[Mr Despair]

why can't Markownikoff's rule be applied on HNO3?
is it that the N atom is slightly positive, thus the carbocation repels it?

[Schrödinger]

What is the reaction that you're dealing with?
HNO₃ is a strong oxidizing agent, so there are possibilities that the reaction that you look for does not actually happen.

[Mr Despair]

What is the reaction that you're dealing with?
HNO₃ is a strong oxidizing agent, so there are possibilities that the reaction that you look for does not actually happen.

i just read the marking scheme of a school's test paper and it stated this:

Markownikoff's Rule: in the addition of an acid to the carbon-carbon double bond of an alkene, the hydrogen of the acid attaches itself to the carbon that already holds the greater number of hydrogens.
             CH3CH==CH2      H--Z     [ CH3HC+-CH3] + Z-   CH3CH(Z)-CH3         
           
            Acids could be HI, HCl, H2SO4, H3O+, HX but not HNO3. The mechanism is electrophilic   
            Addition.

I don't get the point why can't HNO3 do it

[Jorriss]

I think what it is is that, it's not that Nitrate is an exception, it just won't react and bond with your carbocation.

With HI, the hydrogen will bind with the electrons from the double bond leaving a carbocation and then the iodine will bond with the carbocation. Same for sulfuric acid, etc. But I don't think Nitrate would.

[hobobot]

someone correct me if i=I'm wrong, but since the negative charge of NO3- is on the oxygen wouldn't you end up with a R-O-NO2 bond?

[Mr Despair]

someone correct me if i=I'm wrong, but since the negative charge of NO3- is on the oxygen wouldn't you end up with a R-O-NO2 bond?

i'm wondering whether the resonace of NO3- inhibits the reaction to occur

[Jorriss]

someone correct me if i=I'm wrong, but since the negative charge of NO3- is on the oxygen wouldn't you end up with a R-O-NO2 bond?

i'm wondering whether the resonace of NO3- inhibits the reaction to occur

I don't think it's that it stops it as much as, it's not energetically favored, sulfate or phosphates react and they too have resonance stabilization.