Domanda del libro di testo
Would you expect an acetylenic C―H to absorb at a higher or lower wavenumber than the C―H in ethene?
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Ch. 14 - Structural Identification 1: Infrared Spectroscopy and Mass Spectrometry
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
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Non è quello che usi tu?Cambia libro di testo
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Mullins 1st EditionCh. 14 - Structural Identification 1: Infrared Spectroscopy and Mass SpectrometryProblema 20d
Mullins 1st EditionCh. 14 - Structural Identification 1: Infrared Spectroscopy and Mass SpectrometryProblema 20dCapitolo 13, Problema 20d
For each pair, choose the molecule that you expect to have the highest wavenumber for its C=O stretch.
(d) 
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Understand that the C=O stretch in infrared spectroscopy is influenced by factors such as bond strength and the surrounding chemical environment. A stronger bond typically results in a higher wavenumber.
Consider the electronic effects on the carbonyl group. Electron-withdrawing groups can increase the bond strength of the C=O bond, leading to a higher wavenumber.
Evaluate the resonance effects. If a molecule has resonance structures that delocalize the electrons away from the carbonyl group, this can weaken the C=O bond and lower the wavenumber.
Assess the steric effects. Bulky groups near the carbonyl can affect the bond angle and length, potentially influencing the wavenumber.
Compare the molecules in the pair based on these factors to determine which one has the stronger C=O bond and thus the higher wavenumber for its C=O stretch.
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Infrared Spectroscopy
Infrared spectroscopy is a technique used to identify functional groups in molecules by measuring the absorption of infrared light, which causes molecular vibrations. The C=O stretch is a common feature in IR spectra, typically appearing around 1700 cm⁻¹. The exact position can vary based on molecular environment and bonding.
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Percorso guidato
2:56
The UV-Vis Spectroscopy Concept 1
Wavenumber and Bond Strength
Wavenumber, measured in cm⁻¹, is inversely related to wavelength and directly related to the energy of the bond vibration. A higher wavenumber indicates a stronger bond, as more energy is required to stretch it. In the context of C=O bonds, factors like resonance, inductive effects, and hybridization can influence bond strength and thus the wavenumber.
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06:00Single bonds, double bonds, and triple bonds.
Resonance and Inductive Effects
Resonance and inductive effects can alter the electron density around a C=O bond, affecting its strength and the corresponding IR wavenumber. Resonance can delocalize electrons, often weakening the bond and lowering the wavenumber. Inductive effects, from electronegative atoms or groups, can increase electron withdrawal, strengthening the bond and increasing the wavenumber.
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01:47Understanding the Inductive Effect.
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