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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 ...
Free radical nitration of alkanes. [4] 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 ...
In one protocol, 4-chloro-n-butylbenzene is reacted with sodium nitrite in t-butanol in the presence of 0.5 mol% Pd 2 (dba) 3, a biarylphosphine ligand and a phase-transfer catalyst to provide 4-nitro-n-butylbenzene.
Like most azobenzenes, Solvent Yellow 7 can be synthesized by the reaction of the phenyldiazonium salt with phenol.The optimal pH value for this azo coupling is 8.5-10. The reaction is carried out in water, since sodium chloride (or potassium chloride) formed in the reaction is soluble in water, while the product precipitates.
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 ...
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]