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Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions
Bruice - Organic Chemistry 8th Edition
Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook
All textbooksBruice 8th EditionCh. 6 - The Reactions of Alkenes • The Stereochemistry of Addition ReactionsProblem 11d
Chapter 7, Problem 11d

What is the major product obtained from the acid-catalyzed hydration of each of the following alkenes?
d. Chemical structure of cyclohexene with a double bond and a CH2 group indicating an alkene for hydration reaction.

Verified step by step guidance
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Step 1: Recognize that the reaction involves acid-catalyzed hydration of an alkene. This process typically follows Markovnikov's rule, where the hydroxyl group (-OH) adds to the more substituted carbon of the double bond.
Step 2: Analyze the structure of the given alkene. The double bond is located between the cyclopentane ring and the terminal carbon. Identify the two carbons involved in the double bond: one is part of the ring (more substituted), and the other is a terminal carbon (less substituted).
Step 3: In the presence of an acid catalyst, the alkene undergoes protonation. The π electrons of the double bond attack the proton (H⁺), forming a carbocation intermediate. The carbocation will form on the more substituted carbon (the carbon in the ring) due to its greater stability.
Step 4: Water (H₂O) acts as a nucleophile and attacks the carbocation, leading to the formation of an oxonium ion. Subsequently, deprotonation occurs, resulting in the addition of a hydroxyl group (-OH) to the more substituted carbon.
Step 5: The major product of the reaction is an alcohol where the hydroxyl group is attached to the carbon in the cyclopentane ring, following Markovnikov's rule. The terminal carbon remains as part of the alkyl chain.

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Key Concepts

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

Acid-Catalyzed Hydration

Acid-catalyzed hydration is a reaction where an alkene reacts with water in the presence of an acid catalyst, typically sulfuric acid. This process involves the formation of a carbocation intermediate, which is then attacked by water, leading to the formation of an alcohol. The regioselectivity of the reaction follows Markovnikov's rule, where the more substituted carbon of the alkene receives the hydroxyl group.
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Acid-catalyzed hydration mechanism

Markovnikov's Rule

Markovnikov's rule states that in the addition of HX (where X is a halogen or hydroxyl group) to an alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This rule helps predict the major product of reactions involving unsymmetrical alkenes, guiding the placement of functional groups in the final product.
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Carbocation Stability

Carbocation stability is a key factor in determining the outcome of reactions involving alkenes. Carbocations are positively charged carbon species that can vary in stability based on their substitution: tertiary carbocations are more stable than secondary, which are more stable than primary. The stability influences the formation of the major product during acid-catalyzed hydration, as the pathway leading to the more stable carbocation is favored.
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Related Practice
Textbook Question

Answer the following questions about the mechanism for the acid-catalyzed hydration of an alkene:

a. How many transition states are there?

b. How many intermediates are there?

c. Which step in the forward direction has the smallest rate constant?

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Textbook Question

What is the major product of each of the following reactions?

1.

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Textbook Question

What is the major product obtained from the acid-catalyzed hydration of each of the following alkenes?

a. CH3CH2CH2CH=CH2

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Textbook Question

What is the major product of each of the following reactions?

3.

4.

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Textbook Question

The pKa of a protonated alcohol is about -2.5, and the pKa of an alcohol is about 15. Therefore, as long as the pH of the solution is greater than _______ and less than _______, more than 50% of 2-propanol (the product of the reaction on p. 244) will be in its neutral, nonprotonated form.

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Textbook Question

What is the major product of each of the following reactions?

2.

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