What Happened
Solid methyllithium remnants were wiped up in a glove box using kim wipes, which were then wrapped in aluminum foil. This foil packet was then transferred to a fume hood for the quenching procedure. Isopropanol was added dropwise to this foil packet. Upon addition, the kim wipes and isopropanol started to smolder and caught fire within the fume hood. The researcher quickly put the fire out with a fire extinguisher and reported the incident to EH&S.
What went right?
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The quenching procedure was conducted in a fume hood, which helped contain the fire.
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The researcher responded immediately and extinguished the fire with an appropriate fire extinguisher.
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The researcher was not working alone with pyrophoric materials.
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The incident was promptly reported to EH&S.
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The researcher provided a summary of the incident and shared details with EH&S during a follow-up.
What should have been done differently?
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Avoid using combustible materials (e.g. Kimwipes) with pyrophoric materials.
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Carry out the quenching under an inert atmosphere when appropriate.
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Dilute pyrophoric residues in an inert solvent like hexane or toluene (<20 wt%) before initiating alcohol addition.
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Remove all flammable and combustible materials from the fume hood before quenching.
What corrective actions will be taken?
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The incident was discussed with EH&S and the lab will update their quenching procedures and SOP accordingly.
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In the future, Kimwipes or other combustible materials will not be used to clean up methyllithium or other pyrophoric materials.
Lessons Learned
Improper quenching can quickly lead to fires, particularly when pyrophoric reagents such as methyllithium are concentrated on combustible materials and exposed to air. Quenching methods must account for heat generation, air sensitivity, and the physical form of the residue. Careful planning and adherence to established procedures are essential to minimize ignition risk.
