Reactive Materials

Reactive compounds represent unique hazards in the laboratory.  They often react unpredictably with extreme force and violence.  Condensation via evaporation or distillation, heat, shock, or friction can all lead to a sudden reaction.  Exposure to air or water may cause instantaneous combustion.  There are numerous examples of highly reactive compounds in the lab; peroxide-forming compounds and pyrophoric compounds are highlighted here.

Peroxide Forming Chemicals

Peroxide Forming Chemicals

Certain chemicals can form dangerous peroxides on exposure to air and light. Peroxides may detonate with extreme violence when concentrated by evaporation or distillation, when combined with other compounds, or when disturbed by unusual heat, shock or friction. Formation of peroxides is accelerated in opened and partially emptied containers.

Peroxide Testing

  • Peroxide forming chemicals should be used or disposed of prior to the expiration date.  If extenuating circumstances exist for keeping the chemical, routine testing must be performed.
  • Visually inspect all containers before opening for crystal formation or cloudiness.  If either of these conditions are observed, DO NOT OPEN and ALERT EHS.
  • Test strips are available from the EHS Department
  • Any chemical that tests greater than 100ppm should be disposed of, please contact EHS for assistance
  • All test results should be recorded directly on the container.
  • Refer to TABLE 1 for testing or disposal frequency. 
  • Refer to TABLE 2 for a listing of each peroxidizable classification

TABLE 1

Peroxidizable Classification

Dispose or Test After*‡

Unopened from manufacturer

18 months

 

 

Opened Containers

 

List A

3 months

List B, uninhibited

3 Months

List B, inhibited 12 Months

List C, uninhibited

24  hours

List C, inhibited

12 months**

List D

Prior to Use

 

 

* Never open or test containers of unknown origin or age, or those that have evidence of peroxide formation

‡ Unless otherwise specified on the bottle

**Do not store under inert atmosphere

TABLE 2

List A – form peroxides without concentration by evaporation or distillation
Butadiene   Chloroprene    
Divinylacetylene   Isopropyl ether    
Tetrafluoroethylene        
Vinylidene Chloride        
         
List B – form explosive levels of peroxides upon concentration by evaporation or distillation
Acetal   Acetaldehyde   Benzyl Alcohol
2-Butanol   Cumene   Cylcohexanol
2-Cyclohexen-1-ol   Cyclohexene   Decahydronaphthalene
Diacetylene   dicyclopentadiene   Diethyl Ether
Diglyme   Dioxanes   Glyme
4-Hepitanol   2-Hexanol   Methyl Acetylene
3-Methyl-1-butanol   Methylcyclopentane Methyl Isobutyl Ketone
4-methyl-2-pentanol   2-Pentanol   4-Pentene-1-ol
1-Phenylethanol   2-Phenylethanol   2-Propanol
Tetrahydrofuran   Tetrahydronaphthalene Vinyl Ethers
    Other Secondary Alcohols  
         
List C – autopolymerize as a result of peroxide accumulation 
Acrylic Acid   Acrylonitrile   Butadiene
Chloroprene   Chlorotrifluoroethylene Methyl Methacrylate
Styrene   Tetrafluorethylene Vinyl Acetate
Vinylacetylene   Vinyl Chloride   Vinylpyridine
Vinyladiene Chloride        
         
List D – do not fall into the above categories, but require special handling nonetheless. Common chemicals are listed below.  Contact EHS for a more extensive list.
Acrolien   Ethyl Vinyl Ether   Furan
Limonene        

Recommended Work Practices

The following recommendations should be followed to control the hazards of peroxides.

  • Determine if the chemical in question poses a risk of forming peroxides.
  • Inventory all chemical storage at least twice a year.
  • Label containers with the date received, the date first opened and the date for disposal as recommended by the supplier.
  • Minimize peroxide formation in ethers by storing in tightly sealed containers placed in a cool place in the absence of light. Do not store ethers at or below the temperature at which the peroxide freezes or the solution precipitates.
  • Choose the size container that will ensure use of the entire contents within a short period of time.
  • Visually or chemically check for peroxides of any opened containers before use.
  • Clean up spills immediately.
  • More robust PPE and engineering controls may be required when working with peroxides and peroxide forming compounds.  Please contact EHS for a full risk assessment.
  • Do not concentrate solutions that may contain peroxides.  For example, rotary evaporation of an etheryl solvent such as tetrahydrofuran or diethyl ether couls pose a significant risk.
  • Always purchase solvents that are inhibited against peroxide formation. Remove inhibitors using column purification.  If inhibitor free solvent must be purchased, follow all documented instructions for use and always purge with notrogen before storage.
  • Do not use metal spatulas or magnetic stirring bars (which may leach out iron) with peroxide forming compounds, since contamination with metals can lead to explosive decomposition. Ceramic, Teflon or wooden spatulas and stirring blades are usually safe to use.

For more information, refer to the Peroxide-Forming Chemicals informational poster.  To request additional copies of the poster in various sizes, please contact EHS.

Pyrophoric Materials

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 Air-Sensitive Reagents” and “Handling Pyrophoric Reagents”.  Some examples of pyrophoric materials include:

Examples of Pyrophoric/Reactive Compounds
Required Work Practices 
Recommended Personal Protective Equipment
Emergency Procedures
Additional Related Resources

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 Air-Sensitive Reagents” and “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 receommended 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 MetL-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 Public Safety (911 from a campus or 609-258-7882 from a cell phone) 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 labcoat 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 only 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 Public Safety (911 from a campus or 609-258-3333 from a cell phone) immediately.
  • A MetL-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 Air-Sensitive Reagents” and “Handling Pyrophoric Reagents”.

The following articles account a fatal incident involving a UCLA researcher working with t-butyllithium. "Deadly UCLA lab fire leaves haunting questions""Researcher Dies After Lab Fire - UCLA research assistant burned in incident with tert-butyl lithium"

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.