Textbook Question
Show how you would accomplish the following synthetic
conversions by adding an organolithium reagent to an acid.
(c) pentanoic acid → heptan-3-one
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13. Alcohols and Carbonyl Compounds
Organometallic Cumulative Practice
3:30 minutesProblem 52f
Textbook Question
Devise a synthesis for each compound, starting with methylenecyclohexane and any other reagents you need.
f. 1-(phenylmethyl)cyclohexanol
Verified step by step guidance1
Step 1: Begin with methylenecyclohexane as the starting material. Perform a hydroboration-oxidation reaction to convert the alkene into an alcohol. Use BH₃·THF (borane-tetrahydrofuran complex) followed by H₂O₂ (hydrogen peroxide) and NaOH (sodium hydroxide) to yield cyclohexanol.
Step 2: Prepare benzyl bromide (C₆H₅CH₂Br) as the source of the phenylmethyl group. Benzyl bromide can be obtained by reacting toluene (C₆H₅CH₃) with bromine (Br₂) in the presence of light or a radical initiator.
Step 3: Perform a Williamson ether synthesis to attach the phenylmethyl group to cyclohexanol. First, convert cyclohexanol into cyclohexoxide by treating it with a strong base such as NaH (sodium hydride). Then, react cyclohexoxide with benzyl bromide to form 1-(phenylmethyl)cyclohexanol.
Step 4: Ensure stereochemical control during the synthesis, as the reaction may produce a mixture of stereoisomers. If necessary, use purification techniques such as recrystallization or chromatography to isolate the desired product.
Step 5: Verify the structure of the final product, 1-(phenylmethyl)cyclohexanol, using spectroscopic methods such as NMR (nuclear magnetic resonance) and IR (infrared spectroscopy) to confirm the presence of the phenylmethyl group and hydroxyl functionality.
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3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Synthesis in Organic Chemistry
Synthesis in organic chemistry refers to the process of constructing complex organic compounds from simpler ones through a series of chemical reactions. Understanding the synthesis pathway is crucial for determining the necessary reagents and conditions required to achieve the desired product. This involves knowledge of functional group transformations, reaction mechanisms, and the reactivity of different organic compounds.
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Reagents and Reaction Mechanisms
Reagents are substances used in chemical reactions to facilitate the transformation of reactants into products. Each reagent can influence the reaction pathway and the final structure of the compound. Familiarity with common reagents and their mechanisms—such as nucleophilic substitutions, electrophilic additions, and reductions—is essential for planning a successful synthesis.
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Functional Groups and Their Transformations
Functional groups are specific groups of atoms within molecules that determine the chemical properties and reactions of those molecules. In the synthesis of 1-(phenylmethyl)cyclohexanol, recognizing the functional groups present in methylenecyclohexane and the target compound is vital. This knowledge allows chemists to identify appropriate reactions that can introduce or modify these functional groups to achieve the desired compound.
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