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12.8.1 Hazards of Peroxide Formers

Organic peroxides are among the most hazardous substances handled in the chemical lab due to the auto-oxidation process which results in the formation of explosive crystals. They are generally low-power explosives that are sensitive to shock, sparks, or other accidental ignition. They are far more shock-sensitive than most primary explosives such as TNT.

Warning: Do not disturb a container of a peroxide-forming chemical that has been stored several months beyond its storage limit, or that is not marked with its first opening date. CallEH&S (x4866) immediately.

12.8.2 Handling Procedures for Peroxide Formers

Most peroxide formers must be handled in a chemical fume hood to prevent inhalation exposure. Standard PPE should be worn (gloves, a lab coat, and safety glasses). Peroxide formers must be dated when received and again when opened. Once expired, these chemicals must be collected by EH&S in a timely manner, as recommended in Section 12.8.4, Common Peroxide Formers and Storage Limits.

12.8.3 Controls on Peroxide Formers

Peroxide formers should be purchased in the smallest practicable containers appropriate to the rate of use.

Place the following label (shown in Figure III.2 and available from EH&S) on every container of a peroxide-forming compound immediately upon its receipt and enter the receipt date and retention (storage) limit on the label. Retention limits for common peroxide-formers are provided below.

Figure III.2: Every Peroxide Forming Compound Must Bear This Label


     Received                       Opened

Date _____________            _____________



12.8.4 Storage of Peroxide Formers

Store peroxide formers in the flammable cabinet as a group for easy inventory checking. Ethers should not be stored in refrigerators. There is no evidence that cold storage prevents or retards peroxide formation. There are, on the other hand, numerous accounts of refrigerators exploding because of an interior spark igniting trapped ether vapors.

Table Common Peroxide Formers and Storage Limits

Class 1:

Unsaturated materials, especially those of low molecular weight, may polymerize violently and hazardously due to peroxide initiation

Discard or test for peroxides after six months:

  • Acrylic acid
  • Acrylonitrile
  • Butadiene
  • Styrene
  • Tetrafluoroethylene (TFE)
  • Vinyl acetate
  • Vinyl acetylene (MVA)
  • Vinyl chloride
  • Vinyl pyridine
  • Vinylidene chloride
Class 2:

Peroxide hazard dependent on concentration; do not distill or evaporate without first testing for the presence of peroxides

Discard or test for peroxides after six months:

  • Acetal
  • Cumene (isopropylbenzene) chlorobutadiene (chloroprene)
  • Chlorotrifluoroethylene
  • Methyl methacrylate
  • Cyclohexene
  • Cyclooctene
  • Cyclopentene
  • Diacetylene (butadiene)
  • Dicyclopentadiene
  • Diethylene glycol dimethyl ether (diglyme)
  • Diethyl ether
  • Dioxane
  • Ethylene glycol dimethyl ether (glyme)
  • Furan
  • Methyl acetylene
  • Methyl cyclopentane
  • Methyl isobutyl ketone
  • Tetrahydrofuran (THF)
  • Tetralin (tetrahydronaphthalene)
  • Vinyl ethers
Class 3:

Peroxides derived from the following compounds may explode without concentration

Discard within three months


  • Divinyl ether
  • Divinyl acetylene (DVA)
  • Isopropyl ether
  • Vinylidene chloride (1,1-dichloroethylene)
  • Potassium metal
  • Potassium amide
  • Sodium amide (sodamide)

Above information on common peroxide formers and storage limits taken from Prudent Practices in theLaboratory: Handling and Disposal of Chemicals, pp. 54-55.

12.8.5 Inventory Checking and Testing

Periodically check the dates on peroxide formers when retrieving or replacing items in the flammable cabinet. Exposure to air resulting from opened and partially emptied containers accelerates peroxide formation. Opened containers in List 3 should be tested after one month and continue to be tested until emptied. For isopropyl and diethyl ethers, it is recommended that even unopened containers be disposed of after one year.

If only small amounts of peroxides are found, the chemical can be decontaminated. Call EH&S for further information.

12.8.6 Disposal of Peroxide Formers

Peroxide formers must be labeled for collection by EH&S.

12.8.7 Emergency Response: Exposure

  • Skin: Immediately remove affected clothing and flush contacted tissue with copious amounts of water for 15 minutes. If the skin is injured, proceed to the nearest hospital ER.

  • Eye contact: Rinse eyes with copious amounts of water for 15 minutes. Hold lids open while rinsing. Seek medical evaluation.

Complete an Accident-Illness Report Form as soon as possible and mail to EH&S at J3-200.

12.8.8 Emergency Response: Spills

While wearing safety goggles, gloves, and a lab coat, you can absorb a small spill with a universal absorbent. For large spills (>200 ml), call EH&S for clean-up.