Liebermann-Burchard reaction

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The Liebermann-Burchard reaction is a name reaction for the detection of sterols . Traditionally, acetic acid , acetic anhydride and concentrated sulfuric acid are added to a fat extract while cooling with ice. The resulting pentaenyl cation is colored green or red depending on the variant of the tests and the structure of the sterol. It can be used as a qualitative detection reaction or measured photometrically at 620 nm. Iron (III) cations can also be used as oxidizing agents instead of sulfur trioxide .

Reaction sequence of the Liebermann-Burchard reaction

The reaction was widely used in the 20th century and is still a reference method today. It was first described in 1885 by the chemist Carl Liebermann (1842–1914) and later developed further by the physician Hans Richard Ferdinand Burchard (1864–1900) for a quantitative determination of cholesterol . Modern investigations for structural elucidation provide information that the reaction mechanism does not contain any cholestadienes, i-steroids or cholesterol dimers as initially assumed. Instead, cholesterol and its acetate and sulfate derivatives are sulfonated at various points, with skeletal rearrangements often occurring. The elimination of sulphonic acid groups as sulphurous acid creates new double bonds. Repetition leads to polyenes and ultimately aromatic steroids.

Individual evidence

  1. ^ Hans-Dieter Belitz , Werner Grosch , Peter Schieberle : Textbook of food chemistry . 6th completely revised edition. Springer, Berlin / Heidelberg 2008, ISBN 978-3-540-73201-3 , p. 235-236 , doi : 10.1007 / 978-3-540-73202-0 .
  2. ↑ Johannes Büttner , Hans-Dietrich Bruhn : Chemical thinking in medicine . The history of the laboratory of the 1st Medical Clinic of the University of Kiel. tape 1 . Verlag Traugott Bautz , Nordhausen 2007, ISBN 978-3-88309-377-2 , p. 45 ( limited preview in Google Book search).
  3. ↑ Quanbo Xiong, William K. Wilson, Jihai Pang: The Liebermann – Burchard Reaction: Sulfonation, Desaturation, and Rearrangement of Cholesterol in Acid . In: Lipids . tape 42 , no. 1 , 2007, p. 87-96 , doi : 10.1007 / s11745-006-3013-5 .