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3.4.4—Electrophiles

Syllabus
First assessment 2025
Objective
3.4.4
Level
SL

Recognizing Electrophiles

An electrophile is an electron-deficient species that accepts an electron pair from a nucleophile.

Identify the electron-poor atom, not merely a positive-looking formula. H⁺ and carbocations are electrophiles, and the δ⁺ carbon in a polar C–X bond can also accept a pair. The incoming curly arrow ends at this acceptor.

Recognizing Electrophiles

Assessment in practice

Representative question

Question 1

[Maximum number: 1]

Which species is the electrophile?

CH3Br+OH−→CH3OH+Br−\mathrm{CH}_{3} \mathrm{Br}+\mathrm{OH}^{-} \rightarrow \mathrm{CH}_{3} \mathrm{OH}+\mathrm{Br}^{-}
A

OH−\mathrm{OH}^{-}

B

Br−\mathrm{Br}^{-} c. CH3OH\mathrm{CH}_{3} \mathrm{OH} D. CH3Br\mathrm{CH}_{3} \mathrm{Br}

Electron-Pair Sharing Summary

Retrieve the route: classify nucleophiles and electrophiles, show heterolysis, write substitution and addition mechanisms, map Lewis coordination, compare SN1/SN2, and restore aromaticity in benzene substitution.

Check electron-pair arrow origin and destination, leaving-group departure, intermediate identity, carbocation stability and the assessed mechanism boundary.