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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]
Due to mutarotation, glucose is always present to a small extent as an open-chain aldehyde. By adding the Fehling reagents (Fehling (I) solution and Fehling (II) solution), the aldehyde group is oxidized to a carboxylic acid, while the Cu 2+ tartrate complex is reduced to Cu + and forms a brick red precipitate (Cu 2 O).
The aqueous solution in the classical reaction contains glucose, sodium hydroxide and methylene blue. [14] In the first step an acyloin of glucose is formed. The next step is a redox reaction of the acyloin with methylene blue in which the glucose is oxidized to diketone in alkaline solution [6] and methylene blue is reduced to colorless leucomethylene blue.
The nature of the complex formed in Fehling's solution is [Cu(L-tartH-2) 2] 6-(tart = tartrate) Therefore, all hydroxyl groups are deprotonated and the ball and stick model showed in the article is false. Moreover, L-tartaric acid is used to prepare Fehling's solution, so the citation of the publication dealing with complex compounds of copper ...
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]
Reducing form of glucose (the aldehyde group is on the far right) A reducing sugar is any sugar that is capable of acting as a reducing agent. [1] In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a reaction, the sugar becomes a ...
Berberine, a plant compound traditionally used in herbal medicine, is today commonly stocked on the shelves of health food stores and pharmacies as a supplement. Beyond weight loss, berberine also ...
The test is similar to the reaction of Fehling's solution to aldehydes. Composition. Barfoed's reagent consists of a 0.33 molar solution of copper (II) ...