Phenylenediamines

Phenylenediamines

 

(also diaminobenzenes), C6H4(NH2)2, aromatic diamines. Ortho, meta, and para isomers are known, occurring as colorless crystals that darken upon exposure to light and air. Their melting points are 102°, 63°–64°, and 147°C, respectively. Phenylenediamines are soluble in hot water, alcohol, and diethyl ether; they form salts with mineral acids and are readily oxidized and acylated. The meta and para isomers undergo diazotization, a property that forms the basis of their use in the synthesis of dyes (azine, oxazine, thiazine). Polyamides, for example, Phenylone, which are obtained through the condensation of meta-phenylenediamine with isophthalic acid, are important in industry.

Phenylenediamines are used in analytical chemistry. Ortho-phenylenediamine is a reagent for diketones, carboxylic acids, and aldehydes, and meta-phenylenediamine is a reagent for the nitrite ion. The sulfate of N, N-diethyl-para-phenylenediamine is used as a developer in color photography. Phenylenediamines are produced synthetically. Ortho-phenylenediamine is obtained through the reduction of ortho-nitroaniline and through the action of an aqueous ammonia solution on ortho-chloroaniline and ortho-dichlorobenzene; meta-phenylenediamine is obtained through the reduction of meta-dinitrobenzene; and para-phenylenediamine is produced by the reduction of para-nitro-aniline and by the action of aqueous ammonia on para-dichloro-benzene in the presence of CuSO4.

References in periodicals archive ?
To solve this problem, the complex Cd(II) tetrafluoroborates with isomeric phenylenediamines were synthesized and investigated: o-phenylenediamine (OPD, [pK.sub.a]=4.57), m-phenylenediamine (MPD, [pK.sub.a]=5.11), p-phenylenediamine (PPD, [pK.sub.a]=6.31).
The established structure of the coordination sphere of the Cd(II) tetrafluoroborate complexes with isomeric phenylenediamines allows to draw conclusion about their tetrahedral configuration as such structure of coordination node is characteristic for this metal as complexing agent with 4 as coordination number.
Kise, "Oxidative polymerization of phenylenediamines catalyzed by horseradish peroxidase," Journal of Polymer Science A: Polymer Chemistry, vol.
Phenylenediamine PoPd is considered as one of the most investigated conducting polymers and also attracted much interest in many studies with various practical applications because of its high conductivity, outstanding air stability, and special physical, chemical properties compared with other conducting polymers [5, 8-12].
One, referred to as the "primary," is exemplified by the phenylenediamines, and the other, often an aminophenol, is known as the "coupler." These compounds are stable and do not react with each other until they are mixed with hydrogen peroxide.
Chemicals called phenylenediamines (PDD) are added to some dyes to enable absorption of the colour.
Phenylenediamines (PDD): a skin irritant associated with allergic reactions, easily absorbed through the skin.
Habibi, "Electrocatalytic oxidation of methanol on poly(phenylenediamines) film palladized aluminum electrodes, modified by Pt micro-particles: comparison of permselectivity of the films for methanol," Journal of Electroanalytical Chemistry, vol.
Phenylenediamines seem to impede the reduction of viscosity of the powder rubber.
Some of the alkylated diphenylamines are less discoloring than the phenylenediamines and find application in plastics.
For instance, Pearson and Hwang were pioneers in the field and reported many TAPD-based chemosensors formed by crown ethers as ionophore sites and phenylenediamine moiety as a transducer capable of detection of alkaline or alkaline earth cations [12].
Perhaps the three most commonly used antiozonants are N-isopropyl-N'-phenyl-p-phenylenediamine (1PPD), N-1,3-dimethylbutylN'-phenyl-p-phenylene diamine (6PPD) and N,N'-bis(1,4-dimethylpentyl)-p phenylenediamine (77PD).