Posted by Pete McBreen 16 Nov 2010 at 10:30
Lots of interesting articles about the life of a chemist. Particularly interesting are the series of posts about Things I Won’t Work With
Tetrazole derivatives have featured several times here in “Things I Won’t Work With”, which might give you the impression that they’re invariably explosive. Not so - most of them are perfectly reasonable things. A tetrazole-for-carboxyl switch is one of the standard med-chem tricks, standard enough to have appeared in several marketed drugs. And that should be recommendation enough, since the FDA takes a dim view of exploding pharmaceuticals (nitroglycerine notwithstanding; that one was grandfathered in). No, tetrazoles are good citizens. Most of the time.
Well, the authors prepared a whole series of salts of the parent compound, using the bangiest counterions they could think of. And it makes for quite a party tray: the resulting compounds range from the merely explosive (the guanidinium salts) to the very explosive indeed (the ammonium and hydroxyammonium ones). They checked out the thermal stabilities with a differential scanning calorimeter (DSC), and the that latter two blew up so violently that they ruptured the pans on the apparatus while testing 1.5 milligrams of sample. No, I’m going to have to reluctantly give this class of compounds a miss, as appealing as they do sound.