1 Answer | Add Yours
During second electrophilic substitution on benzene ring the position of entry of the incoming group is dictated by the electronic effects imparted upon by the group already sitting there. Methoxy (-OCH3) is an electron donating group (+I, as well as +M) and this additional electron density is delocalised through resonance toward the 2-, 4- and 6- positions with respect to it. Hence the incoming (second) group as E+ favours to enter into these positions i.e. o- and p- positions. The 3- 1nd 5- positions (m-) are not directly fed this extra el. density and as such reman a disfavoured destination for the incoming E+. Hence the result.
We’ve answered 318,946 questions. We can answer yours, too.Ask a question