Aniline is one of the most essential amine substances. It is mainly used to manufacture dyes, drugs, and resins, as a rubber vulcanization accelerator, etc. It can also be used as a black dye by itself. Its derivative methyl orange can be used as an indicator for acid-base titration.
The industrial production of aniline involves the following two steps. First, benzene is nitrated at 50-60 °C in a mixture of concentrated sulfuric acid and concentrated nitric acid to give nitrobenzene; the latter is then catalytically reduced by hydrogenation (reaction temperature usually between 200-300 °C).