near a laboratory. We’re in the middle of an extreme shortage of acetonitrile, a common solvent. This has been going on since back in the fall, but instead of gradually getting better, it’s been gradually getting worse: major suppliers are sending out letters like this one (PDF).
What’s the stuff good for? Well, it’s used on a manufacturing scale in some processes, so they’re in trouble for sure. Acetonitrile is a good solvent, since it’s fairly powerful at dissolving things but still reasonable low-boiling. (That’s the nitrile functional group for you; there’s nothing else quite like it). It’s no DMSO, but then again, DMSO’s boiling point is
three times a lot higher, and compared to acetonitrile it pours like pancake syrup. Nobody does industrial-scale chemistry in DMSO if they can possibly help it.
Those properties mean that acetonitrile/water mixtures are ubiquitous in analytical and prep-sized chromatography systems. This is surely its most widespread use, and is causing the most widespread consternation as the shortage becomes more acute. Many people are switching to methanol/water, which usually works, but can be a bit jumpier. But that’s not always an option. Labs working under regulatory-agency controls (GLP / GMP) have a very hard time changing analytical methods without triggering a blizzard of paperwork and major delays. In many companies, it’s those people who are first in line for what acetonitrile may turn up.
So why are we going dry on the stuff? There seem to be several reasons, one of which, interestingly, is the summer Olympics. The industrial production that the Chinese government shut down to improve Beijing’s air quality seems to have included a disproportionate amount of the country’s acetonitrile production (for example). A US facility on the Gulf Coast was shut down during Hurricane Ike as well. But on top of these acute reasons, there's a secular one: yep, the global economic slowdown. A lot of acetonitrile comes as a byproduct of acrylonitrile production, which is used in a lot of industrial resins and plastics. Those go into making car parts, electronic housings, all sorts of things that are piling up in inventory and thus not being turned out at the rates of a year ago.
So taken together, there’s not much acetonitrile to be had out there. We’ve seen some glitches like this in the past, naturally, since chemical production can depend on a limited number of plants and on raw material prices. When I was an undergraduate, I remember professors complaining aboiut the price of silver reagents during the attempted Hunt brothers corner of that market, for example. But this one will definitely be near the top of the list, and it could be months before the Great Acetonitrile Drought lifts. If you've been saving some in your basement, it’s time to break it out.