Synthetic Routes - Aromatic Compounds

AQA A-level ChemistryOrganic SynthesisLesson 3 of 6

Aromatic compounds contain a benzene ring. Benzene's delocalised ring is very stable, so it reacts by electrophilic substitution, which keeps the ring intact. For AQA, two reactions of benzene start almost every aromatic route.

1. Nitration: concentrated HNO₃ and concentrated H₂SO₄, at about 50 °C. The acids form the nitronium ion, NO₂⁺, which substitutes for an H on the ring to give nitrobenzene, C₆H₅NO₂. Keeping the temperature low limits further nitration.

2. Friedel-Crafts acylation: an acyl chloride with an AlCl₃ catalyst, heated under reflux. The electrophile RCO⁺ substitutes onto the ring to give a phenyl ketone, C₆H₅COR. This is how a new C-C bond is made to the ring.

More in Organic Synthesis

• Organic Synthesis
• Synthetic Routes - Aliphatic Compounds
• Reaction Conditions and Reagents
• Designing Multi-Step Syntheses
• Reducing Steps and Hazardous Solvents

All 6 lessons in Organic Synthesis · All AQA A-level Chemistry topics