Q.11

Electrophile among the following is

Options:

(A) NH₃

(B) SO₃

(C) NO₂

(D) CH≡C⁻

Introduction

In organic chemistry, identifying whether a species is an electrophile or a nucleophile is a fundamental concept and a frequent exam question. An electrophile is an electron-deficient species that accepts an electron pair. In this article, we analyze each given option to determine which one acts as an electrophile.

Key Concept

• Electrophile: Electron-deficient species, accepts electron pair

• Nucleophile: Electron-rich species, donates electron pair

Option-wise Explanation

Option (A): NH₃

• NH₃ has a lone pair of electrons on nitrogen.

• It donates electrons easily.

• Acts as a nucleophile, not an electrophile.

❌ Not correct

Option (B): SO₃

• Sulfur trioxide has an electron-deficient sulfur atom.

• It readily accepts electron pairs.

• Acts as a strong electrophile, especially in reactions like sulfonation.

✅ Correct Answer

Option (C): NO₂

• NO₂ is a neutral free radical.

• It is neither a strong electrophile nor a nucleophile.

• Only NO₂⁺ (nitronium ion) is an electrophile, not NO₂.

❌ Not correct

Option (D): CH≡C⁻

• This is an acetylide ion.

• Negatively charged and electron-rich.

• Strong nucleophile, not an electrophile.

❌ Not correct

✅ Correct Answer

Option (B) – SO₃

Summary Table

Final Conclusion

Among the given species, SO₃ is the only one that is electron-deficient and capable of accepting an electron pair, making it a true electrophile.

^{Correct Answer: Option (B) – SO₃}