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Radical benzylic halogenation

8 real reactions from the literature, on alkylbenzenes and thiophenes. Each scheme shows starting materials, conditions and products, with the yield and reference where the source reports them.

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  1. Benzylic halogenation: 4-bromotoluene (an alkylbenzene) with NBS; AIBN gives 4-bromobenzyl bromide (the benzylic halide). 100% yield.

  2. Benzylic halogenation: 3-methylthiophene with NBS; benzoyl peroxide, benzene, Δ gives 3-(bromomethyl)thiophene (the benzylic halide).

  3. Benzylic halogenation: o-xylene (an alkylbenzene) with Br2, (4 equiv.); hν gives o-bis(bromomethyl)benzene (the benzylic halide).

  4. Benzylic halogenation: p-xylene (an alkylbenzene) with Br2, hν; Δ gives 1,4-bis(bromomethyl)benzene (the benzylic halide).

  5. Benzylic halogenation: (3-bromopropyl)benzene (an alkylbenzene) with NBS, benzoyl peroxide; CCl4, Δ gives 1,3-dibromo-1-phenylpropane (the benzylic halide).

  6. Benzylic halogenation: 4-chlorotoluene (an alkylbenzene) with Cl2, PCl5; hν, Δ gives 1-chloro-4-(chloromethyl)benzene (the benzylic halide).

  7. Benzylic halogenation: 2-nitrotoluene (an alkylbenzene) with NBS; benzoyl peroxide, CCl4, Δ gives alpha-bromo-2-nitrotoluene (the benzylic halide).

  8. Benzylic halogenation: an alkylbenzene gives the benzylic halide. 63 % yield.

    Benzylic halogenationJ. Org. Chem. 2011, 76, 5335