Chemical Safety
Peroxidizable Chemicals

Chemicals of Peroxidizable Chemicals

a. Chemicals that form explosive levels of peroxides without concentration:

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Butadiene a Chloroprene a Divinylacetylene

Isopropryl ether Tetrafiuoroethylene Vinylidene chloride

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b. Chemicals that form explosive levels of peroxides on concentration:

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Acetal Acetaldehyde Benzyl alcohol 2-Butane Cumerie Cyclohexanol 2-Cyclohexen-1-ol Cyclohexene Decahdronaphtalene

Diacetylene Dicyclopentadiene Diethyl ether Diethyl glycol dimethyl ether (dyglyme) Dioxanes Ethylene glycol dimethyl ether (glyme) 4 Heptanol 2-Hexanol Methyl 1 -butanol

Methylcyclopentane Methyl isobutyl ketone 4-Metho1 2- pentanol 2 Pentanol 4-Pentan-1 ol 1 Phenylethanol 2 Phenylethanol 2 Propanol Tetrahydronaphthalene Vinyl ethers Other secondary alcohols

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c. Chemicals that may autopolymerize as a result of peroxide accumulation:

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Acrylic acid b Acrylonitirile b Butadiene c Chloroprene c Methyl Methacrylate b Styrene

Tetrafiuoroethylene c Vinyl acetat Vinyl acetylene Vinyl chloride Vinyladiene chloride

a	When stored as a liquid monomer.
b	Although these chemicals form peroxides, no explosion involving these monomers have been reported.
c	When stored in liquid form, these chemicals form explosive levels of peroxides without concentration. They may also be stored as a gas in gas cylinders. When stored as a gas, these chemicals may autopolymerize as a result of peroxide accumulation.
d	These chemicals easily form peroxides and should probably be considered under part B.
e	OSHA regulated carcinogen.
f	Extremely reactive and unstable compounds.

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d. Chemicals that may form peroxides but cannot clearly be placed in section A - C:

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Acrolein Allyl ether d Allyl ethyl ether p-(n-amyloxy) benzoyl chloride n-Amyl ether Benzyl n-butyl ether d Benzyl ether d Benzyl ethvl ether d Benzyl methyl ether Benzyl 1 napthyl ether 1,2 Bis (2chloroethoxv)ethane Bis (2-chloroethyl)ether Bis (2methoxvethoxv)ethyl ether Bis (2 chloroethyl) ether Bis (2-methoxvethyl) adipate Bis (2-ethoxyethyl) phthalate Bix (2-methoxyethyl) carbonate Bis (2-methoxyethyl) ether Bis (2-methoxyethyl) phthalate Bis (2-methoxymethyl) adipate Bis (2-butoxyethyl) phthalate Bis (2-phenoxyethyl) ether Bis (4-chlorobutyl) ether Bis (chloromethyl) ether c 2-Bromomethyl ether 3-Bromophenetole 0-Bromophenetole p-Bromophenetole 3-Bromopropyl phenyl ether 1,3 Butadiyne Buten 3-yne tert-Butyl ethyl ether tert-Butyl methyl ether n-Butyl phenyl ether n-Butyl vinyl ether Chloroacetadehyde diethylacetal d 2-Chlorobutadiene 1(2-Chlororethoxy)-2-phenoxyethane Chloroethylene Chloromethyl methyl ether c B-Chlorophenetole o-Chlorophenetole Diethyl ethoxymethylnemalonate Diethyl fumarate d

P-Chlorophenetole Cyclooctene d Cyclopropyl methyl ether Diallyl ether d p-Di-n-butoxybenzene 1,2 Dichloroethyl ethyl ether p-Dibenxyloxybenzene d 1, 2 Dichloroethyl ethvl ether 2,4 Dichlorophenetole Diethoxymethane d 2,2 Diethoxypropane Diethyl acetal d Diethylketene f m, o, p - Diethoxybenzene 1,2 Diethoxymethane Dimethoxymethane d 1,1 Dimethoxymethane d Dimethoxyketene f 3,3 Dimethoxpropene 2,4 Dinitrophenetole 1,3 Dioxepane d Di (1 propynyl) ether Di (2-propynyl) ether Di-n-propoxymethane d 1,2 Epoxy 3-isopropoxypropane d 1,2 Epoxy 3-phenoxpropane p-Ethoxyacetophenone 1-(2-Ethoxyethoxy) ethyl acetate 2-Ethoxyethyl acetate (2-Ethoxyethyl)-o-benzoyl benzoate 1-Ethoxynaphthalene o,p,-Ethoxyphenyl isocyanate 1-Ethyoxy-2-propyne 3 -Ethoxyopropionitrile 2-Ethylacrylaldehyde oxime 2-Ethylbutanol Ethyl B-ethoxypropionate 2-Ethylhexxanal Ethyl Vinyl Ether Furan 2,5 Hexadiyn- 1-ol

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e.Chemicals that may form peroxides but cannot be placed in Sections A-C (continued):

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4.5 Hexadien-2-yn- 1-ol n-Hexyl ether o,p-Iodophenetole Isoamyl benzyl ether d Isoamyl ether d Isobutyl vinyl ether lsophorone d 3-Isopropoxypropiontrile d Isopropy 1,2,4,5-trichlorophenoxyacetate Limonene 1,5-p-Methadiene Methyl p-(n-amyloxy) benzoate 4-Methyl-2-pentanone n Methylphenetole	m-Nitrophenetole 1-Octene Oxybis (2 ethyl acetate) Oxybis (2-ethyl benzoate) B,B Oxdipropionitrile 1-Pentene Phenoxy acetyl chloride a-Phenoxypropionitrile chloride Phenyl o-propyl ether p-Phenylphenetone n-Propylisopropyl ether Sodium 8, 11, 14 elcosate traenoate Sodium ethoxyacetylide Tetrahydropyran Triethylene glycol diacetate ·
2-Methyltetrahydrofuran 3-Methoxy- l-butyl acetate 2-Methoxyethanol 3-Methoxyethyl acetate 2-Methoxyethyl vinyl ether Methoxy- 1,3,5,7-cyclooctateraene B-Methoxypropionitrile	Trithylene glycol dipropionate 1,3,3-Trimethoxypropene d l,l,2,3,-Tetrachloro-l,3-butadiene 4-Vinyl Cyclohexene Vinylene carbonate Vinylidene chloride d

In most peroxide safety programs, a concentration of 100 ppm of peroxides is used as a control point. However, this value has no scientific justification. This criterion seems to be based on the practical limit of detection of the potassium iodine method traditionally used to detect peroxides. It is likely that this value is at least I order of magnitude overly conservative in some cases. Notably, this value is almost certainly quite overly conservative and excessively burdensome for the chemicals shown in part B of Table 1 when they are not used as a wipe cleaning compound to 100 ppm.

From a theoretical perspective, it should be impossible for most solutions of <1% peroxides to explode. However, the selection of a rational peroxide concentration control value is complicated by several factors. For example, when peroxidized chemicals are dispensed from screw-cap bottles, some of the liquid may remain on the threads of the cap. Unscrewing the cap may initiate an explosion. Thus, a solvent with modest peroxide contamination may explode because of the peroxide concentration.

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Classes of Peroxide Formers

For some chemicals, the concentration of peroxide reaches dangerous, shock sensitive levels without concentration. Other chemicals do not usually accumulate potentially explosive concentrations of peroxides unless the volatile organic material is reduced in volume. Such reduction may occur through incidental evaporation for very volatile compounds (e.g., diethyl ether) or through distillation. Distillation of peroxide-containing organic compounds has resulted in many serious accidents.

Part A of Table 1 list representative chemicals that may form explosive concentrations of peroxides without concentration by evaporation or distillation. Indeed, some of these may form explosive concentrations of peroxide even if never opened. Part B lists chemicals that accumulate peroxides but that usually become hazardous only if evaporated or distilled or otherwise treated to concentrate the peroxides. Note that the most common laboratory peroxidizable chemicals, including diethyl ether, THF, cyclohexene, the glycol ethers, and 2-propanol (isopropyl alcohol), usually require some concenlration to generate hazardous concentrations of peroxides. However, many of these chemicals are quite volatile, and repeated use of a container may allow enough evaporation to occur to concentrate peroxides to explosive levels. Part C lists certain peroxidizable vinyl monomers that may exothermically polymerize has a result of decomposition of accumulated peroxides; that is, the peroxides initiate very energetic polymerization of the bulk monomer. Part D lists other peroxidizable chemicals that have not been clearly characterized and thus have not been included in Parts A-C.

If properly packaged in manufacturing, peroxidizable pressurized gases such as butadiene, Tetrafluoroethylene, vinyl acetylene, and vinyl chloride should be relatively resistant to autoxidation. However, these gases are sometimes transferred from the manufacturer's cylinder to another container in the laboratory, and it is difficult to completely eliminate residual air from the receiving vessel. An inhibitor should be placed in the receiving container before transfer is accomplished. The hazard of peroxidation may become greater if these gases are condensed inside the cylinder or secondary vessel. All processes involving these gases should be thoroughly evaluated to determine the likelihood of forming a liquid phase.

Various sources suggest that the minimum hazardous concentrations of peroxides in solution in organic chemicals is in the range 0.005-1.0% (50-10,000ppm) as hydrogen peroxide (2,3,9,11,13). It has not been possible to reconcile this broad range (more than 2 orders of magnitude) because none of the authors provide any direct reference to data to support their statements. The high value (1.0%) is quoted from the National Safety Council (3), but the council provides no references .to support this statement and recommends an administrative control value of 100ppm. A University of California at Davis chemical safety document states, "There is not even agreement as to what concentration of peroxide constitutes a hazard". One reference states that with respect to distillation of the easily oxodized isopropyl ether, "the temperature and concentration at which explosion becomes probable has never been authoritatively stated. Even very small concentrated is the still system". The Canadian Center for Occupational Health MSDS for isopropyl ether suggests that when the concentrations of peroxides exceeds 100 ppm a hazard may arise if the solution is concentrated. Presumably, as it concentrates it becomes shock sensitive and more unstable. At some point, the solution spontaneously explodes.

Pursuant to the provisions of section 841(d) of Title 18, United States Code, and 27 CFR 55.23, the
Director, Bureau of Alcohol, Tobacco and Firearms, must publish and revise at least annually in the
FEDERAL REGISTER, a list of explosives determined to be within the coverage of 18 U.S.C.
Chapter 40, Importation, Manufacture, Distribution, and Storage of Explosive Materials. This chapter
covers not only explosives, but also blasting agents and detonators, all of which are defined as
explosive materials in section 841(c) of Title 18, United States Code. Accordingly, the following is the
1997 List of Explosive Materials subject to regulation under 18 U.S.C. Chapter 40, which includes
both the list of explosives (including detonators) required to be published in the FEDERAL
REGISTER and blasting agents. The list is intended to also include any and all mixtures containing any
of the materials on the list. Materials constituting blasting agents are marked by an asterisk. While the
list is comprehensive, it is not all inclusive. The fact that an explosive material may not be on the list
does not mean that it is not within the coverage of the law if it otherwise meets the statutory definitions
in section 841 of Title 18, United States Code. Explosive materials are listed alphabetically by their
common names followed by chemical names and synonyms in brackets. This revised list supersedes
the List of Explosive Materials dated May 9, 1996, FR, Vol. 61 No. 91, and will be effective as of
the date of publication in the Federal Register.

This file was last modified on july 24, 2000.

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