2.2.1. p-Vinylphenylmagnesium Chloride (1)

Magnesium (0.9680 g, 39.8 mmol), which was previously washed with anhydrous diethyl ether (Et₂O) (10 mL), anhydrous tetrahydrofuran (THF) (5 mL) and a few goggles of methyl iodide (MeI) and 4-chlorostyrene were introduced into a 100 mL three-necked flask flamed under nitrogen equipped with mechanical stirrer, condenser, dropping funnel. After starting the reaction by overheating with flame, the mixture, kept under reflux, was added with a solution of 4-chlorostyrene (5.20 g, 37.5 mmol, 4.5 mL) in THF_dry (50 mL) by slow dripping. After further reflux by stirring and disappearance of the metallic magnesium (90′), stirring was continued at r.t. for 1 h. Then, the suspension was decanted to obtain a clear solution of Grignard’s reagent (1), which will be used as it is in the subsequent reaction. To understand the exact title of reagent 1, an aliquot of the obtained solution (1 mL) was transferred in a flask containing 0.1014 N HCl in excess (10 mL) and back titrated with 0.1021 N NaOH (5.20 mL) in the presence of phenolphthalein as indicator. Reagent 1 resulted 0.580 N (85% yield).