3) E-stilbene is an aromatic compound that forms the core of several synthetic dyes. Grignard reaction between benzylmagnesium bromide and benzaldehyde provides a secondary alcohol intermediate which can be treated with concentrated HCI to provide trans-stilbene. Draw the full mechanism for the preparation of E-stilbene from benzymagnesium bromide and benzaldehyde. Indicate all of the reagents that are required for the synthesis. (4 Marks) 4) Scenario: You are working in a production lab, and you prepare E-stilbene according to the mechanism on the previous page. The reactant quantities you used are: 7.9 mL of benzyl bromide, 1.94 g of solid magnesium and 11.9 mL of benzaldehyde. At the end of the synthesis you recover 10.4 g of crude E-stilbene. a) What was the percentage experimental (crude) yield for your synthesis? (1 Mark) b) Upon isolation of your product, you discover that it is contaminated with another compound. You isolate the impurity, and after analysis, you conclude that the impurity is a crystalline solid with a melting point of 52 C. Determine the structure of the impurity and show the complete mechanism for the formation of the impurity (3 Marks)