See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Each Reaction **Option (A): Triose to aldose rearrangement** Glyceraldehyde ($CH_3CHOHCHO$) under basic conditions ($OH^-$) undergoes enediol rearrangement to form dihydroxyacetone ($CH_3-CO-CH_2OH$). This is a **correct** aldose-ketose isomerization. **Option (B): Ethylbenzene side-chain cleavage** $$\text{Benzene-CH}_2\text{CH}_3 \xrightarrow{a^+} \text{Benzene-CH}^+ + \text{CH}_3 + HCl$$ This reaction is **incorrect** for two reasons: 1. **Excessive bond breaking**: The reaction shows breaking of the C–C bond in the ethyl chain AND the C–H bond simultaneously, which is unrealistic. 2. **Improper product**: Formation of a benzyl carbocation ($\text{C}_6\text{H}_5\text{CH}^+$) with loss of a methyl radical and HCl violates stoichiometry and mechanism. 3. **Reality**: Ethylbenzene with acidic catalyst undergoes isomerization to cumene or oxidation, not this fragmentation. **Option (C): Ester formation via carbonyl rearrangement** The nucleophilic acyl substitution mechanism shown (with protonation, nucleophile attack, and tetrahedral intermediate formation) is **correct** for esterification. **Option (D): Hydride shift rearrangement** The 2,2-dimethylpropyl carbocation rearranges via hydride shift to the more stable tert-butyl carbocation. This is a **correct** carbocation rearrangement (1° → 3°). **Answer: Option (B)** shows an incorrect reaction with improper bond cleavage and unrealistic products.