Which of the following compounds will form significant amounts of meta product during mono-nitration reaction?

Question

Hi, I tried to answer this question based wholly on the concepts of inductive effects. But haven't gotten anywhere with it. I would appreciate any help regarding these questions:

What condition makes a compound to give meta product(instead of ortho or para)?
I know there is some flaw with my approach, so what is the correct way to do it?
Can this condition be applied to other compounds as well, or is it just for aromatic compounds?

Which of these compounds will protonate under nitration conditions? Will this change the directing properties? — Waylander, Jan 06 '19 at 20:27
@Waylander As far as I know, all these compounds are ortho-para directors. So, I am really confused how do they give more amounts of meta product. — The Jokster, Jan 06 '19 at 20:31
Would aniline protonate under std nitration conditions of sulfuric acid/nitric acid? Would the anilinium cation still be o/p directing? — Waylander, Jan 06 '19 at 20:46
The answer is it is no longer a strong director once it is protonated so you get a fair bit of meta. — Waylander, Jan 06 '19 at 20:55
@Waylander Okay. But why does it change its character from o-p director to meta director? — The Jokster, Jan 06 '19 at 20:58

Waylander · Accepted Answer · 2019-01-06T21:52:28.350

The answer to the question is (1) Aniline.

This occurs because under standard strongly acidic nitrating conditions (typically cH2SO4/HNO3) the aniline NH2 is protonated removing the ability of nitrogen lone pair to donate any electrons. Consequently the electron-withdrawing polar effect makes it m-directing. Some p-nitroaniline is formed because there is a small amount of the aniline freebase in equilibrium with the anilinium, but that is much more reactive than the anilinium.

Which of the following compounds will form significant amounts of meta product during mono-nitration reaction?

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