Laboratory Burnt Out by small experiment

Scenerio

A small scale sealed tube chlorination of a pyrazole using POCl₃

Few mgs of the pyrazole + 4ml of POCl₃ in a 10ml sealed tube. Pop into a suitable oilbath at 220°C and leave overnight.

Result

Top floor of Research buiding burned out

Cause and Actions

Tube overpressurised (calculated pressure >300psig at 220°C - rated at 200psig at ambient), then POCL₃ leaked from tube, igniting oil bath (with oil above its flash point).

Sealed tube reactions banned, clampdown on proper risk assessments