This post will have one of those stories that I can’t vouch for personally, and I’m very glad of that. It involves making diazomethane, which will have already gotten the attention of the chemists in the crowd.

Diazomethane’s a very useful reagent, but it has to be treated the right way. You can’t buy it – no one will ship the stuff – so you have to make it fresh. (There are several such reagents). For many years there have been chemicals in the catalogs whose only real use has been to generate diazomethane when needed. Generally this involves treating some nasty N-nitroso compound with base in ether, then distilling over the ether solution of the reagent, which is a distinctive bright yellow.

There’s where some of the trickiness comes in. That diazo group is looking for an excuse to revert back to nitrogen gas, which process comes with an inevitable no-substitutions side order of kaboom. The chemist’s job is to not give it that excuse. That means that you can’t heat the stuff up, you don’t make it very concentrated, and you don’t even expose it to sharp or rough surfaces, because that can be enough right there. They sell distillation glassware specifically for diazomethane preps, with weirdly glossy ground-glass joints.

You can keep your yellow solution stockpile in the freezer for a while, and the temptation is always to make a lot of it so you never have to do it again. That leads to phenomena like the big flask of the stuff left behind when someone leaves the grad school group. One of those surprises (“Is this yellow stuff what it looks like it is? How long has it been in here? And who the hell made it, anyway?”) was the cause of a new lab inspection requirement while I was getting my degree. You couldn’t leave until someone determined that you weren’t passing on any explosive bequests.

Of course, sometimes you honestly need a lot of these things. One of the guys in my group was in that situation early in his total synthesis. One summer afternoon, the power went out in the labs during a thunderstorm, and the head of our safety committee came rolling a big cooler of dry ice down the hall. “Anybody need to store something in the cold?” was the call. “Well,” I said, “we’ve got a couple of liters of diazomethane solution.” “That’s not very funny,” he said. “That’s because it’s not a joke”, I replied, and we moved to the front of the line.

So, what’s the stupidest way to handle the stuff? That’s the story told to me by a colleague. He attests that when he was in grad school, he looked across the hall to see someone involved in making a goodly amount of diazomethane – in a large standard ground-glass-joint apparatus. Oh, dear. How the guy was going to get his collection flask off without running the risk of grenading everything, that was the question. As my friend watched in disbelief, the guy reached up to just twist the darn thing right off. . .and it was stuck. A frozen joint – just the perfect time for it. (This is the point where the audience for this story began to bury their heads in their hands).

My colleague swears that he then watched this maniac pick up a propane torch to sweat the joint loose. I believe that someone may have stopped him in time, but I think the teller of this tale decided to adjourn for lunch at some distant location right around then, so I can’t vouch for the outcome. But if anyone has a more drooling, slack-jawed approach to an ether solution of diazomethane than running a propane torch over it, I’d like to know what it is. Short of maybe using it as an HPLC solvent, I’m out of ideas.

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