How is \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}\) prepared by a Grignard reaction with \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}\) and \(\mathrm{CH}_{3} \mathrm{COOC}_{2} \mathrm{H}_{5}\) as the starting materials?

Question: Outline the steps to prepare the compound \((\mathrm{C}_{6} \mathrm{H}_{5})_{2}\mathrm{C}=\mathrm{CH}_{2}\) using a Grignard reaction, starting from \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}\) and \(\mathrm{CH}_{3}\mathrm{COOC}_{2} \mathrm{H}_{5}\). Answer: The preparation of the compound involves the following steps: 1. Formation of Grignard reagent (\(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{MgBr}\)) by reacting \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}\) with magnesium in ether. 2. Reaction of the Grignard reagent with the ester compound (\(\mathrm{CH}_{3}\mathrm{COOC}_{2} \mathrm{H}_{5}\)) to form a ketone (\(\mathrm{C}_{6} \mathrm{H}_{5}\-\mathrm{C}(\mathrm{H})=\mathrm{O}\)). 3. Reaction of the formed ketone with another mole of Grignard reagent, resulting in the alkoxide salt of the target compound. 4. Protonation of the alkoxide salt using an aqueous acid or water, leading to the desired compound \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2}\mathrm{C}=\mathrm{CH}_{2}\) and a magnesium salt side product.