Aromatic Hydrocarbons and Benzene Structure Quiz

Benzene Molecular Formula and Properties

• Molecular formula of benzene is C6H6.
• Benzene readily undergoes electrophilic aromatic substitution reactions.
• Common product of mono-substitution in benzene is substituted benzene (e.g., toluene from methyl substitution).

Reactions Involving Benzene

• When treated with KMnO4/H2O, benzene undergoes oxidation, leading to formation of benzoic acid.
• Benzene is considered a resonance-stabilized molecule in the Kekulé structure.
• Substitution reactions typically involve replacing hydrogen atoms on the benzene ring.

Specific Substitution Reactions

• Acylation involves substitution of an acyl group for a hydrogen atom on a benzene ring, leading to ketone formation.
• The heat of hydrogenation for benzene is lower compared to cyclohexatriene, indicating greater stability in benzene due to resonance.

Aromaticity and Huckel Rule

• Aromatic properties of benzene arise from resonance stabilization and delocalized π electrons.
• Benzene uses sp² hybrid orbitals for bonding, with each carbon atom bonded to two other carbon atoms and one hydrogen atom.
• According to Huckel's rule, for a molecule to be aromatic, 4n+2 π electrons must be present, where n is a non-negative integer.

Aromatic Compounds and Nomenclature

• Compounds not satisfying Huckel's rule (e.g., cyclobutadiene) are considered non-aromatic.
• The compound (CH3)2CHC6H5 is referred to as cumene in benzene derivative nomenclature.
• Alkyl group substitution for a hydrogen atom occurs in alkylation reactions on benzene.

Bond Length Comparisons

• The intermediate carbon-carbon bond length in benzene is approximately equal, and shorter than that of ethylene, but longer than that of ethane, reflecting its resonance structure.