Question

Match the following aromatic compounds with the alkanes that underwent aromatisation to form these.

• A. ${\mathrm{CH}}_3({\mathrm{CH}}_2{)}_5{\mathrm{CH}}_3$
• B. ${\mathrm{CH}}_3({\mathrm{CH}}_2{)}_6{\mathrm{CH}}_3$
• C. ${\mathrm{CH}}_3({\mathrm{CH}}_2{)}_4{\mathrm{CH}}_3$

Answer 1

Alkanes with six or more C atoms, when heated under pressure in the presence of a catalyst (${\mathrm{Al}}_2{O}_3\mathrm{or}{\mathrm{Cr}}_2{O}_3$), S, Se, Pt, or Pd at $600°C$, first cyclise and then aromatize to give benzene or its derivative by dehydrogenation.

• n-hexane is converted to benzene ring during aromatisation reaction.
• For a seven carbon or eight carbon chain, six are involved to form the benzene ring (aromatic) and the

${\mathrm{CH}}_3\mathrm{and}{\mathrm{CH}}_2{\mathrm{CH}}_3$ groups act as the substituents resepectively.