Benzenediazonium chloride

Benzenediazonium chloride

The benzenediazonium ion
Names
IUPAC name Benzenediazonium chloride
Other names Phenyldiazonium chloride
Identifiers
CAS Number	100-34-5
ChemSpider	54953
Jmol interactive 3D	Image
PubChem	60992
InChI InChI=1S/C6H5N2.ClH/c7-8-6-4-2-1-3-5-6;/h1-5H;1H/q+1;/p-1 Key: CLRSZXHOSMKUIB-UHFFFAOYSA-M InChI=1/C6H5N2.ClH/c7-8-6-4-2-1-3-5-6;/h1-5H;1H/q+1;/p-1 Key: CLRSZXHOSMKUIB-REWHXWOFAT
SMILES [Cl-].N#[N+]c1ccccc1
Properties
Chemical formula	C6H5ClN2
Molar mass	140.57 g·mol^−1
Appearance	colorless crystals
Melting point	decomposes
Boiling point	decomposes
Solubility in water	very good, hydroscopic
Hazards
Main hazards	unstable, possibly explosive
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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 including water. It is the parent member of the aryldiazonium compounds,^[1] which are widely used in organic chemistry. Because the salt is unstable, it is not commercially available but is prepared upon demand.

Synthesis

This compound is prepared by diazotization of aniline.^[2] The conversion involves in situ production of nitrous acid (HNO₂), which reacts with the aniline:

C₆H₅NH₂ + HNO₂ + HCl → [C₆H₅N₂]Cl + 2 H₂O

The reactions are conducted at low temperature to minimize decomposition of the diazonium salt.

Diazonium chloride can also be prepared by treating nitrite esters with aniline in presence of HCl. Nitrite esters are formed from alcohol and nitrous acid.^[3]

C₅H₁₁ONO + HCl + C₆H₅NH₂ → [C₆H₅N₂]Cl + C₅H₁₁OH + H₂O

Chemical properties

The diazo group (N₂) can be replaced by many other groups, usually anions, giving a variety of substituted phenyl derivatives:

C₆H₅N₂⁺ + 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.

Safety

The compound is explosive.^[4]

References

1. March, J. (1992). Advanced Organic Chemistry (4th ed.). New York: J. Wiley and Sons. ISBN 0-471-60180-2.
2. Flood, D. T. (1933). "Fluorobenzene". Org. Synth. 13: 46.; Coll. Vol. 2, p. 295 The procedure described the tetrafluoroborate salt of phenyldiazonium.
3. Jain, S. K. (2009). Conceptual Chemistry for class XII. New Delhi: S. Chand & Company. pp. 1179–1183. ISBN 81-219-1623-2.
4. Nesmajanow, A. N. (1932). "β-Naphthylmercuric chloride". Org. Synth. 12: 54.; Coll. Vol. 2, p. 432