Resonance effect for people and the understanding

The transfer of electrons from one end of conjugation (pi-system) to the other through delocalization of electrons is called resonance.

When a compound can be represented by more than one Lewis structure and actual structure is hybrid of all these structure, the compound is said to possess resonance.

The increase in electron density at one position with corresponding decrease at another position is called resonance effect or mesomeric effect.

1. Resonance Effect Reya Organic chemistry – Some basic principles and Technologies

2. Introduction Resonance Effect Introduction Types Positive Resonance The transfer of electrons from one end of conjugation (pi-system) to the other through delocalization of electrons is called resonance. When a compound can be represented by more than one Lewis structure and actual structure is hybrid of all these structure, the compound is said to possess resonance. The increase in electron density at one position with corresponding decrease at another position is called resonance effect or mesomeric effect. 2 Negative Resonance Thanks

3. Types Reya Types Positive Resonance Negative Resonance Thanks 3 Introduction Type-1 Type-2 Positive Resonance {+R/+M} Negative Resonance {-R/-M}

4. Positive Resonance Reya Positive Resonance Negative Resonance Thanks 4 Introduction Types Positive The electron releasing groups show +M/+R effect, when they release electron to the rest of the molecule by delocalization. The electron density on rest of the molecule increased. Example:- -OH, -SH, -OR, -SR

5. Reya Positive Resonance Thanks 5 Introduction Types Negative Resonance Negative Resonance Negative The electron withdrawing groups leave –M/-R effect by attracting delocalised electrons from rest of the molecules as a result the electron density decreases on the rest of the molecules. Example:- -NO 2 ,C=O, -COOH, -C = N.

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7. Thank You R Reya