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Chemical collection and stock control for UK schools, universities and hospitals

Diisopropyl ether (CAS 108-20-3): storage and disposal

Diisopropyl ether, also called isopropyl ether, is a highly flammable solvent held by college and university labs, usually as a forgotten neat bottle. It is one of the most severe peroxide formers on published lists and forms peroxides readily even when unopened. A sealed cap is therefore no reassurance, which sets it apart from most solvents on the shelf. Its age decides everything, and age cannot be judged remotely.

CAS number
108-20-3
Form
Liquid
Storage class
Flammable
Signal word
Danger
Usual EWC code, laboratory stock
16 05 06*
  • Flammable pictogramFlammable
  • Harmful or irritant pictogramHarmful or irritant

This chemical is a manual enquiry

This can become unstable or explosive, especially if it is old or has dried out. Nobody should move it until someone competent has looked at it, so we start with a conversation and usually a store assessment.

Severe peroxide former even unopened.

It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the next step, which depends on what it is. Keep following your own procedures for controlled drugs, radioactive materials, gases and asbestos.

What to do this week

  1. Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf. If there is immediate danger, such as a leak, fumes or a fire, leave the area and call 999.
  2. Write down the label wording, the rough age and where it is stored, from a safe distance.
  3. Send us those details, and a photo if you can take one without touching it.

Safe storage in a school or lab

Read the received date at the shelf before doing anything else, because an unopened bottle of this ether can still be forming peroxides. An opened bottle is due for review at 3 months, a far tighter interval than most peroxide formers get, so it suits only labs with a current use. Keep it in a ventilated fire-resistant cabinet with spill containment, and well away from permanganate, dichromate, chlorate, hypochlorite, chromium trioxide and hydrogen peroxide, as it can ignite or explode with these. Buy the smallest bottle the work allows and order it close to when it is needed. A bottle that has outlived its project should not stay in the cabinet as spare stock, since the next user will have no idea of its history.

How to tell it has deteriorated

Clear, colourless liquid under a tight cap looks normal, and that is the trap, as an ordinary appearance says little about this substance. Crystals around the cap or in the liquid are the signs that demand a stop. Other warnings are no dates on the label and simply an old bottle, opened or not. Dissolved peroxides give few visual signs before crystals appear, and any crystals may be highly sensitive to friction, including the turn of a cap. If you see these signs, do not open or move it. Keep people away and get a specialist assessment. Any peroxide testing belongs with competent staff, and it does not apply to a bottle already showing crystals or one of unknown age.

Severe peroxide former: can form explosive peroxides in storage.

This can form peroxides as it ages, especially after opening. Age and the opened date matter more than appearance, so a container with no opened date should be treated as old.

Review after 3 months: Review interval after opening from the cited peroxide former lists, not an expiry date from a manufacturer. Class C and all other chemicals are left null.

How it is disposed of

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Grouping and packing are decided only after a person has seen the bottle, so it does not simply join other ethers in a lab pack. Online quoting is not available: it is not accepted through the online quote path, because this is a severe peroxide former even when unopened. Send a manual enquiry with the label wording, the received and opened dates if shown, and the view of the cap from where you stand. A store assessment is recommended, as an old bottle can only be assessed in person by a competent chemist, and warning signs may call for an explosives or emergency specialist. Do not open it, move it, or try to make it safe. It must never go into a sink or drain.

Waste codes for Diisopropyl ether
Usual EWC code, laboratory stock16 05 06*
Discarded organic chemical, not a laboratory pack16 05 08*
Usually classed as hazardous wasteYes

20 01 13* (solvents) belongs to municipal collections and is shown for reference only. It is not the normal code for a laboratory collection.

The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. Use the waste code finder to see why.

Do not store with

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidSome acids, especially oxidising acids, can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Calcium hypochloritePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Chromium trioxidePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxidePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Potassium chloratePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Potassium dichromatePeroxide forming ethers can ignite or explode with strong oxidisers.
Show 7 more
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganatePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Sodium chloratePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Sodium dichromatePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.
  • Zinc chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

Common quantities

Usually held as: neat.

Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.

Where it is commonly held

Hazard statements

  • H225 Highly flammable liquid and vapour.
  • H336 May cause drowsiness or dizziness.
  • H412 Harmful to aquatic life with long lasting effects.
  • EUH019 May form explosive peroxides.
  • EUH066 Repeated exposure may cause skin dryness or cracking.
Precautionary statements
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P233 Keep container tightly closed.
  • P240 Ground and bond container and receiving equipment.
  • P241 Use explosion-proof electrical, ventilating and lighting equipment.
  • P242 Use non-sparking tools.
  • P243 Take action to prevent static discharges.
  • P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P271 Use only outdoors or in a well-ventilated area.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water or shower.
  • P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
  • P319 Get medical help if you feel unwell.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P403+P233 Store in a well-ventilated place. Keep container tightly closed.
  • P403+P235 Store in a well-ventilated place. Keep cool.
  • P405 Store locked up.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
  • P273 Avoid release to the environment.

Substance as classified, dilutions may differ.

Questions

Our diisopropyl ether is still sealed. Does that mean it is fine?

No. It forms peroxides readily even when unopened, which is why it sits among the most severe peroxide formers on published lists. Check the received date only if it is visible without touching or moving the bottle. If it is old or has no date, leave it alone and ask for an assessment.

Why is the review after opening so much shorter than for diethyl ether?

Published lists place diisopropyl ether in the most severe class, and peroxides can build up in it quickly. An opened bottle is due for review at 3 months. Most labs without a regular use are better off holding none at all, so ask about clearing any surplus.

Could we just swap it for a safer solvent and keep the old bottle as a reserve?

Changing solvent may suit your work, but the old bottle should not remain as a reserve. Stored stock only gets older and its history becomes harder to prove. Send an enquiry while its dates are still known, and do not open it in the meantime.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula C6H14O. EC number 203-560-6.

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