Concept explainers
(a)
Interpretation:
Explain why the following equilibrium lies far to the right.
Concept introduction:
In chemistry, resonance is a systematic way to describe bonding nature of certain molecules of ions (cation or anion) by combining several structures which are contributing to the core structure. The various structures derived for a molecule is referred as resonance structures or canonical structures.
(b)
Interpretation:
Chemists had always assumed that this reaction would be so fast that compound A could never be isolated. However, this compound was prepared in 1962 and shown to be stable in the gas phase at 70°C, despite the favorable equilibrium constant for its transformation to B.Show why the conversion of A into B above would not be expected to occur as a concerted reaction.
Concept introduction:
Generally, Sigmatropic reaction is referred as the migration of allylic sigma bond at one end of the π-electron system to the other end of the π-electron system as an uncatalyzed intramolecular reaction. Though, the position of π-bond is changed in Sigmatropic reaction, the total number of π-bonds remain unchanged. The sigma bond can be cleaved at the middle or at the end of the π-system. The formation of sigma bond at 3, 3-position of a 1, 5-diene is called as cope rearrangement.
(c)
Interpretation:
The concerted mechanism for the following reaction is to be explained.
Concept introduction:
Generally, Sigmatropic reaction is referred as the migration of allylic sigma bond at one end of the π-electron system to the other end of the π-electron system as an uncatalyzed intramolecular reaction. Though, the position of π-bond is changed in Sigmatropic reaction, the total number of π-bonds remain unchanged. The sigma bond can be cleaved at the middle or at the end of the π-system. The formation of sigma bond at 3, 3-position of a 1, 5-diene is called as cope rearrangement.
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EBK ORGANIC CHEMISTRY
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