Safe Operating Procedure Peroxide Forming Chemicals

Introduction

Certain chemicals can react with oxygen to create peroxides. Concentrated peroxides can explode with impact, heat, or friction. Peroxide forming chemicals can be divided into hazard classes that are based on the method of reaction. This document outlines how to store, handle, and test for the presence of peroxides. Principal Investigators are responsible for following these guidelines for the control and safe use of peroxide forming chemicals.

Maximum Storage Time for Peroxide Forming Chemicals

Unopened chemical containers from manufacturer:

18 months

Opened chemical containers from manufacturer:

Chemicals in Table A 3 months

Chemicals in Tables B and D 12 months

Uninhibited chemicals in Table C 24 hours

Inhibited chemicals in Table C (do not store under an inert atmosphere)

12 months

*If a chemical container is not labeled with the date on which it was opened, the opened date will default to the date at which the chemical was received.

TABLE A: Severe Peroxide Hazard. These chemicals can spontaneously decompose and become explosive after exposure to air, even without concentration. These chemicals must be stabilized or decontaminated and discarded within 3 months of opening.

Butadiene (liquid monomer) Isopropyl ether Sodium amide (sodamide)

Chloroprene (liquid monomer) Potassium amide Tetrafluoroethylene (liquid monomer)

Divinylacetylene Potassium metal Vinylidene chloride

TABLE B: Concentration Hazard. These chemicals require external energy for spontaneous decomposition. They form explosive peroxides when distilled, evaporated, or otherwise concentrated. Discard these chemicals within 12 months of opening.

Acetal Diethyl ether 2-Pentanol

Acetaldehyde Diethylene glycol dimenthyl ether (diglyme)

4-Penten-1-ol

Benzyl alcohol Dioxanes 1-Phenylethanol

2-Butanol Ethylene glycol dimethyl ether (glyme)

2-Phenylethanol

Cumene 4-Heptanol 2-Propanol

Cyclohexanol 2-Hexanol Tetrahydrofuran

2-Cyclohexen-1-ol Methylacetylene Tetrahydronaphthalene

Cyclohexene 3-Methyl-1-butanol Vinyl ethers

Decahydronaphthalene Methylcyclopentane Other secondary alcohols

Diacetylene Methyl isobutyl ketone

Dicyclopentadiene 4-Methyl-2-pentanol

TABLE C: Shock and heat sensitive. These chemicals are highly reactive and can

autopolymerize as a result of internal peroxide accumulation. The peroxides formed

in these reactions are extremely shock and heat sensitive. Inhibited chemicals in this

group should be discarded within 12 months of opening. Uninhibited chemicals in

this group should be discarded within 24 hours of opening.

Acrylic acid Methyl methacrylate Vinyl chloride (gas)

Acrylonitrile Styrene Vinylpyridine

Butadiene (gas) Tetrafluoroethylene (gas) Vinyladiene chloride

Chloroprene Vinyl acetate

Chlorotrifluoroethylene Vinylacetylene (gas)

TABLE D: Chemicals that may form peroxides but cannot clearly be placed in tables A-C. Discard these chemicals within 12 months of opening.

Acrolein p-Chlorophenetole 4,5-Hexadien-2-yn-1-ol

Allyl etherd Cyclooctene

d n-Hexyl ether

Allyl ethyl ether Cyclopropyl methyl ether o,p-Iodophenetole

Allyl phenyl ether Diallyl etherd Isoamyl benzyl ether

d

p-(n-Amyloxy)benzoyl chloride

p-Di-n-butoxybenzene Isoamyl etherd

n-Amyl ether 1,2-Dibenzyloxyethaned Isobutyl vinyl ether

Benzyl n-butyl etherd p-Dibenzyloxybenzene

d Isophorone

d

Benxyl etherd 1,2-Dichloroethyl ethyl

ether

B-Isopropoxy-

propionitriled

Benzyl ethyl etherd 2,4-Dichlorophenetole Isopropyl

Benzyl methyl ether Diethoxymethaned Limonene

Benzyl 1-napthyl etherd 2,2-Diethoxypropane 1,5-p-Methadiene

1,2-Bis(2-chloroethoxy)- ethane

Diethyl ethoxymethylene- malonate

Methyl p-(n- amyloxy)benzoate

Bis(2 ethoxyethyl)ether Diethyl fumarated 4-Methyl-2-pentanone

Bis(2(methoxyethoxy)- ethyl) ether

Diethyl acetald n-Methylphenetole

Bis(2-chloroethyl) ether Diethyketenef 2-Methyltetra-hydrofuran

Bis(2-ethoxyethyl) adipate m,o,p-Diethoxybenzene 3-Methoxy-1-butyl acetate

Bis(2-ethoxyethyl) phthalate

1,2-Diethoxyethane 2-Methoxy-ethanol

Bis(2-methoxyethyl) carbonate

Dimethoxymethaned Methonxy-1,3,5,7-

cyclooctatetraene

Bis(2-methoxyethyl) ether 1,1-Dimethoxyethaned B-Methoxy-propionitrile

Bis(2-methoxyethyl) phthalate

Dimethylketenef m-Nitro-phenetole

Bis(2-methoxymethyl) adipate

3,3-Dimethoxypropene 1-Octene

Bis(2-n-butoxyethyl) phthalate

2,4-Dinitrophenetole Oxybis(2-ethyl acetate)

Bis(2-phenoxyethyl) ether 1,3-Dioxepaned Oxybis(2-ethyl benzoate)

Bis(4-chlorobutyl) ether Di(1-propynyl)etherf B,B-oxydi-propionitrile

Bis(chloromethyl) ethere Di(2-propynyl)ether 1-Pentene

2-Bromomethyl ethyl ether

Di-n-propoxymethaned Phenoxyacetyl chloride

B-Bromophenetole 1,2-Epoxy-3-

isopropoxypropaned

a-Phenoxy-propionyl

chloride

o-Bromophenetole 1,2-Epoxy-3- phenoxypropane

Phenyl o-propyl ether

p-Bromophenetole p-Ethoxyacetho-phenone p-Phenylphenetone

3-Bromopropyl phenyl ether

1-(2-Ethoxyethoxy)-ethyl acetate

n-Propyl ether

1,3-Butadiyne 2-Ethoxyethyl acetate n-Propyl isopropyl ether

Buten-3-yne (2-Ethoxyethyl)-o-benzoyl benzoate

Sodium 8,11,14-eicosa- tetraenoate

tert—Butyl ethyl ether 1-Ethoxynaphthalene Sodium ethoxyacetylidef

tert-Butyl methyl ether o,p-Ethoxyphenyl isocyanate

Tetrahydropyran

n-Butyl phenyl ether 1-Ethoxy-2-propyne Triethylene glycol diacetate

n-Butyl vinyl ether 3-Ethoxyopropionitrile Triethylene glycol

dipropionate

Chloroacetaldehyde

diethylacetald

2-Ethylacrylaldehyde

oxime 1,3,3-Trimethoxy- propene

d

2-Chlorobutadiene 2-Ethylbutanol 1,1,2,3-Tetrachloro-1,3- butadiene

1-(2-Chloroethoxy)-2- phenoxyethane

Ethyl B-ethoxy- propionate

4-Vinyl cyclohexene

Chloroethylene 2-Ethylhexanal 2,4,5-tri- chlorophenoxyacetate

Chloromethyl methyl ether

e

Ethyl vinyl ether Vinylene carbonate

B-Chlorophenetole Furan Vinylidene chlorided

o-Chlorophenetole 2,5-Hexadiyn-1-ol

NOTE: These tables represent prominent organic and inorganic compounds that are able to form peroxides under the right conditions. The tables are not comprehensive. You should refer to the Safety Data Sheet (SDS) or other reference material, contact the chemical manufacturer, or contact EH&S (817-272-2185) to determine if the chemicals you are using are potential peroxide formers.

General Precautions for Storage and Handling of Peroxide Forming Chemicals

1. Know the properties and hazards of all chemicals you are using through adequate research and study. Read the label and Safety Data Sheet (SDS).

2. Segregate these chemicals from incompatible materials. Store away from ignition sources. Protect these chemicals from flames, static electricity, and other sources of heat.

3. Purchase peroxide forming chemicals with inhibitors added by the manufacturer whenever possible.

4. Do not purchase large quantities of peroxide-forming reagents. Purchase the

amount that you will use in a 3-month period.

5. Date all peroxide-formers upon receipt and again upon opening. Discard unopened peroxide-formers 18 months after receipt. See the first table in this document to determine when a chemical should be discarded from an open container. If within the storage time frame and no crystal formation or liquid stratification is evident, these chemicals can be properly disposed through UT Arlington’s normal waste disposal procedure. Peroxides in solution in concentrations of less than 1% do not normally present a shock or detonation hazard.

6. DO NOT OPEN a container of a peroxide forming chemical that has obvious crystal formation or liquid stratification. Do not handle the container or force open the lid. Treat the reagent as potentially explosive material. Immediately call EH&S for assistance (817-272-2185).

7. Store peroxide formers (especially those in Table A) under nitrogen or other

inert gas, or keep and use them in an inert atmosphere chamber. Note: Some inhibitors actually need small amounts of oxygen to prevent peroxide formation and it is recommended that inhibited chemicals are not stored under an inert atmosphere.

8. Store peroxide formers in sealed, air-impermeable containers such as dark

amber glass with a tight-fitting cap. DO NOT store these chemicals in open, partially empty, or transparent containers as these conditions promote formation of peroxides. Containers of peroxide formers should also be stored away from heat and light and protected from physical damage and ignition sources.

9. Avoid distillation of peroxide formers without first testing for the presence of peroxides in the material. Most explosions with the use of peroxide formers occur when a material is distilled to dryness. Leave at least 10-20% s t i l l b o t t o m s . Stir such distillations with a mechanical stirrer or a bubbling inert gas. Air or an oxygen- containing mixture should never be used for bubbling or stirring.

10. Wear proper personal protective equipment, including safety glasses, face shield,

lab coat, gloves, and if possible utilize a safety shield.

Procedure for Testing Peroxide Forming Chemicals with the Water Works Test Strips

Peroxide forming chemicals must be tested for peroxide concentration upon opening and every

three months thereafter. The chemical must be disposed if it has a peroxide concentration greater

than or equal to 100 ppm, or when the maximum storage time is reached.

1. Perform testing in a chemical fume hood.

2. Make sure there are no solids or crystals in either the liquid or around the cap of

peroxide forming chemicals. If they are present do not open or move the

container. Contact EHS (817-272-2185) for disposal.

3. Pour a small volume of the chemical into a compatible secondary container.

4. Dip the test strip in the chemical for 2 seconds and then wait 30 seconds.

5. Dip the test strip in water for 2 seconds and then wait for color change if peroxides

are present.

6. Correctly fill out the label below and attach it to the container.

7. Chemicals with a peroxide concentration ≥ 100 ppm must be disposed.

Label Example

In the above example the peroxide forming chemical was from table B. It did not have a manufacturer’s expiration date. The chemical was opened within the 18 months allowable unopened storage time. The initial test after opening was satisfactory. Subsequent tests every three months were satisfactory until the test on 6/26/06, as this test result was 100 ppm. The chemical must be disposed of as soon as possible.

Peroxide Testing

Commercially available test strips. You can purchase these from most safety or laboratory supply houses. Some examples include Baxter Scientific, Fisher Scientific, and VWR Scientific.

To use most of these, simply immerse the strip in the suspect material and then compare the color on the strip to the calibration chart that comes with the test kit. This gives a quantitative peroxide concentration, usually in ppm. Caution: these strips have finite ranges. You may need to buy several different test kits to cover all possible ranges; read the product information or call the manufacturer for more information.

Potassium iodide indicator. Prepare a fresh solution of 10% (by weight) KI in glacial acetic acid. Add 1 mL of this clear, colorless solution to approximately 10 mL of the test material in a clear vial or test tube, shake well, and wait about 30 seconds for color changes to occur.

Peroxides will oxidize the colorless I- to I2, which gives purple or brownish solutions depending on the solvent. Purple, brown, or purple-brownish colors indicate relatively high concentrations of peroxides and yellowish colors indicate low concentrations.

Starch-iodide indicator. This procedure is identical to the KI test shown above, but shows color changes more easily because any iodine that is generated combines with added starch to form an intensely deep blue solution. Perform the test as indicated above, but add 1 drop of a saturated solution of starch in water. A strong blue color indicates peroxides.

You can prepare your own starch-iodide test strips by immersing strips of filter paper into your starch iodide solution and allowing them to dry. Store these away from light in a dry place. Be sure to test these against fresh, dilute H2O2 solution so you know they work correctly.

Sodium Dichromate indicator. Add no more than 1 milligram of Na2Cr2O7, and 1 drop of dilute

H2SO4 to 1 mL of water. Add approximately 10 mL of your ether to your dilute dichromate solution and shake well. The presence of peroxides is indicated by a blue color in the ether layer.

Ferrous Thiocyanate indicator. 1. Prepare the following solutions:

1% by weight (NH4)2Fe(SO4)2 in water.

1 N H2SO4 in water. Caution: always add acid to water, not vice-versa.

1 M NH4SCN in water. To make 1 L of such a solution, add 7.16 g of NH4SCN to

a 1-L volumetric flask and fill to the mark with distilled water. If necessary, decolorize the solution by adding a trace of zinc metal dust.

Combine 5 mL (NH4)2Fe(SO4)2, 0.5 mL H2SO4, and 0.5 mL NH4SCN. Shake with 6 mL of the suspected material. A red color indicates the presence of peroxides.

Sources

Kelly, Richard J., Chemical Health & Safety, American Chemical Society, 1996, Sept, 28-36

References

Princeton University, Peroxide Forming Compounds and Reactives Stanford University, Information on Peroxide Forming Compounds Interactive Learning Paradigms Incorporated, Compounds that can form

Peroxides Sigma-Aldrich, Peroxide Forming Solvents The Canadian Centre for Occupational Health & Safety, How Do I Work

Safely with Organic Peroxides?

Revised 07/2014