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chemical management factsheet
Peroxide Forming Chemicals:
Management, Retention, and Storage
See also the
Managing Chemical Retention and
Storage in your Laboratory and
Managing Particularly Hazardous
Substances (PHS)
factsheets.
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HAZARDS OF PEROXIDES
A wide variety of organic compounds
spontaneously form peroxides by a free radical reaction of the
hydrocarbon with molecular oxygen. Under normal storage conditions,
formed peroxides can accumulate in the chemical container and may
explode when subjected to heat, friction or mechanical shock. For
this reason, it is imperative that laboratories learn to recognize
and safely handle peroxide-forming compounds.
PRACTICES FOR
CONTROL OF PEROXIDE FORMING MATERIALS
Purchase
Ideally, purchases of peroxide-forming chemicals should be restricted to
ensure that these chemicals are used up completely before they can
become peroxidized. This requires careful experiment planning.
Researchers should purchase no more material than is needed to
complete an experiment within the chemical’s safe shelf life.
Labeling and Shelf-Life Limitation
Peroxides tend to form in
materials as a function of age. Therefore, it is imperative that
researchers are keenly aware of the age of their peroxide-forming
chemicals. Researchers must date each container upon arrival in the
laboratory. Containers must be dated again when opened for the first
time. An appropriate expiration date based on what type of peroxide
susceptible chemical the item is should also be on the label. Track
dates and dispose of items through VEHS prior to expiration.
Storage
Peroxide-forming chemicals shall be stored in sealed,
air-impermeable, light-resistant containers and should be kept away
from light (light can initiate peroxide formation). Peroxide-forming
chemicals should be stored in their original manufacturer’s
container whenever possible. This is very important in the case of
diethyl ether because the iron in the steel containers that the
material is shipped in acts as a peroxide inhibitor.
Inhibitors
Many methods can be used to stabilize or inhibit the peroxidation of
susceptible chemicals. If it does not interfere with the use of the
chemical and if available, peroxide-forming chemicals shall be
ordered with inhibitor added and peroxide scavengers (inhibitors)
shall be added in small quantities to items that have been
redistilled. Contact VEHS at 322-2057 if the peroxide scavenger
interferes with the use of the susceptible chemical.
Management
and disposal of old containers
Older containers of
peroxide-forming chemicals, or containers of unknown age or history,
must be handled very carefully and should never be opened by
researchers. Any peroxide-forming chemical with visible
discoloration, crystallization or liquid stratification should be
treated as potentially explosive. Older steel containers that have
visible rust may also be extremely dangerous. If any of these
conditions are observed on a peroxide-forming chemical container or
if the origin and age are unknown, do not attempt to move or open
the container. Contact VEHS at 2-2057 to have the container
inspected and if necessary disposed of properly.
Safe
Distillation of Peroxide Forming Chemicals
Eliminate the
peroxides with a chemical reducing agent or pass the solvent through
activated alumina.
Adding mineral oil to the distillation pot has
the combined effect of “cushioning” any bumping, maintaining
dilution, and serving as a viscous reaction moderator in case the
peroxides begin to decompose. Carefully monitor the distillation
process to ensure that it does not dry out completely, and then
overheat. Distillation can concentrate peroxides, especially if
taken to a dry state. Peroxides will be present mainly in the still
bottoms.
Small pieces of sodium metal can be added to the
distillation vessel to reduce peroxides. Use benzophenone as an
indicator for the presence of sodium metal (benzophenone in the
presence of sodium metal forms a radical with a deep-blue color).
When the blue color disappears, add more sodium metal to the vessel.
CLASSIFICATION OF PEROXIDE FORMING MATERIALS
Chemicals that
form peroxides are classified into four classes:
Class A:
Peroxide Hazard on Storage – Without Concentration
These
chemicals can form peroxides that are difficult to detect and
eliminate. 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.
Class B: Hazard Due to Peroxide
Concentration
These chemicals can undergo explosive
polymerization initiated by dissolved oxygen. Label these items with
a date of receipt and date of opening and dispose of these items 6
months after opening or 12 months if unopened. When alcohols listed
are used for purposes that do not involve heating, chemical
reaction, bulk evaporation or other activities that may stress the
peroxidizable material, it is not necessary to track and test these
containers for peroxidation.
Class C: Auto Polymerize 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 redistilled in the lab. If a lab
procedure requires the use of an uninhibited item in this Class,
please contact VEHS at 322-2057. 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.
Class D:
May Form Peroxides
These chemicals have the potential to form
peroxides with varying conditions of use but are normally stable.
Consult the manufacturer’s MSDS to determine when peroxide formation
is expected and label accordingly
Common chemicals that
form explosive levels of peroxides (this list is not inclusive)
Class A: Peroxide Hazard on Storage – Without Concentrationa
Butadienec
Vinylidene chloride
Chloroprened
Tetrafluoroethylene
Methacrylate
Divinyl acetylene
Class B: Hazard Due to Peroxide Concentration
Acetal
Acetaldehyde
Benzyl alcohol
Isopropyl ether
Cyclohexanol
2-cyclohexen-1-ol
Cumene
Decahydronaphthalene
Diacetylene
Dicyclopentadiene
Diethyl ether
Diethylene glycol
Dimethyl
ether
Dioxanes
Ethylene glycol dimethyl ether
4-heptanol
Methyl acetylene
Methyl isobutyl ketone
3-methyl-1 butanol
Methyl cyclopentane
2-pentanol
4-penten-1-ol
1-phenylethanol
2-phenylethanol
2-propanol (isoproranol,
“IPA”)
Tetrahydrofuran
Tetrahydronaphthalene
Vinyl ethers
Other secondary alcohols
Class C: Auto-Polymerize as a
Result of Peroxide Accumulation
Acrylic acid
Acrylonitrile
Butadienee
2-butanol
Chlorotrifluoroethylene
Methyl
methacrylate
Stryene
Vinyl acetate
Vinyl acetylene
Vinyl
chloride
Vinyl pyridine
Tetrafluoroethylenec
Class
D: Chemicals that may form peroxides but cannot be clearly placed in
Class A-C
Acrolein
Allyl ether
Allyl ethyl ether
Allyl
phenyl ether
p-(n-Amyloxy)benzoyl chloride
n-Amyl ether
Benzyl n-butyl ether
Benzyl ether
Benzyl ethyl ether
Benzyl
methyl ether
Benzyl-1-napthyl ether
1,2-Bis(2-chloroethoxyl)ethane
Bis(2-ethoxyethyl)ether
Bis(2-(methoxyethoxy)ethyl)
ether
Bis(2-chloroethyl) ether
Bis(2-ethoxyethyl) adipate
Bis(2-methoxyethyl) carbonate
Bis(2-methoxyethyl) ether
Bis(2-methoxyethyl)
phthalate
Bis(2-methoxymethyl) adipate
Bis(2-n-butoxyethyl)
phthalate
Bis(2-phenoxyethyl) ether
Bis(4-chlorobutyl) ether
Bis(chloromethyl) ether
2-Bromomethyl ethyl ether
beta-Bromophenetole
o-Bromophenetole
p-Bromophenetole
3-Bromopropyl phenyl ether
tert-Butyl methyl ether
n-Butyl phenyl ether
n-Butyl vinyl
ether
Chloroacetaldehyde diethylacetal
2-Chlorobutadiene
1-(2-Chloroethoxy)-2-phenoxyethane
Chloroethylene
Chloromethyl
methyl ether
b-Chlorophenetole
o-Chorophenetole
p-Chlorophenetole
Cyclooctene
Cyclopropyl methyl ether
Diallyl ether
p-Di-n-butoxybenzene
1,2-Dibenzyloxyethane
p-Dibenzyloxybenzene
1,2-Dichloroethyl
ethyl ether
2,4-Dichlorophenetole
Diethoxymethane
2,2-Diethoxypropane
Diethyl ethoxymethylenemalonate
Diethyl
fumarate
Diethyl acetal
Diethylketene
m,o,p-Diethoxybenzene
1,2-Diethoxyethane
Dimethoxymethane
1,1-Dimethoxyethane
Di(1-propynl) ether
Di(2-propynl) ether
Di-n-propoxymethane
1,2-Epoxy-3-isopropoxypropane
1,2-Epoxy-3-phenoxypropane
p-Ethoxyacetophenone
1-(2-Ethoxyethoxy)ethyl acetate
2-Ethoxyethyl acetate
(2-Ethoxyethyl)-a-benzoyl benzoate
1-Ethoxynaphthalene
o,p-Ethoxyphenyl isocyanate
1-Ethoxy-2-propyne
3-Ethoxypropionitrile
2-Ethylacrylaldehyde oxime
2-Ethylbutanol
Ethyl-b-ethoxypropionate
2-Ethylhexanal
Ethyl vinyl ether
Furan
2,5-Hexadiyn-1-ol
4,5-Hexadien-2-yn-1-ol
n-Hexyl ether
o.p-Iodophenetole
Isoamyl benzyl ether
Isoamyl ether
Isobutyl vinyl ether
Isophorone
b-Isopropoxypropionitrile
Isopropyl-2,4,5-trichlorophenoxy acetate
n-Methylphenetole
2-Methyltetrahydrofuran
3-Methoxy-1-butyl acetate
2-Methoxyethanol
3-Methoxyethyl acetate
2-Methoxyethyl vinyl
ether
Methoxy-1,3,5,7-cyclooctatetraene
b-Methoxypropionitrile
m-Nitrophenetole
1-Octene
Oxybis(2-ethyl acetate)
Oxybis(2-ethyl
benzoate)
b,b-Oxydipropionitrile
1-Pentene
Phenoxyacetyl
chloride
a-Phenoxypropionyl chloride
Phenyl-o-propyl ether
p-Phenylphenetone
n-Propyl ether
n-Propyl isopropyl ether
Sodium 8-11-14-eicosatetraenoate
Sodium ethoxyacetylide
Tetrahydropyran
Triethylene glycol diacetate
Triethylene
glycol dipropionate
1,3,3-Trimethoxypropene
1,1,2,3-Tetrachloro-1,3-butadiene
4-Vinyl cyclohexene
Vinylene
carbonate
aStore under nitrogen, if practical.
bWARNING! May become unstable if
concentrated intentionally or accidentally by user.
cWhen stored
as an inhibited liquid monomer.
dWhen stored as a liquid
monomer.
eWhen stored as a gas.
R.J. Kelly, "Review of
Safety Guidelines for peroxide-forming Organic Chemicals", Chemical
Health & Safety, September/October 1996, pp 28-36.
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