Reaction between 1,3-dimethylbenzene and HNO3, H2SO4

Question

So this reaction will add a NO2 group to the benzene ring but is there a way to tell on which carbon in the ring will the NO2 group add onto because the mark scheme says to allow any 4-nitro-1,3-dimethylbenzene structure as an answer so would the NO2 group have to join onto the 4th carbon and how would you know its that one?

Answer 1

1, 3 dimethyl benzene has two ortho, para directing groups. Therefore the "2", "4" and "6" positions would be favored. We know that para is slightly more favored than ortho, so that rules out the "2" position, in which the nitro group is ortho to both groups, which is sterically unfavorable.

Now, try drawing the nitro group in the "4" or in the "6" position and what do you find? they are the same molecule!! So the mayor product will be 4-nitro-1, 3-dimethylbenzene.