Schiff's reagent: Difference between revisions

Revision as of 10:52, 19 December 2022

Preparation of Schiff's reagent and principle of its reaction with aldehyde

Schiff's reagent is an aqueous solution of the violet-red dye fuchsinu to which bisulfite or sulfite is added. Hydrogen sulphite is adducted to the central carbon atom, thereby disrupting the quinoid structure that conditions the colour. A colorless fuchsin sulfuric acid solution is formed. After adding even a small amount of aldehyde, sulfuric acid is released from the bond to fuchsin, which binds to the aldehyde group with a stronger bond. In the fuchsin molecule, the quinoid structure is restored and the solution turns violet-red again.

Links

Source

Leníček M, Muchová L: Organika I

@@ Line 1: / Line 1: @@
 <noinclude>
- [[File:Schiffovo_činidlo.png.jpg | 30px | link=User:Mvejr]] [[User:Mvejr|MUDr. Martin Vejražka, PhD.]]|409169|20181128154658}}</noinclude>
+[[File:Schiff's reagent.png|thumb|Preparation of Schiff's reagent and principle of its reaction with aldehyde]]
-[[File:Schiff's reagent.png|preview|Preparation of Schiff's reagent and principle of its reaction with aldehyde]]
 Schiff's reagent is an aqueous solution of the violet-red dye [[fuchsin]]u to which bisulfite or sulfite is added. Hydrogen sulphite is adducted to the central carbon atom, thereby disrupting the quinoid structure that conditions the colour. A colorless fuchsin sulfuric acid solution is formed. After adding even a small amount of aldehyde, sulfuric acid is released from the bond to fuchsin, which binds to the aldehyde group with a stronger bond. In the fuchsin molecule, the quinoid structure is restored and the solution turns violet-red again.