SWIM always thought that Pd/Pt catalyts were used because they gave complete saturation of the molecule, but according to the ref. above and Barium, they don't.
So how does one know if hydrogenation of a nitrostyrene will yield an oxime or an amine? SWIM has read numerous papers on reductions of nitrostyrenes to amines using solvent/strong acid/catalyst(Pd or Pt) substrates. Will the use of a strongly acidic media yield primary amine, and not the oxime?
Possibly not using the acid inhibits hydrogenation, causing only partial saturation and leaving the amino-carbon double bond? With further saturation SWIM would bet there would also be some hydroxylamine product too, but those are also yummy.
So bottom line, if partial saturation occurs we will have at least oxime,
R-CH=N-OH, which can give a variety of products with continued hydrogenation...
1. R-CH2-NH2 + H2O
2. R-CH2-NH-OH
3. R-CH=NH + H2O
1 is great, 2 is acceptable, but 3 nobody wants.
Will higher pressures(4-5 bar), more catalyst, and more time(24h) help complete saturation of the starting alkene? SWIM wants an elegant one-pot nitrocompound --> amine, not a series of dual stage partial hydrogenations. (Barium's is a special case, because it involved and acid-sensitive molecule)
Skita and Keil, Ber. 65, 424 (1932) describes reductions of nitriles, oximes, and nitrostyrenes to amines using platinum catalysts. So why are there so many conflicting reports!
Can somebody please help SWIM out?