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2,3-Diaminonaphthalene is a highly selective colorimetric and fluorometric reagent for selenium detection and also used for the fluorometric determination of nitrite. It is also useful for detection of ketones and alpha-keto acids.
2,3-Diaminonaphthalene reacts with nitrosonium, which is formed from nitrite at low pH, to form the fluorescent dye 1 H-naphthotriazole. This method can be used to detect 10 nM to 10 uM of nitrite (NO2-) and is compatible with 96-well format.
Fluorometric probe for nitrite
Quantify 10 nM to 10 uM of nitrite
Yellow orange solid soluble in DMSO

colourless to white crystalline powder

2,3-diaminonaphthalene (DAN) is a fluorometric probe for nitrite. It reacts with nitrosonium, which is formed from nitrite at low pH, to form the fluorescent dye 1 H-naphthotriazole. This method can be used to detect 10 nM to 10 uM of nitrite (NO2-) and is compatible with 96-well format.

Reaction of 2,3-Diaminonaphthalene with NO2.

General procedure for the synthesis of 2,3-diaminonaphthalene from 2,3-dichloronaphthalene: Dissolve 2,3-dichloronaphthalene (2 g) in anhydrous ethanol. Ammonium chloride (1.5 g) was added and diluted. Subsequently, a catalytic amount of hydrochloric acid and an excess of concentrated aqueous ammonia solution were added to the reaction system and the reaction was refluxed on a water bath for 6 hours until the reaction solution showed a persistent dark green color. After completion of the reaction, the reaction solution was cooled and placed in a deep freezer overnight. Green crystals were obtained by filtration, dried and recrystallized with methanol. Dark green crystals were obtained; 75% yield; thin layer chromatography Rf values of 0.89 and 0.82; melting point 150 °C; IR spectra (νmax, KBr, cm-1): 758, 854, 1473 (aromatic C-N stretching vibration), 1500 (aromatic C=C stretching vibration), 1681 (N-H bending vibration), 3049 (N-H stretching vibration); 1H NMR (CDCl3, 500 MHz): δ 7.45-7.46 (dd, J=3.5-4 Hz, 2H, Ar-H), 7.12-7.14 (dd, J=3-3.5 Hz, 2H, Ar-H), 7.09 (s, 2H, Ar-H), 7.05 (s, 4H, Ar-NH2).

Crystallise the diamine from water, or dissolve it in 0.1M HCl, by heating to 50o. After cooling, the solution is extracted with decalin to remove fluorescent impurities and centrifuged. [Beilstein 13 IV 346.]

[1] Oriental Journal of Chemistry, 2017, vol. 33, # 2, p. 821 - 828