Question

Propose a synthesis of triphenylmethane from benzene, the only source of aromatic rings, and any other necessary reagents.

Short answer

Question: Outline the steps and reagents necessary to synthesize triphenylmethane from benzene. Answer: The synthesis of triphenylmethane from benzene involves the following steps and reagents: 1. Bromination of Benzene: React benzene with bromine in the presence of Iron(III) Bromide (FeBr3) to form bromobenzene. 2. Formation of Grignard Reagent: Convert bromobenzene to phenylmagnesium bromide by reacting with magnesium in an anhydrous ether solvent. 3. Reaction with Methyl Carbonate: React phenylmagnesium bromide with methyl carbonate (dimethyl carbonate) to yield triphenylmethanol. 4. Reduction to Triphenylmethane: Reduce triphenylmethanol to triphenylmethane using lithium aluminum hydride (LiAlH4) in an anhydrous ether solvent or hydrogen gas with a palladium catalyst on carbon (H2/Pd-C).

Step-by-step solution

Bromination of Benzene

Benzene reacts with bromine in the presence of a catalyst - Iron(III) Bromide (FeBr3) to form bromobenzene. The balanced equation can be written as: Benzene + Br2 (in the presence of FeBr3) ⟶ Bromobenzene

Formation of Grignard Reagent

We can easily convert bromobenzene to a Grignard reagent phenylmagnesium bromide. To achieve this, react bromobenzene with magnesium in an anhydrous ether solvent, like diethyl ether. The balanced equation for the reaction is: Bromobenzene + Mg (in anhydrous ether) ⟶ Phenylmagnesium bromide

Reaction with Methyl Carbonate

Phenylmagnesium bromide (Grignard reagent) reacts with methyl carbonate (dimethyl carbonate) to yield triphenylmethanol. The balanced equation for this reaction is: 3 Phenylmagnesium bromide + (MeO)2CO ⟶ Triphenylmethanol + 3 MgBrOCH3

Reduction to Triphenylmethane

Triphenylmethanol can be reduced to triphenylmethane using a reducing agent like lithium aluminum hydride (LiAlH4) in an anhydrous ether solvent or hydrogen gas with a palladium catalyst on carbon (H2/Pd-C). The balanced equation for the reduction using LiAlH4 can be written as: Triphenylmethanol + LiAlH4 ⟶ Triphenylmethane + LiOH + Al(OH)3 By combining these four steps, we have successfully synthesized triphenylmethane from benzene using necessary reagents.