Sciencemadness Discussion Board

Preparation of methanol by electrolysis

Heptylene - 15-8-2018 at 04:28

I thought I would share this gem I found on youtube (french).

This guy made methanol in 24 % yield from acetic acid and sodium hydroxide in water by electrolysis with carbon electrodes. This is known apparently as Hofer-Moest electrolysis. The video is in french but the translated subtitles are helpful. In any case here's an outline of the interesting bit, starting at 11:00 :

To a vacuum filtration flask there was added 34 g sodium hydroxide, water and 50 ml of 80 % v/v acetic acid. A tube was connected to the gas outlet to evacute the gasses generated (hydrogen) and carbon electrodes were placed through the neck of the flask. Some carbon dioxide is produced and absorbed the sodium hydroxide.

Time of electrolysis: 4 days at 6 volts and 2 amps. The electrolysis was considered done when the current dropped.

The liquid from the electrolysis cell was fractionated to yield methanol coming over at 65-70°C. This represents a yield of 24 % based on acetic acid. This fraction was analyzed by IR spectroscopy and found to be relatively pure methanol.

Of course he could have started from sodium acetate instead of neutralizing acetic acid.

I haven't done any further research because I am not particularly interested in making methanol from scratch. I can buy relatively easily. But I think this might be useful to some people who can't get methanol.

[Edited on 15-8-2018 by Heptylene]

Sulaiman - 15-8-2018 at 05:11

An unusual direction for synthesis,
normally acetic acid is manufactured by the carbonylation of methanol

For us amateurs I guess that methanol can be obtained by distilling fermented fruits ?
Or by the original destructive distillation of wood route ?