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

Acetyl chloride (CAS 75-36-5): storage and disposal

College and university organic stores keep acetyl chloride as a neat liquid in a glass bottle with a tight cap. It is a highly flammable liquid that causes severe skin burns and eye damage and may be corrosive to metals. It reacts violently with water, releasing hydrogen chloride, so damp is its main enemy and the water based stock on the next shelf is its main hazard.

CAS number
75-36-5
Form
Liquid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable
  • Corrosive pictogramCorrosive

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

A glass bottle with a good liner is the usual form, and the first job is deciding what it must not be near. Acetyl chloride reacts with water, releasing heat and corrosive gas, so keep it away from ammonia solution, formalin, hydrochloric acid, hydrogen peroxide, sodium hydroxide and sodium hypochlorite, and from any other water based stock. It is a highly flammable liquid, so it goes in a ventilated fire-resistant cabinet with spill containment, away from ignition sources. Because it may be corrosive to metals, use a plastic or resistant tray, not a bare metal shelf. Do not store it in a fridge unless the fridge is spark-free and dry.

How to tell it has deteriorated

Fumes are the characteristic sign: in moist air acetyl chloride gives off white fumes of hydrogen chloride, so a misty neck of the bottle on opening, or acrid fumes noticed in the store room, mean moisture is getting in. Over time that shows as a white crust round the cap, a corroded metal cap liner, rust or pitting on nearby shelving and a stuck lid. A reduced level and a stained label are further signs. Do not open an old bottle to look, since opening releases the fumes. Record the cap condition, the crust and any fumes noticed, and ask for advice.

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.

Pouring it away or adding water to empty the bottle is exactly what must not happen, since the reaction with water is violent and releases hydrogen chloride. It goes by specialist collection under UN 1717, in UN approved packaging selected for its corrosive and water-reactive properties. The specialist collector confirms compatible packing and keeps it segregated from aqueous and other incompatible stock. Waste code 16 05 06* fits a laboratory chemical, with 16 05 08* where it is discarded organic chemical outside a lab pack. Keep the cap tight, the bottle upright in its tray, and note the crust, label wording and approximate volume for the description.

Waste codes and transport details for Acetyl chloride
EWC code, laboratory chemicals16 05 06*
Discarded organic chemical, not a laboratory pack16 05 08*
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.
  • Ammonia solutionReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Calcium hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • FormalinReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Hydrochloric acidReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Hydrogen peroxideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
Show 6 more
  • Potassium permanganateOxidisers can ignite flammable materials or make a fire far more intense.
  • Sodium hydroxideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Sodium hypochloriteReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • 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

  • H225 Highly flammable liquid and vapour.
  • H290 May be corrosive to metals.
  • H314 Causes severe skin burns and eye damage.
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.
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • 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.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • 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.
  • P234 Keep only in original packaging.
  • P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
  • P270 Do not eat, drink or smoke when using this product.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P317 Get medical help.
  • P330 Rinse mouth.
  • P390 Absorb spillage to prevent material damage.
  • P406 Store in corrosive resistant container with a resistant inner liner.

Substance as classified, dilutions may differ.

Questions

Why do water based chemicals matter so much for acetyl chloride?

It reacts violently with water, releasing hydrogen chloride and heat. A leaking bottle of ammonia solution, formalin or hydrochloric acid next to it could set that off. Keep it in its own cabinet, away from any aqueous stock.

There is white crust on the neck of our bottle. What does it mean?

It usually means moisture has reached the contents at the cap and produced a crust, and that fumes may be escaping. Do not try to clean it or open the bottle. Record the crust and cap condition, keep the bottle upright in its tray and ask for collection.

Can we keep it in a fridge to slow ageing?

Only a spark-free refrigerator can hold flammable stock, and a fridge brings moisture and temperature swings, both unhelpful here. A dry, ventilated flammable cabinet with tight caps is the usual arrangement. Check your own store rules and keep all water based stock out of it.

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 C2H3ClO. EC number 200-865-6.

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