The beaver is a proud and noble animal

Derek Lowe is an organic chemist. He’s worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer’s, diabetes, osteoporosis and other diseases. He also has a very amusing blog that contains, among other gems, a comprehensive list of things he’ll never work with.

http://pipeline.corante.com/archives/things_i_wont_work_with/

Some choice quotes:

Mercury Azides: Explosions are definitely underappreciated as a mixing technique, but in this case, they are keeping you from forming any larger crystals, a development which the paper says, with feeling, “should be avoided by all means”.

Azidoazide Azides: We’re talking high-nitrogen compounds here, and the question is not whether such things are going to be explosive hazards. (That’s been settled by their empirical formulas, which generally look like typographical errors). The question is whether you’re going to be able to get a long enough look at the material before it realizes its dream of turning into an expanding cloud of hot nitrogen gas.

Selenophenol: The chemical literature has numerous examples of people who are at a loss for words when it comes to describing its smell, but their attempts are eloquent all the same. “Imagine 6 skunks wrapped in rubber innertubes and the whole thing is set ablaze. That might approach the metaphysical stench of this material.” So we’ll start with that.

Hexanitrohexaazaisowurtzitane: There’s a recent report of a method to make a more stable form of it, by mixing it with TNT. Yes, this is an example of something that becomes less explosive as a one-to-one cocrystal with TNT. Although, as the authors point out, if you heat those crystals up the two components separate out, and you’re left with crystals of pure CL-20 soaking in liquid TNT, a situation that will heighten your awareness of the fleeting nature of life.

Dioxygen Difluoride: At seven hundred freaking degrees, fluorine starts to dissociate into monoatomic radicals, thereby losing its gentle and forgiving nature. But that’s how you get it to react with oxygen to make a product that’s worse in pretty much every way.

Chalcogen Polyazides: The experimental section of the paper enjoins the reader to wear a face shield, leather suit, and ear plugs, to work behind all sorts of blast shields, and to use Teflon and stainless steel apparatus so as to minimize shrapnel.

Chlorine Trifluoride: It is apparently about the most vigorous fluorinating agent known, and is much more difficult to handle than fluorine gas. That’s one of those statements you don’t get to hear very often. The compound also a stronger oxidizing agent than oxygen itself, which also puts it into rare territory. ”It is, of course, extremely toxic, but that’s the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively. It can be kept in some of the ordinary structural metals-steel, copper, aluminium, etc.-because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminium keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.”