Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub
Find number of compound which can show Tautomerism :
Answer:
Solution:
Question Explanation:
The question asks to determine how many of the given compounds are capable of exhibiting tautomerism.
Concept:
This question is based on the structural requirements for tautomerism (mainly keto-enol or nitro-aci tautomerism).
Solution: For tautomerism to occur, the molecule must satisfy:
Presence of at least one α-hydrogen on an sp3 carbon adjacent to an electron-withdrawing group
such as –C=O, –NO2, –CN, etc.
The structure must allow proton migration and double-bond shift.
In conjugated (α,β-unsaturated) systems, γ-hydrogens may also participate through vinylogy.
Compounds lacking α-hydrogen adjacent to the functional group do not show tautomerism.
Among the eight given compounds, seven (1 to 7) possess at least one acidic α-hydrogen (or equivalent
hydrogen in a conjugated system) that enables tautomerism.
The circled carbon atoms contain enolisable (α- or γ-) hydrogen atoms, which can undergo tautomerism under suitable acidic or basic conditions.
One compound lacks the necessary α-hydrogen and therefore cannot undergo tautomerism.