Peroxide Forming Chemicals

The testing program begins when a peroxide forming chemical is ordered. The Risk & Safety Team inspects all hazardous materials that arrive on campus to ensure that they are not putting our community at risk. If the package passes inspection, our staff will place a neon yellow PFC sticker on the chemical container to notify the end user that they must maintain the life of this chemical.

Risk & Safety will communicate to the lab when the PFC’s are required to be tested. A Safety Specialist will provide an orientation on how to test for peroxides using an SOP and the provided testing material.

If the peroxide develops a color signaling that the container has high concentrations of peroxides, the container must be sent to disposal.

A number of common laboratory solvents and chemicals (i.e. potassium, ether, tetrahydrofuran) can undergo autoxidation even under normal storage conditions. This section is a list of common
peroxidizable compounds found in research laboratories. The section is divided into 4 subsections that correspond to the different classifications of peroxidizable compounds. Each Class has unique safe handling requirements that correlate to the chemical’s potential to accumulate/form peroxides.
These tables represent prominent organic and inorganic compounds that are able to form peroxides under the right conditions. The sections are illustrative, not comprehensive. You should refer to ChemTracker, the Safety Data Sheet (SDS) or other reference material, contact the chemical manufacturer or Safety Team, safety@utdallas.edu, to determine if the chemicals you are using are potential peroxide formers.

Class A: Peroxide Hazard on Storage – Without Concentration

These chemicals can form peroxides that are difficult to detect and eliminate. Unsaturated materials, especially those of low molecular weight, tend to polymerize violently and hazardously due to peroxide initiation. Label these items with a date of receipt and date of opening and dispose of these items 3 months after opening or 12 months if unopened.

Isopropyl ether	Divinyl acetylene	Potassium metal
Potassium amide	Sodium amide	Vinylidene chloride
Divinyl ether	—	—

Class B: Hazard Due to Peroxide Concentration

These chemicals require external energy for spontaneous decomposition. They form explosive peroxides when distilled, evaporated, or otherwise concentrated. Class B solvents should never be distilled or concentrated to dryness or near dryness unless the absence of peroxides is assured. Test for peroxide formation or discard after 12 months.

Acetal	Acetaldehyde	Benzyl alcohol
2-Butanol	Chlorofluoroethylene	Cumene (isopropylbenzene)
Cyclohexene	2-Cyclohexen-1-ol	Cyclopentene
Decahydronaphthalene (decalin)	Diacetylene (butadiyne) (gas)	Dicyclopentadiene
Diglyme	Diethyl ether (ether)	Ethylene glycol ether acetates
Furan	4-Heptanol	2-Hexanol
Methyl acetylene (gas)	3-methyl-1-butanol	Methyl isobutyl ketone
4-methyl-2-pentanol	2-pentanol	4-Penten-1-ol
1-Phenylethanol	Tetrahydrofuran (THF)	Tetrahydronaphthalene (tetralin)
Vinyl ethers	Secondary alcohols	Dioxanes
Ethylene glycol dimethyl ether (glyme)		Methyl cyclopentane

Class C: Autopolymerize as a Result of Peroxide Accumulation

These chemicals may explode when relatively small quantities of peroxides are formed. These items normally have an inhibitor (scavenger) added to the substance by the manufacturer in order to prevent peroxides from forming. This inhibitor can be removed if it interferes with the use of the chemical or the chemical is re-distilled in the lab. If a lab procedure requires the use of an uninhibited item in this Class, please contact the Safety Team (safety@utdallas.edu). Label these items with a date of receipt and date of opening and dispose of inhibited items after 12 months and uninhibited items within 24 hours of use.

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

Class D: May Form Peroxides

Chemicals that may form peroxides but cannot be clearly placed in Classes A – C. These chemicals have the potential to form peroxides with varying conditions of use but are normally stable. Consult the manufacturer’s SDS to determine when peroxide formation is expected and label accordingly.

Acrolein	p-Chlorophenetole	4,5-Hexadien-2-yn-1-ol
Allyl ether	Cyclooctene	n-Hexyl ether
Allyl ethyl ether	Cyclopropyl methyl ether	o.p-Iodophenetole
Allyl phenyl ether	Diallyl ether	Isoamyl benzyl ether
p-(n-Amyloxy)benzoyl chloride	p-Di-n-butoxybenzene	Isoamyl ether
n-Amyl ether	1,2-Dibenzyloxyethane	Isobutyl vinyl ether
Benzyl n-butyl ether	p-Dibenzyloxybenzene	Isophorone
Benzyl ether	1,2-Dichloroethyl ethyl ether	b-Isopropoxypropionitrile
Benzyl ethyl ether	2,4-Dichlorophenetole	Isopropyl-2,4,5-trichlorophenoxy acetate
Benzyl methyl ether	Diethoxymethane	n-Methylphenetole
Benzyl-1-napthyl ether	2,2-Diethoxypropane	2-Methyltetrahydrofuran
1,2-bis(2-chloroethoxyl)ethane	Diethyl ethoxymethylenemalonate	3-Methoxy-1-butyl acetate
Bis(2-ethoxyethyl)ether	Diethyl fumarate	2-Methoxyethanol
Bis(2-(methoxyethoxy)ethyl) ether	Diethyl acetal	3-Methoxyethyl acetate
Bis(2-chloroethyl) ether	Diethylketene	2-Methoxyethyl vinyl ether
Bis(2-ethoxyethyl) adipate	Diethoxybenzene (m-,o-,p-)	Methoxy-1,3,5,7-cyclooctatetraene
Bis(2-methoxyethyl) carbonate	1,2-Diethoxyethane	b-Methoxypropionitrile
Bis(2-methoxyethyl) ether	Dimethoxymethane	m-Nitrophenetole
Bis(2-methoxyethyl) phthalate	1,1-Dimethoxyethane	Oxybis(2-ethyl acetate)
Bis(2-methoxymethyl) adipate	Di(1-propynl) ether	Oxybis(2-ethyl benzoate)
Bis(2-n-butoxyethyl) phthalate	Di(2-propynl) ether	b,b-Oxydipropionitrile
Bis(2-phenoxyethyl) ether	Di-n-propoxymethane	1-Pentene
Bis(4-chlorobutyl) ether	1,2-Epoxy-3-isopropoxypropane 1	Phenoxyacetyl chloride
Bis(chloromethyl) ether	1,2-Epoxy-3-phenoxypropane	a-Phenoxypropionyl chloride
2-Bromomethyl ethyl ether	p-Ethoxyacetophenone	Phenyl-o-propyl ether
beta-Bromophenetole	1-(2-Ethoxyethoxy)ethyl acetate	p-Phenylphenetone
o-Bromophenetole	2-Ethoxyethyl acetate	n-Propyl ether
p-Bromophenetole	(2-Ethoxyethyl)-a-benzoyl benzoate	n-Propyl isopropyl ether
3-Bromopropyl phenyl ether	1-Ethoxynaphthalene	Sodium 8-11-14-eicosatetraenoate
tert-Butyl methyl ether	o,p-Ethoxyphenyl isocyanate	Sodium ethoxyacetylide
n-Butyl phenyl ether	1-Ethoxy-2-propyne	Tetrahydropyran
n-Butyl vinyl ether	3-Ethoxypropionitrile	Triethylene glycol diacetate
Chloroacetaldehyde diethylacetal	2-Ethylacrylaldehyde oxime	Triethylene glycol dipropionate
2-Chlorobutadiene	2-Ethylbutanol	1,3,3-Trimethoxypropene
1-(2-Chloroethoxy)-2- phenoxyethane	Ethyl-b-ethoxypropionate	1,1,2,3-Tetrachloro-1,3-butadiene
Chloroethylene	Ethylene glycol monomethyl ether	4-Vinyl cyclohexene
Chloromethyl methyl ether	2-Ethylhexanal	Vinylene carbonate
beta-Chlorophenetole	Ethyl vinyl ether
o-Choropheno	2,5-Hexadiyn-1-ol

Labeling and Shelf Life

All PFC’s must be dated upon receipt of the material(s) into the lab’s chemical inventory and upon opening the container. Neon yellow PFC warning labels are supplied by the Safety Team and affixed to all PFC containers and used to document the age and testing history of each chemical. To understand the safe storage periods (shelf life) of the different chemicals, please review the common PFC’s on Campus Section or refer to the Safety Data Sheet.

Storage Requirements

• Ensure the container is air-impermeable, tightly closed, and protected from light (light can initiate peroxide formation) at all times. NOTE: Dark amber glass with a tight fitting cap is appropriate.
• Keep in a dry, well-ventilated area away from incompatible materials and environments.
• Containers which are opened must be carefully resealed and kept upright to prevent leakage.
• Store peroxides at the lowest possible temperature consistent with their solubility and freezing point. CAUTION: Do not store liquid or solutions of peroxides at a temperature below that at which the peroxide freezes or precipitates. Peroxides in this form are extremely shock and heat-sensitive. Additionally, refrigeration does not prevent (and may not inhibit) peroxide formation. Refrigerated storage of peroxides or other flammable chemicals must be ONLY in “Lab-Safe” or explosion-proof units.
• Do not use glass containers with screw-cap lids or glass stoppers for extended storage. Use
  polyethylene containers, screw caps or stoppers.
• If the material is flammable, reactive, or explosive, keep away from heat and open flame.
• Store PFCS in their original manufacturer’s container whenever possible. NOTE: This is very important in the case of diethyl ether because the iron embedded in the steel container acts as a peroxide inhibitor.

Handling Requirements

• Provide hazardous chemical and specific SOP training to personnel working with the PFCs and any other personnel authorized or required to be in the laboratory or shared space during work with the chemicals.
• The laboratory where the material is being handled must have an approved/certified emergency eyewash and safety shower.
• Minimize exposure of the chemical to oxygen by keeping the container securely capped when not actively transferring from the reagent container.
• Test chemicals for peroxide before any distillation or purification of peroxide forming chemicals.
• NEVER distill potential peroxide-forming chemicals to dryness. Always leave a minimum of 20% still bottoms. When possible, add a non-volatile organic compound (such as mineral oil) to dilute any peroxides remaining after distillation.
• Use extreme caution before concentrating or purifying peroxide forming chemicals as most explosions occur during these processes.

It is best practice to visually inspect your inventory of peroxide forming chemicals before starting any laboratory operations. Containers that exhibit unusual visual characteristics, should be assumed to contain dangerous levels of peroxides and should not be further manipulated or disturbed. Notify the Safety Team (Safety@utdallas.edu) for further evaluation of the chemical. Chemicals determined to pose a risk to daily operations will be tagged out of use and sent to waste.

What are examples of characteristics for a potentially hazardous PFC?

Liquid Chemicals:

• Identify and/or age of chemical are unknown
• Crystallization & precipitation (around the cap or in the liquid)
• Visible discoloration
• Turbidity (cloudiness of the liquid)
• Liquid stratification (creation of distinct layers in solution)
• Evaporation greater than 10%
• Misshapenness of container (e.g., bulging)

Solid Chemicals

• Discoloration and/or formation of a surface crust (e.g., potassium metal forms a yellow or orange superoxide at the surface)

Only chemicals that pass visual inspection should be tested.

Several methods are commonly used to detect for peroxides in the laboratory but perhaps the most
convenient method is the use of commercially available peroxide test strips which may be purchased through most chemical manufacturing companies and/or laboratory vendors. Wet chemical detection methods are also available; however, the test strips are gentler, easier, faster, and have greater sensitivity and accuracy, and therefore are recommended for most applications. Test strips for the detection of peroxides may be purchased from various safety-supply vendors, including Amazon, VWR, Grainger, and Fisher Scientific. Ensure that test strips are capable of providing a colorimetric scale for at least concentrations of 50 and 100 ppm.

General Testing Procedures (Liquids ONLY)

• Don appropriate PPE (minimum requirements: gloves, goggles, and FRCP laboratory coat)
• Perform test behind a fume hood sash and/or blast shield.
• Carefully open chemical container using fume hood sash/blast shield as a barrier.
• Remove a test strip from the container, closing the container to limit exposure to moisture.
• Place a few drops of the PFC on the test pad/strip. Allow test pad/strip to dry until the solvent has
  evaporated or fully absorbed onto the test pad/strip (typically, 3 – 20 seconds).
• Moisten the test pad/strip with deionized water and allow water to fully absorb onto test pad/strip
  (10 – 20 seconds, but not more than 1 minute).
  NOTE: Water is necessary for the color change to occur. Water can be contaminated with
  peroxides, thus it is recommended to run a negative control/blank on the water prior to
  beginning.
• Evaluate the test results & record results on PFC Testing Label. A change in color indicates the presence of peroxides. Compare the color
  of the test pad/strip to the colorimetric scale provided by the manufacturer.

If you find a hazardous material that does not pass the visual inspection, DO NOT TOUCH THE BOTTLE!!

Immediately alert the Risk & Safety Team for emergency disposal. Our Hazardous Materials Manager will work with a disposal team to assist in creating a safer work environment.

To submit PFCs for waste disposal that are past their expiration date or that have tested positive for peroxides:

• Use the ‘Pickup Used /Spent Material’ request form
• Select the ‘Reactive’ check box, type peroxide forming, and include test results.
• Place a green tag on the container

If safe to do so, place the container in your laboratory waste storage area for pick-up.