General organic chemistry reaction mechanism part 2
In this part General organic chemistry reaction mechanism part 2, discuss resonance effect. resonance effect also called mesomeric effect. The mesomeric effect in chemistry is a property of substituents or functional groups in a chemical compound. The mesomeric effect is negative (–M) when a 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 > –S(=O)2−OH > –CHO > –C=O > –COOCOR > –COOR > –COOH > –CONH2 > –COO−