[plankk]

It is commonly known how to reduce a nitro compounds to an amine. But I've never heard about a converse route. Is it possible? If yes, with which substrate?

Thanks in advance.

[Arctic-Nation]

I've never done more than check on Scifinder to test the possibility of a theorethical synthetic route involving such an oxidation, but from what I can remember, yes, it is possible. I don't know any typical reagents, but most very strong oxidizers should be able to do the trick (peroxides, ozone, permetallates,...). However, these reactions tend not to be very clean, and that's why my supervisor advised me not to use them. Yields are a lot lower than with the reduction reaction, and good luck with any other group even remotely sensitive to oxidation. However, choose your substrate and conditions wisely, and it will work.

[Smrt guy]

Tertiary amines can be converted to the corresponding N-oxides by using peracids such as mCPBA.  In principle it seems as though the reaction should work with primary amines as well, but as I've never seen the reaction, it is probably not useful for some reason.

[fawad0418]

probably best n efficient way is to use dimethyl dioxirane..

[408]

Reagent depends on the substrate.

Diaminofurazan can be converted to aminonitrofurazan with H2SO4, H2O2, and ammonium peroxydisulfate.

Alkyl amines can be converted in low yield by ozone when supported on silica.

Many amine--> NO2 reactions are actually sandmeyer reactions where nitrite is the nuclephile.  Example the synthesis of nitrotetrazole from aminotetrazole.