University of Iowa

Peroxide Formers

Peroxide formers, or peroxidizables, are materials which react with oxygen to form peroxides which can explode from impact, heat, or friction. This generic chemical safety guidance describes basic prudent safety practice for handling this chemical in research labs. The principal investigator (PI) or the lab manager is responsible for developing and implementing standard operating procedures (SOPs) for the purchase, storage, and safe handling of this chemical that are specific to the PI’s research

Peroxide-forming compounds can be divided into three hazard categories. Storage times are based on time after opening the container. Most chemicals will have an expiration date on the chemical label based on the type of chemical. 

Category 1: compounds forming peroxides that can spontaneously decompose during storage. Chemicals that form peroxides, which may explode even without being concentrated (e.g., concentration such as by evaporation and distillation). Take extra care to manage these materials because they may become hazardous even if never opened. Test container for peroxides quarterly after opening or after expiration date has passed.

Examples:

  • Divinyl ether
  • Isopropyl ether
  • Potassium metal
  • Potassium amide
  • Sodium amide
  • Vinylidene chloride

Category 2: compounds forming peroxides that require the addition of a certain amount of energy (distillation, shock) to explosively decompose. Chemicals that form hazardous levels of peroxides when concentrated such as by evaporation or distillation. Test container for peroxides quarterly after expiration date has passed. Containers without expirations dates should be dated upon receipt and tested quarterly.

Examples:

  • Acetal
  • t-Butyl alcohol
  • Cumene
  • Cyclohexene
  • Cyclooctene
  • Cyclopentene
  • Diacetylene
  • Dicyclopentadiene
  • Diethylene glycol dimethyl ether (Diglyme)
  • 1, 4-Dioxane
  • Ethyl ether (diethyl ether)
  • Ethylene glycol dimethyl ether (Glyme)
  • Furan
  • Methyl acetylene
  • Methyl cyclopentane
  • Methyl isobutyl ketone
  • Tetrahydrofuran
  • Tetrahydronaphthalene
  • Vinyl ethers

Category 3: compounds that have the potential to form peroxide polymers, a highly dangerous form of peroxide that precipitate from solution easily and are extremely heat- and shock-sensitive. May polymerize violently and hazardously due to initiation by peroxide accumulation in solution. They are typically stored with polymerization inhibitors to prevent this from occurring. Contact the manufacturer for questions regarding the shelf life of these chemicals.

Examples:

  • Acrylic acid
  • Acrylonitrile
  • Butadiene *
  • Chlorobutadiene (Chloroprene) *
  • Chlorotrifluoroethylene
  • Methyl methacrylate
  • Styrene
  • Tetrafluoroethylene *
  • Vinyl acetate
  • Vinyl acetylene
  • Vinyl chloride
  • Vinyl pyridine

All labs should actively manage peroxide-forming chemicals. Utilize the following practices:

  • Purchase chemicals in small quantities.
  • Date containers upon receipt.
  • Date containers when first opened.
  • Obtain peroxide test strips such as KI/starch, Aquafast, EM Quant, or Quantofix. They are available from most large chemical distributors, such as VWR, Fisher and Aldrich.
  • Test contents for peroxides as stated above.
  • Record test date and results on container.
  • Dispose of containers once chemicals start showing peroxide formation.
  • Containers must be disposed of before reaching 25 ppm peroxide. For containers above 25 ppm see Disposal Procedure for Improperly Managed Peroxide-Forming Chemicals. 
  • Contact EHS for disposal.
  •  Do not open any container with evidence of peroxide formation such as obvious crystal formation around the lid or in the liquid, or visible discoloration.
  • Keep peroxide-forming chemicals in their original containers to minimize conditions that accelerate peroxide formation.
  • Other precautions are similar to those used for flammables.

The PI is responsible for SOPs specific to use of this chemical in their lab. The PI/Lab Manger is responsible for the site specific and hands-on training for the use of this chemical in their lab. Training should be directly documented in the researcher’s lab notebook. On each day of training, both trainer and trainee should sign the lab notebook.

Initially, researchers should perform the reactions with the PI or senior researcher present to observe the safe handling of this chemical. Review the reagent-specific safety data sheets (SDSs). Evaluate the hazards associated with the chemical reaction and experimental setup.