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

Ethyl butanoate (CAS 105-54-4): storage and disposal

Ethyl butanoate, also sold as ethyl butyrate, is a pineapple-scented ester kept as a neat liquid in school, college and university stores. Its single listed hazard is that it is a flammable liquid and vapour. It is a fairly ordinary stock item and often turns up as one of a row of ester bottles used for smell and structure demonstrations, which is where mislabelling tends to happen.

CAS number
105-54-4
Form
Liquid
Storage class
Flammable
Signal word
Warning
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable

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

Flammability is the hazard that decides where it goes. Keep the bottle in a ventilated fire-resistant cabinet with spill containment, away from ignition sources, oxidisers and oxidising acids, which can ignite flammable materials or make a fire far more intense. A leak from corrosive stock can also break down a flammable container, so keep corrosives in a separate store. Only a spark-free refrigerator should hold it if cooling is needed. Because teaching sets usually hold several esters with similar smells, put the full name on each bottle and shelve them in a labelled row, not mixed with solvents.

How to tell it has deteriorated

The telltale change in an old bottle is a smell, because the ester can break down slowly in damp air. A bottle that once smelt fruity and now gives off a sharp, rancid, sweaty odour has been releasing butanoic acid, usually because the cap has not kept moisture out. Check the level against the record, as a flammable liquid in a poorly closed bottle drops over time. Look for a swollen cap liner, a damp neck, a faded label and a bulging container. A strong fruity smell outside the cabinet is a sign of a leaking cap. Otherwise this ester shows few visible signs of age.

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.

What must not be done is the first point: it is never poured into a sink, never put in the bin and never left open so the fruity smell can clear, and nobody should try to treat it. It leaves by specialist collection, in a lab pack with compatible organic liquids, described under waste code 16 05 06*, or 16 05 08* for a discarded organic chemical outside a pack. Record every name on the label, such as ethyl butyrate or butanoic acid ethyl ester, plus the bottle size and fill, and note any rancid smell.

Waste codes and transport details for Ethyl butanoate
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.
  • Calcium hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideOxidisers can ignite flammable materials or make a fire far more intense.
  • 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.
  • Potassium permanganateOxidisers can ignite flammable materials or make a fire far more intense.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
Show 2 more
  • 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.
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.
  • P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
  • 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.
  • P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P337+P317 If eye irritation persists: Get medical help.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P403+P235 Store in a well-ventilated place. Keep cool.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

Why does our ethyl butanoate smell of sweat instead of pineapple?

Moisture can split the ester slowly and release butanoic acid, which smells rancid. The bottle is aged stock. Keep it capped upright in the cabinet and declare it as waste with a note about the smell.

Is ethyl butyrate the same as ethyl butanoate?

Yes, they are two names for the same ester. Old labels use ethyl butyrate. Record both names and the CAS number if printed, so the collection description matches the bottle on your shelf.

Can we keep the school's esters together on one shelf?

They can share a fire-resistant cabinet, but label each bottle in full and keep the row separate from acids and oxidisers. Do not combine esters into one bottle, since that changes what the waste is.

Is ethyl butanoate treated as hazardous waste?

Yes, because it is a flammable liquid and vapour. It is described under 16 05 06* in a lab pack and goes by specialist collection. Give the collector the name, size and fill of each bottle.

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 C6H12O2. EC number 203-306-4.

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