Question

How can the following changes be done? (Give chemical equations only) (i) Propan-1-ol from ethyl magnesium chloride:

Hint:

Grignard reagents are used to form alcohols from carbonyl compounds, and dehydration of alcohols typically produces alkenes.

Answer 1

Propan-1-ol can be prepared from ethyl magnesium chloride (a Grignard reagent) by reacting it with formaldehyde (H\(_2\)C=O) followed by hydrolysis: \[ \text{C}_2\text{H}_5\text{MgCl} + \text{H}_2\text{C=O} \xrightarrow{\text{H}_2\text{O}} \text{C}_3\text{H}_7\text{OH} \]
(ii) 2-methyl propan-2-ol from methyl magnesium bromide: % Solution
Solution:
2-methyl propan-2-ol can be synthesized from methyl magnesium bromide by reacting it with acetone (CH\(_3\)COCH\(_3\)) followed by hydrolysis: \[ \text{CH}_3\text{MgBr} + \text{CH}_3\text{COCH}_3 \xrightarrow{\text{H}_2\text{O}} \text{(CH}_3\text{)_3}\text{COH} \]
(iii) Benzoic acid from benzyl alcohol: % Solution
Solution:
Benzoic acid can be prepared from benzyl alcohol by oxidation with potassium permanganate (KMnO\(_4\)): \[ \text{C}_6\text{H}_5\text{CH}_2\text{OH} + [O] \xrightarrow{\text{KMnO}_4} \text{C}_6\text{H}_5\text{COOH} \]
(iv) Picric acid from phenol: % Solution
Solution:
Picric acid (2,4,6-trinitrophenol) is obtained by nitration of phenol with a mixture of concentrated nitric and sulfuric acids: \[ \text{C}_6\text{H}_5\text{OH} + 3\text{HNO}_3 \rightarrow \text{C}_6\text{H}_2(\text{NO}_2)_3\text{OH} \]
(v) Dehydration of propan-2-ol: % Solution
Solution:
Dehydration of propan-2-ol (isopropanol) using concentrated sulfuric acid gives propene (C\(_3\)H\(_6\)): \[ \text{CH}_3\text{CH(OH)}\text{CH}_3 \xrightarrow{\text{H}_2\text{SO}_4} \text{CH}_2\text{CH}_2\text{CH}_3 + \text{H}_2\text{O} \]