Grignard reagents are `singma`- bonded organometallic compound. There exists covalent bond between carbon and magnesium atoms. Grignard reagent finds applications in the sysnthesis of variety of compounds. Gringnard reagent reacts as carbanion and the reaction of carbanion with the proton of an acid is acid- base reaction. Cabonyl compound (including ester) on interation with grignard reagent generates alkoxide ion and thus can be converted into alcohols. Grignard reagent react with almost all functional groups. Notable exceptions are tertiary amines aliphatic and aromatic `C=C` bonds.
Q. Which of the following compounds gives benzene as a major product on reaction with `PhMgBr` (1eq)