Domanda del libro di testo
A misguided chemist attempted to synthesize trans-1,2-dimethylcyclohexane via the hydrogenation of 1,2-dimethylcyclohexene. Explain why this is not possible.
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Ch. 9 - Alkenes 2: Oxidation and Reduction
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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TOC.tableOfContents
- 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 1: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes 2: 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 1: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification 2: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution 1: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution 2: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems 1: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems 2: Pericyclic Reactions54
- Ch. 23 - Benzene 1: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene 2: 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
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Capitolo 8, Problema 38a
Conjugated dienes, molecules containing two alkenes separated by one single bond, are discussed in detail in Chapter 21.
(a) Considering the observed ∆H° of hydrogenation, is hexa-1,3-diene (conjugated) or hexa-1,4-diene (unconjugated) more stable?
Guida verificata passo dopo passo1
Understand the concept of conjugation: Conjugated dienes have alternating double and single bonds, allowing for delocalization of π-electrons across the system. This delocalization provides extra stability compared to unconjugated dienes, where the double bonds are isolated and cannot interact.
Recall the relationship between stability and the heat of hydrogenation (∆H°): A lower (more negative) ∆H° of hydrogenation indicates that the molecule releases less energy upon hydrogenation, meaning it is more stable to begin with.
Compare the structures of hexa-1,3-diene and hexa-1,4-diene: Hexa-1,3-diene is a conjugated diene because the double bonds are separated by a single bond, allowing for delocalization. Hexa-1,4-diene is an unconjugated diene because the double bonds are separated by two single bonds, preventing delocalization.
Analyze the observed ∆H° of hydrogenation: The conjugated diene (hexa-1,3-diene) will have a less negative ∆H° of hydrogenation compared to the unconjugated diene (hexa-1,4-diene) due to the additional stability provided by conjugation.
Conclude based on the ∆H° values: Hexa-1,3-diene (conjugated) is more stable than hexa-1,4-diene (unconjugated) because conjugation lowers the energy of the molecule, as evidenced by the less negative ∆H° of hydrogenation.
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Conjugated vs. Unconjugated Dienes
Conjugated dienes have alternating double and single bonds, allowing for resonance stabilization, while unconjugated dienes have isolated double bonds. This resonance in conjugated systems leads to lower energy states and increased stability compared to their unconjugated counterparts, which lack this delocalization of electrons.
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03:27
Conjugated states
Hydrogenation and Enthalpy Change (∆H°)
Hydrogenation is the process of adding hydrogen to a compound, typically resulting in the saturation of double bonds. The enthalpy change (∆H°) during hydrogenation indicates the stability of the original compound; a lower ∆H° value suggests greater stability of the starting diene, as less energy is released when converting it to a saturated alkane.
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04:38Calculating Enthalpies
Stability and Energy Considerations
In organic chemistry, the stability of a molecule is often inversely related to its energy content. More stable molecules have lower energy due to factors like resonance, sterics, and electronic effects. When comparing hexa-1,3-diene and hexa-1,4-diene, the one with the lower enthalpy of hydrogenation is considered more stable, as it indicates a more favorable energy state.
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03:43The radical stability trend.
Pratica correlata
Domanda del libro di testo
Conjugated dienes, molecules containing two alkenes separated by one single bond, are discussed in detail in Chapter 21.
(b) How might you account for this difference in stability?
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Domanda del libro di testo
Without concerning yourself with the mechanism of the reaction, calculate the equilibrium constant for the following equilibrium processes. (Assume T = 298 K.)
(a)
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Domanda del libro di testo
Identify the alkene that would react with Ti(OiPr)₄, (+) -diethyltartrate, and t-butylhydroperoxide to give the following chiral, nonracemic epoxides.
(a)
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Domanda del libro di testo
Questions (a)–(d) all refer to the following reaction, which has been engineered to produce one enantiomer to the exclusion of the other.
(c) Suppose the difference in activation energy is 1.6 kcal/mol. At what temperature would you produce C in 99% ee?
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Domanda del libro di testo
Because deuterium behaves like hydrogen in chemical reactions yet is detected differently, chemists use the incorporation of deuterium to better understand the subtleties of reaction mechanisms. Deuterium is incorporated by replacing H₂ with D₂ in the hydrogenation reaction. Identify the product expected when the alkenes in Assessment 9.34 react with D₂ and Pd/C. [Don't worry about showing all diastereomers.]
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