Under these conditions, the azodyes ( couplers ) react with the remaining diazonium salt and undergo a chemical reaction that results in the unexposed lines changing color from invisible ( or yellow ) to a visible dark color.
32.
Phenylhydrazine is prepared by oxidizing aniline with sodium nitrite in the presence of hydrogen chloride to form the diazonium salt, which is subsequently reduced using sodium sulfite in the presence of sodium hydroxide to form the final product.
33.
In a novel kilogram-scale metal-free Meerwein arylation the diazonium salt is formed from 2-nitroaniline, the alkene isopropenyl acetate is an adduct of propene and acetic acid and the reaction product 2-nitrophenylacetone:
34.
An aromatic ( or heterocyclic ) amine quickly reacts with a nitrite to form an aryl diazonium salt, which decomposes in the presence of copper ( I ) salts, such as CuCl, to form the desired aryl halide.
35.
The bilirubin combines with a diazonium salt ( 2, 4-dichloroaniline or 2, 6-dichlorobenzene-diazonium-tetrafluoroborate ) in an acid medium to produce an azo dye with colouration that varies from pink to violet:
36.
An electron-withdrawing group ( EWG ) on the alkene makes it electron deficient and although the reaction mechanism is unclear, involvement of an aryl radical is presumed after loss of nitrogen in the diazonium salt followed by a free radical addition.
