Explosion in sealed flask
The chemist had charged 3-methylaminopyridone hydrochloride into a 60ml bottle, with DMSO and excess DBU. The bottle was sealed with a cap, and heated with a heat gun, with occasional shaking by hand. After 3-4 minutes the dissolution of the amine hydrochloride was completed. Suddenly a discolouration was observed, the heat was removed and the bottle placed in the fume cupboard with the sash window closed. Effervescing was observed, followed by a loud bang, the lid of the bottle came off, and smoke was generated, and the distinct smell of thiol was observed. There were no injuries.
- Heating mixtures of DMSO and NaH are known to cause explosions. The MSDS also suggests that other strong bases may have an effect (including DBU). It is not known if the other ingredients are also likely to affect the stability - this was not further investigated.
- One should avoid heating anything in sealed vessels, even when the boiling points are very high.
- Heat guns should not be used as heat sources for reactions, as the temperature inside a reaction vessel is difficult to control. There is a risk of forming hot spots, which may be a potential cause for explosions.