N-(1-Naphthyl)ethylenediamine
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IUPAC name
N-(1-Naphthyl)-1,2-ethanediamine
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| Other names
N-1-Naphthyl-1,2-ethanediamine
Naphthylethylenediamine |
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
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PubChem CID
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| Properties | |
| C12H14N2 | |
| Molar mass | 186.26 g·mol−1 |
| Appearance | Off-white crystals (dihydrochloride) |
| Odor | Odorless |
| Density | 380 kg/m3 (dihydrochloride) |
| 30 g/1000 mL (dihydrochloride, 20 °C) | |
| Hazards | |
| Main hazards | Irritant |
| R-phrases (outdated) | R36 R38 |
| S-phrases (outdated) | S22 |
| NFPA 704 | |
| Flash point | Non-flammable |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
N-(1-Naphthyl)ethylenediamine, also called a 'Griess reagent' is an organic compound. It is commercially available and finds application in quantitative inorganic analysis of nitrates, nitrite and sulfonamide in blood, using Griess test.
This compound can be prepared by the reaction of 1-naphthylamine with 2-chloroethanamine. It is commercially available as the dihydrochloride salt.
N-(1-Naphthyl)ethylenediamine undergoes most reactions typical to naphthylamine and primary amines such as diazotation. Similar to its analog ethylenediamine, it can also act as a bidentate ligand to give several coordination compounds. However, it is a weaker bidentate ligand as the nitrogen atom in the naphthylamine group is weakly coordinating due to the dispersal of charge by resonance. For example, it reacts with potassium tetrachloroplatinate in aqueous solution to give (N-1-naphthyl-ethylenediamine)-dichloroplatinum(II).
N-(1-Naphthyl)ethylenediamine dihydrochloride is widely used in the quantitative analysis of nitrate and nitrite in water samples by colorimetry. It readily undergoes a diazonium coupling reaction in the presence of nitrite to give a strongly colored azo compound. Sample containing nitrite ions is first neutralized and then treated with dilute hydrochloric acid at 0 - 5 °C to give nitrous acid. Then an excess but fixed volume of sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride solution is added. With nitrous acid as the limiting reagent, the azo coupling reaction produces an azo dye quantitatively with respect to the nitrite ions:
The diazo compound formed accounts for the red coloration typical for a positive result. The color intensity of the resulting solution is then measured by a colorimeter and checked against a calibration curve to determine the nitrite ion concentration.
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