Organic Chemistry — Question 6

(a) Ethanol under high pressure and low temperature when treated with oxidising agent like acidified potassium dichromate produces ethanoic acid (acetic acid).

$\underset{ \text{ ethanol[ethyl alcohol]}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanal [acetaldehyde] }}{\text{CH}_3\text{CHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{ \text{ethanoic acid[acetic acid]} }{\text{CH}_3\text{COOH}}$

(b) Acetylene is first converted to acetaldehyde by passing it through a 40 percent H₂SO₄ solution at 60°C in the presence of 1% Mercury(II) Sulphate [HgSO₄].

$\underset{\text{acetylene}}{\text{C}_2\text{H}_2} + \text{H}_2\text{O} \xrightarrow{\text{H}_2\text{SO}_4\text{(dil) , HgSO}_4}\underset{\text{ethanal [acetaldehyde] }}{\text{CH}_3\text{CHO}}$

The acetaldehyde is oxidised to acetic acid by passsing a mixture of acetaldehyde vapous and air over manganese acetate at 70°C

$\underset{\text{ethanal [acetaldehyde] }}{2\text{CH}_3\text{CHO}} + \text{O}_2 \xrightarrow[\text{Catalyst}]{\Delta} \underset{ \text{ethanoic acid[acetic acid]} }{2\text{CH}_3\text{COOH}}$