Come up with a five-step synthesis using benzene as the starting material and any
functional group transformations you like.
Step 1: Conversion of benzene to bromobenzene
React benzene with bromine in the presence of a Lewis acid catalyst, such as iron or aluminum bromide. This substitution reaction replaces one hydrogen atom of benzene with a bromine atom, yielding bromobenzene.
Step 2: Conversion of bromobenzene to benzoic acid
Treat bromobenzene with sodium hydroxide (NaOH) in the presence of a copper catalyst (Cu), resulting in a benzoic acid formation. This reaction, known as a Rosenmund von Braun synthesis, involves the replacement of the bromine atom with a carboxyl group.
Step 3: Conversion of benzoic acid to benzaldehyde
Subject benzoic acid to oxidation using a strong oxidizing agent like potassium permanganate (KMnO4) or chromic acid (CrO3) to produce benzaldehyde. This oxidation reaction breaks the carbon-carboxyl bond and converts the carboxyl group to an aldehyde group.
Step 4: Conversion of benzaldehyde to benzyl alcohol
React benzaldehyde with sodium borohydride (NaBH4) in the presence of a solvent like methanol to obtain benzyl alcohol. Sodium borohydride acts as a reducing agent, breaking the carbonyl group in benzaldehyde and replacing it with a hydroxyl group.
Step 5: Conversion of benzyl alcohol to benzyl chloride
Overwhelming benzyl alcohol with thionyl chloride (SOCl2) facilitates the substitution of the hydroxyl group with a chlorine atom, resulting in the formation of benzyl chloride. Thionyl chloride acts as a dehydrating agent as well, removing the water molecule produced in the reaction.