Sulfanilic acid explained

Sulfanilic acid (4-aminobenzenesulfonic acid) is an organic compound with the formula H3NC6H4SO3. It is an off-white solid. It is a zwitterion, which explains its high melting point. It is a common building block in organic chemistry.[1]

Synthesis

Sulfanilic acid can be produced by sulfonation of aniline with concentrated sulfuric acid.[2] This proceeds via phenylsulfamic acid; a zwitterion with a N-S bond. Eugen Bamberger originally proposed a mechanism involving a series of intramolecular rearrangements, with phenylsulfamic acid forming orthanilic acid, which rearranged to sulfanilic acid on heating.[3] [4] Subsequent radiosulphur studies showed that the process is intermolecular, with the phenylsulfamic acid desulfating to generate sulfur trioxide, which then reacts with aniline at the para position in manner similar to a Bamberger rearrangement.[5] [6]

Applications

As the compound readily forms diazo compounds, it is used to make dyes and sulfa 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.[7]

It is also used as a standard in combustion analysis and in the Pauly reaction.

Environmental aspects

Reflecting its wide use, sulfanilic acid is found in the leachates of landfills.[8] It is produced by reduction of some azo dyes.[9]

Derivatives

See also

Notes and References

  1. "Sulphanilic acid". A Dictionary of Chemistry. Oxford University Press, 2000. Oxford Reference Online. Oxford University Press.
  2. Siegfried Hauptmann: Organische Chemie, 2nd Edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 511, .
  3. Bamberger . Eug. . Kunz . Jac. . Umlagerung von Sulfonsäuren. (II.) . Berichte der Deutschen Chemischen Gesellschaft . May 1897 . 30 . 2 . 2274–2277 . 10.1002/cber.189703002211.
  4. Illuminati . Gabriello . A Reinvestigation of the Role of Phenylsulfamic Acid in the Formation of Aminobenzenesulfonic Acids . Journal of the American Chemical Society . June 1956 . 78 . 11 . 2603–2606 . 10.1021/ja01592a075.
  5. Spillane . W.J. . Scott . F.L. . Radiosulphur studies on the rearrangement of phenylsulphamic acid to sulphanilic acid . Tetrahedron Letters . January 1967 . 8 . 14 . 1251–1253 . 10.1016/S0040-4039(00)90678-6.
  6. Scott . F.L. . Spillane . W.J. . The isomerization of orthanilic acid to sulphanilic acid in the presence of sulphuric acid-S35 . Tetrahedron Letters . January 1967 . 8 . 28 . 2707–2711 . 10.1016/S0040-4039(01)89979-2.
  7. Book: Vogel's Textbook of Quantitative Chemical Analysis, 5th Edition. Colorimetry and Spectrophotometry. G. H. Jerffery . J. Bassett. J. Mendham. R. C. Denney. Longman. 1989. 0-582-44693-7. 702.
  8. 10.1021/es00005a039. Occurrence and Distribution of Pharmaceutical Organic Compounds in the Groundwater Downgradient of a Landfill (Grindsted, Denmark). 1995. Holm. John V.. Ruegge. Kirsten.. Bjerg. Poul L.. Christensen. Thomas H.. Environmental Science & Technology. 29. 5. 1415–1420. 22192041. 1995EnST...29.1415H . 2994687 .
  9. 10.1016/S0043-1354(99)00331-0. Reduction of azo dyes with zero-valent iron. 2000. Nam. S.. Water Research. 34. 6. 1837–1845. 2000WatRe..34.1837N .
  10. .

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sulfanilic acid".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.