Grignard reagents have the general formula RMgX, where R is a hydrocarbon group and X is a halogen. The Grignard reagent C6H5MgBr is used as an intermediate in the reaction between bromobenzene, C6H5Br, and ethanal, CH3CHO, to prepare 1-phenylethanol, C6H5CH(OH)CH3. An organic solvent, ethoxyethane, is used. The equations for the three reactions that take place during the preparation are shown. reaction 1 Mg + C6H5Br → C6H5MgBr reaction 2 C6H5MgBr + CH3CHO → C6H5CH(CH3)OMgBr reaction 3 C6H5CH(CH3)OMgBr + H⁺ → C6H5CH(OH)CH3 + Mg²⁺ + Br⁻ The preparation involves the following steps. step 1 Set up the apparatus shown in [Figure 1.1] with approximately 1.25g of Mg powder and 5 cm³ of ethoxyethane in the round-bottomed flask. step 2 Add 0.0500 mol of liquid C6H5Br to the round-bottomed flask dropwise using the tap funnel. Leave until reaction 1 is complete. step 3 Dissolve 3.00 cm³ of CH3CHO in 15cm³ of ethoxyethane and add this solution to the round-bottomed flask using the tap funnel. Leave until reaction 2 is complete. step 4 Remove the condenser, tube Y and the tap funnel from the round-bottomed flask. step 5 Add 40 cm³ of dilute hydrochloric acid, HCl(aq), to the round-bottomed flask so that reaction 3 takes place. step 6 Transfer the contents of the round-bottomed flask to a separating funnel. Allow the liquids to settle so that two layers are formed. step 7 Open the tap of the separating funnel and run the lower layer into a beaker labelled A. Run the upper layer into a beaker labelled B. step 8 Allow the ethoxyethane to evaporate from the beaker containing C6H5CH(OH)CH3. Some relevant data are shown in Table 1.1. Table 1.1 substance density /gcm⁻³ boiling point /°C hazard bromobenzene 1.50 156 flammable, toxic, skin irritant distilled water 1.00 100 non-hazardous ethoxyethane 0.714 35 flammable, toxic ethanal 0.788 21 flammable, eye and respiratory irritant 1-phenylethanol 1.01 204 flammable, toxic, eye irritant