Textbook Question
To this point, we have seen four reactions that can be done by Gilman reagents. What are they? What do they have in common?
2
views
Ch. 21 - Conjugated Systems I: Stability and Addition 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. 21 - Conjugated Systems I: Stability and Addition ReactionsProblem 50
Mullins 1st EditionCh. 21 - Conjugated Systems I: Stability and Addition ReactionsProblem 50Chapter 20, Problem 50
On a per alkene basis, which would have the more negative heat of hydrogenation?
Verified step by step guidance1
Understand the concept of heat of hydrogenation: It is the heat released when an alkene is converted to an alkane by the addition of hydrogen. A more negative heat of hydrogenation indicates a less stable alkene.
Identify the factors affecting alkene stability: More substituted alkenes (those with more alkyl groups attached to the double-bonded carbons) are generally more stable due to hyperconjugation and inductive effects.
Compare the degree of substitution: Determine the number of alkyl groups attached to the double-bonded carbons in each alkene. The alkene with fewer substituents will typically have a more negative heat of hydrogenation.
Consider the presence of any additional stabilizing or destabilizing factors: Look for conjugation with other double bonds or aromatic rings, which can stabilize the alkene, or steric hindrance, which can destabilize it.
Evaluate the alkenes based on these criteria: The alkene with the least stability (fewest substituents and least conjugation) will have the more negative heat of hydrogenation.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Heat of Hydrogenation
The heat of hydrogenation is the amount of energy released when an alkene undergoes hydrogenation, converting into an alkane. It is a measure of the stability of the alkene; more stable alkenes have less negative heats of hydrogenation because they release less energy upon hydrogenation. This concept helps compare the relative stabilities of different alkenes.
Recommended video:
Guided course
00:48
The definition of hydrogenation.
Alkene Stability
Alkene stability is influenced by factors such as the degree of substitution and the presence of electron-donating or withdrawing groups. More substituted alkenes are generally more stable due to hyperconjugation and the inductive effect, which stabilize the double bond. Understanding these factors is crucial for predicting which alkene will have a more negative heat of hydrogenation.
Recommended video:
Guided course
04:28Understanding trends of alkene stability.
Substitution Patterns in Alkenes
Substitution patterns refer to the number and type of groups attached to the carbon atoms of the double bond in an alkene. Tetrasubstituted alkenes are more stable than trisubstituted, disubstituted, and monosubstituted alkenes. This hierarchy is important because more substituted alkenes tend to have less negative heats of hydrogenation, indicating greater stability.
Recommended video:
Guided course
08:06Common Splitting Patterns
Related Practice
Textbook Question
Would you expect the following molecules to absorb in the UV–visible region of the electromagnetic spectrum?
(a)
(b)
(c)
(d)
(e)
1
views
Textbook Question
Which of the following reactions would you expect to be faster/more favorable in each pair? Why?
(b)
1
views
Textbook Question
Suggest a reagent and a reactant that could be used to form the following molecules by conjugate addition of a cuprate. There can be multiple possibilities.
(c)
1
views
Textbook Question
Draw the molecular orbital picture of octa-1,3,5,7-tetraene, indicating which is the HOMO and which is the LUMO.
3
views
Textbook Question
How many 𝝅 electrons are involved in the conjugated system for each of the following molecules?
(a)
5
views