o-Phenylenediamine

o-Phenylenediamine
o-Phenylenediamine[1]
Identifiers
CAS number 95-54-5 YesY
ChemSpider 13837582 YesY
UNII 8B713N8Q0F N
ChEBI CHEBI:34043 N
ChEMBL CHEMBL70582 YesY
Jmol-3D images Image 1
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 (Other sources: 256 — 258 °C.)

Solubility in water soluble in hot water
Hazards
MSDS Oxford MSDS
EU classification Toxic (T); Dangerous for the environment (N)
NFPA 704
NFPA 704.svg
1
2
0
 N (verify) (what is: YesY/N?)
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.

Contents

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] This compound darkens in air; impurities may be removed by treating a hot aqueous solution with sodium dithionite (reducing agent) and activated carbon, and allowing the product to cool crystallize.

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", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0501 ; Coll. Vol. 2: 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. 
  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. 

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Look at other dictionaries:

  • Phenylenediamine — may refer to:* o phenylenediamine or OPD, a chemical compound C6H4(NH2)2 * m phenylenediamine or MPD, a chemical compound C6H4(NH2)2 * p phenylenediamine or PPD, a chemical compound C6H8N2 …   Wikipedia

  • phénylènediamine — ● phénylènediamine nom féminin Diamine C6H4(NH2)2 dérivée du benzène. (Les phénylènediamines sont employées dans la fabrication des colorants, des résines et dans l industrie du caoutchouc.) …   Encyclopédie Universelle

  • phenylenediamine — fenilendiaminas statusas T sritis chemija formulė C₆H₄(NH₂)₂ atitikmenys: angl. phenylenediamine rus. фенилендиамин …   Chemijos terminų aiškinamasis žodynas

  • phenylenediamine — noun any of the three isomeric di amino benzenes, used as intermediates in the manufacture of pharmaceuticals, plastics etc …   Wiktionary

  • phenylenediamine — phe·nyl·ene·di·amine fen əl .ēn dī ə .mēn, fēn n any of three toxic isomeric crystalline compounds C6H8N2 that are derivatives of benzene containing two amino groups attached to carbon atoms in the ortho, meta, or para positions see QUINOXALINE …   Medical dictionary

  • phenylenediamine — phenyl·ene·diamine …   English syllables

  • phenylenediamine — | ̷ ̷ ̷ ̷ˌ ̷ ̷+ noun Etymology: International Scientific Vocabulary phenylene + diamine : any of three toxic isomeric crystalline compounds C6H4(NH2)2 that are ortho, meta, and para diamino derivatives of benzene of which the ortho and para… …   Useful english dictionary

  • P-Phenylenediamine — Chembox new ImageFile = P phenylenediamine.png ImageSize = IUPACName = 1,4 diaminobenzene OtherNames = Section1 = Chembox Identifiers CASNo = 106 50 3 PubChem = SMILES = Nc1ccc(N)cc1 InChI=1/C6H8N2/c7 5 1 2 6 (8)4 3 5/h1 4H,7 8H2 Section2 =… …   Wikipedia

  • O-Phenylenediamine — chembox new ImageFile = o phenylenediamine.png ImageSize = 120px IUPACName = Benzene 1,2 diamine OtherNames = o Phenylenediamine 1,2 Diaminobenzene Reference = [http://www.dupont.com/specintermediates/opd.html DuPont Specialty Intermediates: o… …   Wikipedia

  • p-Phenylenediamine — IUPAC name 1,4 diaminobenzene …   Wikipedia

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