Benzene and its reactions Flashcards
State the boiling point of Benzene and explain why it has a high boiling point
Boiling point= 80°C (liqiud at r.t.p). High boiling point is due to the strong id-id attraction because of the large contact area and large number of electrons in a Benzene molecule.
State the 6 reactions of Benzene
- Halogenation.
- Nitration.
- Friedel-Crafts alkylation.
- Friedel-Crafts acylation.
- Hydrogenation.
- Complete/Incomplete combustion.
Halogenation of Benzene (REAGENTS, CATALYSTS, CONDITIONS)
Reactants= Benzene + Cl₂/ Br₂/ I₂.
Catalyst= Anhydrous Halogen carrier (AlCl₃/ AlBr₃/ AlI₃).
Conditions= No other conditions.
Halogenation of Benzene (EXAMPLE)
Benzene + Cl₂ —> Chlorobenzene + HCl(g)
Nitration of Benzne (REAGENTS, CATALYSTS, CONDITIONS)
Reactants= Benzene + concentrated HNO₃.
Catalyst= concentrated H₂SO₄.
(concentrated HNO₃ + concentrated H₂SO₄= NITRATING MIXTURE)
Conditions= 25-60°C.
Nitration of Benzene (EXAMPLE)
Benzene + conc.HNO₃ —> Nitrobenzene + H₃O⁺(aq)
Friedel-Crafts alkylation (REAGENTS, CATALYSTS, CONDITIONS)
Reactants= Benzene + Halogenoalkane.
Catalyst= Anhydrous Halogen carrier.
Conditions= Heat.
Friedel-Crafts alkylation (EXAMPLE)
CH₃CH₂Br + Benzene —> Ethylbenzene + HBr(g)
Friedel-Crafts acylation (REAGENTS, CATALYSTS, CONDITIONS)
Reactants= Benzene + Acyl chloride.
Catalyst= Anhydrous AlCl₃.
Conditions= Heat.
Friedel-Crafts acylation (EXAMPLE)
Benzene + Acyl chloride —> Phenylethanone + HCl(g)
Hydrogenation of Benzene (REAGENTS, CATALYSTS, CONDITIONS)
Reactants= Benzene and Hydrogen gas.
Catalyst= Pt/Ni.
Conditions= Heat.
Hydrogenation (EXAMPLE)
Benzene + 3H₂ —> Cyclohexane.
(π system lost)
Electrophilic substitution mechanism steps
- Formation of electrophile.
- Attack of electrophile (π system broken).
- Reformation of π system.
