nucleophilic aromatic substitution of both chlorines is possible but leads to a compound withthe wrong molecular formula (C6H7N3O2).To obtain a fnal product with the correct molecular formula, the original nitration reactionmust lead not to a mononitro but to a dinitro derivative. This is reasonable in view of the factthat this reaction is carried out at elevated temperature (120°C).This two-step sequence has been carried out with product yields of 70–71% in the frst stepand 88–95% in the second step.(d)This problem also involves two transformations, nitration and nucleophilic aromatic substitu-tion. Nitration will take place ortho to chlorine (meta to triFuoromethyl).(e)The primary alkyl halide is more reactive toward nucleophilic substitution than the arylhalide. A phosphonium salt forms by an SN2 process.(f)N-Bromosuccinimide (NBS) is a reagent used to substitute benzylic and allylic hydrogenswith bromine. The benzylic bromide undergoes SN2 substitution with the nucleophile,
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