Tests for the Functional Group Present in the Organic Compounds - MeitY OLabs

Tests for the functional group present in

the organic compounds Tests for unsaturation Bromine water test. Take the unknown compound using a spatula. Add it into a test tube. Take 2 ml of distilled water in a measuring

cylinder. Pour it into the test tube and shake it well. Take 1-2 drops of bromine water. Add it to the test tube and shake it well. The disappearance of orange-red colour of

bromine indicates unsaturation. Otherwise, it is saturation. Baeyer�s Test. Add some unknown compound into a test tube

using a spatula. Take 2 ml of distilled water in a measuring

cylinder. Add it to the test tube and shake it well. Now, add 2-3 drops of KMnO4solution to it. Decolourisation of pink colour of KMnO4 indicates

unsaturation. Otherwise, it is saturation. Alcoholic Group

Sodium Metal Test. Take a clean and dry measuring jar. Pour 1ml of the given unknown compound into

it. Pour it into a dry test tube. Add a small amount of anhydrous calcium sulphate

in it. Shake well. Place a funnel over a test tube. A filter paper is set into the funnel. Filter the solution into the test tube. Remove the funnel. Take small pieces of sodium metal using a

forceps. Place it on a filter paper and dry it with

another filter paper. Add 2-3 pieces of sodium metal into the test

tube using a forceps. Alcohols react with active metals like sodium

to produce effervescence due to the liberation of hydrogen gas. Ester Test. Take a measuring jar. Pour 1 ml of the unknown compound into the

measuring jar. Transfer it into another dry test tube. Take another measuring jar. Pour 1ml of glacial acetic acid into it. Pour it into the test tube. Take a dropper. Add 2-3 drops of concentrated sulphuric acid

into the test tube. Warm the mixture in a water bath for 10 min. Add this mixture into 20 ml of cold water

taken in a beaker and smell it. Alcohol reacts with carboxylic acid in presence

of concentrated sulphuric acid to form fruity smelling compound called esters. A fruity smell indicates the presence of an

alcoholic group. Ceric Ammonium Nitrate Test. Take a measuring jar. Pour 1ml of the given unknown compound into

it. Pour it into a dry test tube. Add few drops of ceric ammonium nitrate reagent

into it. Shake well. Alcoholic compounds on reaction with ceric

ammonium nitrate to give a red colouration due to the formation of alkoxy cerium (IV)

complex. Acetyl Chloride Test. Take a measuring jar. Pour 1ml of the given unknown liquid into

it. Pour it into a dry test tube. Add a small amount of anhydrous calcium sulphate

into it. Shake well. Place a funnel over a test tube. Place a filter paper in the funnel. Filter the liquid in the test tube. Remove the funnel. Add 2-3 drops of acetyl chloride into it. Take a glass rod and dip it in ammonium hydroxide

solution. Bring the glass rod near the mouth of the

test tube. Alcohols on reaction with acetyl chloride

form esters and give out hydrogen chloride gas. The hydrogen chloride gives white fumes of

ammonium chloride with ammonium hydroxide. Iodoform Test

Take a measuring jar. Pour 1ml of the given unknown liquid into

it. Pour it into a dry test tube. Take 1 ml of 1% iodine solution in a measuring

jar. Add it to the test tube. Add dilute Sodium hydroxide solution drop

wise until the brown colour of iodine is discharged. Warm the mixture gently in a water bath. Formation of yellow precipitate of Iodoform

indicates the presence of alcoholic group. Lucas Test

Take a small quantity of primary, secondary and tertiary alcohols in three different test

tubes. Using a dropper, take a small quantity of

Lucas reagent. Add few drops of Lucas reagent into tertiary

alcohol. Tertiary alcohol reacts instantaneously with

Lucas reagent to form alkyl chloride, which being insoluble, results in cloudiness in

the solution. Take Lucas reagent using the dropper. Add a few drops of it into the secondary alcohol

and keep the test tube undisturbed for 5 minutes. Secondary alcohol reacts in about 1-5 minutes

with Lucas reagent to form alkyl chloride, which being insoluble, results in cloudiness

in the solution. Again take Lucas reagent. Add a few drops of it into the primary alcohol. Using a tests tube holder, take the test tube

containing primary alcohol. Heat the test tube over the Bunsen burner. On warming, primary alcohols react with the

Lucas reagent to form alkyl chloride, which being insoluble, results in cloudiness in

the solution. Tests for Phenolic group

Litmus test Take some unknown liquid from the test tube. Take a moist blue litmus paper. Pour a drop of the given liquid onto the paper

using a dropper. Phenol is a weak acid: it turns the color

of blue litmus paper red. Ferric chloride test

Take a measuring jar. Pour 1ml of neutral ferric chloride into it. Pour it into a dry test tube. Add 2-3 drops of given liquid into the test

tube. Phenol, on reaction with neutral ferric chloride,

gives a violet color due to the formation of a complex. Liebermann�s test

Take a test tube. Add 2-3 crystals of sodium nitrite into it. Take a measuring jar. Pour 1ml of phenol into it. Pour it into the test tube. Heat it gently for a half a minute and allow

it to cool. Take a measuring jar. Pour 1ml of conc. Sulphuric acid into it. Pour it into the tube. Phenol, on reaction with sodium nitrite in

the presence of conc. sulphuric acid, gives a deep blue or green

colored product. Add water to it carefully. The blue or green colour changes to red or

brown colour on treatment with water due to the formation of indophenol. Add excess of sodium hydroxide solution to

the test tube. The red colour again changes to blue or green

by the addition of a strong alkali, due to the formation of indophenol anion. Phthalein dye test

Take a small quantity of phenol in a test tube. Using a spatula take small quantity of phthalic

anhydride. Add it into the test tube containing phenol. Take the test tube using a test tube holder. Using a dropper, add a small quantity of concentrated

sulphuric acid to the test tube. Heat the contents of the test tube in an oil

bath for about 1 minute. Pour the reaction mixture carefully into a

beaker containing sodium hydroxide solution. On heating, phenol reacts with phthalic anhydride

in the presence of sulphuric acid to produce phenolphthalein, which is colourless. Phenolphthalein gives pink colour with an

alkali such as NaOH. Tests for Aldehydic and Ketonic Group

2,4-Dinitrophenyl hydrazine Test. Take a spatula. Take some given unknown compound and add it

to a dry test tube. Take a dropper. Add some drop of rectified spirit until the

compound just dissolves. Take 5 ml of 2, 4-Dinitrophenyl hydrazine

solution in a measuring jar. Add it to the test tube. Shake the mixture. Allow it to stand for 5 minutes. Yellow or orange crystals form, indicating

the presence of aldehydes or ketones. Sodium bisulphite test. Take 2ml of sodium bisulphite in a measuring

jar. Pour it into a dry test tube. Add some unknown compound to it with a spatula. Cork the test tube. Shake it and allow it to stand for 20 minutes. Formation of crystalline white precipitate

confirms the presence of carbonyl group. Tests for Aldehydes

Schiff�s test Take a dropper. Take few drops of given unknown solution using

a dropper. Pour the taken solution into a test tube. Take 1 ml of the Schiff's reagent in a measuring

jar. Take the test tube containing organic compound. Pour Schiff�s reagent into the compound

and Shake it. Appearance of pink colour confirms the presence

of aldehydic group. Tollen�s tets

Take 1 ml of silver nitrate solution in a test tube. Pour it into a clean test tube. Take another measuring cylinder. Take 2 ml of dil. NaOH solution in it. Pour it into the same test tube. Silver nitrate reacts with sodium hydroxide

to form brown precipitate of silver oxide. Take a dropper

Add dil. Ammonia solution dropwise to the test tube

The precipitate will dissolve in the solution. Add 2-3 drops of the given liquid to the test

tube Warm the test tube on a water bath for 5 minutes. In the presence of aldehydes, the silver ions

in the test reagent are reduced to elemental silver and accumulate on the inner surface

of the reaction vessel, producing a silver mirror effect on the inner surface of the

vessel. Fehling�s test

Take 1 ml of Fehling�s solution A in a measuring jar. Pour it into the test tube. Take 1 ml of Fehling�s solution B in a measuring

jar. Add it to the test tube. Add 4-5 drop of given solution into the test

tube using a dropper. Warm the test tube in a water bath for 5 minutes. Aldehydes reduce the Cu(II) ions in the test

reagent to red precipitate of copper (I) oxide. Tests for ketones

m-Dinitrobenzene Test. Take a dropper. Take some drops of given liquid. Pour it into a test tube. Add a small amount of powdered m-dinitrobenzene

to it. Take a small quantity of sodium hydroxide

solution using a dropper. Add some amount of dil. Sodium hydroxide solution to it. Shake well. Appearance of a violet colour that slowly

fades confirms ketonic group. Sodium nitroprusside test

Take a spatula. Take some crystals of sodium nitroprusside

into a test tube. Add some amount of distilled water to it and

shake the test tube well. Take a small amount of given compound using

a spatula. Add it into the test tube. Shake well

Add some drops of sodium hydroxide solution. The anion of the ketone formed by an alkali,

reacts with nitroprusside ion to form a red coloured complex. Tests for Carboxylic Group

Sodium biocarbonate test. Take a dropper. Take few drops of unknown solution. Add it into the test tube. Take a small quantity of sodium bicarbonate

using a spatula. Add it into the test tube, Carboxylic acid

reacts with sodium bicarbonate to produce brisk effervescence due to the formation of

carbon dioxide gas. Ester test

Take a dropper. Take few drops of unknown solution. Add it into the test tube. Take few drops of ethyl alcohol using a dropper. Add ethyl alcohol into the test tube. Take 1-2 drops of Conc. sulphuric acid using another dropper. Add it into the test tube. Take the test tube. Place it in a boiling water bath and heat

the contents of the test tube for 5 min. Pour it into a small beaker containing distilled

water. Carboxylic acid reacts with alcohol in the

acidic medium to produce fruity smelling compounds called esters. Litmus test. Take a small quantity of unknown solution

using a dropper. Drop 2-3 drops of it on a moist blue litmus

paper. Carboxylic acid turns blue litmus red, indicating

it is acidic in nature. Tests for amino group

Litmus test. Take a small quantity of unknown solution

using a dropper. Pour few drops of it on to the moist red litmus

paper. Amines are basic in nature, which turns red

litmus paper blue. Solubility test

Take some amount of given compound in a test tube using a spatula. Add a small quantity of dil. HCl to the test tube. Organic compounds containing the amino group

are basic in nature and easily react with acids to form soluble salts. Carbylamine test

Take some potassium hydroxide in a test tube. Take 2ml of ethanol in a measuring jar. Add it into the test tube. Warm the test tube until potassium hydroxide

dissolves. Using a dropper, take few drops of chloroform. Add it into the test tube. Add a small amount of the given unknown compound

in the same test tube. Gently warm it. Aliphatic, as well as aromatic primary amines,

when warmed with chloroform and alcoholic KOH, give

isocyanide, which has an offensive smell. Azo � dye test. We require organic compound, dil. HCl, sodium nitrite, distilled water, beta-naphthol,

dil. NaOH,

spatula, droppers, test tubes etc. Take a small quantity of organic compound

using a dropper and transfer it into the test tube A.

Using another dropper take small quantity of dil. HCl. Add it into the test tube A and shake the

test tube well to dissolve the compound in HCl. Take a small quantity of sodium nitrite using

the spatula. Take the test tube B.

Transfer it into test tube B. Now add a small quantity of distilled water to the test tube

and shake the test tube well to dissolve sodium nitrite. Place the test tube in the test tube rack. Using another spatula, take a small quantity

of beta-naphthol. Transfer it into test tube C.

Using a dropper, take a small quantity of dil. NaOH. Add it into test tube C and shake the test

tube well to dissolve naphthol. Take the test tubes. Place them in an ice bath and cool the test

tubes for some time. Take the test tubes A and B.

Add sodium nitrite solution into test tube A. Now add the resulting solution from test

tube A to test tube C. Aromatic primary amine reacts with nitrous

acid generated in situ by the reaction of sodium nitrite

with HCl at 0�5 degree celcius to produce diazonium salt. This couples with beta-naphthol to give a scarlet red dye. Nitrous acid test. Take a small quantity of sodium nitrite using

a spatula. Take the test tube A.

Transfer sodium nitrite into test tube A. Pour small quantity of distilled water to

it and shake the test tube well to dissolve sodium nitrite. Place the test tube in the rack. Using a dropper transfer a small quantity

of organic compound into test tube B. Using another dropper add a small quantity

of conc. HCl to test tube B and shake the test tube

well to dissolve the compound in HCl. Take the test tubes. Place them in an ice bath and allow them to

cool form sometime. Mix both the solutions. No visual change is observed, in the case

of tertiary amine because tertiary amine has formed a soluble nitrite salt by

reacting with the acid present. Primary amine reacts with nitrous acid to

liberate bubbles of nitrogen gas. Secondary amine reacts

with nitrous acid to form a yellow, oily layer of nitrosamine. Hinsberg test

Using a dropper take a small quantity of 25% NaOH and add few drops of it into the test

tunes A, B and C. Now add small quantity of distilled water to the test tubes A, B and

C. Using a dropper take a small quantity of benzene

sulphonyl chloride and add few drops of it into the test tubes A, B and C.

Shake the test tubes well. Cool the test tubes by placing them in a beaker

containing water. Primary amine reacts with benzene sulphonyl

chloride and sodium hydroxide to form a soluble sulfonamide salt. Secondary amine reacts with benzene sulphonyl

chloride and sodium hydroxide to form an insoluble sulfonamide. Tertiary amine will not react with the sulphonyl

chloride, but is insoluble. Using another dropper, take small quantity

of Conc. HCl. Add it into the tests tubes A, B and C. In

test tube A, the soluble sulfonamide salt formed precipitates after addition of HCl. In test tube B acidification of the mixture

does not dissolve the insoluble sulphonamide. In test tube C, the insoluble amine is converted

to a soluble ammonium salt.