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Reactions and uses: carboxylic acids, esters, orthoesters, acyl halides all react similarly
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==Reactions and uses==
==Reactions and uses==
''o''-Phenylenediamine condenses with [[ketone]]s and [[aldehyde]]s to give rise to a variety of useful products. Reactions with esters affords [[benzimidazole]]s. The herbicide [[benomyl]] is prepared in this manner. Also, [[quinoxaline]]dione 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. Condensation of subtituted ''o''-phenylenediamine with various [[diketone]]s is used in the preparation of a variety of pharmaceuticals.<ref>See for example, {{cite journal | author = Renault, J. et al. | title = Heterocyclic quinones. Quinoxaline-5,6 and 5,8 diones, potential antitumoral agents | journal = Eur. J. Med. Chem. | year = 1981 | volume = 16 | pages = 545–550}}</ref>
''o''-Phenylenediamine condenses with [[ketone]]s and [[aldehyde]]s to give rise to a variety of useful products. Reactions with [[carboxylic acid]]s and their derivatives afford [[benzimidazole]]s. The herbicide [[benomyl]] is prepared in this manner. Also, [[quinoxaline]]dione 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. Condensation of subtituted ''o''-phenylenediamine with various [[diketone]]s is used in the preparation of a variety of pharmaceuticals.<ref>See for example, {{cite journal | author = Renault, J. et al. | title = Heterocyclic quinones. Quinoxaline-5,6 and 5,8 diones, potential antitumoral agents | journal = Eur. J. Med. Chem. | year = 1981 | volume = 16 | pages = 545–550}}</ref>


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 [[imine|diimine]] derivatives, which are intensely coloured and often exist in multiple stable oxidation states.<ref>{{cite journal | author = Warren, L. F. | title = Synthesis of [M'-N<sub>4</sub>] and [M'-N<sub>6</sub>] Complexes Based on ''o''-Benzoquinone Diimine with Cobalt, Iron, and Ruthenium | journal = [[Inorg. Chem.]] | year = 1977 | volume = 16 | pages = 2814–2819 | doi = 10.1021/ic50177a028}}</ref>
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 [[imine|diimine]] derivatives, which are intensely colored and often exist in multiple stable oxidation states.<ref>{{cite journal | author = Warren, L. F. | title = Synthesis of [M'-N<sub>4</sub>] and [M'-N<sub>6</sub>] Complexes Based on ''o''-Benzoquinone Diimine with Cobalt, Iron, and Ruthenium | journal = [[Inorg. Chem.]] | year = 1977 | volume = 16 | pages = 2814–2819 | doi = 10.1021/ic50177a028}}</ref>


==Safety==
==Safety==

Revision as of 15:24, 8 May 2011

o-Phenylenediamine[1]
Names
IUPAC name
Benzene-1,2-diamine
Other names
o-Phenylene diamine
1,2-Diaminobenzene
1,2-phenylenediamine
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.002.210 Edit this at Wikidata
  • InChI=1S/C6H8N2/c7-5-3-1-2-4-6(5)8/h1-4H,7-8H2 checkY
    Key: GEYOCULIXLDCMW-UHFFFAOYSA-N checkY
  • Key: GEYOCULIXLDCMW-UHFFFAOYAR
  • Nc1ccccc1N
Properties
C6H8N2
Molar mass 108.1 g/mol
Density 1.031 g/cm3
Boiling point 252 °C (486 °F; 525 K)
soluble in hot water
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

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 carboxylic acids and their derivatives afford 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. Condensation of subtituted o-phenylenediamine with various diketones is used in the preparation of a variety of pharmaceuticals.[4]

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 colored and often exist in multiple stable oxidation states.[5]

Safety

With an LD50 of 44 mg/L (aquatic), o-phenylenediamine is about 1000 times 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.[6]

References

  1. ^ DuPont Specialty Intermediates: o-Phenylenediamine (OPD)
  2. ^ Robert A. Smiley “Phenylene- and Toluenediamines” in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_405
  3. ^ E. L. Martin (1943). "o-Phenylenediamine". Organic Syntheses; Collected Volumes, vol. 2, p. 501.
  4. ^ See for example, Renault, J.; et al. (1981). "Heterocyclic quinones. Quinoxaline-5,6 and 5,8 diones, potential antitumoral agents". Eur. J. Med. Chem. 16: 545–550. {{cite journal}}: Explicit use of et al. in: |author= (help)
  5. ^ 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.
  6. ^ Deshpande SS (1996). Enzyme Immunoassays: From Concept to Product Development. New York: Chapman & Hall. p. 169. ISBN 978-0412056017.