Question

Set(s) of reagents that convert(s) benzoyl chloride to aniline is/are

• A. (i) NH$_3$; (ii) Br$_2$, NaOH; (iii) H$_2$O
• B. (i) CH$_2$N$_2$; (ii) H$_2$O
• C. (i) NaN$_3$; (ii) H$_2$O
• D. (i) NH$_2$OH; (ii) TsCl, Pyridine; (iii) NaOH, $\Delta$; (iv) H$_2$O

Hint:

Hofmann, Curtius and Beckmann rearrangements are key reactions to convert carbonyl compounds into amines with one carbon less

Answer 1

The Correct Option is A, C, D

Step 1: Target transformation.
We need to convert benzoyl chloride (C$_6$H$_5$COCl) to aniline (C$_6$H$_5$NH$_2$)This requires removal of the carbonyl carbon (loss of one carbon)

Step 2: Analyze option (A).
NH$_3$ converts benzoyl chloride to benzamideThen Br$_2$/NaOH (Hofmann bromamide reaction) converts amide to amine with loss of CO
\[ \text{C}_6\text{H}_5\text{CONH}_2 \xrightarrow{\text{Br}_2/\text{NaOH}} \text{C}_6\text{H}_5\text{NH}_2 \]
Thus, (A) is correct

Step 3: Analyze option (B).
CH$_2$N$_2$ converts acid chlorides to diazoketones and further to acids or estersIt does not lead to anilineThus, (B) is incorrect

Step 4: Analyze option (C).
NaN$_3$ converts acid chloride to acyl azide, which on hydrolysis undergoes Curtius rearrangement
\[ \text{C}_6\text{H}_5\text{COCl} \rightarrow \text{C}_6\text{H}_5\text{CON}_3 \xrightarrow{\Delta} \text{C}_6\text{H}_5\text{NCO} \xrightarrow{\text{H}_2\text{O}} \text{C}_6\text{H}_5\text{NH}_2 \]
Thus, (C) is correct

Step 5: Analyze option (D).
NH$_2$OH forms oxime, TsCl converts it into a good leaving groupUnder basic heating, Beckmann rearrangement followed by hydrolysis gives anilineThus, (D) is correct

Step 6: Key concept.
All valid methods involve rearrangement reactions (Hofmann, Curtius, Beckmann) which reduce carbon chain length by one

Step 7: Conclusion.
\[ \boxed{\text{(A), (C) and (D)}} \]