Domanda del libro di testo
Choose the bond in each pair that you expect to vibrate at the higher wavenumber.
(b) C―H vs. C―O
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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 18a
Mullins 1st EditionCh. 14 - Structural Identification 1: Infrared Spectroscopy and Mass SpectrometryProblema 18aCapitolo 13, Problema 18a
Would you expect an acetylenic C―H to absorb at a higher or lower wavenumber than the C―H in ethene?
Guida verificata passo dopo passo1
Understand the concept of wavenumber in IR spectroscopy: Wavenumber is inversely proportional to wavelength and is directly related to the energy of the bond vibration. Higher wavenumbers correspond to higher energy vibrations.
Identify the types of C―H bonds in question: An acetylenic C―H bond is found in alkynes, where the carbon is sp-hybridized. In ethene, the C―H bond is found in alkenes, where the carbon is sp2-hybridized.
Consider the hybridization of the carbon atoms: sp-hybridized carbons (as in alkynes) have more s-character (50%) compared to sp2-hybridized carbons (33% s-character) in alkenes. More s-character results in a stronger, shorter bond.
Relate bond strength to wavenumber: Stronger bonds typically absorb at higher wavenumbers because they require more energy to vibrate.
Conclude based on bond strength and hybridization: Since the acetylenic C―H bond is stronger due to higher s-character, it will absorb at a higher wavenumber compared to the C―H bond in ethene.
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Infrared Spectroscopy
Infrared spectroscopy is a technique used to identify functional groups in organic molecules by measuring the absorption of infrared light, which causes molecular vibrations. Different bonds absorb at characteristic wavenumbers, allowing for the identification of specific types of bonds, such as C―H, C=C, and C≡C, based on their unique vibrational frequencies.
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Percorso guidato
2:56
The UV-Vis Spectroscopy Concept 1
Bond Strength and Wavenumber
The wavenumber at which a bond absorbs infrared light is related to the bond strength and the masses of the atoms involved. Stronger bonds, such as triple bonds, typically absorb at higher wavenumbers compared to double or single bonds. This is because stronger bonds require more energy to vibrate, resulting in higher frequency and wavenumber absorption.
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06:00Single bonds, double bonds, and triple bonds.
Acetylenic vs. Ethylenic C―H Bonds
Acetylenic C―H bonds, found in alkynes, are associated with sp-hybridized carbon atoms, while ethylenic C―H bonds, found in alkenes, involve sp2-hybridized carbons. The sp-hybridized C―H bond is stronger and shorter than the sp2-hybridized C―H bond, leading to a higher wavenumber absorption for acetylenic C―H in infrared spectroscopy compared to ethylenic C―H.
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04:39Heterolytic vs. Homolytic Bond Cleavage .
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