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Questions and Answers
What infix is used in IUPAC nomenclature to indicate the presence of a carbon-carbon double bond?
What infix is used in IUPAC nomenclature to indicate the presence of a carbon-carbon double bond?
How should the parent chain be numbered to identify the first carbon of a double bond in alkenes?
How should the parent chain be numbered to identify the first carbon of a double bond in alkenes?
What is the configuration name when higher-priority groups are on opposite sides of a carbon-carbon double bond?
What is the configuration name when higher-priority groups are on opposite sides of a carbon-carbon double bond?
Which of the following statements is true regarding the priority assignment for E,Z configuration?
Which of the following statements is true regarding the priority assignment for E,Z configuration?
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In the context of alkyne nomenclature, which infix is utilized to represent a carbon-carbon triple bond?
In the context of alkyne nomenclature, which infix is utilized to represent a carbon-carbon triple bond?
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When numbering a cycloalkene, which atoms should be numbered first?
When numbering a cycloalkene, which atoms should be numbered first?
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What is a common distinction for low-molecular-weight alkenes in nomenclature?
What is a common distinction for low-molecular-weight alkenes in nomenclature?
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Which of the following represents the primary criterion for establishing the priority of substituents in E,Z configuration?
Which of the following represents the primary criterion for establishing the priority of substituents in E,Z configuration?
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Which hybrid orbital corresponds to the lone pair of electrons in the anion derived from a terminal alkyne?
Which hybrid orbital corresponds to the lone pair of electrons in the anion derived from a terminal alkyne?
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What is the relationship between the stability of an anion and the s character of the orbital containing the negative charge?
What is the relationship between the stability of an anion and the s character of the orbital containing the negative charge?
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In comparing the acidity of terminal alkynes, alkenes, and alkanes, which statement is true?
In comparing the acidity of terminal alkynes, alkenes, and alkanes, which statement is true?
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How many cis-trans isomers are possible for a compound with two carbon-carbon double bonds?
How many cis-trans isomers are possible for a compound with two carbon-carbon double bonds?
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Which of the following correctly describes the s character of an alkane anion?
Which of the following correctly describes the s character of an alkane anion?
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What is the general formula for an alkene?
What is the general formula for an alkene?
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Which statement correctly describes the structure of a double bond in alkenes?
Which statement correctly describes the structure of a double bond in alkenes?
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What characterizes the stability of trans alkenes compared to cis alkenes?
What characterizes the stability of trans alkenes compared to cis alkenes?
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Which of the following describes the functional group that is characteristic of alkynes?
Which of the following describes the functional group that is characteristic of alkynes?
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What type of isomerism is observed in alkenes due to restricted rotation about the carbon-carbon double bond?
What type of isomerism is observed in alkenes due to restricted rotation about the carbon-carbon double bond?
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Which of the following statements about the bond angles in alkenes is correct?
Which of the following statements about the bond angles in alkenes is correct?
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How many pi and sigma bonds are present in a carbon-carbon triple bond of an alkyne?
How many pi and sigma bonds are present in a carbon-carbon triple bond of an alkyne?
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What is the primary reason for the restricted rotation around a carbon-carbon double bond?
What is the primary reason for the restricted rotation around a carbon-carbon double bond?
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Which of the following statements is true regarding the cis-trans isomerism of double bonds in cycloalkenes?
Which of the following statements is true regarding the cis-trans isomerism of double bonds in cycloalkenes?
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How many distinct cis-trans isomers can 2,4-heptadiene produce?
How many distinct cis-trans isomers can 2,4-heptadiene produce?
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What is the general relationship between the nonpolarity of alkenes and alkynes and their physical properties?
What is the general relationship between the nonpolarity of alkenes and alkynes and their physical properties?
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What characteristic distinguishes the acidity of terminal alkynes from alkenes?
What characteristic distinguishes the acidity of terminal alkynes from alkenes?
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Which of the following statements about the solubility of alkenes and alkynes is correct?
Which of the following statements about the solubility of alkenes and alkynes is correct?
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Why can hydroxide ion not participate in an acid-base reaction with a terminal alkyne?
Why can hydroxide ion not participate in an acid-base reaction with a terminal alkyne?
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What is the significance of the all-trans configuration of Vitamin A?
What is the significance of the all-trans configuration of Vitamin A?
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Which factor solely influences the attractive forces between alkene and alkyne molecules?
Which factor solely influences the attractive forces between alkene and alkyne molecules?
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The acidity of terminal alkynes is greater than that of alkanes due to the anion's stability from the orbital with 50% s character.
The acidity of terminal alkynes is greater than that of alkanes due to the anion's stability from the orbital with 50% s character.
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An alkene anion has a lone pair of electrons in an sp hybrid orbital.
An alkene anion has a lone pair of electrons in an sp hybrid orbital.
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A terminal alkyne is the least stable and most acidic compared to alkanes and alkenes.
A terminal alkyne is the least stable and most acidic compared to alkanes and alkenes.
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Only terminal alkynes can exhibit cis-trans isomerism due to their linear structure caused by triple bonding.
Only terminal alkynes can exhibit cis-trans isomerism due to their linear structure caused by triple bonding.
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The lone pair of electrons of an alkane anion is located in an sp2 hybrid orbital.
The lone pair of electrons of an alkane anion is located in an sp2 hybrid orbital.
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An alkyne has the general formula CnH2n-2.
An alkyne has the general formula CnH2n-2.
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The bond angles around the carbon atoms in a double bond are approximately 109.5°.
The bond angles around the carbon atoms in a double bond are approximately 109.5°.
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Cis isomers of alkenes have higher stability than trans isomers due to lower nonbonded interaction strain.
Cis isomers of alkenes have higher stability than trans isomers due to lower nonbonded interaction strain.
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The functional group of an alkyne consists of a single sigma bond.
The functional group of an alkyne consists of a single sigma bond.
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Arene compounds include only those with carbon-carbon triple bonds.
Arene compounds include only those with carbon-carbon triple bonds.
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Restricted rotation around a carbon-carbon single bond is not a factor in isomerism.
Restricted rotation around a carbon-carbon single bond is not a factor in isomerism.
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The infix used in IUPAC nomenclature for alkenes to indicate a carbon-carbon double bond is -yn-.
The infix used in IUPAC nomenclature for alkenes to indicate a carbon-carbon double bond is -yn-.
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The configuration of a trans alkene is less stable than that of a cis alkene due to orbital overlap.
The configuration of a trans alkene is less stable than that of a cis alkene due to orbital overlap.
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In the E,Z configuration system, if the priority groups are on the same side of the double bond, the configuration is E.
In the E,Z configuration system, if the priority groups are on the same side of the double bond, the configuration is E.
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In the structure of alkenes, one bond is formed by the overlap of sp2 hybrid orbitals and one by the overlap of parallel 2p orbitals.
In the structure of alkenes, one bond is formed by the overlap of sp2 hybrid orbitals and one by the overlap of parallel 2p orbitals.
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The atoms participating in a double bond are treated as if they are bonded to an equivalent number of similar atoms by single bonds when determining priority.
The atoms participating in a double bond are treated as if they are bonded to an equivalent number of similar atoms by single bonds when determining priority.
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For cycloalkenes, numbering starts with the carbon carrying the double bond as the first atom regardless of the other carbon positions.
For cycloalkenes, numbering starts with the carbon carrying the double bond as the first atom regardless of the other carbon positions.
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Priority rules in E,Z configuration are based solely on the number of atoms bonded to a double bond carbon.
Priority rules in E,Z configuration are based solely on the number of atoms bonded to a double bond carbon.
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Common names for low-molecular-weight alkenes are generally more widely recognized than their IUPAC names.
Common names for low-molecular-weight alkenes are generally more widely recognized than their IUPAC names.
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The configuration E represents substituents that are in the same orientation around a carbon-carbon double bond.
The configuration E represents substituents that are in the same orientation around a carbon-carbon double bond.
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In nomenclature, the first carbon of a triple bond in alkynes is numbered so that it receives the highest possible number.
In nomenclature, the first carbon of a triple bond in alkynes is numbered so that it receives the highest possible number.
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Cyclooctene is the smallest cycloalkene that can accommodate a cis double bond.
Cyclooctene is the smallest cycloalkene that can accommodate a cis double bond.
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Alkenes and alkynes exhibit only dispersion forces as intermolecular attractions.
Alkenes and alkynes exhibit only dispersion forces as intermolecular attractions.
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The hydrogen atom of a terminal alkyne has a pKa value higher than that of water.
The hydrogen atom of a terminal alkyne has a pKa value higher than that of water.
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For an alkene with two carbon-carbon double bonds, a total of four cis-trans isomers can be formed.
For an alkene with two carbon-carbon double bonds, a total of four cis-trans isomers can be formed.
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Terminal alkynes are more acidic than alkenes and alkanes with similar structures.
Terminal alkynes are more acidic than alkenes and alkanes with similar structures.
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Cycloheptene cannot accommodate a trans double bond due to its size.
Cycloheptene cannot accommodate a trans double bond due to its size.
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Hydroxide ion is a strong enough base to remove a hydrogen from a terminal alkyne.
Hydroxide ion is a strong enough base to remove a hydrogen from a terminal alkyne.
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The physical properties of alkenes and alkynes are identical to those of alkanes.
The physical properties of alkenes and alkynes are identical to those of alkanes.
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Study Notes
Alkenes and Alkynes
- Unsaturated Hydrocarbons: Contain one or more carbon-carbon double or triple bonds, or benzene-like rings.
- Alkene: Contains a carbon-carbon double bond, general formula CnH2n.
- Alkyne: Contains a carbon-carbon triple bond.
- Arene: Benzene and its derivatives (Chapter 9). Although benzene contains C-C double bonds, they are not reactive in the same ways as in chapters 4-8. Phenyl groups aren't reactive under conditions described in chapters 5-8.
- Benzene and Phenyl Groups: Benzene and its derivatives are covered in Chapter 9 later. Structural formulas of compounds containing phenyl groups are shown before that.
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Structure of Alkenes: Carbon atoms of a double bond and the atoms bonded to them lie in a plane, bond angles ~120°.
- Ethylene, Propene: Examples with diagrams.
- Figure 4.1: A double bond consists of one σ bond formed from overlap of sp2 hybrid orbitals, and one π bond from overlap of parallel 2p orbitals. Rotating by 90° breaks the pi bond.
- Cis-Trans Isomerism: Restricted rotation around a C—C double bond causes groups to be either cis or trans. Trans is more stable because of nonbonded interaction strain.
- Structure of Alkynes: The functional group is a carbon-carbon triple bond, which consists of one σ bond formed by the overlap of sp hybrid orbitals, and two π bonds from overlap of sets of parallel 2p orbitals.
- Nomenclature of Alkenes: Use the infix "-en-" to indicate the presence of a carbon-carbon double bond. Number the parent chain to give the first carbon of the double bond the lower number. Follow IUPAC rules for numbering and naming substituents. For a cycloalkene, number the ring atoms starting with the carbons of the double bond.
- Examples of nomenclature: Several examples are present in the text (1-hexene, 4-methyl-1-hexene, 2-Ethyl-3-methyl-1-pentene, 3-Methyl-1-butyne, 6,6-Dimethyl-3-heptyne). Common names are also shown (e.g., ethene/ethylene, propene/propylene, 2-Methylpropene/Isobutylene).
- Nomenclature of Alkynes: Use the infix "-yne-" to indicate the presence of a carbon-carbon triple bond, similar to alkene naming.
- Configuration: Cis-Trans: Cis-trans configuration determined by the orientation of atoms in the main chain.
- Configuration: E/Z: Assign priority to substituents on each carbon of the double bond. Z configuration if higher priority groups are on the same side. E configuratin if they are on opposite sides.
- Priority Rules (E/Z): Priority based on atomic number (higher = higher priority). If priorities cannot be determined from directly bonded atoms, look at the next set of atoms.
- Configuration (E/Z): Atoms in a double or triple bond are treated as equivalent. Example diagrams given.
- Physical Properties: Alkenes and alkynes are nonpolar, with dispersion forces as the only intermolecular attraction. Physical properties are similar to corresponding alkanes with similar carbon skeletons. Liquids are less dense than water and soluble in each other and nonpolar solvents. Insoluble in water.
- Acidity of Terminal Alkynes: Terminal alkyne hydrogen is sufficiently acidic (pKa 25) to be removed by strong base NaNH2, forming an alkyne anion. Acidity is attributed to the stability of the alkyne anion (50% s character). Acidity compared to alkanes and alkenes (e.g., pKa values).
- Problem 4.39: Zoapatanol in Montanoa tomentoa. (a) Specify the configuration of each C—C double bond. (b) Determine the possible cis-trans isomers.
- Problem 4.40: Pyrethrin II and pyrethrosin from chrysanthemum family. (a) Label C—C double bonds for cis/trans isomerism. (b) Determine number of possible isomers.
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Description
Test your knowledge on unsaturated hydrocarbons, including alkenes, alkynes, and arene structures. This quiz covers the properties, formulas, and examples of these compounds as discussed in Chapter 9. Dive into the details of carbon-carbon bonds and their structural implications.
