Beilstein test

The flame turns green

Scientific name: The reaction between copper oxide and halogenated organic compounds leads to the formation of copper halides. Reactions can qualitatively determine the presence of halogen atoms in the compound.


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Wear eye protection goggles. Use gloves.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

2 Cu + O2 → 2 CuO

RHal + CuO → CuHal + CuHal2 + CO2 + H2O

2 CHCl3 + 5 CuO → CuCl2 + 4 CuCl + 2 CO2 + H2O

Step-by-step instruction

  1. Make a spiral of copper wire.
  2. Heat the spiral over an alcohol lamp until it’s red hot.
  3. Wait until the wire cools.
  4. Lower the wire in any halogenated organic compound. For example, you can take chloroform.
  5. Put the wire into the flame again.
  6. Observe the green flames.
  7. Repeat steps 2-6 for the other compounds. Make sure that the test is positive for halogens (except fluorine). For example, you can also use 1-bromobutane and any product made from polyvinyl chloride.

Scientific background

Heating copper in air leads to the formation of copper oxide. Copper oxide reacts with halogenated organics under heating and leads to the formation of copper salts, which make the flame green.

Due to the simplicity, Beilstein test widely is used for the rapid analysis of organic compounds.


Published on 15 May 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst