Question Details

Considering the following reaction sequence, the correct statement(s) is (are)



Options

A

Compounds P and Q are carboxylic acids

B

Compounds S decolorizes bromine water.

C

Compounds P and S react with hydroxylamine to give the corresponding oximes.

D

Compound R reacts with dialkylcadmium to give the corresponding tertiary alcohol.

Show Answer

Correct Answer :

Option A

Compounds P and Q are carboxylic acids

Option C

Compounds P and S react with hydroxylamine to give the corresponding oximes.

Solution :

The correct statement(s) are: Compounds P and Q are carboxylic acids and Compounds P and S react with hydroxylamine to give the corresponding oximes.


Let us analyze the step-by-step chemical transformations visible in the reaction sequence image:


Step 1: Formation of Compound P
Benzene reacts with succinic anhydride in the presence of anhydrous AlCl3 (Friedel-Crafts acylation). The succinic anhydride ring opens to form a keto-acid compound:
Compound P: C6H5-C(=O)-CH2-CH2-COOH (3-benzoylpropanoic acid).
Compound P contains both a carbonyl ketone group (-C(=O)-) and a carboxylic acid group (-COOH).


Step 2: Formation of Compound Q
Compound P undergoes Clemmensen reduction using amalgam zinc and concentrated hydrochloric acid (Zn/Hg, HCl). The carbonyl group (>C=O) is reduced to a methylene group (>CH2), while the carboxylic acid group remains unchanged:
Compound Q: C6H5-CH2-CH2-CH2-COOH (4-phenylbutanoic acid).
Hence, both P and Q contain terminal -COOH groups and are carboxylic acids.


Step 3: Formation of Compound R
Reaction of 4-phenylbutanoic acid (Q) with thionyl chloride (SOCl2) converts the carboxylic acid into an acyl chloride:
Compound R: C6H5-CH2-CH2-CH2-COCl (4-phenylbutanoyl chloride).


Step 4: Formation of Compound S
Treatment of acyl chloride (R) with anhydrous AlCl3 undergoes intramolecular Friedel-Crafts acylation to form a cyclic ketone:
Compound S: α-Tetralone (1-tetralone), which contains a carbonyl keto group (>C=O) fused to the benzene ring.


Now let us evaluate each statement option:

1. Compounds P and Q are carboxylic acids:
As derived, Compound P (3-benzoylpropanoic acid) and Compound Q (4-phenylbutanoic acid) both contain carboxylic acid functionality. (Correct)


2. Compounds P and S react with hydroxylamine to give the corresponding oximes:
Both Compound P and Compound S contain carbonyl keto groups (>C=O). Carbonyl compounds react readily with hydroxylamine (NH2OH) to form oximes (>C=N-OH). (Correct)


3. Compound S decolorizes bromine water:
Compound S (α-tetralone) is a saturated cyclic ketone fused to an aromatic ring. It does not have non-aromatic carbon-carbon double or triple bonds to undergo addition reaction with bromine water. Thus, it does not decolorize bromine water. (Incorrect)


4. Compound R reacts with dialkylcadmium to give the corresponding tertiary alcohol:
Dialkylcadmium (R2Cd) reacts with acyl chlorides (like Compound R) to give ketones, not tertiary alcohols, because dialkylcadmium is not nucleophilic enough to react further with the resulting ketone. (Incorrect)

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