How are methanol and ethanol obtained commercially? Give two uses of each, and explain denaturation of alcohol.

How to lay out the answer. Follow the frame, then write it in your own words.

1 · Methanol manufacture. CO + 2H₂ → CH₃OH, with ZnO-Cr₂O₃ at 573 to 673 K and 200 to 300 atm.
2 · Ethanol by fermentation.
- C₁₂H₂₂O₁₁ + H₂O → C₆H₁₂O₆ + C₆H₁₂O₆ (invertase)
- C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ (zymase, from yeast), without air (anaerobic)
3 · Uses. Methanol: solvent for paints and varnishes; making methanal. Ethanol: solvent in the paint industry; raw material for many carbon compounds.
4 · Denaturation. Add copper sulphate and pyridine to make ethanol unfit to drink.
5 · Danger of methanol. Oxidised in the body to methanal and methanoic acid: blindness or death.
6 · Link to real life. Spurious liquor deaths in India are usually methanol poisoning.
7 · Close in one line. So methanol is a useful industrial chemical but must never be drunk.

Scoring tip: Name both enzymes and their source (yeast); the enzyme names carry marks.