Textbook Question
Tributyltin hydride (Bu3SnH) is often used as a 'radical carrier' in radical reactions. Which bond would you expect to be weaker, Sn–H or C–H? How might this relate to radical stability? Explain your answer.
946
views
Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
All textbooks
Mullins 1st EditionCh. 11 - Properties and Synthesis of Alkyl Halides: Radical ReactionsProblem 60
Mullins 1st EditionCh. 11 - Properties and Synthesis of Alkyl Halides: Radical ReactionsProblem 60Chapter 10, Problem 60
Haloalkanes can be reduced to alkanes using radical reactions involving Bu₃SnH and a catalytic amount of AIBN. Suggest a mechanism for this reaction. [Pay close attention to the bonds formed and broken in developing your mechanism.]
Verified step by step guidance1
Begin by understanding the role of AIBN (azobisisobutyronitrile) in the reaction. AIBN is a radical initiator that decomposes upon heating to form two 2-cyanoprop-2-yl radicals. This step is crucial as it initiates the radical chain reaction.
The 2-cyanoprop-2-yl radical generated from AIBN abstracts a hydrogen atom from Bu₃SnH, forming a Bu₃Sn radical. This step is important as it generates the tin radical necessary for the propagation of the radical chain reaction.
The Bu₃Sn radical then abstracts the bromine atom from the haloalkane, forming an alkyl radical and Bu₃SnBr. This step involves the breaking of the C-Br bond and the formation of a new C-Sn bond.
The alkyl radical formed in the previous step abstracts a hydrogen atom from another molecule of Bu₃SnH, forming the alkane product and regenerating the Bu₃Sn radical. This step completes the radical chain reaction and ensures the continuation of the process.
Finally, the regenerated Bu₃Sn radical can continue to react with more haloalkane molecules, propagating the radical chain reaction. This step highlights the catalytic nature of the reaction, as the Bu₃Sn radical is continuously regenerated.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
8mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Radical Initiation
Radical initiation is the first step in radical reactions where radicals are generated. In this mechanism, AIBN (azobisisobutyronitrile) acts as a radical initiator, decomposing upon heating to form nitrogen gas and two 2-cyanoprop-2-yl radicals. These radicals are crucial for starting the chain reaction by abstracting hydrogen from Bu₃SnH, generating a tin radical.
Recommended video:
Guided course
03:49
What are Radical Initiators?
Radical Propagation
Radical propagation involves the reaction of radicals with stable molecules to form new radicals, continuing the chain reaction. The tin radical generated in the initiation step abstracts the halogen atom from the haloalkane, forming an alkyl radical and Bu₃SnBr. The alkyl radical then reacts with Bu₃SnH, regenerating the tin radical and forming the alkane product.
Recommended video:
1:01Radical Polymerization Concept 3
Radical Termination
Radical termination occurs when two radicals combine to form a stable molecule, effectively ending the chain reaction. In this mechanism, termination can happen when two alkyl radicals or two tin radicals combine, although the primary focus is on the propagation steps that lead to the desired alkane product. Termination ensures that the reaction does not continue indefinitely, stabilizing the system.
Recommended video:
1:30Radical Polymerization Concept 4
Related Practice
Textbook Question
If a small amount of a moderately nonpolar poisonous compound was added to a pond, why would it be safer to drink the water than it would be to eat the fish that live there?
1186
views
Textbook Question
Cyclizations can be carried out under radical conditions involving Bu₃SnH and a catalytic amount of AIBN. Suggest a mechanism for this reaction. [Pay close attention to the bonds formed and broken in developing your mechanism. It may be helpful to number the carbons.]
700
views
Textbook Question
Other molecules can be used as initiators in radical reactions. One such molecule is 2, 2'-azobisisobutyronitrile (AIBN). Show an arrow-pushing mechanism that rationalizes the formation of the following radical species. What are the driving forces of this reaction?
784
views
Textbook Question
A halogenation intended to make compound A formed B instead.
(a) Suggest a mechanism for the intended formation of A.
1048
views
Textbook Question
A halogenation intended to make compound A formed B instead.
(b) Suggest a mechanism that rationalizes the formation of B.
799
views