Sulfanilic acid

Sulfanilic acid
Names
	IUPAC name p-aminobenzenesulphonic acid
	Other names Sulphanilic acid
Identifiers
CAS Number	121-57-3 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.004.075
PubChem CID	8479;
CompTox Dashboard (EPA)	DTXSID6024464 ;
	InChI InChI=1/C6H7NO3S/c7-5-; 1-3-6(4-2-5)11(8,9)10/h1-4H,; 7H2,(H,8,9,10)/f/h8H;
	SMILES C1=CC(=CC=C1N)S(=O)(=O)O;
Properties
Chemical formula	C6H7NO3S
Molar mass	173.19
Density	1.485
Melting point	288 °C (550 °F; 561 K)
Solubility in water	>20 g/l
Related compounds
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Sulfanilic acid (4-aminobenzenesulfonic acid ) is an off-white crystalline solid which finds application in quantitative analysis of nitrate and nitrite ions. The solid acid exists as a zwitterion, and has an unusually high melting point. ^[1]

Synthesis

Sulfanilic acid can be produced by sulfonation of aniline:^[2]

Applications

As the compound readily form diazo compounds, it is used to make dyes and sulpha drugs. ^[1] This property is also used for the quantitative analysis of nitrate and nitrite ions by diazonium coupling reaction with N-(1-Naphthyl)ethylenediamine, resulting in an azo dye, and the concentration of nitrate or nitrite ions were deduced from the color intensity of the resulting red solution by colorimetry. ^[3]

It is also used as a standard in combustion analysis.

References

^ ^a ^b "Sulphanilic acid". A Dictionary of Chemistry. Oxford University Press, 2000. Oxford Reference Online. Oxford University Press.
^ Siegfried Hauptmann: Organische Chemie, 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, ISBN 3-342-00280-8.
^ G. H. Jerffery; J. Bassett; J. Mendham; R. C. Denney (1989). "Colorimetry and Spectrophotometry". Vogel's Textbook of Quantitative Chemical Analysis, 5th Edition. Longman. p. 702. ISBN 0-582-44693-7.

[DOC-1] "Sulphanilic acid". A Dictionary of Chemistry. Oxford University Press, 2000. Oxford Reference Online. Oxford University Press.

[Hauptmann-2] Siegfried Hauptmann: Organische Chemie, 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, ISBN 3-342-00280-8.

[Vogel-3] G. H. Jerffery; J. Bassett; J. Mendham; R. C. Denney (1989). "Colorimetry and Spectrophotometry". Vogel's Textbook of Quantitative Chemical Analysis, 5th Edition. Longman. p. 702. ISBN 0-582-44693-7.

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