Nitro- and aminonaphthalenes

Nitronaphthalenes are obtained by treating naphthalene with nitric acid they form the basis for the production of naphthylamine. Since 2-naphthylamine has lost its earlier large-scale commercial importance, especially as a dye intermediate, because of its carcinogenic properties, mononitration of naphthalene is used exclusively today to produce 1-nitronaphthalene. 

When the nitration is carried out at 40 to 55 °C, the selectivity of the reaction can be well governed so that the 2-nitronaphthalene forms only 5% of the reaction product, and dinitronaphthalenes are formed to an extent less than 0.3%. The technical grade 1-nitronaphthalene is recovered from the reaction mixture by distillation. 

1-Nitronaphthalene is reduced with iron or hydrogen with nickel catalysts it is purified by distillation. In modem processes, the 2-naphthylamine content can be reduced to below 10 ppm. 

1-Naphthylamine is a significant intermediate for azo dyes and it is also used as the amino component in the manufacture of the herbicide naptalam Uniroyal), which is obtained by reaction with phthalic anhydride in xylene at 25 °C. 

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