Textbook Question
Show how you would accomplish the following synthetic conversions by adding an organolithium reagent to an acid.
(d) phenylacetic acid → 3,3-dimethyl-1-phenylbutan-2-one
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13. Alcohols and Carbonyl Compounds
Organometallic Cumulative Practice
3:53 minutesProblem 7b
Textbook Question
Show how you would accomplish the following synthetic conversions by adding an organolithium reagent to an acid.
(b) 
Verified step by step guidance1
Step 1: Begin by converting the alkyl bromide (cyclopentyl bromide) into an organolithium reagent. This can be achieved by reacting cyclopentyl bromide with metallic lithium in a dry, inert solvent such as hexane or ether. The reaction forms cyclopentyllithium.
Step 2: Prepare the acid that will react with the organolithium reagent. In this case, the acid should be acetic acid (CH₃COOH), as the target molecule contains a ketone group derived from acetic acid.
Step 3: Add the cyclopentyllithium reagent to acetic acid. The organolithium reagent acts as a nucleophile and attacks the carbonyl carbon of acetic acid, forming an intermediate.
Step 4: Allow the intermediate to undergo proton transfer and rearrangement. This step leads to the formation of the desired ketone product, cyclopentanone.
Step 5: Purify the product using standard organic chemistry techniques such as distillation or recrystallization to isolate the cyclopentanone.
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3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Organolithium Reagents
Organolithium reagents are highly reactive compounds containing a carbon-lithium bond. They act as strong nucleophiles and are commonly used in organic synthesis to form carbon-carbon bonds. In the context of the question, they can react with electrophiles, such as carbonyl compounds, to facilitate the conversion of halogenated cyclic compounds into more complex structures.
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Reagents
Nucleophilic Substitution
Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile replaces a leaving group in a molecule. In this case, the organolithium reagent acts as the nucleophile, attacking the carbon atom bonded to the bromine atom, leading to the formation of a new carbon-carbon bond and the release of bromide ion as a leaving group.
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Formation of Carbonyl Compounds
The formation of carbonyl compounds involves the introduction of a carbonyl functional group (C=O) into a molecule. In the given reaction, the organolithium reagent adds to the cyclic compound, followed by a reaction with an acid to convert the resulting intermediate into a stable carbonyl compound. This transformation is crucial in organic synthesis for creating various functionalized molecules.
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01:40Defining meso compounds.
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