PEROXIDE-FORMING CHEMICALS
STANDARD OPERATING PROCEDURE TEMPLATE
(see also these related SOPs in the UCSB SOP Library: “Flammable Liquids”, “Solvent Use: Extractions,
Distillations and Still Quenching” )
Type of SOP:
Process
Hazardous Chemical
Hazard Class
To customize this SOP, add lab-specific information to the sections below marked in
RED, as applicable. Completion of the last section (“Lab-Specific Information”) is
required. Also, any of the content below may be amended with lab-specific information
to enhance worker safety as desired.
1.
HAZARD OVERVIEW
Organic peroxides are among the most hazardous substances handled in the chemical
laboratory. They are generally low-power explosives that are sensitive to shock, sparks, or
other accidental ignition. They are far more shock-sensitive than most primary explosives such
as TNT.
Organic peroxides can be obtained in two ways:
1. purchased as such, e.g. benzoyl peroxide, or
2. occur spontaneously when certain chemicals (see below) are stored for prolonged
periods, concentrated through distillation, evaporation, or air exposure, and also as a
result of polymerization.
This SOP only deals with the second avenue – peroxides that can form in the lab.
Organic peroxides that are purchased are addressed in a separate UCSB SOP template titled:
Organic Peroxides and Self-Reactive Chemicals.
Organic peroxides are organic compounds containing the peroxide functional group (R-O-OR'), where R = an organic group. These materials are sensitive to oxygen, heat, friction,
impact, light, and strong oxidizing and reducing agents.
Peroxide forming chemicals are compounds that undergo auto-oxidation to form organic
hydroperoxides and/or peroxides when exposed to the oxygen in air. Especially dangerous are
ether bottles that have evaporated to dryness. A peroxide present as a contaminant in a
reagent or solvent can be very hazardous and can change the course of a planned reaction.
Auto-oxidation of organic materials (solvents and other liquids are most frequently of primary
concern) proceeds by a free-radical chain mechanism. For the substrate R—H, the chain is
initiated by ultraviolet light.
The unusual stability problems of this class of compounds make them a serious fire and
explosion hazard that requires careful management.
Template rev. 11/14
2.
HAZARDOUS CHEMICALS/CLASS OF HAZARDOUS CHEMICALS
The following are examples of specific compounds that are prone to forming peroxides:
Acetal
Butadiene
Cumene
Cyclohexene
Cyclooctene
Decahydronaphthalene
Decalin
Diacetylene
Dicyclopentadiene
Diethylene glycol
Diisopropyl ether
Dioxane
Dimethyl ether
Divinyl acetylene
Ethyl ether
Ethylene glycol dimethyl ether
Isopropyl ether
Methyl acetylene
Methylcyclopentane
Potassium metal
Sodium amide
Styrene
Tetrahydrofuran
Tetrahydronaphthalene
Tetralin
Vinyl acetate
Vinyl actylene
Vinyl chloride
Vinyl ethers
Vinylidene chloride
Most of the above specific examples fall into these chemical structure types:
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3.
Ethers, especially cyclic ethers and those containing primary and secondary alkyl groups
(never distill an ether before it has been shown to be free of peroxide)
Aldehydes
Compounds containing benzylic hydrogen
Compounds containing allylic hydrogens (C=C-H), including most alkenes; vinyl, and
vinylidene compounds
Compounds containing a tertiary C-H group (e.g., decalin and 2,5-dimethyl hexane)
PERSONAL PROTECTIVE EQUIPMENT (PPE)
See the PPE information under Sec. II of the UCSB Chemical Hygiene Plan regarding:
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4.
the UC PPE Policy and policy summary (what PPE is needed and when/where to use)
obtaining your PPE via use of the Laboratory Hazard Assessment Tool
glove selection criteria
respirator use, etc.
ENGINEERING/VENTILATION CONTROLS
1. Use at least one of the following engineering controls:
a. Fume hood: Work inside a certified chemical fume hood at all times.
b. Glove box: When inert or dry atmospheres are required.
c. Portable explosion shield: May also be required to control the risk of explosion.
d. Gas cabinet: If the material is classified as a compressed gas.
2. Use bonding and grounding equipment to minimizing the likelihood of an ignition from static
electricity during the transfer of all Class I flammable liquids – see the Flammable Liquids
SOP template in the UCSB SOP library.
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3. Know where your safety equipment is located (i.e., fire extinguisher, eye wash/safety
shower, and first aid kit).
4. Have the appropriate fire extinguisher available.
For further information see the following pages in Sec. II of the UCSB Chemical Hygiene Plan:
 Fume Hood Usage Guide
 Criteria for Implementing Engineering Controls
5.
SPECIAL HANDLING PROCEDURES AND STORAGE REQUIREMENTS
1. At least one other person should be present in the same laboratory, or nearby, when any
work involving peroxide forming chemicals is carried out.
2. Eliminate or substitute a less hazardous material when possible.
3. Design your experiment to use the smallest amount of material possible to achieve the
desired result.
4. Verify your experimental set-up and procedure prior to use.
5. Ensure all equipment is appropriate for the task.
6. Avoid inadvertent incompatibles:
a. Heat sources, open flames and oxidizers
b. Consult with the campus Chemical Hygiene Officer if work involves large quantities.
7. Conduct distillation, extraction or crystallization, and other processes that concentrate the
organic peroxides only when it is explicitly known safe to do so.
Diethyl ether must be used in a fume hood. THF-containing mobile phase must be prepared in
the fume hood but may be used outside of the fume hood on HPLC equipment so long as the
mobile phase supply container is covered. Refrigeration of diethyl ether is not recommended.
Reduced temperature can impede the peroxide-scavenging ability of added preservatives and
may actually increase peroxide formation. Reduced temperature may also decrease the
solubility of any solid peroxides that have formed, thereby increasing the hazard.
STORAGE:
1. Purchase and use the minimum amount of material necessary to perform your research.
2. Label peroxide-forming materials clearly and promptly with the date upon receipt or
synthesis. Dispose of old materials when past their expiration date. For many ethers this
is usually in the 6 to 12 months range.
3. The presence of peroxides in some cases is indicated by the appearance of a precipitate
or oily layer in the container.
4. Store all peroxide forming materials inside of a flammable cabinet
5. Review your inventory frequently to prevent peroxide-forming chemicals from becoming
unsafe.
6. Test materials for peroxide formation before using, particularly if the materials is to be
concentrated via distillation/evaporation. See test methods below.
7. Do not handle old or expired peroxide-forming materials that are discovered. Inform your
Principal Investigator immediately and dispose of the item as a hazardous waste.
8. Ether solvents: Ether solvents stored in solvent drying cartridge manifolds can be excluded
since these are kept air-free under a positive pressure of inert gas. The dangers associated
with ether solvents depend on and can be exacerbated by these factors:
a. Exposure to air (oxygen)
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b.
c.
d.
e.
f.
g.
h.
i.
Exposure to light
Temperature
Friction
Shock
Concentration
Chemical structure
Distillation that removes stabilizers
Slow evaporation of volatile ethers over time
j.
Impurities
Peroxide Detection Tests
From Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards, 2011. Sec.
6.G.3.2: The following tests will detect most (but not all) peroxy compounds and all hyperperoxides. Results of
peroxide detection tests must be indicated on the container/tag with test date, test results/method, and initials
of the authorized person conducting the test. NOTE: These tests should not be used for testing materials
potentially contaminated with inorganic peroxides (i.e., potassium).
Option 1. Add 1-3 ml of the liquid to be tested to an equal volume of acetic acid, add a few drops of 5%
potassium iodide (KI) solution and shake. The appearance of a yellow to brown color indicates the presence of
peroxides.
Option 2. Addition of 1 ml of a freshly prepared 10% KI and 10 ml of an organic solution in a 25 ml glass
cylinder should produce a yellow color if peroxides are present.
Option 3. Add 0.5 ml of the liquid to be tested to a mixture of 1 ml of 10% KI solution and 0.5 ml of dilute
hydrochloric acid to which a few drops of starch solution have been added just before the test. The presence of
a blue-black color within a minute indicates the presence of peroxides.
Option 4. Peroxide test strips that turn an indicative color in the presence of peroxides. Take care to follow
manufacturer instructions for effective detection. In general, the strips must be air dried until the solvent
evaporates and then exposed to moisture for proper operation.
6.
SPILL AND INCIDENT PROCEDURES
See directions under the “Chemical Incident” and “Medical Emergency” tabs of the UCSB Emergency
Information Flipchart – should already be posted in all labs.
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7.
DECONTAMINATION
If there are incidental drips of peroxidizable solvent on the fume hood work surface, secure ignition
sources and lower the sash to allow for evaporation. If bench paper becomes contaminated, it must
be removed, replaced and disposed of as hazardous waste.
8.
WASTE DISPOSAL
See “Chemical Waste Disposal” in Sec. II of the UCSB Chemical Hygiene Plan. If you suspect a
material is peroxidized, let the EH&S waste disposal personnel know this.
9.
PRIOR APPROVAL/REVIEW REQUIRED
As they deem necessary, the PI/supervisor should insert here any prior approval or review needed
before an individual can do the operation.
The Principal Investigator must be notified and approval must be obtained if diethyl ether will be
heated above room temperature or if the solvent volume will be reduced under reduced pressure
(rotary evaporation technique). This is a very hazardous process, and concentration of the diethyl
ether could cause crystals of potentially explosive ethereal peroxides to form. Consult with the
Principal Investigator for alternative methods for reducing solvent volume.
10.
DESIGNATED AREA
As they deem necessary, the PI/supervisor should insert here any information about whether a
special use-area is designated for this material/process.
Work should be completed in a laboratory fume hood.
11.
SAFETY DATA SHEETS
Found online at: http://ehs.ucsb.edu/labsafety/msds
Review R.J. Kelly’s paper Review of Safety Guidelines for Peroxidizable Organic Chemicals (Journal
of Chemical Health and Safety; Sept/Oct 1996).
12.
LAB-SPECIFIC INFORMATION (required) (Examples of appropriate content)
Add appropriate lab-specific information here describing how this material(s) is generally used. E.g.,
name of protocol, typical frequency done, quantities used, temperature and any additional safety
measures, etc.
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