Propose products (if any) and mechanisms for the following AlCl 3 -catalyzed reactions: b. methyl chloride with anisole

Hello, everyone. Today, we have the following problem, propose the plausible product or products and mechanism for the given reaction. So this is an example of a Frito crafts alkyl reaction that involves adding an alky group to aromatic ring. So if we examine the substituents, we have an a oxy group and this is an electronic donating group which means that it activates the benzene ring to be an Ortho and pare. So we will have two products. So what occurs is we will first have a nucleic attack of the ethane Kay on. So if we redraw our starting material, we will have a nuclear filled attack of the following in the Ortho para direction such that when this reaction is catalyzed using aluminum tri chlorine and are starting Alky Hale, we will have the following set of mechanisms. So this will be the mechanism that leads to the Ortho product. So once we add that ethel group from the alki hali onto our benzene ring, we will have the following resonant structures. Now that we have the carbo car down in the Ortho position, we will then have a dep protonation or a elimination reaction were in our loose acid can then deproteinate that hydrogen to restore aromatic and yield our Ortho product. As for our pera product and its mechanism, we will have the following resonance structures. And as before, once we have the carbo count on and the pair position where we want it, we will have that elimination that will restore aromatic and grant us the following pera product. And so with that, we have solved the problem overall, I hope this helped. And until next time.

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19. Reactions of Aromatics: EAS and Beyond

EAS:Friedel-Crafts Alkylation Mechanism

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

EAS:Friedel-Crafts Alkylation Mechanism

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8:22 minutes

Problem 15b

Textbook Question

Propose products (if any) and mechanisms for the following AlCl₃-catalyzed reactions:
b. methyl chloride with anisole

Verified step by step guidance

Step 1: Recognize that the reaction involves Friedel-Crafts alkylation, a common electrophilic aromatic substitution reaction. Anisole (methoxybenzene) acts as the aromatic compound, and methyl chloride (CH₃Cl) is the alkylating agent. AlCl₃ serves as the Lewis acid catalyst.

Step 2: Understand the role of AlCl₃ in generating the electrophile. AlCl₃ interacts with methyl chloride to form a carbocation intermediate. The reaction can be represented as: CH₃Cl + AlCl₃ → CH₃⁺ + AlCl₄⁻.

Step 3: Identify the reactive site on anisole. The methoxy group (-OCH₃) is an electron-donating group, which activates the aromatic ring and directs substitution to the ortho and para positions relative to the methoxy group.

Step 4: Propose the mechanism for the electrophilic aromatic substitution. The carbocation (CH₃⁺) generated in Step 2 attacks the activated aromatic ring of anisole at either the ortho or para position. This forms a sigma complex (arenium ion), which is stabilized by resonance.

Step 5: Complete the reaction by restoring aromaticity. The sigma complex loses a proton (H⁺), regenerating the aromatic ring and yielding the alkylated product. The final products are ortho-methyl anisole and para-methyl anisole, with para-methyl anisole typically being the major product due to steric considerations.

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Key Concepts

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

Electrophilic Aromatic Substitution

Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. In this context, anisole, which contains a methoxy group that activates the aromatic ring, can undergo EAS with methyl chloride acting as the electrophile. Understanding EAS is crucial for predicting the products of the reaction.

Lewis Acid Catalysis

Lewis acid catalysis involves the use of a Lewis acid, such as AlCl3, to enhance the reactivity of electrophiles. In this reaction, AlCl3 coordinates with methyl chloride, increasing its electrophilic character and facilitating its interaction with the aromatic ring of anisole. Recognizing the role of Lewis acids is essential for understanding the mechanism and product formation.

Nucleophilic Attack and Rearrangement

In the proposed reaction, the nucleophilic aromatic ring of anisole attacks the activated methyl chloride, leading to the formation of a sigma complex. This intermediate can undergo rearrangement to restore aromaticity, resulting in the final product. Grasping the concepts of nucleophilic attack and the stabilization of intermediates is vital for predicting the outcome of the reaction.

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