Question

How do you get ethanoic acid from ethyne gas?

Answer 1

Hydrated Ethyne`(H_2C_2)` is first converted to vinyl alcohol and tautomerises to form acetaldehyde.This type of tautomerization is keto-enol tautomerization .

`"What is tautomerization?"`

Keto-enol tautomerization involves the interconversion of the two forms that involves the movement of an alpha hydrogen.

You can refer to this video

Iken Edu(source)

When ethyne is reacted with water in presence of `Hg^2+` salt vinyl alcohol is formed and then it tautamerizes to form acetaldehyde

`C_2H_2 + Hg^(2+) + H_2O → (CH_2CHOH rarr CH_3CHO + Hg)`

The enol is vinyl alcohol which is being converted to keto acetaldehyde. You can determine the keto and enol by looking at the structure of the compound. For example we can etermine that vinyl alcohol is enol because the O-H is bonded with C wich is further double bonded(=) with C. Whenever you see a structure like that you should be sure that its an enol

When acetaldehyde is produced the acetaldehyde is oxidized to form acetic or ethanoic acid.

`3CH_3CHO + K_2Cr_2O_7 + 4H_2SO_4 = 3CH_3COOH + K_2SO_4 + Cr_2(SO_4)_3 + 4H_2O`