Question

How do you get ethanoic acid from ethyne gas?

Answer 1

Hint: To obtain ethanoic acid from ethyne gas, total three steps are involved. In the first step alcohol is formed which is further oxidized using the oxidizing agent to form ethanoic acid. The ethanoic acid is also known as acetic acid.

Complete step by step answer:
The ethyne is the chemical compound containing triple bond. The chemical formula of ethyne is ${C_2}{H_2}$.
The compound ethyne is when reacted with water in presence of mercury ion, it yields vinyl alcohol which is the simplest enol and the chemical formula of vinyl alcohol is $C{H_2}CHOH$.
The reaction between the ethyne with water in presence of mercury ion is shown below.
${C_2}{H_2} + {H_2}O\xrightarrow{{H{g^{2 + }}}}C{H_2}CHOH$
Next, the vinyl alcohol undergoes tautomerism to form acetaldehyde.
Tautomerism is defined as the phenomenon where a single chemical compound exists in two or more structures which cannot be converted. The two compounds are different in terms of the relative position of one atomic nucleus which is generally the hydrogen atom. The two structures are called tautomers and these types of isomer compounds are different from each other only in the number of electrons and protons.
$C{H_2}CHOH \to C{H_3}CHO$
The acetaldehyde is then oxidized using potassium dichromate in presence of sulfuric acid to form ethanoic acid.
The reaction for the conversion of acetaldehyde into ethanoic acid is shown below.
\[3C{H_3}CHO + {K_2}C{r_2}{O_7} + 4{H_2}S{O_4} \to 3C{H_3}COOH + {K_2}S{O_4} + C{r_2}{(S{O_4})_3} + 4{H_2}O\]
In this reaction, three mole of acetaldehyde reacts with one mole of potassium dichromate and four mole of sulfuric acid to form three mole of ethanoic acid, one mole of potassium sulfate, one mole of chromium sulfate and four mole of water.

Note: The enol group can be determined where the OH is bonded with the carbon- carbon double bond. Whenever this exists in a structure, the compound is surely enol.