[desperad0oo7]

How can you synthesize a benzene ring with 2 nitro groups in ortho position to each other?
 I was told it's possible but can't figure out a synthesis process.

[Custos]

The standard way is to start with aniline, acylate it with acetic anyhdride to make the amide and then nitrate with nitric acid and sulphuric acid. You get a mixture of ortho and para nitroanalides which can be separated. Then the analide is hydrolysed and the aniline product treated with sodium nitrite and HBF₄ to make the diazonium fluoborate. This is treated with sodium nitrite and copper in water to give the ortho dinitrobenzene. (see for example Organic Syntheses, Coll. Vol. 2, p.225 (1943) for the similar para dinitrobenzene proceedure).

The fluoroboric acid is made by adding boric acid slowly to hydrofluoric acid. This is not for the faint hearted - it has to be done slowly, in and ice bath and in a copper, lead, or silver-plated container placed. HBF₄ is pretty nasty.

[AhmedEzatAlzawalaty]

1-benzene+HNO3/CH2SO4=NitroBenzene
2-Nitrobenzene+SnCl2/HCl=Aniline
3-Aniline+CH2SO4/CHNO3=ortho nitro aniline
4-ortho nitro aniline + H2SO5(Caro?s acid)=orho nitroso nitro benzene
5-the latter + HNO3=Ortho dinitro benzene.
 
and i dont know how to draw it and send.

[charco]

Why doesn't the bulky N substuituted amide group on the benzene ring sterically hinder the ortho position and leave just the para nitro substituted intermediate?

[RBF]

It's not that bulky.  Besides the -C(O)CH3 group, the N atom has only a lone pair and H atom surrounding it.  Electrophiles can attack at the ortho position without much steric interference.

[maakii]

Why can't we use NaNO₂ and H₂SO₄, instead of HBF₄? Is there a special significance of using that nasty acid?

[Custos]

3-Aniline+CH2SO4/CHNO3=ortho nitro aniline.

Aniline tends to oxidise in nitric acid giving a black tar. Nitrating the anilide is a much cleaner reaction.

Regarding the use of HBF₄, it's possible to use sulfuric acid I guess but you run the risk of hydrolysis to the phenol. Also, the diazonium fluoroborates are pretty stable compared to the diazonium sulfates or chlorides. Concentrated sulfuric is pretty nasty too 

[desperad0oo7]

1-benzene+HNO3/CH2SO4=NitroBenzene
2-Nitrobenzene+SnCl2/HCl=Aniline
3-Aniline+CH2SO4/CHNO3=ortho nitro aniline
4-ortho nitro aniline + H2SO5(Caro?s acid)=orho nitroso nitro benzene
5-the latter + HNO3=Ortho dinitro benzene.
 
and i dont know how to draw it and send.

In step 3 u can't add nitro to ortho position in acidic conditions, once you do that the amine would be protonated and becomes a meta deactivator.

[desperad0oo7]

would this work?
start with benzene
1-make chlorobenzene (Cl2/AlCl3)
2-sulfonate at para position with (H2SO4)
3-nitrate at ortho position to chlorine with (H2SO4/HNO3)
4-because the ring is very low in electron density with deactivatore in ortho and para to Cl u can substitue Cl with NH2 via nucleophilic aromatic substitution (-NH2)
5-remove the sulfonate group with water and heat.
6-oxidize the NH2 to NO2 as mentioned above.

would that work?