Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

11. Radical Reactions

Free Radical Halogenation

Organic Chemistry

11. Radical Reactions

Free Radical Halogenation

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4:06 minutes

Problem 45b

Textbook Question

The radical fluorination of 2-methyl propane resulted in a 14:86 ratio of products.

(b) From the relative reactivity, calculate the difference in energy between the transition states of the first propagation steps leading to a 1° and 3° radical.

Verified step by step guidance

Identify the key concept: The problem involves radical halogenation, specifically fluorination, and the relative reactivity of primary (1°) and tertiary (3°) radicals. The energy difference between the transition states can be calculated using the ratio of products and the Boltzmann distribution equation.

Write the Boltzmann distribution equation: \( \frac{[P_1]}{[P_2]} = e^{-\Delta E / RT} \), where \([P_1]\) and \([P_2]\) are the concentrations (or ratios) of the products, \( \Delta E \) is the energy difference between the transition states, \( R \) is the gas constant (8.314 J/mol·K), and \( T \) is the temperature in Kelvin.

Substitute the given product ratio into the equation: The ratio of products is 14:86, so \( \frac{[P_{1°}]}{[P_{3°}]} = \frac{14}{86} \). This ratio corresponds to the relative reactivity of the 1° and 3° radicals.

Rearrange the equation to solve for \( \Delta E \): Take the natural logarithm of both sides to isolate \( \Delta E \). The equation becomes \( \Delta E = -RT \ln \left( \frac{[P_{1°}]}{[P_{3°}]} \right) \).

Plug in the known values: Use \( R = 8.314 \) J/mol·K, the given ratio \( \frac{14}{86} \), and the temperature (assume room temperature, \( T = 298 \) K, unless otherwise specified). Simplify the expression to calculate \( \Delta E \), the energy difference between the transition states.

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Key Concepts

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

Radical Reactivity

Radical reactivity refers to the tendency of different types of radicals to undergo reactions. In organic chemistry, the stability of radicals is crucial; tertiary (3°) radicals are more stable than secondary (2°) and primary (1°) radicals due to hyperconjugation and inductive effects. This stability influences the rate of reactions and the distribution of products formed during radical processes.

Transition States

A transition state is a high-energy state during a chemical reaction that represents the point of maximum energy along the reaction pathway. The energy difference between transition states for different pathways can indicate the relative reactivity of the involved species. In this context, comparing the transition states for forming 1° and 3° radicals helps to understand the energy barriers and the favorability of each reaction pathway.

Energy Calculations in Radical Reactions

Energy calculations in radical reactions involve determining the energy differences between the transition states leading to different products. By using the ratio of products formed, one can apply the principle of microscopic reversibility and the Arrhenius equation to estimate the energy difference. This calculation is essential for predicting the outcome of radical reactions and understanding the underlying thermodynamics.

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Textbook Question

For each alkane,

1. draw all the possible monochlorinated derivatives.

c. 2-methylpentane

d. 2,2,3,3-tetramethyl butane

Textbook Question

The chlorination of pentane gives a mixture of three monochlorinated products.

a. Draw their structures.

Textbook Question

Predict the major monohalogenation product(s) of the following reactions. Indicate whether you think the reaction will be selective and justify your position.

(a)

Textbook Question

The radical fluorination of 2-methyl propane resulted in a 14:86 ratio of products.

(a) On the basis of this ratio, calculate the relative reactivity of 1° and 3° C―H bonds in the radical fluorination.

Textbook Question

Show how free-radical halogenation might be used to synthesize the following compounds. In each case, explain why we expect to get a single major product.

(a) 1-chloro-2,2-dimethylpropane (neopentyl chloride)

(b) 2-bromo-2-methylbutane

Textbook Question

Rationalize the fact that reaction A results in an unequal mixture of products, but reaction B yields an equal mixture of two products.

Textbook Question

Because of the angle strain present in cyclopropanes, they tend to open up in the presence of nearby radicals. Show a mechanism for the following reaction that demonstrates this principle.

Textbook Question

When (1R,3S)-1-tert-butyl-1,3-dimethylcyclopentane is halogenated, one stereoisomer is produced in excess.

(a) Predict the identity of the major stereoisomer

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