different types of hyperconjugation with it's explanation
Answers
Hyperconjugation Examples
- Ethyl carbocation. ...
- Nitromethane. ...
- Acetonitrile and propyne. ...
- Toluene. ...
- Stability of unsaturated hydrocarbons. ...
- Stability of reaction intermediates. ...
- Anomeric effect.
There are many molecules and reaction intermediates which can show hypercojugation. Some of the common examples are following.
1. Ethyl carbocation
In carbocation such as ethyl carbocation, the sigma electrons of Csp3-hydrogen bond are delocalized with empty p-orbital of positively charged carbon atom and show four contributing structures
Ethyl Carbocation
2. Iso-propyl carbocation
Like ethyl carbocation, iso-propyl carbocation also shows hyper conjugation. In this intermediate, there are six carbon- hydrogen sigma bonds which can interact with pi-electron therefore it shows seven contributing structures and more stable than ethyl carbocation.
Iso-Propyl Carbocation
3. Free radicals
Similarly free radicals get stabilized through hyper conjugation. Like carbocation, the sigma electrons of carbon-hydrogen bonds of methyl group next to carbon atom contain odd electron interact with p-orbital having odd electron. As the number of alpha carbon-hydrogen bond increases, contributing structures increases results more stability.
Free Radicals
4. Nitromethane
The nitrogen-oxygen pi-bond interacts with alpha carbon-hydrogen bond and show hyper conjugation.
Nitromethane
5. Acetonitrile and propyne
The presence of triple bond between carbon-carbon or carbon-nitrogen also show hyper conjugation with alpha carbon-hydrogen bond like in acetonitrile and propyne molecule.
Acetonitrile and Propyne
6. Toluene
The carbon - hydrogen sigma bond interacts with pi-bond of aromatic ring to form four contributing structures of toluene.
Toluene
7. 2-Butene
The interaction of pi-bond with alpha carbon-hydrogen bond forms six resonating structure of 2-butene. While 1-butene shows only two contributing structures and less stable than 2-butene.
2-Butene