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Ch. 20 - Carboxylic Acids
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
Chapter 20, Problem 36g

Show how you would accomplish the following syntheses efficiently (you may use any necessary reagents).
(g)

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1
Step 1: Begin with the starting material, benzyl carboxylic acid (C₆H₅CH₂COOH). Convert the carboxylic acid group (-COOH) into an acid chloride (-COCl) using thionyl chloride (SOCl₂). This reaction replaces the hydroxyl group (-OH) of the carboxylic acid with a chlorine atom, forming benzyl acid chloride.
Step 2: React the benzyl acid chloride (C₆H₅CH₂COCl) with methylamine (CH₃NH₂). This is a nucleophilic acyl substitution reaction where the amine attacks the carbonyl carbon of the acid chloride, replacing the chlorine atom with the methylamino group (-CONHCH₃). This forms the desired amide product.
Step 3: Ensure the reaction is carried out in a suitable solvent, such as dichloromethane (CH₂Cl₂), and under controlled conditions to prevent side reactions. Use a base like pyridine to neutralize the HCl byproduct formed during the reaction.
Step 4: Purify the product using techniques such as recrystallization or column chromatography to isolate the desired benzyl methylamide (C₆H₅CH₂CONHCH₃).
Step 5: Confirm the structure of the final product using spectroscopic methods such as NMR (nuclear magnetic resonance) and IR (infrared spectroscopy) to verify the presence of the amide functional group and the absence of impurities.

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Key Concepts

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

Synthetic Pathways

Synthetic pathways refer to the series of chemical reactions and transformations that convert starting materials into desired products. Understanding these pathways is crucial for planning efficient syntheses, as it involves selecting appropriate reagents and conditions to achieve the target molecule with minimal steps and byproducts.
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Reagents and Catalysts

Reagents are substances used in chemical reactions to facilitate the transformation of reactants into products. Catalysts, on the other hand, are substances that increase the rate of a reaction without being consumed. Knowledge of various reagents and catalysts is essential for optimizing reaction conditions and improving yield in organic synthesis.
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Functional Group Transformations

Functional group transformations involve the conversion of one functional group into another, which is a common strategy in organic synthesis. Mastery of these transformations allows chemists to modify molecular structures effectively, enabling the construction of complex molecules from simpler precursors while maintaining or enhancing their chemical properties.
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