Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives

Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook

Bruice 8th Edition

Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives

Problem 62c

Chapter 17, Problem 62c

Show how each of the following compounds can be prepared, using the given starting material:
c.

Verified step by step guidance

Step 1: Analyze the starting material and the target compound. The starting material is cyclopentanol (a cyclic alcohol), and the target compound is N-ethylcyclopentylamine (a cyclic amine with an ethyl group attached to the nitrogen). This indicates that the hydroxyl group (-OH) must be replaced with an amine group (-NH2), followed by alkylation to introduce the ethyl group.

Step 2: Convert the alcohol group (-OH) into a good leaving group. This can be achieved by reacting cyclopentanol with a reagent like thionyl chloride (SOCl₂) or phosphorus tribromide (PBr₃) to form cyclopentyl chloride (a cyclic alkyl halide). This step ensures the hydroxyl group is replaced with a halide, which is more reactive for substitution reactions.

Step 3: Perform nucleophilic substitution to replace the halide group with an amine group (-NH2). React cyclopentyl chloride with ammonia (NH₃) under appropriate conditions to yield cyclopentylamine. This step introduces the amine functionality into the molecule.

Step 4: Alkylate the amine group to introduce the ethyl group. React cyclopentylamine with ethyl bromide (C₂H₅Br) or ethyl iodide (C₂H₅I) in the presence of a base like potassium carbonate (K₂CO₃). This step results in the formation of N-ethylcyclopentylamine.

Step 5: Purify the product using techniques such as distillation or recrystallization, depending on the physical properties of N-ethylcyclopentylamine, to ensure the final compound is free of impurities.

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Key Concepts

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

Alcohol to Amine Conversion

The conversion of an alcohol to an amine typically involves the substitution of the hydroxyl (-OH) group with an amine (-NH2) group. This can be achieved through various methods, such as using reagents like thionyl chloride (SOCl2) to convert the alcohol into a better leaving group, followed by nucleophilic substitution with ammonia or an amine.

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions are fundamental in organic chemistry, where a nucleophile attacks an electrophilic carbon atom, replacing a leaving group. In the context of alcohols, the hydroxyl group is a poor leaving group, so it is often converted into a better leaving group to facilitate the reaction with nucleophiles like amines.

Reactivity of Alcohols

Alcohols are versatile compounds in organic synthesis, but their reactivity depends on the structure and the presence of functional groups. Primary alcohols can be converted to amines more readily than tertiary alcohols due to steric hindrance and the stability of the resulting carbocation during the reaction process.

Show how each of the following compounds can be prepared, using the given starting material:c.