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 84c

Chapter 17, Problem 84c

How can the following compounds be prepared from the given starting materials?
c.

Verified step by step guidance

Step 1: Analyze the starting material and the target compound. The starting material is cyclohexyl bromide, and the target compound is cyclohexylacetic acid. This transformation involves replacing the bromine atom with a carboxylic acid functional group.

Step 2: Perform a nucleophilic substitution reaction. Treat cyclohexyl bromide with cyanide ion (e.g., NaCN or KCN) to replace the bromine atom with a nitrile group, forming cyclohexylacetonitrile. This is an SN2 reaction where the cyanide ion acts as the nucleophile.

Step 3: Hydrolyze the nitrile group to a carboxylic acid. Subject cyclohexylacetonitrile to acidic or basic hydrolysis (e.g., HCl/H2O or NaOH/H2O) to convert the nitrile group (-CN) into a carboxylic acid (-COOH), yielding cyclohexylacetic acid.

Step 4: Purify the product. After hydrolysis, isolate and purify the cyclohexylacetic acid using techniques such as extraction, recrystallization, or distillation, depending on the reaction conditions and impurities.

Step 5: Verify the structure of the product. Use spectroscopic methods such as IR (to confirm the presence of the carboxylic acid group) and NMR (to confirm the structure of cyclohexylacetic acid) to ensure the desired compound has been synthesized.

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Key Concepts

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

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophilic carbon atom, replacing a leaving group. In this case, the bromine atom (a good leaving group) is substituted by a hydroxyl group (OH), forming an alcohol. Understanding the mechanism of this reaction, including the role of nucleophiles and the stability of intermediates, is crucial for predicting the outcome of the transformation.

Reactivity of Alkyl Halides

Alkyl halides, such as the brominated compound in the question, are reactive due to the polar C-X bond, where X is a halogen. The carbon atom bonded to the halogen is electrophilic, making it susceptible to nucleophilic attack. The structure of the alkyl halide, including steric hindrance and the nature of the halogen, influences the reaction pathway (SN1 or SN2) and the rate of substitution, which is essential for understanding how to prepare the desired alcohol.

Formation of Alcohols

Alcohols can be synthesized from various organic compounds through different methods, including nucleophilic substitution of alkyl halides. In this reaction, the hydroxide ion (OH-) acts as a nucleophile, attacking the carbon atom bonded to the bromine, leading to the formation of an alcohol. Recognizing the conditions and reagents required for this transformation, such as the use of a strong base or water, is vital for successfully preparing alcohols from halogenated starting materials.

How can the following compounds be prepared from the given starting materials?c.