Methanol and ethanol

Methanol, CH₃OH, was once obtained by destructive distillation of wood, hence 'wood spirit'. Today most of it comes from carbon monoxide and hydrogen combined over a ZnO–Cr₂O₃ catalyst at high temperature and pressure.

Methanol is a colourless liquid boiling at 337 K. It is highly poisonous: small amounts can cause blindness and larger amounts death. It is a solvent for paints and varnishes and is used chiefly to make formaldehyde.

Ethanol, C₂H₅OH, is made commercially by fermentation of sugars. The enzyme invertase turns the sugar of molasses, sugarcane or grapes into glucose and fructose, both C₆H₁₂O₆, and zymase from yeast ferments these to ethanol.

Fermentation is anaerobic (no air), and carbon dioxide is given off. Zymase stops working once the alcohol content passes 14 percent.

If air enters the fermenting mixture, oxygen oxidises ethanol to ethanoic acid, which spoils the taste of the drink.

Ethanol is a colourless liquid boiling at 351 K, used as a solvent in the paint industry and to make many carbon compounds. Large amounts are now also made by hydration of ethene.

Denaturation: commercial alcohol is made unfit to drink by adding a little copper sulphate (for colour) and pyridine (for a foul smell).

Taken in, ethanol acts on the central nervous system: moderate amounts impair judgement, larger amounts cause nausea and loss of consciousness, and still more can stop spontaneous breathing.