Chlorination of benzene in the presence of iron (III) chloride involves mechanism of:
Correct answer: B. Electrophilic substitution
- A. Electrophilic addition
- B. Electrophilic substitution
- C. Free radical substitution
- D. Free radical halogenation
Explanation
Iron three chloride acts as a halogen carrier, polarising the chlorine molecule to generate an electrophile that attacks the electron rich ring, and a hydrogen is then lost so the aromatic system is preserved. Substitution rather than addition is what keeps the delocalised sextet intact. In ultraviolet light and without the catalyst, benzene undergoes free radical addition instead, which is why the conditions matter.
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About Benzene and Aromatic Compounds
Benzene has a planar ring of delocalised π electrons, giving aromatic stability and equal carbon-carbon bond lengths. The topic covers resonance, electrophilic substitution reactions such as nitration, halogenation, sulphonation and Friedel-Crafts reactions, along with substituent effects and the distinction between substitution in benzene and addition in ordinary alkenes.
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