Chapter 22, Problem 74A

Interpretation Introduction

Interpretation:

The type of reaction or process in each step of the given multistep synthesis pathway needs to be explained.

Concept introduction:

Organic compounds undergo different types of chemical reactions depending on the functional groups present in them. For example, in the substitution reaction, one functional group in a reactant is replaced by other. In an addition reaction, one molecule simply combines to other to form a larger molecule. There is no side product formed in the reaction.

Explanation of Solution

The given synthesis pathway is as follows:

$\begin{array}{l}\text{Petroleum}\to \mathrm{ethane}\to chloroethane\to ethene\to \\ ethanol\to ethanoicacid\end{array}$

Ethane can be obtained from petroleum gas as a byproduct of petroleum refining. Ethane can be converted to chloroethane is an halogenations or chlorination reaction. Here, H atom in ethane is replaced by chlorine atom. Now, chloroethane can be converted to ethene via elimination reaction. This can take place in the pretence of a strong base.

Ethene to ethanol is a hydration reaction where addition of water takes place at double bond of the ethene which results in the formation of an alcohol or ethanol.

Ethanol to ethanoic acid is an oxidation reaction. Here, -CH₂OH group gets oxidized to form -COOH or carboxylic acid group. The reaction takes place in the presence of a cold acidified potassium manganate (VII) which is a strong oxidizing agent. Here, manganese gets reduced to IV oxidation state to form manganese oxide and oxidizes the − CH₂OH group.