Ch. 11 - Radical ReactionsWorksheetSee 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

Alkanes are the backbone of organic molecules, yet they are almost completely unreactive.

The only reaction alkanes undergo is radical halogenation, the gateway to the rest of organic synthesis.

Concept #1: The one reaction that alkanes will actually undergo. 

Concept #2: Radical Chain Reaction Mechanism.

Alkanes will react with diatomic halogens in the presence of heat, light or any other radical initiator.

  • Think of the radical as a “hot potato” that the alkanes want to keep passing along!

Example #1: Explaining the following example problem.

Example #2: Show the entire chain reaction mechanism for the following Radical Halogenation reaction, predicting which would be the structure of the major alkyl halide produced. 

Additional Problems
Propose a mechanism for the radical chlorination of methane. Include its initiation, propagation, and termination steps.
Which of the following is the rate-determining step in the free-radical bromination of methane?
Which of the following would not be a correct propagation step in the free radical chlorination of ethane?
Which term most accurately describes the process shown below? A. coupling B. hydrogen abstraction C. halogen abstraction D. homolytic cleavage E. addition to a π bond   
Provide the major product for each of the following alkene reactions. 
Determine the major product(s) formed from the radical reaction.
Use correct arrow formalism to show the propagation steps in the chlorination of propane to produce 2-chloropropane.
A graduate student was attempting to functionalize an alkane for a research project to make her advisor happy. While characterizing the products of her radical bromination reaction, she isolated the byproduct 2,3,3,4,4,5-hexamethylhexane (below). Please answer the following questions concerning the radical reaction. a. Provide the overall reaction scheme for the desired radical bromination. You will need to determine what the starting materials were, reaction conditions, as well as the major products. b. Provide a detailed mechanism including all three parts of radical bromination to show how the isolated side product 2,3,3,4,4,5-hexamethylhexane was formed. c. Other than resonance, what explains the stabilization of alkyl radicals? Provide the name of this stabilization and using both pictures and words, explain this term.
Draw and name the product obtained from the coupling of the following radicals. 
Which reaction coordinate diagram represents the reaction shown in which radical Y is very nonregioselective?
Using the carbon-source provided, predict reagents and conditions for synthesis of the following molecules. Show organic product after each step of the sequence. Do not show mechanisms.
In the context of a free radical chain reaction, define the following three terms:
To minimize the length of the free radical chain in a free radical halogenation, the concentration of radicals should be:
Draw the major monobromination product when the following alkane is subjected to radical bromination at 25oC If there is more than one product, both may be drawn in the same box
Predict the major product of the following reaction. You do not have to consider stereochemistry. You do not have to explicitly draw H atoms.
The compound below is treated with chlorine in the presence of light. Draw the structure for the organic radical species produced by reaction of the compound with a chlorine atom. Assume reaction occurs at the weakest C-H bond. You do not have to consider stereochemistry. You do not have to explicitly draw H atoms.  
Which of the following is the major product for the free radical bromination reaction (Br2/hv) of 2,2,3-trimethylbutane?a. IIb. IIIc. Id. IV 
Predict and name the product of the following reaction. Draw all hydrogen atoms.The systematic name of the hydrocarbon product is ___________ .
Draw the major monobromination product when the following alkane is subjected to radical bromination at 25oC If there is more than one product, they both may be drawn in the same box.
Which of the following is the rate-determining step for the monobromination of cyclohexane?