CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

Please explain +E and -E electromeric effects with examples.


Open in App
Solution

Electromeric effect:

  • The electromeric effect is a temporary effect operating in unsaturated compounds only at the demand of a nearby reagent.
  • It involves the complete transfer of π electrons of multiple bonds.
  • During the attack of a carbonyl group by a nucleophile the π-electron pair-bonding the Carbon and Oxygen is transferred entirely to Oxygen, that is,

  • Here the positively charged Carbon in the above-polarised structure of the carbonyl group is then the center of attack by the nucleophilic reagent.
  • The displacement of the electron pair to Oxygen rather than to Carbon is due to the greater electronegativity of the Oxygen atom as compared to the Carbon atom.
  • The Electromeric effect is also of two types i.e. +E effect and –E effect.

+E effect:

  • When the transfer of π electrons takes place towards the atom where the attacking reagent (Electrophile) gets finally attached, the effect is called +E effect.

  • The example of the +E effect is

  • Here the double bond breaks and the transfer of π electrons takes place towards the Hydrogen ion

–E effect

  • When the transfer of π electrons occurs away from the attacking reagent ('Nucleophile), the effect is called -E effect.

  • The example of -E effect is

  • Here the double bond breaks and the transfer of π electrons occurs away from the Cyanide ion.

flag
Suggest Corrections
thumbs-up
3
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Electromeric Effect
CHEMISTRY
Watch in App
Join BYJU'S Learning Program
CrossIcon