Benzenediazonium chloride is a colorless solid and have so many uses in organic chemistry. In this tutorial, we will cover how to prepare benzenediazonium chloride , its reactions and physical properties.
If temperature is increased in aqueous benzene diazonium chloride, it decomposes to phenol. Therefore, benzene diazonium is prepared when it is required for some purpose.
Benzene diazonium chloride is prepared by aniline. When aniline reacts with nitrous acid under low temperature (0-50C), benzenediazonium chloride is given as the product. If temperature is increased benzene diazonium chloride decomposes to phenol. Therefore, you have to be careful with temperature when you prepare benzene diazonium chloride.
Note: In the laboratory, you will not see nitrous acid in your chemical store. Therefore you have to prepare it. Nitrous acid is prepared by mixing aqueous sodium nitrite and cold dilute hydrochloric acid.
We can categorize reactions of benzenediazonium chloride into two categories.
Benzene diazonium chloride is used as a raw material in the production of dyes. In next section, we will look those dye preparing reactions too.
BenzeneDiazonium chloride (C6H5-N2Cl) can be converted to another important aromatic organic compounds such as chlorobenzene, bromobenzene, phenol and more. -N2Cl group is replaced by another group such as -Cl, -Br, -OH, etc.
SandMeyer reactions were found in 1884 by a Swiss chemist Traugott Sandmeyer. From sandmeyer reactions, we can prepare chloribenzene, bromebenzene, benzonitrile, iodobenzene and flurobenzene as products.
Benzene, acetaldehyde and nitrogen gas are given as products by this reaction. You can see, ethanol is oxidzed to acetaldehyde which is an aldehyde compound.
When benzene diazonium chloride reacts with sodium nitrite and copper (I), nitrobenzene is given.
Benzene diazonium chloride reacts with phenol, β-napthol, aniline, 2-methylaniline to form azo dyes. In these reactions, a HCl molecule is eliminated.
When benzene reacts with benzene diazonium chloride, red color organic dye is prepared. This dye is used to manufacture textiles. Reaction medium should be a basic.
This reaction gives 1-(phenylazo)-2-naphthol, orange color dye. This dye also is used to prepare color textiles. Reaction medium should be a basic.
This reaction also give an organic dye. Benzene diazonium chloride reacts with aniline in basic medium to form p-aminoazobenzene which is Brownish-yellow needles with bluish cast.
When N-methylaniline reacts with benzene diazonium chloride in the presence of basic medium, p-methylaminoazobenzene is given.
Bromobenzene is the product formed when benzenediazonium chloride is treated with CuBr/HBr. Also, you can use Cu with HBr to prepare bromobenzene.