EAS2 Flashcards
What type of reaction does benzene primarily undergo?
Benzene undergoes electrophilic substitution reactions, where an electrophile replaces a hydrogen atom on the ring.
What is the general mechanism of electrophilic substitution in benzene?
- Formation of the electrophile. 2. Attack of the electrophile on the benzene ring, forming a carbocation intermediate. 3. Loss of a proton to restore aromaticity.
What are the reagents used in the nitration of benzene?
Nitric acid (HNO₃) and sulfuric acid (H₂SO₄).
What is the electrophile in the nitration of benzene?
The nitronium ion (NO₂⁺).
What reagents are needed for the halogenation of benzene?
Halogen (X₂) and a Lewis acid catalyst like FeCl₃ or AlCl₃.
What is the electrophile in the halogenation of benzene?
The halonium ion (X⁺), such as Cl⁺ or Br⁺.
What reagents are used in the sulfonation of benzene?
Fuming sulfuric acid (H₂SO₄ containing SO₃).
What is the electrophile in the sulfonation of benzene?
Sulfur trioxide (SO₃).
What are the reagents for Friedel-Crafts alkylation?
An alkyl halide (R–X) and a Lewis acid catalyst (AlCl₃).
What is the electrophile in Friedel-Crafts alkylation?
A carbocation (R⁺) formed from the alkyl halide and AlCl₃.
What are the reagents for Friedel-Crafts acylation?
An acyl chloride (R–COCl) and a Lewis acid catalyst (AlCl₃).
What is the electrophile in Friedel-Crafts acylation?
The acylium ion (R–C⁺=O).
What is the product of Friedel-Crafts acylation?
A ketone attached to the benzene ring (C₆H₅COR).
Why does Friedel-Crafts acylation avoid carbocation rearrangements?
The acylium ion is stable and does not rearrange like a carbocation.
What effect do electron-donating groups (EDGs) have on electrophilic substitution reactions?
EDGs activate the benzene ring and are ortho/para-directing.
