Types of Electromeric Effect

The electromeric effect can be classified into two types:

1. Positive Electromeric Effect (+E Effect): In this type, the Ï€-electrons are transferred towards the attacking reagent. For example, in the reaction of ethene with H⁺, the Ï€-electrons of ethene are transferred to the carbon atom that forms a bond with the proton.
2. Negative Electromeric Effect (-E Effect): In this type, the π-electrons are transferred away from the attacking reagent. For example, in the reaction of a carbonyl compound with a nucleophile, the π-electrons of the C=O bond are transferred towards the oxygen atom, making the carbon atom more positively charged and susceptible to attack by the nucleophile.