. Explain Electromeric Effect with Positvie and Negative Effect


Best Answer

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.

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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+)

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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?

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(+I) effect of CH3CH2— is larger than that of CH3–, hence  electron transfer is from C3 to C2

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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–)

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