(a)
Interpretation:Whether norbornene is chiral or not should be explained.
Concept introduction:Chiral carbon is any stereocenter attached to four different alkyl substituents. If any two of the substituent happen to be similar the center is regarded as achiral. However, the most essential criteria that help to distinguish a chiral or non-chiral system ispresence of any symmetry element. If any plane center or axis of symmetry is identified it makes molecule achiral and optically inactive.
Four kinds of symmetry elements that may be present are tabulated as follows:
The non-classical cation is unique carbocation that involves delocalization of electron density of filled bonding orbital over three carbons. It exists for systems such as phenonium ions,norbornyltosylate, brosylate, and nortricyclonium cations. They can be understood as carbocation that has transition state for two asymmetric equilibrium cation derived from anchimeric-assistance that represents neighboring group participation in the stabilization of positive charge as illustrated below.
(b)
Interpretation:Three chiral centers in
Concept introduction:Chiral carbon is any stereocenter attached to four different alkyl substituents. If any two of the substituent happen to be similar the center is regarded as achiral. However, the most essential criteria that help to distinguish a chiral or non-chiral system ispresence of any symmetry element. If any plane center or axis of symmetry is identified it makes molecule achiral and optically inactive.
(c)
Interpretation: Chemical structure for the stereoisomer of
Concept introduction: Chiral carbon is any stereocenter attached to four different alkyl substituents. If any two of the substituent happen to be similar the center is regarded as achiral. However, the most essential criteria that help to distinguish a chiral or non-chiral system isthe presence of any symmetry element. If any plane center or axis of symmetry is identified it makes molecule achiral and optically inactive.
The enantiomers are identical chemical compounds that have a mirror-image relationship to each other while diastereomers do not hold mirror image relationships.
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