Hydrogen fluoride2 forms a suitable solvent in which catalytic hydrogenations can be carried out. Its well-known condensing action3 becomes a dominant factor when nitro compounds are hydrogenated by themselves or in the presence of second reactive components. Thus diphenylamines are obtained when aromatic nitro bodies substituted in the para position are hydrogenated in the presence of reactive second components. x-@ so2/+ o-.+ J0-q\-Y
![Phenol,4-[(4-methylphenyl)amino]- Structure](https://image.chemsrc.com/caspic/160/29813-87-4.png)