Routine for peroxide forming chemicals
SU FV-3008-24
Responsible unit: Property Management Office
Contact: Hanna Gustavsson
(The document is updated in 2024.)
A variety of organic compounds spontaneously forms peroxides by a free radical reaction of the hydrocarbon with molecular oxygen in a process of autoxidation. The reaction can be initiated by light, heat or by contamination.
The reaction is self-propagating and one initiating event may form many peroxide molecules. To bring attention to these chemicals a label must be attached to their containers and a note, together with the instruction, put on the cabinet where it is stored. See appendix 3 and 4.
As a class peroxides are exceptionally prone to violent decomposition that can be initiated by heat, friction or mechanical shock as from opening the container. Dry crystals are much more likely to ignite than liquid but once ignited the burn rate increases as the fire progress.
The peroxideizable chemicals are divided into four different categories (Jackson et al. 1970 and Kelly 1996). Category A-C contains a limited number of chemicals and each category is well described. Category D chemicals are those that do not fit in to any of the first categories, often due to lack of known data.
In some cases, they are less likely to produce peroxides under normal handling but others have been involved in violent explosions also under “normal” handling. Read safety data sheet and/or Bretherick’s Handbook of Reactive Chemical Hazards to find out more. Share important information on the label.
Some frequently used classes of chemicals that could be peroxide forming are: ethers, acetals and ketals, aldehydes, secondary alcohols and compounds containing benzylic or allylic hydrogens. In this document you will find chemicals listed in alphabetical order separated by class and also by CAS no.
Many peroxide forming solvents are distributed with an inhibitor. The inhibitor will be consumed over time. It will also be removed in distillation processes. Category C chemicals usually contain an inhibitor. Category C chemicals without inhibitor must be taken care of within 24h after opening. Especially important is to store diethyl ether in its original container as the iron acts as an inhibitor.
Paper towels, napkins or other organic material in contact with the peroxide forming chemicals must be avoided. And when needed, be taken care of with the greatest care and precautions.
There are no known safe dilution concentrations for peroxides or peroxide forming chemicals.
Read more, see references: Clark and Bretherick’s.
If any error, new CAS no. or new information is discovered inform the Chemical Compliance Officer, labsafety@su.se.
Plan purchases
- Buy as much as you plan to use, not more.
- Buy as much as you will use within a 3-month period.
Select smaller containers (1L or smaller).
Receiving routine
- Must always be taken care of directly on arrival.
- Before handling the containers, a visual check must be made.
- Always label the containers with a properly marked label with arrival date, opening dates, testing frequencies and other important information. (Other information is especially important for the cat D chemicals). Think about not to cover any important information on the original container. Labels can be put directly on the container, if possible, or attached by a string. (The string should not be attached too close to the cap or opening as there will be an increased risk with crystal formation on the string as well as this might prevent seeing any crystals formed under the cap.)
Storage and handling
- Store in darkness at cool temperatures, follow the storage recommendations in the SDS.
- Should be stored in original containers whenever possible.
When working in the lab take only out the daily volume and protect it from light. - Avoid using containers with loose fitting lids and ground glass stoppers.
- Before handling the containers, a visual check must be made.
- Never lift the container by the cap.
- When handling protect from light and heat.
- Testing for peroxides should be performed as often as required and always before distillation or evaporation of peroxidizable chemicals.
- Solid peroxidizable chemicals are generally not tested and must be sent for destruction before expiration date.
- Diluted peroxidizable chemicals should also be tested. (Essential to use clean glass.)
- Never use force to open a cap that “is stuck” or rusty. There might be invisible crystal formation.
- Especially important is to store diethyl ether in its original container as the iron acts as an inhibitor.
- When transferring solvents with iron, BHT or other particles added as inhibitor make sure you get some into the new flask.
- It is not allowed to keep transferred category C chemicals without inhibitor for more than 24h.
Visual inspection
This is done in two steps first on the shelf and then after carefully lifting it out.
- Is the container in good condition? (No deformation cracks etc.)
- Is the container and cap free of crystals (DO NOT OPEN TO DETERMINE THIS)?
- Is the container free of stratification, cloudiness & wisp-like structures?
- If any of the answers is ‘No’ do not touch/ move the container. It is safe as long as it is not disturbed. Inform local laboratory safety coordinator or head of department. Contact the University’s hazardous waste contractor.
Concentration control
Should only be done by an experienced chemist.
- Easiest done by using test strips like Sigma-Aldrich Quanofix 1-100 mg/L or 0,5-25 mg/L (semi quantitative test). Test strips need to be fresh. Contact your local laboratory safety coordinator of how to get these.
- If there is any indication that you have crystals under the cap or if you see any stratification, cloudiness or wisp-like structures, do not touch! Contact the University’s hazardous waste contractor and inform your local laboratory safety coordinator.
- If pH is out of the range 1-9 buffering might be needed, see instructions.
- If test result is
o <3 mg/L safe to use.
o 3<x<30 mg/L handle as hazardous waste
o >30 mg/L Cautiously close lid and contact the University’s hazardous waste contractor and inform your local laboratory safety coordinator.
Waste management
- Peroxidizable chemicals waste should be taken care of separately, if possible, in smaller containers that is never stored for more than a week at the time. Handle as hazardous waste.
- Always check the waste container for accurate concentrations of peroxides before leaving it for destruction. Confirm the testing on the waste label. Note any detectable concentration. Residues of additional chemicals can initiate peroxide formation.
- Old containers of peroxidizable chemicals, or containers of unknown age or history, or containers where it is not possible to see its content, must be handled very carefully. Handle as if the concentration is >30mg/L.
5 (20) - If a container has been mistreated for example exposed to light, higher temperatures or stored for too long, handle as if the concentration is >30 mg/L.
- Any spill should be taken care of by Vermiculite or similar adsorbent. Slurry with suitable solvent and handled as hazardous waste.
- Paper towels used to wipe up peroxide forming chemicals must be taken care of with great care and precautions. Peroxide formation on organic material is a well-documented risk. Slurry with suitable solvent and handled as hazardous waste.
- The waste slurry can be treated with acidic ferrous solution (Clark 2001).
References
Jackson H.L et al., Control of Peroxidizable Compounds, J.Chem. Educ. 1970, 47, A175
Kelly, R.J., Review of Safety Guidelines for Peroxidizable Organic Compounds, Chemical Health & Safety, 1996, 3(5), 28
Clark D.E., Peroxides and Peroxide-forming Compounds, Chemical Health & Safety, 2001, 8(5), 12-21
Breatherick’s Handbook of Reactive Chemical Hazards (7th ed) 2015, Vol 2 - Peroxidisable Compounds, 317-321
Appendix
Appendix 1 Peroxidizable chemicals sorted by group
Appendix 2 Peroxidizable compounds sorted by CAS number
Appendix 3 Sign to be posted on cabinets containing peroxidizable compounds
Appendix 4 Label for containers with peroxidizable compounds.
Known peroxidizable chemicals
Should be labelled with EUH019 - Chemicals that may form peroxides.
There might be other peroxidizable compounds that is not included in this list. Always read SDS carefully.
