Furan undergoes electrophilic aromatic substitution more readily than benzene; mild reag...

Furan undergoes electrophilic aromatic substitution more readily than benzene; mild reagents and conditions are sufficient. For example, furan reacts with bromine to give 2-bromofuran.

(a) Propose mechanisms for the bromination of furan at the 2-position and at the 3-position. Draw the resonance forms of each sigma complex, and compare their stabilities.

(b) Explain why furan undergoes bromination (and other electrophilic aromatic

substitutions) primarily at the 2-position.