Question

Suitable reagent(s) to bring about the conversion of P to Q in good yield is/are 

• A.
• B.
• C.
• D.

Hint:

Friedel–Crafts alkylation is an essential reaction in organic chemistry for adding alkyl groups to aromatic compounds. When working with more reactive intermediates, additional reagents like hydrazines and bases help to refine the final product.

Answer 1

The Correct Option is B, D

The conversion shown in the problem involves the transformation of a benzene ring (P) into an alkylated benzene (Q). Let’s look at the details of the options and the reactions they represent:
1. Option (A) – \( \text{Cl} \), \( \text{AlCl}_3 \):
- This reaction is likely a Friedel–Crafts alkylation reaction, where \( \text{Cl} \) represents a chloroalkyl group. In this case, the alkyl group reacts with the benzene ring in the presence of the Lewis acid catalyst \( \text{AlCl}_3 \). However, this method generally does not lead to a successful conversion in the required yield as it would typically produce a more substituted product.
2. Option (B) – \( \text{Cl} \), \( \text{AlCl}_3 \), followed by \( \text{H}_2 \text{NNH}_2 \), \( \text{KOH} \):
- In this case, \( \text{Cl} \) and \( \text{AlCl}_3 \) initiate the alkylation of the benzene ring, but the subsequent use of \( \text{H}_2 \text{NNH}_2 \) and \( \text{KOH} \) suggests a reduction and further rearrangement leading to the final desired product, making this a good choice for the conversion. The product achieved here is the desired alkylated benzene with a good yield.
3. Option (C) – \( \text{C}_3 \text{H}_2 \), \( \text{HF} \):
- This reaction is highly unlikely, as it suggests the addition of an alkynyl group (\( \text{C}_3 \text{H}_2 \)) with \( \text{HF} \), but this does not lead to the proper alkylation of the benzene ring and is not a typical reagent combination for this conversion.
4. Option (D) – \( \text{C}_2 \text{O}_2 \), \( \text{AlCl}_3 \), and \( \text{Zn(Hg)}, \text{HCl} \):
- This represents a typical Wolff–Löffler reduction of an aldehyde to an alkyl group, where the intermediate group is reduced by zinc in acid. This method also leads to the formation of the desired alkylated product. Therefore, this is another correct reagent combination.
Thus, the best reagents for the conversion of \( P \) to \( Q \) are found in options (B) and (D).