To demonstrate the organic synthesis of a specific compound using retrosynthesis, let's consider the synthesis of a target molecule: 4-phenylbutan-2-one.Target molecule: 4-phenylbutan-2-oneStep 1: Retrosynthetic analysis disconnection approach In retrosynthesis, we work backward from the target molecule to simpler precursors by breaking bonds and identifying possible synthetic routes. For 4-phenylbutan-2-one, we can disconnect the bond between the carbonyl group and the phenyl group. This disconnection suggests that our target molecule can be synthesized from an acyl compound acetyl chloride and an organometallic reagent phenylmagnesium bromide .Step 2: Forward synthesisNow that we have identified the precursors, we can proceed with the forward synthesis using the following reactions:Reaction 1: Preparation of phenylmagnesium bromide Grignard reagent Reagents: Bromobenzene, magnesium, etherConditions: Dry, anhydrous conditions, refluxMechanism: Single electron transfer SET from magnesium to bromobenzene, followed by coordination of the resulting phenyl anion to the magnesium cation.Ph-Br + Mg Ph-Mg-BrReaction 2: Reaction of phenylmagnesium bromide with acetyl chlorideReagents: Acetyl chloride, phenylmagnesium bromideConditions: Dry, anhydrous conditions, low temperature 0C Mechanism: Nucleophilic addition of the phenyl anion to the carbonyl carbon of acetyl chloride, followed by protonation of the resulting alkoxide intermediate.Ph-Mg-Br + CH3COCl Ph-CH2-CO-CH3 + MgBrClStep 3: Purification and isolation of the productThe crude product mixture can be purified by extraction, washing, and drying, followed by recrystallization or chromatography to obtain the pure 4-phenylbutan-2-one.In summary, the retrosynthetic analysis of 4-phenylbutan-2-one led to the identification of acetyl chloride and phenylmagnesium bromide as suitable precursors. The forward synthesis involved the preparation of the Grignard reagent phenylmagnesium bromide and its reaction with acetyl chloride to form the target molecule. The product was then purified and isolated using standard techniques.