Sciencemadness Discussion Board

Would H2S reduce nitro groups to amines?

Tacho - 10-5-2005 at 04:35

For instance, would nitrobenzene become aniline by passing a stream of (very poisonous) H2S? Or would nitroethane become ethylamine if kept in a plastic bag with H2S?

Thanks in advance for any info.

Pyridinium - 11-6-2005 at 18:38

I know it's an old post, but nobody answered it, so...

I have a source that says you can reduce aromatic R-NO2 to R-NH2 with ammonium sulfide, amm. polysulfide, or sodium sulfhydride (NaHS). NaHS can be made by passing H2S into NaOH solution.

I don't know about direct reduction with H2S but it would probably work (under a ventilation hood).

Picramic acid

Lambda - 11-6-2005 at 20:08

Picramic acid, made via a solution of NaOH and saturating it with H2S and reacting this with picric acid (2-4-6 trinitrophenol), is a wel known route of -NO2 to -NH2 reduction. The same route may allso be performed with Na2S, instead of the above mentioned saturated solution. The enviroment of this reduction process is however basic in these cases.

Aniline on the other hand can be made by reducing nitrobenzene with Hydrogen "in situ". The Hydrogen is obtained by dissolving a metal like Fe or Zn in hydrochloric acid. The enviroment of -NO2 to -NH2 reduction is in this case acidic, and the resulting acid salt of aniline is thus formed.

In a basic enviroment, you most probably can use H2S for your -NO2 to -NH2 ruduction process.

A catalytic process may be optional.
Quote:
The never ending competition of mister basic and mister acid is fought out, who will win this time ?


[Edited on 12-6-2005 by Lambda]