The benzenediazonium ion
|Jmol-3D images||Image 1|
|Molar mass||140.57 g mol−1|
|Solubility in water||very good, hydroscopic|
|Main hazards||unstable, possibly explosive|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Benzenediazonium chloride is an organic compound with the formula [C6H5N2]Cl. It is a salt of a diazonium cation and chloride. It exists as a colourless solid that is soluble in polar solvents. It is representative of a family of aryldiazonium compounds that are used to prepare azo dyes.
This compound is easily prepared by ordinary methods of diazotization: by dissolving aniline in ice-cold hydrochloric acid, followed by addition of sodium nitrite. This mixture produces nitrous acid (HNO2), which proceed to react with the aniline:
- C6H5NH2 + HNO2 + HCl → [C6H5N2]Cl + 2 H2O
The temperature must be controlled to avoid the product decomposition. Due to its instability, this salt is not commercially available.
Diazonium chloride is also prepared by treating nitrite esters with aniline in presence of HCl. Nitrite esters are formed from alcohol and nitrous acid.
- C5H11ONO + HCl + C6H5NH2 → [C6H5N2]Cl + C5H11OH + H2O
Benzenediazonium chloride is a colourless crystalline solid. It is readily soluble in water but less soluble in alcohol. It turns brown on exposure to air.
The diazo group (N2) can be replaced by many other groups giving a variety of substituted phenyl derivatives:
- C6H5N+ + Nu- → C6H5Nu + N2
These transformations are associated with many named reactions including the Schiemann reaction, Sandmeyer reaction, and Gomberg-Bachmann reaction. A wide range of groups that can be used to replace N2 including halide, SH-, CO2H-, OH-. Of considerable practical value in the dye industry are the diazo coupling reactions.
Workers have mentioned the violent decomposition of this compound.
- March, J. (1992). Advanced Organic Chemistry (4th ed.). New York: J. Wiley and Sons. ISBN 0-471-60180-2.
- Flood, D. T. (1933), "Fluorobenzene", Org. Synth. 13: 46; Coll. Vol. 2: 295 This procedure described the tetrafluoroborate salt of phenyldiazonium.
- Jain, S. K. (2009). Conceptual Chemistry for class XII. New Delhi: S. Chand & Company. pp. 1179–1183. ISBN 81-219-1623-2.
- Nesmajanow, A. N. (1932), "β-Naphthylmercuric chloride", Org. Synth. 12: 54; Coll. Vol. 2: 432