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Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
All textbooksMullins 1st EditionCh. 5 - Chemical Reaction Analysis: Thermodynamics and KineticsProblem 51a
Chapter 4, Problem 51a

For each set of reactive intermediates, rank them in order of reactivity (1 = most reactive).
(a) Illustration of various carbocations with positive charges, including a methoxy and a chloro group, for reactivity ranking.

Verified step by step guidance
1
Step 1: Understand the concept of reactive intermediates. Reactive intermediates are short-lived, high-energy species formed during chemical reactions. Common types include carbocations, carbanions, free radicals, and carbenes. Their reactivity depends on factors such as stability, electronic structure, and the ability to participate in reactions.
Step 2: Identify the reactive intermediates provided in the problem. For example, if the intermediates are carbocations, consider their stability based on the number of alkyl groups attached to the positively charged carbon (tertiary > secondary > primary > methyl). If they are free radicals, analyze their stability similarly.
Step 3: Apply the concept of stabilization factors. For carbocations, hyperconjugation and resonance stabilize the intermediate. For carbanions, electron-withdrawing groups stabilize the negative charge. For free radicals, resonance and hyperconjugation also play a role. Rank the intermediates based on these stabilization factors.
Step 4: Consider steric effects and electronic effects. Steric hindrance can reduce reactivity, while electronic effects such as inductive effects can either stabilize or destabilize the intermediate. Use these considerations to refine the ranking.
Step 5: Rank the intermediates in order of reactivity (1 = most reactive). The most reactive intermediate is typically the least stable, as it is more eager to participate in a reaction to achieve stability. Ensure the ranking aligns with the principles discussed in the previous steps.

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Key Concepts

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

Reactive Intermediates

Reactive intermediates are transient species that form during the course of a chemical reaction. They include carbocations, carbanions, and free radicals, each possessing unique stability and reactivity characteristics. Understanding the nature of these intermediates is crucial, as their stability directly influences the rate and pathway of the reaction.
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Introduction to the reactive intermediates.

Stability of Intermediates

The stability of reactive intermediates is determined by factors such as hybridization, resonance, and inductive effects. For example, tertiary carbocations are more stable than primary ones due to greater hyperconjugation and inductive effects from surrounding alkyl groups. This stability hierarchy is essential for predicting the reactivity of different intermediates.
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Reactivity Trends

Reactivity trends in organic chemistry often follow the principle that less stable intermediates are more reactive. For instance, free radicals are generally more reactive than stable carbocations due to their incomplete octet. Recognizing these trends allows chemists to rank intermediates based on their likelihood to participate in subsequent reactions.
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Related Practice
Textbook Question

The A value of a substituent on a cyclohexane ring is essentially the ∆G° for a substituent going from the equatorial to the axial position in a chair–chair interconversion. Because most substituents prefer to be in the equatorial position, A values are, by definition, positive numbers. Use the table of A values to calculate ∆G° and Keq for the chair–chair interconversions shown.

(c)

1262
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Textbook Question

The A value of a substituent on a cyclohexane ring is essentially the ∆G° for a substituent going from the equatorial to the axial position in a chair–chair interconversion. Because most substituents prefer to be in the equatorial position, A values are, by definition, positive numbers. Use the table of A values to calculate ∆G° and Keq for the chair–chair interconversions shown.

(b)

1330
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Textbook Question

For each set of reactive intermediates, rank them in order of reactivity (1 = most reactive).

(b)

587
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Textbook Question

The A value of a substituent on a cyclohexane ring is essentially the ∆G° for a substituent going from the equatorial to the axial position in a chair–chair interconversion. Because most substituents prefer to be in the equatorial position, A values are, by definition, positive numbers. Use the table of A values to calculate ∆G° and Keq for the chair–chair interconversions shown.

(d)

1448
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Textbook Question

For each set of reactive intermediates, rank them in order of reactivity (1 = most reactive).

(c)

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Textbook Question

Predict the product(s) of the following halogenation reactions. Only one equivalent of the halogen is used in each case. If the reaction proceeds selectively, indicate this by only drawing the major product. If the reaction is not selective, draw all possible products.

(b)

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