ELECTROMERIC EFFECT Class xii What is electromeric effect

ELECTROMERIC EFFECT Class xii

What is electromeric effect? (ELECTRO= ELECTRON, MEROS= PART) Temporary effect which is observed in presence of reagents involving transfer of electrons in an unsaturated system.

ELECTROMERIC EFFECT

TYPES OF ELECTROMERIC EFFECT 1. Positive Electromeric Effect 2. Negative Electromeric Effect

POSITIVE ELECTROMERIC EFFECT In this effect the pi-electrons of the multiple bond are transferred to that atom to which the reagent gets attached.

POSITIVE ELECTROMERIC EFFECT

NEGATIVE ELECTROMERIC EFFECT In this the pi-electrons of the multiple bond are transferred to that atom to which the attacking reagent does not get

NEGATIVE ELECTROMERIC EFFECT

ADDITION OF HBr TO AN ALKENE

ELECTROMERIC EFFECT This effect is very helpful in explaining polarization produced in a substrate molecule containing multiple bonds. Poloarity is caused by the complete transfer of an electron-pair to one of the two atoms joined by the multiple bond. This is purely a temporary effect.

ELECTROMERIC EFFECT DIFFERENT FROM INDUCTIVE EFFECT ELECTROMERIC EFFECT INDUCTIVE EFFECT Ø Shown by substrate molecules containing double or triple bonds. q Shown by molecules containing single bonds. Ø Takes place when the molecule is exposed to an attack of a reagent. q Takes place under the influence of a substituent Ø Polarity is caused by complete q Polarity is caused by the transfer of electron-pair to one of the displacement of bonding electrontwo atoms joined by multiple bond. pair from one atom towards the other. Ø It is temporary effect. q It is permanent effect. Ø The effect disappears with the removal of the attacking reagent. q This effect depends on the structure of the substrate molecule.