If it worked, it wouldn't produce 4-chloro derivatives.
She first takes the dichlorobenzene, PhCl2, and forms a monogrignard, ClPhMgCl, then reduces the grignard reagent with acid to form ClPhH, a.k.a. PhCl, chlorobenzene.
Then a second grignard is formed, PhMgCl, and this is reacted with allyl chloride, forming allyl-benzene + MgCl2.
I personally don't think it will work, but this is the idea as I understand it.
PrimoPyro
Vivent Longtemps La Ruche!