Question

what is mesomeric effect??

Answer 1

The mesomeric effect in chemistry is a property of substituents or functional groups in a chemical compound. The effect is used in a qualitative way and describes the electron withdrawing or releasing properties of substituents based on relevant resonance structures and is symbolized by the letter M. The mesomeric effect is negative (–M) when the substituent is an electron-withdrawing group and the effect is positive (+M) when the substituent is an electron releasing group.

+M EFFECT ORDER

- O > -NH2 > -NHR > -OR > -NHCOR > -OCOR > -Ph > -F > -Cl > -Br > -I

-M EFFECT ORDER

-NO2 > -CN > -CHO > -C=O > -COOCOR > -COOR > -COOH > -CONH2 > -COO−

Answer 2

The mesomeric effect in chemistry is a property of substituents or functional groups in a chemical compound.