Sciencemadness Discussion Board

Can fuming nitric acid be used for nitration without sulfuric acid?

nagyepf - 25-2-2020 at 09:37

If 68% HNO3 mixed with 98% H2SO4 works well what is the sense of using >99%HNO3?Is it usable without H2SO4?

wessonsmith - 25-2-2020 at 10:26

Here is a 2014 patent on nitration.

They do indicate that you can nitrate some things without sulfuric acid.

https://patentimages.storage.googleapis.com/12/e3/0f/29467c7...

I make my ETN by first dehydrating it in sulfuric acid. This process eliminates the possibility of a runaway reaction when I add it to the fuming nitric acid for nitration. For the record, I use 98% sulfuric acid. Not that water down 93% crap you get at the hardware store. With that same sulfuric acid I produce fuming nitric acid with a potassium nitrate/sulfuric acid distillation.

[Edited on 25-2-2020 by wessonsmith]

greenlight - 25-2-2020 at 10:30

The 70% nitric to 98% sulfuric mixture is generally used for C-nitration of aromatics with higher conc nitric and temps for the final NO2 addition.
The mixture is also generally used for o-nitration for nitro esters, but I have seen people use 99% nitric and sulfuric for PETN before.
The same result can be obtained from the 70% nitric and sulfuric so why waste 99% nitric.
The sulfuric acid is there more like a catalyst to absorb water formed during the nitration. It may also serve another purpose that escapes me at this moment.

99% nitric is used on its own for N-nitrolysis though for explosives likeRDX, HMX, etc. The nitrolysis of hexamine dinitrate for instance uses only 99% nitric to form the final RDX.

B(a)P - 25-2-2020 at 10:32

Many things can be nitrated using 99% HNO3 or even 68% HNO3 with out H2SO4. What are you wanting to nitrate?

nagyepf - 26-2-2020 at 12:04

Quote: Originally posted by B(a)P  
Many things can be nitrated using 99% HNO3 or even 68% HNO3 with out H2SO4. What are you wanting to nitrate?

Nothing,I am just interested for example if we react cellulose or glycerol with nitric acid without adding sulfuric acid,will we get nitrocellulose and nitroglycerin?

Tsjerk - 26-2-2020 at 14:08

Yes, to a degree, depending on how much nitric you use.

caterpillar - 3-3-2020 at 03:24

Use it for the preparation of nitramines. Some interesting organic salts can be prepared as well. And there are some compounds, that require N2O5 dissolved in HNO3. Such a solution can be prepared if you have P2O5.

Madchemistrystudent - 22-3-2020 at 12:02

Nitration produces water which the sulfuric acid binds with to prevent water from forming.

njl - 22-3-2020 at 12:11

To add to what @Madchemistrystudent said, the sulfuric acid is there to push the equilibrium towards the nitrated product by preventing the water formed in the reaction from hydrolyzing the new bond. Some nitrations won't have water as a byproduct so an additional dehydrating agent isn't needed. But if the nitration if forming a nitro-ester (like in nitroglycering) there will be a byproduct of water.

rockyit98 - 23-3-2020 at 05:31

phenols and anilines can be able to perform nitration even with dil. HNO3.