1,8-Diaminonaphthalene

Off white powder. 1,8-Naphthalenediamine [479-27-6]. 1,8-diaminonaphthalene, Deltamin, C10H10N2, Mr 158.2, turns brown in air even in the absence of light. Its solutions give a brown precipitate on addition of iron(III) chloride. Treatment with boiling aqueous sodium bisulfite followed by addition of alkali gives 8-amino-1-hydroxynaphthalene. Sulfonation takes place in the 4- position. Coupling with azo compounds also occurs in the 4-position, but in almost neutral solution 4,5-bis coupling can occur. The resulting bisazo compound is reduced with SnCl2– HCl to give 1,4,5,8-tetraaminonaphthalene.

Lubricating-oil antioxidant, analytical reagent

1,8-Diaminonaphthalene is an important raw material and intermediate used in organic synthesis, pharmaceuticals and agrochemicals. 1,8-Naphthalenediamine has minor use as an antioxidant for lubricating oils and as an analytical reagent for the detection of selenium and nitrites.

Reduction of 1,8-dinitronaphthalene is carried out with iron and acetic acid in xylene or by catalytic hydrogenation.

Non flammable

Crystallise 1,8-diaminonaphthalene from water or aqueous EtOH, and sublime it in a vacuum. The N,N'-dimethyl derivative [20734-56-9] has m 103-104o and pK2 5 5.61, the N,N,N'-trimethyl-derivative [20734-57-0] has m 29-30o and pK2 5 6.43. [Hodgson et al. J Chem Soc 202 1945, Beilstein 13 IV 344.]