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Aldehyde and ketone testing detected

Compounds that have carbonyl functional group are in, if the carbonyl group is substituted withhydrogen or alkyl groups, aldehyde (RCHO) or ketone (RCOR) are called. Chemistry of these compounds, the carbonyl functional group is chemistry. Identification of these compounds characterized by reactions of carbonyl functional group is possible.

  

  

To identify aldehydes and ketones are several tests that can be used to test 2 and 4 - D-nitro-phenyl hydrazine, chromic acid test, test Ydvfrm, Talnz test, test and test Fuschin Benedict cited.

 

Test 2 and 4 - D-nitro-phenyl hydrazine 

Aldehydes and ketones with the reagent 2 and 4 - D-nitro-phenyl hydrazine orange to red precipitate the day. The test for identifying aldehydes and ketones are used from other compounds. Aldehyde or ketone test if a law in which case you will tend towards the red the color of sediments. 

In the following reaction between a ketone and reagents 2 and 4 - D-nitro-phenyl hydrazine see

chemical  & physical properties

 

 

Preparation of reagents 2 and 4 - D-nitro-phenyl hydrazine

 

1 g 2 and 4 - D-nitro-phenyl hydrazine in 5 mL of concentrated sulfuric acid solution and the solution cautiously 7 ml of water and add 25 ml of 95% ethanol. After the solution is strongly

pressed, you remove it from the solids dissolved

MSDS of phenylhydrazine

www.sciencelab.com/msds.php?msdsId=9926503

 

  Question: 

If the aldehyde or ketone We have a conjugate structure with double bond or benzene ring is reddish orange color. Why

Among the high intensity of transmission electron transfer allowed *    only molecules that have an unsaturated double bonds that have been observed. When a combination is linked  can absorb photons ofUV-ViS area and it is being colored.

 

Identification Methods 

Two or three drops of the unknown liquid (05/0 grams of solid) in 2 ml of ethanol solution and a drop of reagent 2 and 4 - D-nitro-phenyl hydrazine to add it. Orange to red scale formation due to the presence of an aldehyde or ketone is. The presence of conjugated double bonds with the carbonyl group becomes reddish sediment.

Complications

Some ketones give oils which will not solidify

Some allylic alcohols are oxidized by the reagent to aldehydes and give a positive test

Some alcohols, if not purified, may contain aldehyde or ketone impurities

sodume bisulfit test

chemical properties

 

Uses of the reaction

The reaction is usually used during the purification of aldehydes (and any ketones that it works for). The addition compound can be split easily to regenerate the aldehyde or ketone by treating it with either dilute acid or dilute alkali.

physical properties

http://www.chemguide.co.uk/organicprops/carbonyls/addition.html

Talnz test or Tulns 

Talnz test (Tvlns) is another method for the detection of ketones and aldehydes to be used. Aldehydes react with reagents Talnz (Tulns) production of silver mirror in the wall of the test tube. 

In the following reaction was to test Talnz (Tulns) See

chemical properties 

 

Talnz reagent preparation method  

A solution of silver nitrate solution of 3 g water is available in 30 ml of solution B is 10% soda solution. Reagent should be used immediately after preparation. To prepare the reagent Talnz (Tvlns), one ml of solution A and solution B with a mill mix. Silver oxide precipitate is formed. Then add drops of concentrated ammonia solution, the deposition of silver oxide to be resolved. Reactive now ready for testing. 

In the following reactions related to the preparation of Talnz (Tvlns) See

chemical properties 

 

Note: Reactive Talnz (Tvlns) must be provided during use and the remainder is disposed of in the sink. If storage solution, the possibility of forming explosive Fulminating silver deposits there. The mixture of nitride deposition of silver (Ag 3 N) and silver azide (AgN 3) is. 

method  

5.0 ml of reagent Talnz (Tvlns) will add 3 drops or 1/0 gram of material unknown. A silver mirror or black deposits indicate that the test is positive. If you did not receive a response at room temperature, dissolved in a little warm water Human heat.

 

Tip 1: If you are not completely clean test tube, silver for silver mirror is not formed in the wall of the test tube, and for sediment or suspensions appear black.

 

Note 2: Some simple ketones such as acetone and methyl ethyl ketone respond to this test.

physical properties 

 

 

Tollens' test: left side positive (silver mirror), right side negative

talens test video

http://s8.picofile.com/file/8279223034/a_750p96h1i5jo2l8mnnl7n8p61nn2ln59m8901282797_b97c8.mp4.html

complication 

Reagents should not be heated in dye penetration test, and the test solution should be alkaline. When testing the unknown, it is a known aldehyde used as a control

The test tube must be clean and oil-free if a silver mirror is to be observed

Easily oxidized compounds give a positive test. For example: aromatic amine and some phenols

Fuchsin reagent or reagent preparation method 

5.0 g of pure dye penetration (Rvzanylyn hydrochloride) (rosaniline hydrochloride) in 500 ml of distilled water and straightened solution; 500 ml of distilled water with sulfur dioxide, saturated with dye thoroughly mixed and leave for one night. This method of production is colorless and sensitive.

 

In the figure below represents the structure or Rvzanylyn hydrochloride Fuschin see

chemical properties 

 

 

physical properties

 

method  

2 ml of reagent Fuschin - aldehyde in a test tube and add a drop of aldehyde being tested. See the color within a few minutes. (For example, Bvtanal purple-violet appear within 3 to 4 minutes.) It is recalled that should not be heated reagent. 

Benedict test 

Benedict reagent, a reagent labeled with the name of an American chemist (Stanley Rossiter Benedict) is. To identify aliphatic aldehydes (non-aromatic) no sulfur and alpha-hydroxy ketones are used. In the following reaction of an aldehyde and an alpha-hydroxy ketones by introducing see Benedict:

Benedict's Reagent MSDS

https://www.sciencelab.com/msds.php?msdsId=9925648

chemical properties 

physical properties 

 

 

Benedict reagent preparation method

 

173 g of sodium citrate and 100 g of anhydrous sodium carbonate in 800 ml of water and 850 ml by adding distilled water to give it volume. In another within 3/17 gram of copper sulfate and hydrated in 100 ml of water and the resulting solution while stirring citrate solution and add carbonate solution and the final volume by adding water to one liter daily.

 

Solid derivatives 

The aldehydes and ketones are two solid directly used, toxic derivative and derivative Karbazvn 2 and 4 - D is nitro-phenyl hydrazine. (Preparation of these derivatives was previously described.) To aldehydes and ketones derived oxime is prepared. 

Oxime derivatives and derivative toxic reaction Karbazvn you can see in the image below

 

 

 

refference

http://organic-compounds.persianblog.ir/

 

 



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