Question

Draw the major organic product of the below reaction. Do not draw inorganic side products. H3C Br2 CH3 FeBr3

Answer 1

94 C H H, C Fe Bv Major Podut Possible Resonanca StrucHures CH 3 1 1l 4S Hye

Explanation: Bromination of an aryl ring in the presence of a Lewis acid (Here, it is FeBr3) is directed mainly by the substituents present in it. In this case, we have a methyl group and an acyl group in a benzene ring that are para to one another. The attacking position of the electrophile is directed by the strong deactivating group i.e. the acyl group. Hence, the incoming electrophile has only two relatively electron rich carbons in the benzene ring to attack which are ortho to the methyl group and meta to the acyl group. Since the ring is deactivated by the acyl substituent despite having an activating methyl group, the first bromination step would be slower than the subsequent one. In this reaction, the exact amount of Br2 added is not specified. Hence, a possible major product is 3,5-dibromo-4-methylacetophenone.