See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Tautomerism Analysis **Understanding Tautomerism:** Tautomerism is a special case of isomerism where two structural isomers (tautomers) rapidly interconvert through migration of a hydrogen atom and rearrangement of double bonds. The most common type is **keto-enol tautomerism**. **Evaluating Each Option:** **(A) $(CH_3)_3CNO$** ✓ - Exists as two tautomers: - **Keto form:** $(CH_3)_3C-N=O$ (isocyanate) - **Enol form:** $(CH_3)_3C-O-N$ (N-oxide structure with rearrangement) - The N-O group readily undergoes H-migration and bond rearrangement - **Exhibits clear tautomerism** **(B) $(CH_3)_2NH$** - Simple amine with no mobile hydrogen on unsaturated systems - No keto-enol type equilibrium possible - No tautomerism **(C) $R_3CNO_2$** - Nitro compound (C-NO₂ bond is very stable) - Cannot undergo tautomeric shift - No enol or alternate form **(D) $RCH_2NO_2$** - Primary nitro compound - Nitro group is stable; only acidic H is on the methylene carbon - Cannot exhibit typical tautomerism (would require unrealistic rearrangement) **Answer: (A)** because $(CH_3)_3CNO$ readily exhibits keto-enol tautomerism between its isocyanate and amine oxide forms.