JEE Challenger
More from Alcohols, Phenols and Ethers
ChemMedAdv 2023 • Paper 1

Identification and Physiological Action of Product in Reaction Scheme

In the given reaction scheme, P\mathbf{P} is a phenyl alkyl ether, Q\mathbf{Q} is an aromatic compound; R\mathbf{R} and S\mathbf{S} are the major products.

P→HIQ→(ii) CO2(iii) H3O+(i) NaOHR→(ii) H3O+(i) (CH3CO)2OS\mathbf{P} \xrightarrow{\mathrm{HI}} \mathbf{Q} \xrightarrow[\substack{\text{(ii) }\mathrm{CO_2} \\ \text{(iii) }\mathrm{H_3O^+}}]{\text{(i) }\mathrm{NaOH}} \mathbf{R} \xrightarrow[\text{(ii) }\mathrm{H_3O^+}]{\text{(i) }\mathrm{(CH_3CO)_2O}} \mathbf{S}

The correct statement about S\mathbf{S} is

Options

A

It primarily inhibits noradrenaline degrading enzymes.

B

It inhibits the synthesis of prostaglandin.

Correct
C

It is a narcotic drug.

D

It is \textit{ortho}-acetylbenzoic acid.

Topics & Concepts

Alcohols, Phenols and EthersAlcohols and EthersChemistry in Everyday Life

Step-by-Step Solution

To determine the correct statement about compound S\mathbf{S}, let us analyze the reaction sequence step by step:

  1. Cleavage of Phenyl Alkyl Ether (P\mathbf{P}): When a phenyl alkyl ether (P\mathbf{P}, Ar-O-R\text{Ar-O-R}) is treated with HI\text{HI}, cleavage of the alkyl-oxygen bond occurs because the aryl-oxygen bond (Csp2-O\text{C}_{\text{sp}^2}\text{-O}) possesses partial double-bond character due to resonance. P (Ar-O-R)→HIQ (Phenol, C6H5OH)+R-I\mathbf{P} \ (\text{Ar-O-R}) \xrightarrow{\text{HI}} \mathbf{Q} \ (\text{Phenol, }\text{C}_6\text{H}_5\text{OH}) + \text{R-I} Hence, the aromatic compound Q\mathbf{Q} is phenol.

  2. Kolbe's Reaction of Phenol (Q\mathbf{Q}): Phenol reacts with sodium hydroxide (NaOH\text{NaOH}) to form sodium phenoxide, which undergoes electrophilic substitution with carbon dioxide (CO2\text{CO}_2) followed by acidification to yield salicylic acid as the major product: Q (C6H5OH)→(iii) H3O+(i) NaOH, (ii) CO2R (Salicylic acid, 2-hydroxybenzoic acid)\mathbf{Q} \ (\text{C}_6\text{H}_5\text{OH}) \xrightarrow[(iii)\ \text{H}_3\text{O}^+]{(i)\ \text{NaOH}, \ (ii)\ \text{CO}_2} \mathbf{R} \ (\text{Salicylic acid}, \ 2\text{-hydroxybenzoic acid}) Thus, R\mathbf{R} is salicylic acid (o-HO-C6H4-COOHo\text{-HO-C}_6\text{H}_4\text{-COOH}).

  3. Acetylation of Salicylic Acid (R\mathbf{R}): Treatment of salicylic acid with acetic anhydride in the presence of an acid catalyst results in the acetylation of the phenolic hydroxyl group: R (o-HO-C6H4-COOH)→(ii) H3O+(i) (CH3CO)2OS (2-acetoxybenzoic acid / Aspirin)\mathbf{R} \ (o\text{-HO-C}_6\text{H}_4\text{-COOH}) \xrightarrow[(ii)\ \text{H}_3\text{O}^+]{(i)\ (\text{CH}_3\text{CO})_2\text{O}} \mathbf{S} \ (2\text{-acetoxybenzoic acid / Aspirin}) Therefore, compound S\mathbf{S} is aspirin (2-acetoxybenzoic acid2\text{-acetoxybenzoic acid}, o-CH3COO-C6H4-COOHo\text{-CH}_3\text{COO-C}_6\text{H}_4\text{-COOH}).

  4. Physiological Action and Properties of Aspirin (S\mathbf{S}):

    • Aspirin is a non-narcotic (non-addictive) analgesic and antipyretic drug.
    • It functions by inhibiting the cyclooxygenase (COX) enzymes, which are responsible for the synthesis of prostaglandins. Prostaglandins stimulate inflammation in tissues and cause pain and fever.
    • Aspirin is 2-acetoxybenzoic acid2\text{-acetoxybenzoic acid}, not ortho-acetylbenzoic acidortho\text{-acetylbenzoic acid}.

Thus, statement B is correct: It inhibits the synthesis of prostaglandin.

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