Green flame

Ghostly flame dances over the flask

Scientific name: Trimethyl borate produced in situ from methanol and boric acid combusts with a green flame


Combustion of trimethyl borate

Combustion of Trimethyl Borate

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Wear eye protection goggles. Open air or hood. Non-combustible materials must be around.

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

Reaction formula

3 CH3OH + H3BO3 → B(OCH3)3 + 3 H2O

2 B(OCH3)3 + 9 O2 → B2O3 + 6 CO2 +9 H2O

2 CH3OH + 3 O2 → 2 CO2 + 4 H2O

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. Preparation of trimethyl borate. It can be prepared from boric acid and methanol.
  2. Weigh 5-10 grams of boric acid and put it in a flask.
  3. Pour 50-100 ml of methanol into the flask.
  4. Add a few drops of concentrated sulfuric acid.
  5. Heat the mixture to boiling.
  6. Ignite the generated vapor.
  7. Observe the low-temperature green colored flame

Scientific background

Esterification is an equilibrium reaction therefore it does not proceed to completion. Thus, it is necessary to use sulfuric acid as a catalyst and a dehydrating agent. Many boron compounds burn with a spectacular green flame. The green color is due to the emission from the excited BO* intermediate species (most prominent band at 518 nm)


Published on 26 March 2015

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