Millon's reaction
The Millon reaction (also Millon probe ) is a detection reaction for proteins that is specific for the amino acid tyrosine . It was named after the French chemist Eugène Millon .
A solution of mercury (I) nitrate (HgNO 3 ) in nitrous acid (HNO 2 ) is used as the detection reagent . With proteins, it forms a brick-red mercury-protein complex.
The Millon reaction is a group-specific detection reaction: It works with all compounds that have a phenol group with a free ortho position . This ortho position is initially nitrosated by nitrous acid, which results in a stabilized hydroxyl group and a nitrosyl group on the aromatic ring in the immediate vicinity. Two such molecules can complex an Hg 2+ ion; the resulting complex is brick-red in color:
Of the naturally occurring amino acids, only tyrosine has such a reactive structure; the reaction can also be used to detect phenol or thymol .
literature
- Otto Nasse: About the usability of Millon's reagent . In: Archives for the entire physiology of humans and animals . tape 83 , no. 8 , February 1, 1901, p. 361-368 , doi : 10.1007 / BF01662536 .
Individual evidence
- ↑ Entry on Millon's reaction. In: Römpp Online . Georg Thieme Verlag, accessed on January 19, 2012.
- ^ Paul Elsinghorst: Color reactions . (PDF; 367 kB) p. 19.