Benedict’s solution

Benedict s solution Is prepared as follows. Dissolve 86-5 g. of crystallised sodium citrate (2Na,C,H(0, l 1H,0) and 50 g. of anhydrous sodium carbonate in about 350 ml. of water. Filter, if necessary. Add a solution of 8-65 g. of crystallised copper Sulphate in 50 ml. of water with constant stirring. Dilute to 500 ml. The resulting solution should be perfectly clear if it is not, pour it through a fluted filter paper. 

Aromatic aldehydes react with the dimedone reagent (Section 111,70,2). All aromatic aldehydes (i) reduce ammoniacal silver nitrate solution and (ii) restore the colour of SchifiF s reagent many react with sodium bisulphite solution. They do not, in general, reduce Fehling s solution or Benedict s solution. Unlike aliphatic aldehydes, they usually undergo the Cannizzaro reaction (see Section IV,123) under the influence of sodium hydroxide solution. For full experimental details of the above tests, see under Ali-phalic Aldehydes, Section 111,70. They are easily oxidised by dilute alkaline permanganate solution at the ordinary temperature after removal of the manganese dioxide by sulphur dioxide or by sodium bisulphite, the acid can be obtained by acidification of the solution. 

Read over the entire laboratory activity. Form a hypothesis about what will happen when you mix the four sugars with the Benedict s solution. Record your hypothesis in the next column. 

Place 5 mL of the solutions of glucose, fructose, sucrose, and starch into the appropriately labeled test tube, numbered 1 through 4. Add 4 mL of Benedict s solution to each test tube and shake each solution until thoroughly mixed. Place each test tube in the boiling-water bath and heat for... 

After 5 minutes of heating, remove the test tubes and place them in the test-tube rack to cool. Record your observations in Data Table 1. Note any color changes or precipitate that formed. Benedict s solution contains an oxidizing agent... 

Drug/Lab test interactions False-positive urine glucose reactions may occur with penicillin therapy if Clinitest, Benedict s Solution, or Fehling s Solution are used. It is recommended that enzymatic glucose oxidase tests (such as Clinistix or Tes-Tape) be used. Positive Coombs tests have occurred. High urine concentrations of some penicillins may produce false-positive protein reactions (pseudoproteinuria) with the P.870... 

Drug/Lab test interactions A false-positive reaction for urine glucose may occur with Benedict s solution, FeMng s solution, or with C//n/fesf tablets, but not with enzyme-based tests such as Clinistix and Tes-Tape. 

Non-reducing sugars may be hydrolysed by boiling with dilute hydrochloric acid if the solution is then neutralised with aqueous sodium hydroxide the reduction of Fehling s solution or Benedict s solution occurs readily. 

Copper ammonium CUSO4NH4OH Benedict s solution drugstore... 

Gather these materials Two thistle tubes or small glass funnels 2 pint jars 2 upright stands and clamps 3 test tubes an alcohol burner some transparent cellulose wrapping paper 2 rubber bands sucrose (C12Hg2On) crystals of copper sulfate (CuS04) and some Benedict s solution. 

Follow this procedure 1. First you will have to learn how to test for the presence of sugar, because you will need to know this later in the experiment. Label the jars 1 and 2. Fill jar No. 1 halfway with warm water. Dissolve 3 teaspoonfuls of sugar in the water. Now pour a little of the sugar solution into a test tube and add 3 teaspoonfuls of Benedict s solution. Heat the test tube over the alcohol burner until the liquid boils. Now place 2 teaspoonfuls of plain water in a fresh test tube and add an equal amount of Benedict s solution. Heat the test tube over the alcohol burner until the liquid boils. 

Results When you boiled the sugar solution with Benedict s solution added, it turned brick red. The color of the plain water with Benedict s solution added... 

Aldoses reduce Tollens reagent, as we would expect aldehydes to do. They also reduce Fehling s solution, an alkaline solution of cupric ion complexed with tartrate ion (or Benedict s solution, in which complexing is with citrate ion) the deep-blue color of the solution is discharged, and red cuprous oxide precipitates. These reactions are less useful, however, than we might at first have expected. 

When borneol (ROH) is fed to a dog, this toxic substance is excreted as compound P, QHgOe—OR, where R stands for the bornyl group. Compound P does not reduce Benedict s solution. It reacts with aqueous NaHC03 with the liberation of a gas. Treatment of P with aqueous acid yields borneol (ROH) and D-glucuronic acid (Table 34.1), which is oxidized by bromine water to D-glucaric acid. 

The optically inactive carbohydrate bio-inonose, QH10O5, reduces Benedict s solution, but does not react with bromine water. It is reduced to R and S, of formula C6H12O6. Compounds R and S are oxidized by HIO4 to six moles of HCOOH, and react with acetic anhydride to yield products of formula CigH240i2. Vigorous oxidation of bio-inonose yields DL-idaric acid (the dicarboxylic acid from idose) as the only six-carbon fragment. 

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