The synthesis of ibuprofen from 2-methylpropylbenzene and carbon dioxide can be achieved through the following steps:1. Friedel-Crafts Alkylation:Reagents: 2-methylpropylbenzene, propionyl chloride, and aluminum chloride AlCl3 as a catalyst.Reaction conditions: Heat the mixture at 40-50C for several hours.Mechanism: The AlCl3 acts as a Lewis acid, activating the propionyl chloride by forming a complex with the carbonyl group. This generates an electrophilic acylium ion, which then reacts with the 2-methylpropylbenzene through an electrophilic aromatic substitution reaction. The product is a ketone with a 2-methylpropyl group attached to the benzene ring.2. Reduction of the ketone to an alcohol:Reagents: Sodium borohydride NaBH4 or lithium aluminum hydride LiAlH4 .Reaction conditions: Add the reducing agent to the ketone in an anhydrous solvent e.g., tetrahydrofuran or diethyl ether at 0C, then slowly warm to room temperature.Mechanism: The hydride ion from the reducing agent attacks the carbonyl carbon, forming a new C-H bond and reducing the ketone to an alcohol.3. Formation of the carboxylic acid group:Reagents: Carbon dioxide CO2 and a base, such as sodium hydroxide NaOH or potassium hydroxide KOH .Reaction conditions: Bubble CO2 through a solution of the alcohol and base in a solvent e.g., water or alcohol at room temperature.Mechanism: The base deprotonates the alcohol, forming an alkoxide ion. The alkoxide ion then reacts with CO2, forming a carboxylate ion. The carboxylate ion can be protonated to form the carboxylic acid.4. Formation of the ibuprofen ester:Reagents: Ethyl chloroformate ClCOOEt and a base, such as triethylamine Et3N .Reaction conditions: Add the reagents to a solution of the carboxylic acid in an anhydrous solvent e.g., dichloromethane at 0C, then slowly warm to room temperature.Mechanism: The base deprotonates the carboxylic acid, forming a carboxylate ion. The carboxylate ion reacts with ethyl chloroformate, forming an ester and releasing a chloride ion.5. Formation of the final ibuprofen product:Reagents: Hydrazine N2H4 and a base, such as potassium hydroxide KOH .Reaction conditions: Heat the mixture of the ester, hydrazine, and base in an alcohol solvent e.g., ethanol under reflux for several hours.Mechanism: The hydrazine reacts with the ester, forming a hydrazone intermediate. The base then deprotonates the hydrazone, which undergoes a rearrangement to form the final ibuprofen product and regenerate the hydrazine.