Question

From the given option, which structure exhibits tautomerism?

• A. ${\left(C{H}_3\right)}_{2}NH$
• B. ${\left(C{H}_3\right)}_{3}CNO$
• C. $R_{3}CN{O}_2$
• D. $RC{H}_{2}N{O}_2$

Answer 1

The correct option is D

$RC{H}_{2}N{O}_2$

Explanation for the correct answer:

Option (D) $RC{H}_{2}N{O}_2$

• Tautomerism is a phenomenon where a single chemical compound tends to exist in two or more interconvertible structures.
• There is a condition for this tautomerism that is, there should be an alpha-hydrogen attached to the ${\mathrm{sp}}^3$ hybridized carbon atom.
• In this given option we have $RC{H}_{2}N{O}_2$with the structure:

• And here we can see that there are 2 alpha hydrogen attached to the carbon atom which is ${\mathrm{sp}}^3$ hybridized.
• Thus, tautomerism can be shown as:

• Hence it is the correct option.

Explanation for the incorrect answer:-

Option (C) $R_{3}CN{O}_2$

• In this compound there is no alpha hydrogen attached to the carbon atom:

• Thus this compound will not undergo tautomerism.
• Hence it is the incorrect option.

Option (B) ${\left(C{H}_3\right)}_{3}CNO$

• In this compound also there is no alpha hydrogen attached to the carbon atom:

• Thus this compound will not undergo tautomerism.
• Hence it is the incorrect option.

Option (A) ${\left(C{H}_3\right)}_{2}NH$

• In this compound also there is alpha hydrogen attached to the carbon atom with respect to Nitrogen:

• But there is no double bond present in this compound.
• Thus this compound will not undergo tautomerism.
• Hence it is the incorrect option.

Hence option D is the correct answer.