LiAlH4 fire after pressure pushes out syringe needle

Title

Wednesday, September 2, 2015

Situation

A LiAlH4 reduction of a nitro in ether was being performed under N2 at -78 degrees Celsius. When the bath was removed to allow the reaction to warm to room temperature, a pressure build up caused a needle to clog and the septum of the round bottom flask was ejected due to the high pressure. A fire formed above the reaction vessel lasting ∼ 2 minutes. The fire was observed by another researcher who alerted the rest of the lab and acquired the fire extinguisher in case the fire spread or intensified.

Suggestions

Using the correct glassware and being hooked up to a bubbler. Many groups do the "quick and dirty" N2 work with needles thru septa into flasks. This is OK for a lot of things, but it is certainly a really really bad idea whenever you're working with pyrophorics.
Keep the reaction at -78 degrees Celsius for a longer period of time. When warming up a reaction to room temperature, slowlyincreases the temperature from -78 to -35 degrees Celsius as this will greatly reduce the chances of run away reactions.
If you do see a fire please know that there's no punishment that comes with using a fire extinguisher to put out a fire!!