[liznerd]

Hello, would hope to gain some enlightenment from here..

1)Why do we not need H2SO4 as acid catalyst for dinitration of veratrole?

2)and why does the 2nd nitro groups go to positions 4 or 5, following the directing effects of the MeO- group? Doesnt the first nitro group that has been substituted into the compound have any efect on its position?

[OrgXemProf]

Some points to consider:

I. Question 1): By what mechanism might sulfuric acid serve as a catalyst to promote nitration of benzene?

2. What do you know about the relative reactivity of benzene rings that bear electron withdrawing (EW) vs. electron donating (ED) substituents toward electrophiles (like NO2⁺)? Then, when a ring contains both EW and ED substituents, which type of substituent is likely to win out in the competition to direct attack by an incoming electrophile?
 
3. Question 2) implies that the first nitration step places NO2 into the 3- (or 6-) position of veratrole, leaving the 4- (or 5-) position free to incorporate NO2 in the second nitration step. Can you explain why you believe that substitution by the first NO2 group prefers the 3- (rather than 4-) position in veratrole?