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o-Nitrophenol (2-nitrophenol; OH and NO 2 groups are neighboring, a yellow solid. m-Nitrophenol (3-nitrophenol, CAS number: 554-84-7), a yellow solid (m.p. 97 °C) and precursor to the drug mesalazine (5-aminosalicylic acid). It can be prepared by nitration of aniline followed by replacement of the amino group via its diazonium derivative. [2]
The reduction of nitroaromatics is conducted on an industrial scale. [1] Many methods exist, such as: Catalytic hydrogenation using: Raney nickel [2] or palladium-on-carbon, [3] [4] [5] platinum(IV) oxide, or Urushibara nickel. [6] Iron in acidic media. [7] [8] [9] Sodium hydrosulfite [10] Sodium sulfide (or hydrogen sulfide and base ...
The reaction produces fragments from the parent alkane, creating a diverse mixture of products; for instance, nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane are produced by treating propane with nitric acid in the gas phase (e.g. 350–450 °C and 8–12 atm).
Azo dyes are also prepared by the condensation of nitroaromatics with anilines followed by reduction of the resulting azoxy intermediate: ArNO 2 + Ar'NH 2 → ArN(O)=NAr' + H 2 O ArN(O)=NAr' + C 6 H 12 O 6 → ArN=NAr' + C 6 H 10 O 6 + H 2 O. For textile dying, a typical nitro coupling partner would be disodium 4,4′-dinitrostilbene-2,2 ...
A solution of 4-nitrophenol appears colorless below pH 5.4 and yellow above pH 7.5. [3] This color-changing property makes this compound useful as a pH indicator. The yellow color of the 4-nitrophenolate form (or 4-nitrophenoxide) is due to a maximum of absorbance at 405 nm (ε = 18.3 to 18.4 mM −1 cm −1 in strong alkali). [4]
[1] [2] [3] Nitration reactions are notably used for the production of explosives, for example the conversion of guanidine to nitroguanidine and the conversion of toluene to trinitrotoluene (TNT). Nitrations are, however, of wide importance virtually all aromatic amines are produced from nitro precursors. Millions of tons of nitroaromatics are ...
Azobenzene is a photoswitchable chemical compound composed of two phenyl rings linked by a N=N double bond.It is the simplest example of an aryl azo compound.The term 'azobenzene' or simply 'azo' is often used to refer to a wide class of similar compounds.
Azo printing exploits this reaction as well. In this case, the diazonium ion is degraded by light, leaving a latent image in undegraded diazonium salt which is made to react with a phenol, producing a colored image: the blueprint. [3] Prontosil, the first sulfa drug, was once produced by azo coupling. The azo compound is a prodrug that is ...