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In organic chemistry, Fehling's solution is a chemical reagent used to differentiate between water-soluble carbohydrate and ketone (>C=O) functional groups, and as a test for reducing sugars and non-reducing sugars, supplementary to the Tollens' reagent test. The test was developed by German chemist Hermann von Fehling in 1849. [1]
Tollens' test for aldehyde: left side positive (silver mirror), right side negative Ball-and-stick model of the diamminesilver(I) complex. Tollens' reagent (chemical formula ()) is a chemical reagent used to distinguish between aldehydes and ketones along with some alpha-hydroxy ketones which can tautomerize into aldehydes.
In analytical chemistry, a reagent is a compound or mixture used to detect the presence or absence of another substance, e.g. by a color change, or to measure the concentration of a substance, e.g. by colorimetry. Examples include Fehling's reagent, Millon's reagent, and Tollens' reagent.
Fehling's reagent: used to differentiate between water-soluble aldehyde and ketone functional groups Fenton's reagent: a solution of hydrogen peroxide and an iron catalyst that is used to oxidize contaminants or waste waters Formaldehyde
The Schiff reagent is the reaction product of a dye formulation such as fuchsin and sodium ... Tollens' reagent; Fehling's reagent; 2,4-Dinitrophenylhydrazine ...
Unable to resist the call of his former professor Wöhler, Tollens returned to Göttingen in 1872 and there he remained in various positions until he died in 1918. It was during this final time in Göttingen that he started his work on carbohydrates , which yielded structures of several sugars, the Tollens' reagent , and most of his publications.
α-hydroxy ketones give positive Tollens' and Fehling's test. Some acyloins rearrange with positions swapped under the influence of base in the Lobry–de Bruyn–van Ekenstein transformation; A similar reaction is the so-called Voigt amination [6] where an acyloin reacts with a primary amine and phosphorus pentoxide to an α-keto amine: [7]
Benedict's reagent (often called Benedict's qualitative solution or Benedict's solution) is a chemical reagent and complex mixture of sodium carbonate, sodium citrate, and copper(II) sulfate pentahydrate. [1] It is often used in place of Fehling's solution to detect the presence of reducing sugars and other reducing substances. [2]