Ibuprofen has the molecular formula C13H18O2 and is a widely used nonsteroidal anti-inflammatory drug NSAID . A viable multi-step synthesis of ibuprofen from commercially available starting materials can be achieved through the following retrosynthetic analysis:1. Starting material: Iso-butylbenzene commercially available 2. First step: Friedel-Crafts acylation Reagents: Acetyl chloride CH3COCl and aluminum chloride AlCl3 Conditions: Anhydrous conditions, room temperature Product: 4'-isobutylacetophenone3. Second step: Reduction of the carbonyl group Reagents: Sodium borohydride NaBH4 Conditions: Methanol MeOH as solvent, 0C to room temperature Product: 4'-isobutyl-1-phenylethanol4. Third step: Conversion to the corresponding carboxylic acid Reagents: Potassium permanganate KMnO4 Conditions: Aqueous solution, reflux Product: 4'-isobutyl--methylbenzylcarboxylic acid5. Fourth step: Conversion to the corresponding acid chloride Reagents: Thionyl chloride SOCl2 Conditions: Anhydrous conditions, reflux Product: 4'-isobutyl--methylbenzylcarbonyl chloride6. Fifth step: Formation of the final product ibuprofen Reagents: Sodium salt of 2-methylpropionic acid prepared by treating 2-methylpropionic acid with sodium hydroxide Conditions: Anhydrous conditions, room temperature Product: IbuprofenThis synthesis route involves five steps, starting from commercially available iso-butylbenzene and using well-established reactions and reagents. The overall yield can be optimized by carefully controlling reaction conditions and purifying intermediates as needed.