Peroxide formers, or peroxidizables, are materials which react with oxygen to form peroxides which can explode with impact, heat, or friction.
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. Examples are shown below.
- Compounds forming peroxides that can spontaneously decompose during storage.
- Maximum storage time is 3 months. Examples include divinyl acetylene, isopropyl ether, potassium metal, sodium amide, vinylidene chloride.
- Compounds forming peroxides that require the addition of a certain amount of energy (distillation, shock) to explosively decompose.
- Maximum storage time is 12 months. Examples include acetyl, cyclohexene, diacetylene, dicyclopentadiene, diethyl ether, dioxane, 1,2-dimethoxyethane, methyl acetylene, methyl cyclopentane, methyl isobutylketone, tetrahydrofuran, vinyl ethers, tetrahydronaphthalene.
- Compounds that have the potential to form peroxide polymers, a highly dangerous form of peroxide which precipitate from solution easily and are extremely heat and shock-sensitive.
- Maximum storage time is 12 months. Examples include acrylic acid, acrylonitrile, butadiene, chloroprene, chlorotrifluoroethylene, methyl methacrylate, styrene, tetrafluoroethylene, vinyl acetate, vinyl chloride, vinyl pyridine.
Precautions for Peroxide-Formers
All labs should actively manage peroxide-forming chemicals. Utilize the following practices:
- Date all peroxidizables upon receipt and opening. Unless the manufacturer has added an inhibitor, materials should be disposed of in a timely manner.
- Periodically test contents for peroxides using peroxide test strips; record test date and results on container.
- 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.