When 3,5-dimethoxy-toluene reacted with N-bromosuccinimide (NBS) in the presence of azobisisobutyronitrile, the product was not 3,5-dimethoxy benzylbromide, but a mixture of 2-bromo-3,5-dimethoxy-toluene and 2,6-dibromo-3,5- dimethoxy-toluene. Under the same conditions, 3,5-diacetoxy-toluene reacted with NBS to generate 3,5-diacetoxy-benzyl bromide. The charge density distributions calculated by GAUSSIAN 03 indicated that the charge density of carbon atom of benzene ring in 3,5-dimethoxy-toluene was higher than the one of the carbon atom of the side chain. Thus, bromine radical was easy to replace the hydrogen in the ring. While the charge density distributions of 3,5-diacetoxy toluene was quite the opposite, hence, the product was 3,5-diacetoxy-benzyl bromide.