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

Acetic anhydride (CAS 108-24-7): storage and disposal

A bottle of acetic anhydride is a familiar sight in college organic stores and a smaller one on some histology benches, where it is held as a neat liquid. It is flammable, harmful if swallowed or inhaled and causes severe skin burns and eye damage. It also reacts with water to give acetic acid and heat, so the damp air of an ordinary store room is part of the hazard.

CAS number
108-24-7
Form
Liquid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable
  • Corrosive pictogramCorrosive
  • Harmful or irritant pictogramHarmful or irritant

What to do this week

  1. Check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as flammable stock and apart from the items listed under "Do not store with".
  3. If you no longer need it, add it to your disposal list so it goes on the next collection.

Safe storage in a school or lab

Fire and burns decide the shelf together, since it is a flammable liquid that also causes severe skin burns. A ventilated fire-resistant cabinet with spill containment suits it, kept clear of ignition sources. It reacts with water, releasing acetic acid and heat, so a cabinet that also holds aqueous stock or sits beneath a wash area is a poor choice. Keep chromium trioxide, hydrogen peroxide, nitric acid, perchloric acid and potassium permanganate well apart, because each can ignite or react violently with organic liquids, and it can explode with nitric acid. In a school or college prep room, keep it out of the acid shelf that holds nitric acid.

How to tell it has deteriorated

The first thing most technicians notice is the smell: a sharp vinegar odour in the store room means acetic acid is escaping, usually because moisture has reached the bottle or the cap has not sealed. On the shelf, look for a crust or wet ring around the neck, a corroded cap, rust on nearby metal shelving and a lowered level. Because it reacts with water, a bottle that has been opened many times may hold partly converted stock, though that is not visible from outside. Do not open it to check. Record the cap, the label and any smell, and ask for advice if the container looks compromised.

How it must be disposed of

By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a flammable laboratory pack with compatible chemicals.

Waste code 16 05 06* is the entry for a laboratory chemical sent in a lab pack, 16 05 08* is used where it is discarded organic chemical outside one, and 18 01 06* is the code that fits a healthcare or histology setting. The liquid goes by specialist collection under UN 1715, packed in UN approved packaging with compatible organic liquids and kept from oxidisers and nitric acid. Because it reacts with water, it must not be rinsed out, diluted or poured into a drain, and it should not be left open while waiting. Keep the cap tight and record the label wording and approximate volume.

Waste codes and transport details for Acetic anhydride
EWC code, laboratory chemicals16 05 06*
Discarded organic chemical, not a laboratory pack16 05 08*
Human healthcare setting18 01 06*
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 is mixed with. Use the waste code finder to see why.

Do not store with

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising 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 hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • Chromium trioxideChromium trioxide can ignite organic liquids on contact.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideConcentrated peroxide with these liquids can form unstable organic peroxides.
  • Nitric acidNitric acid reacts violently with organic solvents and can ignite them or build pressure in waste bottles.
  • Perchloric acidPerchloric acid forms explosive mixtures with organic material.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
Show 4 more
  • Potassium permanganatePermanganate can ignite or explode with these materials.
  • 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 we collect

Usually held as: neat.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Hazard statements

  • H226 Flammable liquid and vapour.
  • H302 Harmful if swallowed.
  • H314 Causes severe skin burns and eye damage.
  • H332 Harmful if inhaled.
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.
  • P260 Do not breathe dust, fume, gas, mist, vapours or spray.
  • P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P270 Do not eat, drink or smoke when using this product.
  • P271 Use only outdoors or in a well-ventilated area.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
  • P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • 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.
  • P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316 Get emergency medical help immediately.
  • P317 Get medical help.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P330 Rinse mouth.
  • P363 Wash contaminated clothing before reuse.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • 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.

Substance as classified, dilutions may differ.

Questions

Why does acetic anhydride smell of vinegar from a closed bottle?

It reacts with moisture to give acetic acid, which has the vinegar smell. A noticeable smell outside the bottle means vapour is getting out, often through a worn cap or seal. Leave it closed, record the smell and cap condition, and keep the bottle away from water based stock.

Can it go on the same shelf as nitric acid?

No. Nitric acid reacts violently with organic liquids, and acetic anhydride can explode with nitric acid. Keep them in separate cabinets, with the organic liquids in the flammable cabinet and the acid in the corrosive store, ideally not adjacent.

Which waste code applies to a histology lab?

Healthcare and histology settings use 18 01 06* for chemicals that are hazardous. A school or university lab uses 16 05 06* when the bottle goes in a lab pack. Tell us which setting you are, and the description is completed accordingly.

Is an old bottle that has partly evaporated still hazardous?

Yes. A lower level does not change the classification. It is still flammable and corrosive, and the remaining liquid may have taken in moisture. Treat it as the same hazardous waste and have it collected with its label intact.

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 C4H6O3. EC number 203-564-8.

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