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Ch. 18 - Ketones and Aldehydes
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh. 18 - Ketones and AldehydesProblem 60b
Chapter 18, Problem 60b

Show how you would accomplish the following syntheses.
(b) benzonitrile → propiophenone

Verified step by step guidance
1
Step 1: Begin by hydrolyzing the nitrile group (-CN) in benzonitrile to form a carboxylic acid (-COOH). This can be achieved using acidic or basic hydrolysis conditions, such as HCl and water or NaOH and water, followed by acidification.
Step 2: Convert the carboxylic acid (-COOH) to an acid chloride (-COCl) using a reagent like thionyl chloride (SOCl₂). This step activates the carboxylic acid for further reactions.
Step 3: Perform a Friedel-Crafts acylation reaction using the acid chloride and benzene in the presence of a Lewis acid catalyst, such as AlCl₃. This introduces the ketone group (-COCH₃) onto the benzene ring.
Step 4: Ensure the reaction conditions are controlled to avoid over-acylation or side reactions. Purify the product using standard organic chemistry techniques like distillation or recrystallization.
Step 5: Verify the structure of the final product, propiophenone, using spectroscopic methods such as IR (to confirm the presence of the ketone group) and NMR (to confirm the structure of the aromatic ring and ketone substituent).

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Key Concepts

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

Nitrile Reactivity

Nitriles, such as benzonitrile, are compounds containing a cyano group (-C≡N). They are versatile intermediates in organic synthesis, often undergoing nucleophilic addition reactions. In this synthesis, the nitrile group can be converted into a ketone through hydrolysis and subsequent reactions, making it essential to understand how nitriles react under different conditions.
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Grignard Reagents

Grignard reagents are organomagnesium compounds that act as strong nucleophiles. They are commonly used to form carbon-carbon bonds in organic synthesis. In the transformation from benzonitrile to propiophenone, a Grignard reagent can be employed to add a phenyl group to the carbonyl carbon, facilitating the formation of the desired ketone.
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Hydrolysis of Nitriles

Hydrolysis of nitriles involves the reaction of the nitrile with water, often in the presence of an acid or base, to yield carboxylic acids or amides. This step is crucial in the synthesis of propiophenone, as it converts the nitrile into an intermediate that can be further transformed into the ketone. Understanding the conditions and mechanisms of hydrolysis is vital for successful synthesis.
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Related Practice
Textbook Question

There are three dioxane isomers: 1,2-dioxane, 1,3-dioxane, and 1,4-dioxane. One of these acts like an ether and is an excellent solvent for Grignard reactions. Another one is potentially explosive when heated. The third one quickly hydrolyzes in dilute acid. Show which isomer acts like a simple ether, and then explain why one of them is potentially explosive.

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Textbook Question

Show how you would accomplish the following syntheses.

(a) benzene → n-butylbenzene

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Textbook Question

The Wittig reaction is useful for placing double bonds in less stable positions. For example, the following transformation is easily accomplished using a Wittig reaction.

(a) Show how you would use a Wittig reaction to do this.

(b) Show how you might do this without using a Wittig reaction, and then explain why the Wittig reaction is a much better synthesis.

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Textbook Question

Show how you would accomplish the following syntheses.

(c) benzene → p-methoxybenzaldehyde

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Textbook Question

When LiAlH4 reduces 3-methylcyclopentanone, the product mixture contains 60% cis-3-methylcyclopentanol and 40% trans-3-methylcyclopentanol. Use your models, and make three-dimensional drawings to explain this preference for the cis isomer.

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Textbook Question

Show how you would accomplish the following syntheses.

(d)

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