Ch. 11 - Radical ReactionsSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Not all radicals are born equal! Some of them are going to make pretty smart decisions from an energy perspective, while others are a little on the crazy side. Let’s turn to some potential role models for guidance on this topic. 

Drinking Responsibly vs. Getting Destroyed:

Concept #1: Radical selectivity: Alcoholics Anonymous Version

Selectivity is defined as the ability to only halogenate the carbons with most stable radical intermediates.

Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Example #1: Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Example #2: Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Example #3: Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Example #4: Predict the product of the following Radical Halogenation. Would the following reaction be synthetically useful? (Yielding only one product). 

Hammond’s Explanation:

Early transition states could care less what they look like, whereas late transition states have to be much more careful about the arrangements they take. 

Concept #2: Using the Hammond Postulate to describe radical chlorination. 

Concept #3: Using the Hammond Postulate to describe radical bromination. 

Additional Problems
Which species represents an intermediate formed during the reaction shown?
Predict the major product(s) of the following reaction.
Which of the following products could be formed in good yield through radical chlorination in excess alkane?   1. A and D only 2. C and D only 3. A, C and D only 4. A, B, C and D  5. Only C
Each of the following reactions has been described in the chemical literature and involves an organic starting material somewhat more complex than those we have encountered so far. Nevertheless, on the basis of the topics covered in this chapter, you should be able to write the structure of the principal organic product of each reaction. 
Which of the following statements is TRUE regarding the radical chain reaction of diatomic iodine in excess alkane: a. Would lead to a fully polyiodonized alkane products unless reacted in excess alkane. b. Would yield mostly monoiodonized alkanes due to the high bond dissociation energy of diatomic iodine and its very high selectivity. c. Iodine is NOT used in radical halogenation due to its extremely high reactivity. It can lead to lab explosions. d. More than one of the above is true e. None of the above are true
Which of the following products could be formed in good yield through radical chlorination in excess alkane?  
Predict the major constitutional isomer(s) formed in each of the following reactions. Write "No reaction" where appropriate.
Reaction of bromine radicals with the following polycyclic alkane would lead to the formation of how many different alkyl halides (you may neglect stereoisomers)
Select the answer that best completes the following statement:  Radical halogenation reactions using ______ are the most ______ and often lead to multiple products. While radical halogenation reactions using ______ are the most ______ and produce primarily the major product.  (A) bromine, selective, chlorine, reactive        (B) bromine, reactive, chlorine, selective                                            (C) chlorine, reactive, bromine, selective       (D) chlorine, selective, bromine, reactive
Provide the reagents or starting materials to perform the indicated transformation. More than one reaction may be required.
Predict the major product obtained upon radical bromination of t-butylcyclohexane.   A)  1-bromo-1-tert-butylcyclohexane   B)  2-bromo-1-tert-butylcyclohexane   C)  3-bromo-1-tert-butylcyclohexane   D)  4-bromo-1-tert-butylcyclohexane   E)   (1-bromo-1,1-dimethyl)ethylcyclohexane
Draw all possible products of the following reaction. Indicate which is likely to be the major product.
Predict the major product(s) of the following reaction:  
Draw all possible monochlorination products of 3,3-dimethylpentane, including stereoisomers.  
How many monochloro products would be formed in the reaction of Cl 2 in light with alkane (E) below?
How many dibromo products would be formed in the reaction of Br 2 in light with alkyl bromide (F) below?
How many dichloro products would be formed in the reaction of Cl 2 in light with chlorocubane (G) below?
For the compound shown below, draw the major product of free-radical bromination
Draw the major monobromination product formed by heating the following alkane with bromine.
Identify the hydrogen that will react the fastest in a radical halogenation reaction. a. hydrogen 1 b. hydrogen 2 c. hydrogen 3 d. hydrogen 4 e. hydrogen 5