. Explain Electromeric Effect with Positvie and Negative Effect
In presence of an electrophile, there is complete transfer of -electrons from one atom to other to produce temporary polarity on atoms joined by multiple bonds; it is called Electromeric Effect.
If electrophile is removed, charge disappears and substrate attains its original form. Thus this effect is reversible and temporary.
Positive Electromeric Effect
When -electrons transfer takes place C to C (as alkenes, alkynes etc.) it is called Positive Electromeric effect (denoted byb E+)
In this there is also (+I) effect of –CH3 group which cause - electron transfer C2 to C1. What do you think in the following case?
(+I) effect of CH3CH2— is larger than that of CH3–, hence electron transfer is from C3 to C2
Negative Electromeric Effect
When pie electrons transfer takes place to more electronegative atom (O,N,S) joined by multiple bonds, it is called Negative Electromeric Effect (denoted by E–)