Pyrophoric Compounds

Certain stock reagents and in-situ products are pyrophoric, reacting violently when exposed to water and humid or dry air. These chemicals are useful to research and many are essential to catalyze certain reactions or are incorporated into final products. To handle these materials safely, review the Aldrich technical bulletins “Handling Pyrophoric Reagents”.

Some examples of pyrophoric materials include:

Organo-metallic reagents (i.e. Grignard reagents)
Alkali earth elements (sodium, potassium, cesium)
Finely divided metals (Raney nickel, aluminum powder, zinc dust)
Metal hydrides (sodium hydride, germane, lithium aluminum hydride)
Alkyl metal hydrides (butyllithium, trimethylaluminum, triethylboron)
Metal carbonyls (nickel carbonyl, iron pentacarbonyl)
Gases (arsine, diborane, phosphine, silane)
Silicon halides (dichloromethylsilane)

Exposure to air or moisture can cause these materials to evolve heat, fire, flammable or corrosive byproducts by violent decomposition. Since they are typically packaged and stored under an inert atmosphere, under oil, or within a solvent, appropriate methods must be utilized to preserve the material during storage and while dispensing. See Highly Toxic Gases for work with pyrophoric gases.

Required Work Practices

Detailed information about transferring pyrophorics can be found in Aldrich technical bulletins “Handling Pyrophoric Reagents”.

The following general guidelines must be followed while working with pyrophoric materials.

Know the properties and hazards of all chemicals you are using through adequate research and study, including reading the label and SDS.
Select and obtain all necessary materials to dispense and use the reagent(s) safely.
Use pyrophoric materials in a glovebox when possible.
When using a fumehood for preparation or for air sensitive (Schlenk) techniques, ensure the sash is lowered as far as possible to assist with containment in event of a violent reaction and to provide a barrier between the lab worker and the reaction.
Use a double-tipped needle (cannula) for transferring materials.
Ensure a source of inert gas in available for transfers and pressure equilibration.
Ensure your glassware is DRY before assembly and introducing pyrophorics.
Thoroughly purge all air from the apparatus with the proper inert gas.
Use secure fittings, keep air-tight with a light coat of vacuum grease.
Secure septa to all addition/withdrawal orifices.
Incorporate bubblers filled with mineral oil to prevent air backflow.
Use pressure rated glassware and fittings for pressurized reactions.
Use the recommended inert gas for purging air and material transfer. Nitrogen is not suitable for all materials, consult the SDS.
Syringes may also be used to withdraw small quantities of liquid reagent (<50 mL) from containers when a supply of inert gas is provided to displace the quantity withdrawn. Ensure these are gas-tight syringes.
- Ensure the syringe is completely DRY and purged with appropriate inert gas.
- Insert a line into the septum, connected to a mineral oil-filled bubbler to prevent overpressure.
- Insert a low-pressure inert gas source line into the septum.
- Insert an extraction syringe into the septum and slowly withdraw reagent.
Select and use the appropriate personal protective equipment, see below.
Never work alone with pyrophorics.
Ensure someone can see or hear you.
Purchase quantities that will ensure use of the entire product within one year.
Use containers with transfer septa (i.e. Aldrich Sure/Seal) for liquid reagents.
Septa prevent exposure to air and moisture and allow you to safely transfer the pyrophoric material when an inert working atmosphere is not available.
Visually check the container and reaction vessel septa for degradation before use.
A Met-L-X fire extinguisher or powdered lime should be available in the lab. ABC and CO2 extinguishers can cause some pyrophorics to react more vigorously. Powdered lime can be used to cover spills and slow the reaction with air/humidity. Lime is hydroscopic; keep storage containers closed to prevent absorption of atmospheric moisture. Do not clean up spills. Contain the spill and/or extinguish the fire only if you can do so safely. Evacuate the lab and contact SUU Police 911 or 435-586-1911 immediately.

Recommended Personal Protective Equipment

Wear closed toed shoes made of a nonporous material, leather is preferred.
Use a face shield and chemical splash goggles to protect your face.
Wear a cloth lab coat or apron that can be quickly removed if needed.
Do not use plastic that can melt and adhere to your clothing/skin in event of a fire.
Use gloves made of a material resistant to the solvent/reagent.
Fire-resistant outer gloves with good dexterity are recommended.
Know where the nearest safety shower is from the reaction area.

In The Event Of An Emergency

If there is fire on your clothing or skin, stop-drop-and roll, unless you are within a few feet of a safety shower.
Keep in mind that unreacted materials may reignite until they are washed off.
If you are contaminated with a pyrophoric, remove your contaminated clothing while using the safety shower.
The copious amounts of water will flush away the heat of reaction.
If you have significant amounts of dry reactive compound on your body, you may brush off the bulk of it before you enter the shower. However, it is only safe to do so if it is not reacting.
Do not clean up spills.
Contain the spill and/or extinguish the fire only if you can do so safely.
Evacuate the lab and contact SUU Police 911 or 435-586-1911 immediately.
A Met-L-X fire extinguisher or powdered lime should be available in the lab. ABC and CO2 extinguishers can cause some pyrophorics to react more vigorously. Powdered lime can be used to cover spills and slow the reaction with air/humidity.

Additional Related Resources

Detailed information about transferring pyrophorics can be found in Aldrich technical bulletins “Handling Pyrophoric Reagents”.

The following articles account for a fatal incident involving a UCLA researcher working with t-butyllithium.

A peer-reviewed publication "Safe handling of organolithium compounds in the laboratory" made available by the Division of Chemical Health and Safety of the American Chemical Society.