The Electrophilic Reaction of NBS with Substituted Benzene and its Application

Toluene with different substituted group was selected to react with NBS under diffent conditions. The factors that effect reaction including the polarity of solvent, the electron effect of substituteed group and reaction temperature were discussed. The results indicated that the regioselectivity of substitutent reaction depend greatly on reaction solvent and the electronic effect of substitutent group. It is shown that the electro-phic substitution of benzene ring is favored in more polar solvents and for compounds with strong electron-donating groups. Otherwise, the free radical reaction in theα-site was favorable. On the base of the results, a new synthetic route of brominated Q0 was reported. The method was more favorable for the preparation of Q0, and the yield was above 86% .