What you’ll learn4 learning objectivesChoose one objective for a focused lesson, or study the complete topic.30.1.1Chemistry of arenes• Describe the chemistry of arenes as exemplified by the following reactions of benzene and methylbenzene:- (a) substitution reactions with Cl ₂ and with Br₂ with a catalyst, Al Cl ₃ or Al Br₃, to form halogenoarenes (aryl halides)- (b) nitration with a mixture of conc. HNO₃ and conc. H₂SO₄ at a temperature between- 25 °C and 60 °C- (c) Friedel–Crafts alkylation by CH₃Cl and Al Cl ₃ and heat- (d) Friedel–Crafts acylation by CH₃COCl and Al Cl ₃ and heat- (e) complete oxidation of the side-chain using hot alkaline KMnO₄ and then dil. acid to give a benzoic acid- (f) hydrogenation of the benzene ring using H₂ and Pt/Ni catalyst and heat to form a cyclohexane ringSyllabus objective30.1.2Mechanism: electrophilic substitution in arenes• Describe the mechanism of electrophilic substitution in arenes:- (a) as exemplified by the formation of nitrobenzene and bromobenzene- (b) with regards to the effect of delocalisation (aromatic stabilisation) of electrons in arenes to explain the predomination of substitution over additionSyllabus objective30.1.3Whether halogenation will occur• Predict whether halogenation will occur in the side-chain or in the aromatic ring in arenes depending on reaction conditionsSyllabus objective30.1.4In the electrophilic substitution of arenes,• Describe that in the electrophilic substitution of arenes, different substituents direct to different ring positions (limited to the directing effects of –NH₂, –OH, –R, –NO₂, –COOH and –COR)Syllabus objective