Question

Once phenol is nitrated, would the major organic product formed be: ortho, meta, para or a combination?

Answer 1

I'm assuming you mean if phenol is nitrated, not after it's nitrated. In that case, phenol is otherwise known as hydroxybenzene.

The hydroxyl group is an electron-donating group. Those strongly-activate the ring for electrophilic aromatic substitution, the mechanism of nitration, at the ortho + para positions.

The following is the nitration mechanism for just benzene.

1. Nitric acid has a higher pKa than sulfuric acid (`-1.3` vs. `-3`), so it is readily protonated. NOTE: In order for the mechanism to proceed, it must be protonated on the hydroxyl!
2. The newly-generated `"H"_2"O"` leaving group leaves, giving an activated nitronium ion.
3. This becomes the electrophile for the nucleophile to attack in electrophilic aromatic substitution (EAS).
4. The EAS mechanism finishes when some base comes in to eliminate the proton adjacent to the carbocation, restoring aromaticity.

Maybe you can analogize with phenol; the only difference is that an `"OH"` is on the top-middle carbon.

Strongly-activating groups are ortho/para directors, but the nitration product would be a mixture (not combination) of the ortho and para products.