Concept explainers
(a)
Interpretation:
The given molecule is chiral or not is to be identified.
Concept introduction:
The absence of chiral centers does not guarantee that a molecule is achiral. For a molecule to be chiral, it must not be superimposable on its mirror image. Allenes are the cumulated dienes in which one carbon atom is attached with each of its two neighbouring carbon atoms by double bonds. Disubstituted allenes are the ones in which the two hydrogen atoms on the same carbon or on adjacent carbon atoms are replaced by two non-hydrogen substituents.
Examine both “ends” of the allene. If either of those ends is attached to two identical substituents, it is achiral – because it will have a mirror plane. If neither of the ends are attached to two identical substituents, then it is chiral.
(b)
Interpretation:
The given molecule is chiral or not is to be identified.
Concept introduction:
The absence of chiral centers does not guarantee that a molecule is achiral. For a molecule to be chiral, it must not be superimposable on its mirror image. Allenes are the cumulated dienes in which one carbon atom is attached with each of its two neighbouring carbon atoms by double bonds. Disubstituted allenes are the ones in which the two hydrogen atoms on the same carbon or on adjacent carbon atoms are replaced by two non-hydrogen substituents.
Examine both “ends” of the allene. If either of those ends is attached to two identical substituents, it is achiral – because it will have a mirror plane. If neither of the ends are attached to two identical substituents, then it is chiral.
(c)
Interpretation:
The given molecule is chiral or not is to be identified.
Concept introduction:
The absence of chiral centers does not guarantee that a molecule is achiral. For a molecule to be chiral, it must not be superimposable on its mirror image. Allenes are the cumulated dienes in which one carbon atom is attached with each of its two neighbouring carbon atoms by double bonds. Disubstituted allenes are the ones in which the two hydrogen atoms on the same carbon or on adjacent carbon atoms are replaced by two non-hydrogen substituents.
Examine both “ends” of the allene. If either of those ends is attached to two identical substituents, it is achiral – because it will have a mirror plane. If neither of the ends are attached to two identical substituents, then it is chiral.
(d)
Interpretation:
The given molecule is chiral or not is to be identified.
Concept introduction:
The absence of chiral centers does not guarantee that a molecule is achiral. For a molecule to be chiral, it must not be superimposable on its mirror image. Allenes are the cumulated dienes in which one carbon atom is attached with each of its two neighbouring carbon atoms by double bonds. Disubstituted allenes are the ones in which the two hydrogen atoms on the same carbon or on adjacent carbon atoms are replaced by two non-hydrogen substituents.
Examine both “ends” of the allene. If either of those ends is attached to two identical substituents, it is achiral – because it will have a mirror plane. If neither of the ends are attached to two identical substituents, then it is chiral.
(e)
Interpretation:
The given molecule is chiral or not is to be identified.
Concept introduction:
The absence of chiral centers does not guarantee that a molecule is achiral. For a molecule to be chiral, it must not be superimposable on its mirror image. Allenes are the cumulated dienes in which one carbon atom is attached with each of its two neighbouring carbon atoms by double bonds. Disubstituted allenes are the ones in which the two hydrogen atoms on the same carbon or on adjacent carbon atoms are replaced by two non-hydrogen substituents.
Examine both “ends” of the allene. If either of those ends is attached to two identical substituents, it is achiral – because it will have a mirror plane. If neither of the ends are attached to two identical substituents, then it is chiral.
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Chapter 5 Solutions
Organic Chemistry: Principles and Mechanisms (Second Edition)
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