Show how each of the following compounds can be synthesized from benzene:
f. m-xylene

Verified step by step guidance

Step 1: Begin with benzene as the starting material. Benzene is an aromatic compound with a six-membered ring and alternating double bonds.

Step 2: Perform a Friedel-Crafts alkylation reaction to introduce the first methyl group onto the benzene ring. Use methyl chloride (CH₃Cl) as the alkylating agent and aluminum chloride (AlCl₃) as the catalyst. This will yield toluene (methylbenzene).

Step 3: Carry out a second Friedel-Crafts alkylation to introduce the second methyl group. Use methyl chloride (CH₃Cl) and aluminum chloride (AlCl₃) again, ensuring that the reaction conditions favor substitution at the meta position relative to the first methyl group. This is due to the electron-donating nature of the methyl group, which directs further substitution to the meta position.

Step 4: Carefully control the reaction conditions to avoid over-alkylation or formation of undesired isomers (e.g., o-xylene or p-xylene). The product formed will be m-xylene (1,3-dimethylbenzene).

Step 5: Purify the m-xylene product using techniques such as distillation or recrystallization to ensure the desired compound is isolated.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electrophilic Aromatic Substitution (EAS)

Electrophilic Aromatic Substitution is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This reaction is crucial for synthesizing substituted aromatic compounds, such as m-xylene from benzene. The process typically involves the generation of a carbocation intermediate, which is stabilized by resonance, allowing for the substitution to occur without disrupting the aromaticity of the ring.

Regioselectivity in Substitution Reactions

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the case of m-xylene synthesis, understanding the directing effects of substituents on the benzene ring is essential. The presence of electron-donating groups can influence the position where new substituents are added, leading to the formation of meta, ortho, or para products.

Catalysts in Organic Reactions

Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. In the synthesis of m-xylene from benzene, catalysts such as aluminum chloride (AlCl3) are often used to facilitate the electrophilic aromatic substitution. These catalysts help generate the electrophile and stabilize the transition state, making the reaction more efficient and selective for the desired product.

Show how each of the following compounds can be synthesized from benzene: f. m-xylene