Question

Write an equation for the reaction of benzene, \(\mathrm{C}_{6} \mathrm{H}_{6}\), with chloromethane, \(\mathrm{CH}_{3} \mathrm{Cl}\), in the presence of an \(\mathrm{AlCl}_{3}\) catalyst.

Short answer

The equation for the reaction is \(C6H6 + CH3Cl \xrightarrow[{}]{AlCl3} C6H5CH3 + HCl\)

Step-by-step solution

Identify Reactants and Catalyst

Reactants are benzene (\(C6H6\)) and chloromethane (\(CH3Cl\)). The catalyst which speeds up the reaction but is not consumed, is \(\) AlCl3.

Writing Initial Reaction Step

Write the reactants and catalyst on the left side of the equation. \(C6H6 + CH3Cl -> ?\), with the presence of AlCl3

Annotate Catalyst

Catalyst is a substance that speeds up the reaction but not consumed, to denote it, the catalyst is written above the arrow. \(C6H6 + CH3Cl \xrightarrow[{}]{AlCl3} ? \)

Identify the Product

In this reaction, one hydrogen atom of benzene is replaced by the methyl group (\(CH3\)), while an \(HCl\) molecule is also formed. So, the products are methylbenzene and \(HCl\).

Writing the Final Reaction

Complete the reaction equation by putting the products on the right side of the equation. \(C6H6 + CH3Cl \xrightarrow[{}]{AlCl3} C6H5CH3 + HCl \)

Key concepts

Friedel-Crafts alkylation

Friedel-Crafts alkylation is a fundamental reaction in organic chemistry that involves the introduction of an alkyl group into an aromatic ring. In simpler terms, this process allows us to attach carbon chains, like a methyl group, onto an aromatic structure such as benzene.

Here's how it typically works: during the reaction, an alkyl halide like chloromethane reacts with benzene under the influence of a catalyst, often aluminum chloride ( AlCl_3 ). The alkyl group from chloromethane replaces one of the hydrogen atoms on the benzene ring.

Key points to remember about Friedel-Crafts alkylation include:

• The aromatic ring, such as benzene, acts as a reactant.
• An alkyl group, in this case, a methyl group from chloromethane, is introduced.
• A catalyst, usually AlCl_3 , is used to facilitate the reaction.
• One of the benzene's hydrogen atoms is replaced by the alkyl group.
• The process is highly efficient for forming complex aromatic compounds.

This method is widely used in the synthesis of numerous important chemicals and pharmaceuticals.

catalysis

Catalysis is a crucial concept in many chemical reactions, especially in organic chemistry. A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. In the context of Friedel-Crafts alkylation, aluminum chloride ( AlCl_3 ) serves as the catalyst.

Here's how catalysts work: they lower the activation energy required for the reaction to take place, which means the reaction can proceed faster and more efficiently. It's important to remember that while catalysts are essential for accelerating reactions, they do not alter the final outcome or the equilibrium of the reaction.

Some key aspects of catalysis include:

• Catalysts are not part of the final products.
• They facilitate the reaction by providing an alternative reaction pathway.
• AlCl_3 modifies the electron distribution in chloromethane, which helps in the removal of the chlorine atom to bind the methyl group to benzene.
• Catalytic cycles can repeat numerous times, given that the catalyst remains unchanged.

Through catalysis, processes that would normally take an impractical amount of time can proceed swiftly and smoothly.

reaction equations

Reaction equations in organic chemistry represent the transformation of reactants into products. They are a concise way to depict the molecular processes happening during chemical reactions. In Friedel-Crafts alkylation, the reaction's equation captures the essence of the transformation.

The typical format involves reactants on the left, the catalyst above or near the reaction arrow, and the products on the right. In our specific example, it looks like this: \[ C_6H_6 + CH_3Cl \xrightarrow{AlCl_3} C_6H_5CH_3 + HCl \] This equation has several important components:

• It illustrates benzene (C_6H_6) and chloromethane (CH_3Cl) as reactants.
• AlCl_3 is clearly indicated as the catalyst above the reaction arrow.
• The products are methylbenzene (C_6H_5CH_3) and hydrochloric acid (HCl).
• The arrow signifies the direction of the transformation from reactants to products.

Understanding reaction equations is vital for predicting the outcomes of chemical experiments and for mastering the art of chemical synthesis.