o-Phenylenediamine
| O-Phenylenediamine[1] | |
|---|---|
| File:O-phenylenediamine.png | |
| Benzene-1,2-diamine | |
| Other names o-Phenylene diamine 1,2-Diaminobenzene 1,2-phenylenediamine | |
| style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers | |
| CAS number | 95-54-5 
|
| SMILES | Script error: No such module "collapsible list". |
| style="background: #F8EABA; text-align: center;" colspan="2" | Properties | |
| Molecular formula | C6H8N2 |
| Molar mass | 108.1 g/mol |
| Density | 1.031 g/cm3 |
| Melting point |
102-104 °C, 375-377 K, 216-219 °F |
| Boiling point |
252 °C, 525 K, 486 °F |
| style="background: #F8EABA; text-align: center;" colspan="2" | Hazards | |
| MSDS | Oxford MSDS |
| EU classification | Toxic (T); Dangerous for the environment (N) |
| NFPA 704 | |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
o-Phenylenediamine is a organic compound with the formula C6H4(NH2)2. This aromatic diamine is an important precursor to many heterocyclic compounds. It is isomeric with m-phenylenediamine and p-phenylenediamine.
Preparation
Most commonly 2-nitrochlorobenzene is treated with ammonia, and the resulting 2-aminonitrobenzene is then hydrogenated:[2]
- ClC6H4NO2 + 2 NH3 → H2NC6H4NO2 + NH4Cl
- H2NC6H4NO2 + 3 H2 → H2NC6H4NH2 + 2 H2O
In the laboratory, the reduction of the nitroaniline is effected with zinc powder in ethanol, followed by purification of the diamine as the hydrochloride.[3]
Reactions and uses
o-Phenylenediamine condenses with ketones and aldehydes to give rise to a variety of useful products. Reactions with esters affords benzimidazoles. The herbicide benomyl is prepared in this manner. Also, quinoxalinedione may be prepared by condensation of o-phenylenediamine with dimethyl oxalate. Condensation with xanthate esters affords mercaptoimidazoles, which are used as antioxidants in rubber products. Treatment with nitrous acid give benzotriazole, a corrosion inhibitor.
In coordination chemistry, phenylenediamine is an important ligand precursor. Schiff base derivatives, such as those derived from salicylaldehyde, are excellent chelating ligands. Oxidation of its metal-phenylenediamine complexes affords the diimine derivatives, which are intensely coloured and often exist in multiple stable oxidation states.[4]
Safety
With an LD50 of 44 mg/L (aquatic), o-Phenylenediamine is about 1000x less toxic than the para isomer. Anilines are typically handled as if they are carcinogenic. For many applications, OPD has been replaced by safer alternatives such as 3,3',5,5'-tetramethylbenzidine.[5]
References
- ↑ DuPont Specialty Intermediates: o-Phenylenediamine (OPD)
- ↑ Robert A. Smiley “Phenylene- and Toluenediamines” in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_405
- ↑ E. L. Martin (1943), "o-Phenylenediamine", Org. Synth.; Coll. Vol., 2: 501 Missing or empty
|title=(help) - ↑ Warren, L. F. (1977). "Synthesis of [M'-N4] and [M'-N6] Complexes Based on o-Benzoquinone Diimine with Cobalt, Iron, and Ruthenium". Inorg. Chem. 16: 2814–2819. doi:10.1021/ic50177a028.
- ↑ Deshpande SS (1996). Enzyme Immunoassays: From Concept to Product Development. New York: Chapman & Hall. p. 169. ISBN 978-0412056017.
it:1,2-fenilendiammina pt:O-Fenilenodiamina ja:O-フェニレンジアミン fi:O-fenyleenidiamiini zh:邻苯二胺
