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*** Benzene is a carcinogen (cancer-causing agent). *** Very flammable. The pure material, and any solutions containing it, constitute a fire risk. Safe handling: Benzene should NOT be used at all unless no safer alternatives are available. If benzene must be used in an experiment, it should be handled at all stages in a fume cupboard.
Of considerable practical value in the dye industry are the diazo coupling reactions. The reaction of phenyldiazonium salts with aniline gives 1,3-diphenyltriazene. [3] The structure of the salt has been verified by X-ray crystallography. The N-N bond distance is 1.083(3) Å. [4]
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group [R−N + ≡N]X − where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent compound where R is hydrogen, is diazenylium.
By virtue of the two nitro substituents, the chloride in DNCB is particularly susceptible to nucleophilic substitution, at least relative to simple chlorobenzene. In this way, the compound is a precursor to many other compounds. [4] [5] [6] In one example, DNCB is as a substrate in Glutathione S-Transferase, relevant to activity assays. [7]
m-Phenylenediamine, also called 1,3-diaminobenzene, is an organic compound with the formula C 6 H 4 (NH 2) 2.It is an isomer of o-phenylenediamine and p-phenylenediamine.This aromatic diamine is a colourless solid that appears as needles, but turns red or purple on exposure to air due to formation of oxidation products. [3]
Chlorobenzene (abbreviated PhCl) is an aryl chloride and the simplest of the chlorobenzenes, consisting of a benzene ring substituted with one chlorine atom. Its chemical formula is C 6 H 5 Cl. This colorless, flammable liquid is a common solvent and a widely used intermediate in the manufacture of other chemicals.
Difluorobenzenes can be prepared by the Balz-Schiemann reaction, which entails conversion of diazonium tetrafluoroborate salts to their fluorides. The synthesis of 1,2-difluorobenzene starts with 2-fluoroaniline: [3] C 6 H 4 F(NH 2) + HNO 2 + HBF 4 → [C 6 H 4 F(N 2)]BF 4 + 2 H 2 O [C 6 H 4 F(N 2)]BF 4 → C 6 H 4 F 2 + N 2 + BF 3
[8] [9] The diazotization reaction can be effected with nitrosonium salts such as [NO]SbF 6 without isolation of the diazonium intermediate. [2] As a practical matter, the traditional Balz–Schiemann reaction consumes relatively expensive BF 4-as a source of fluoride. An alternative methodology produces the fluoride salt of the diazonium compound.