It is the temporary effect in which displacement of pi-electron and lone pair of electron takes place in the presence of attacking reagent is called the electromeric effect.
if the attacking reagent is removed from the field of reaction, the field-effect is destroyed so this effect is called the temporary effect.
The electromeric effect occurs only in double-bonded systems. Thus this reaction or effect is seen in reaction media only.
The difference between the electrometric effect and inductive effect is that :
- Electromeric effect is the temporary efffect while the inductive effect is the permanent displacement and operates in sigma skeleton.
- Electromeric effect is dominated over inductive effect.
Examples:
- Markovnikov’s rule is an example of electromeric effect.
- Aldehyde and ketone giving nucleophili addition reaction is an example of electromeric effect.
- Aldol condensation is also an example of electromeric effect.
- Cross aldol and Claisen reaction is also is an example of electromeric effect.
- Alkene and Alkyne give electrophilic addition reaction , but alkynes under certain condition also give nucleophilic addition reaction. These cases are accompained by electromeric effect.