Peroxide
Chem. Training

Session 5E

Control Procedures for Peroxide Forming Chemicals

Upon completion of this session, you will learn additional methods to protect yourself from the hazards of peroxide forming chemicals.

It should  take you about 10 minutes to complete this training session.  When you have read through the material, you will be asked to answer 5 questions.

The information presented in this section is a summary of the hazards and controls for these compounds.  This is done for training purposes.  However, if you wish to get more detailed information, please consult the CHSP.

    Peroxide Formation

    Peroxide formation in common laboratory chemicals is caused by an autoxidation reaction.  The reaction can be initiated by light, heat, introduction of a contaminant or the loss of an inhibitor.  Most organic peroxides are sensitive to heat, shock, or friction, and their accumulation in laboratory reagents has resulted in numerous explosions.   For this reason, it is important to recognize the types of chemicals which readily form potentially explosive peroxides. 

    Peroxide Forming Compounds

    In general, the more volatile the compound, the greater its hazard, since the evaporation of the compound allows the peroxide to concentrate.  Some common compounds which are known to form peroxides are listed in Table 1. 

    • Group A is a representative list of chemicals which spontaneously form explosive peroxides on exposure to air.  These materials should be tested or disposed of within three months of opening (testing is discussed below). 
    • Group B lists chemicals which form explosive levels of peroxides only upon concentration by evaporation or distillation.  The materials in this list should be tested or disposed of within one year of opening their containers. 
    • Group C is a representative list of monomers that form peroxides which may decompose resulting in the explosive polymerization.

TABLE 1. COMMON PEROXIDE-FORMING COMPOUNDS

Group A- Chemicals that form explosive levels of peroxides without concentration

(Safe storage time after opening - 3 months)

Butadiene1

Chloroprene (2-Chloro-1,3-Butadiene) 1

Divinyl acetylene

Isopropyl ether            

Potassium Metal

Sodium amide   

Tetrafluoroethylene1

Vinylidene chloride  

Group B-Chemicals that form explosive levels of peroxides on concentration

(Safe storage time after opening - 12 months)

Acetal    

Acetaldehyde   

Acrylic Acid

Acrylonitrile   

Benzyl alcohol

2-butanol

tert-butanol

Cumene (Isopropylbenzene) 

Cyclohexanol

Cyclohexene

Cyclopentene

Decahydronaphthalene

Diacetylene

Dibenzocyclopentadiene

Dicyclopentadiene

Diethylene glycol dimethyl ether (Diglyme)

Dihydroanthracene

Dioxanes   

Ethyl ether

Ethylene glycol dimethyl ether

Ethylene glycol ether acetates

Ethylene glycol monoethers (Cellosolves)

Furan

4-heptanol

2 hexanol

Indene

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   

Group C- Chemicals which may autopolymerize as a result of peroxide accumulation

(Safe storage time after opening: inhibited chemicals- 12 months; uninhibited chemicals: - 24 hours)

Note: Do not store inhibited chemicals in this group under inert atmospheres

Acrylic acid2  

Acrylonitrile2   

Butadiene3   

Chloroprene3

Chlorotrifluoroethylene

Divinylacetylene

Methyl methacrylate2

Tetrafluoroethylene

Vinyl acetylene   

Vinyl acetate

Vinyl chloride   

Vinyl pyridine   

Vinyladiene chloride

Styrene

    1. When stored as a liquid monomer

    2. Although these form peroxides, no explosions involving these monomers have been reported

    3. Also stored as a gas in gas cylinders.

    Substitution

    The use of peroxide forming compounds should be evaluated by an EH&S Industrial Hygienist to ensure that appropriate controls are in place.

    • If possible use a material that does not form peroxides, otherwise, purchase peroxide forming chemicals containing an inhibitor when possible.

    Engineering Controls

    • Use a fume hood or other appropriate exhaust ventilation shall be used when handling peroxide forming chemicals in a manner that may produce an airborne hazard.  This includes procedures such as transfer operations, preparation of mixtures, blending, sonification, spraying, heating, evaporation and distilling.
    • Place safety shields in front of reaction vessels, distillation columns and other apparatuses when fire, explosion or detonation may occur.
    • Leave at least 10% bottoms distilling peroxide forming chemicals.

    Personal Protective Equipment

    • Wear safety glasses with side shields, laboratory coats (or appropriate coveralls in shop settings) and closed toed shoes will be worn when handling these materials.
    • Additional PPE such as face shields, chemical aprons, disposable coveralls, chemically resistant gloves and respiratory protection shall be worn as appropriate.  Contact an EH&S Industrial Hygienist for assistance in selecting appropriate gloves, respiratory protection and other PPE.

    Storage

    • Separate incompatible chemicals.
    • Storage guidelines can be found in Storage Guidelines.
    • Store peroxide forming chemicals in a cool, dry environment, away from light and free from extremes of temperature and humidity.  Storage cabinets provide the best means of storage.

    Note:  It is Laboratory policy that chemical storage cabinets located in new facilities and renovated laboratories will be connected to the facility's exhaust ventilation system.

    • All peroxide forming chemicals should be stored in sealed, air-impermeable containers.  Dark amber glass containers with tight-fitting caps are required.  Containers with loose fitting lids or glass stoppers should not be used.
    • Use secondary containment for all liquids.
    • Ordinary domestic refrigerators must not be used for the storage of peroxide forming chemicals (many of which are flammable liquids) because they contain built-in ignition sources (such as electrical contacts).  These sources of ignition may initiate a fire or an explosion if flammable vapors are present. Explosion proof refrigerators shall be used when cold storage is needed.  Contact Procurement for information on how to purchase an explosion proof refigerator.

    Safe Storage Times

    • Table 1 provides safe storage times and testing frequencies. 
    • Peroxide forming compounds may be safely stored for the indicated time periods.  Storage for longer periods of time is allowable provided that testing is conducted at the indicated frequencies and that the results are within acceptable limits (see Peroxide Testing Method). 
    • Unopened containers from the manufacturer may be safely stored up to 18 months, after which testing or disposal is required.

    Peroxide Testing Method

    Peroxide forming compounds should be tested on a regular basis (as discussed above) to detect the presence of peroxides before they reach dangerous concentrations.

    • The testing method used at the Berkeley Lab is the redox test strip (available through Sigma Aldrich ).  The strip contains the enzyme peroxidase which transfers oxygen from the peroxide to an organic redox indicator, which is then converted to a blue oxidation product.  Follow manufacturer's instructions for testing and interpreting results.
    • Although it has not been determined what concentration of peroxide is explosive, the following rules should provide a reasonable margin of safety.
      • If the peroxide concentration is greater than 25 ppm, but less than 100 ppm, the chemical may be used, but DO NOT DISTILL OR CONCENTRATE.
      • If the peroxide concentration is greater than 100 ppm, it should be considered as potentially explosive and should not be used.  It should be disposed of as hazardous waste (see next section).

    Disposal

    If a peroxide forming compound has been stored either beyond its useful shelf life or safe storage time/testing frequency, or if its age or history can not be determined, it shall be considered potentially explosive and shall be disposed of as hazardous waste.  Please submit a Hazardous Waste Disposal Requisition Form to Waste Management.  Write "Peroxide Forming  Compound" on the form to alert EH&S Waste Management Group to the potential hazard.  Contact the Industrial Hygienist supporting your Division if you have questions regarding safety.  Waste disposal questions should be addressed to the EH&S Waste Management Group.

    Labeling

    • All materials listed in Table 1, as well as any other suspect peroxide former, shall be dated when the container is received and when the container is first opened.   A label for this purpose is available through Stores (Part No. 4280-90376).

    • The chemicals shall be tested or disposed of according to the frequencies listed in Table 1.
    • Primary and secondary containers, shall be labeled with the identity of the substance and its hazards.  The entrance to the work area shall be posted with a Pictogram depicting the hazards.

    Emergency Procedures

    • Do not attempt to open any container of uncertain age or condition. It should be isolated and disposed of promptly: See the section on Disposal for guidance.

 

 

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