CH3Br + NaOH Reaction | Methyl bromide and Sodium Hydroxide Reaction
CH3Br (Methyl bromide / bromoethane) reacts with aqueous NaOH (sodium hydroxide) and produce methanol (CH3OH). The bromine atom in CH3Br is replaced by -OH group. Reactants, products, mechanism, safety and more of this reaction is explained in this tutorial.
Written by: Eng . H.N. Demuni, Bsc. Chemical and Process Engineering, University of Peradeniya
CH3Br + NaOH → CH3OH + NaBr
Methyl bromide reacts with aqueous NaOH and gives methanol and sodium bromide as products. Methyl bromide is an alkyl halide compound and sodium hydroxide is a strong base. We learn this reaction in alkyl halide section of organic chemistry too.
Mechanism of the reaction
Because CH3Br is a primary alkyl halide, this reaction happens in a single step. With the attack of hydroxyl ion towards carbon atom, the bond between bromine atom and carbon atom is weaken. As a result, bromine atom is eliminated as bromide ion. Finally, -OH group is attached with carbon atom to give methanol and bromide ion is combined with sodium cation to form sodium bromide.
How reaction should be mixed to react?
CH3Br is a gas at room temperature and not soluble in water. Therefore, mixing reactants as two aqueous solutions is not possible. But, products of the reaction, methanol and NaBr are soluble in water. Therefore, products phase is soluble in water.
The best way to do this reaction is bubbling CH3Br gas into the aqueous NaOH solution.
Reaction with physical states
CH3Br(g) + NaOH(aq) → CH3OH(aq) + NaBr(aq)
Except CH3Br, all other compounds are soluble in water.
Aqueous sodium hydroxide is prepared by dissolving NaOH crystals in water.
Safety during the reaction
Read Material Safety Data Sheets (MSDS) before, doing a reaction. It will be easy to identify what are the possible injuries can be happened due to relevant chemicals.
- CH3Br - This is a highly toxic gas. Short time Inhaling CH3Br will severely damage lung. Long time exposure to CH3Br will lead to neurological effects in human body.
- NaOH - Very corrosive. Can irritate to the eyes, skin and mucous membranes. Can be allergic.
- CH3OH - Ingestion of methanol cause to series of health effects including death too.
- NaBr - Has very low toxicity.
In the preparation of aqueous NaOH solution, a large heat is released at the dissolving NaOH in water and temperature increases immediately. Be careful in this step to prevent any burnings due to high temperature.
Can this reaction be used to treat CH3Br in an effluent gas stream?
Yes. It is possible. But, you should have a proper method to manage methanol because it is also a very toxic chemical. However, methanol has a marketable value and can sell if proper methanol separation system is available to separate methanol from the mixture of water, methanol, NaBr and other constitutes.
