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


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


List A – form peroxides without concentration by evaporation or distillation
Butadiene   Chloroprene    
Divinylacetylene   Isopropyl ether    
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

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.


Stanley Howell
Sr. Program Manager
Chemical Safety

Steve Elwood
Associate Director for Laboratory Safety