Fehling solution

LaForge and Hudson194 prepared an osone from the phenylosazone obtained from sedoheptulose (D-aZ(ro-heptulose). The osone reduced Fehling solution strongly, formed the original osazone with phenylhydrazine, and gave a crystalline derivative with o-phenylenediamine. 

Lewis201 postulated maltosone as the first product in the oxidation of maltose by Fehling solution, but no osone was detected when maltose was treated with Fenton s reagent.23 Oxidation of maltosone with bromine water gave 2-oxo-maltobionic acid, isolated as its brucine salt.191... 

Reducing sugars are normally identified by their ability to reduce metallic salts, for example, Fehling solution. In order to do this, the sugar must have a carbonyl function in the form of a hemiacetal. 

A sample (2 ccs) is diluted with 2 ccs of coned hydrochloric acid. This mixture is boiled with Fehling s solution (1) prior to the addition ofFehling solution (2). If no reduction of the Fehling solution takes place the reduction of the oxime is finished. 

Drug/Lab test interactions A false-positive reaction for glucose in the urine may occur. This has been observed with Benedict and Fehling solutions but not with the glucose enzymatic test. 

Semicarbazide, like other hydrazines, reduces Fehling solution and, unless substituted in the 1-position, undergoes the typical hydrazine reactions with esters, carbonyl compounds and halides, etc. On heating, it decomposes to hydrazine and biurea. 

TO 10 mil PER CENT STARCH SOLUTION ADD 10 DROPS HYDROCHLORIC ACID. BOIL FOR 2 MINUTES. TEST THE RESULT WITH FEHLING SOLUTION. YOU GET RED PRECIPITATE THAT SHOWS PRESENCE OF GLUCOSE. UNTREATED STARCH SOLUTION DOES NOT REACT WITH THE FEHLING SOLUTION. 

D FILTER THE WHEY. TEST THE FILTRATE WITH FEHLING SOLUTION (SEE PAGE 85). MILK SUGAR GIVES RED CujO PRECIPITATE. 

Other methods of fractionation which utilize the presence of ionizable groups, either natural (such as carboxyl or amino groups), or induced (such as borate complexes), may be useful. Such methods have been discussed in reviews.248 2W Complexation (for example, with Fehling solution) was found useful in the study of a polymannose.216 An insoluble complex was formed, as with natural mannans. 

If n is the total dilution to which the original filtrate is subjected to obtain the solution used in the Fehling titration, and a the number of c.c. of the diluted solution required to decolorise the 50 c.c. of Fehling solution, the lactose (hydrated) L contained in 100 grams of the milk analysed is given by the formula ... 

From the data of the Fehling titration (see 2, a), the number of c.c. F of Fehling solution which would be reduced by the total reducing sugars present in 100 grams of milk is calculated by means of the formula2 ... 

Ascorbic acids reduce Fehling solution in the cold, and react with ferric chloride to produce the violet color typical of enolic compounds. They are readily oxidized reversibly to their primary oxidation products, 2,3-glycodiulosono-1,4-lactones (commonly known as dehydroascorbic acids 148, Scheme 16), by such mild oxidizing agents as aqueous iodine. Titration with such oxidants constitutes a quantitative method for distinguishing ascorbic acids from 2-glyculosonic acids. 

All these substances reduce hot Fehling solution, though the anilide LXXIX required heating at 95° for two minutes. Treatment with 0.003 M barium methoxide in dry methanol at room temperature decomposed 3-keto-n-butyl 0-D-glucopyranoside tetraacetate (X), to yield D-glucose and methyl vinyl ketone (LXXX). 

Pseudomonas aeruginosa, which is composed of L-rhamnose and ( —)-2-hydroxynonane-l-carboxylicacid. Although it is a glycoside of a j3-hydroxy ester, it was reported to be non-reducing to Fehling solution. 

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