systematic organic analysis

SYSTEMATIC ANALYSIS OF ORGANIC COMPOUNDS

Compiled By: Dr.K.Kesavan M.Sc., Ph.D., Former Professor and Head, Presidency College, Chennai. S.No

EXPERIMENT

1.

Colour

OBSERVATION

INFERENCE

Pink or dark brownPhenol or aromatic solid or liquid amines Yellow liquid or solid Nitro compound Colorless liquid or Absence of phenols white solid. or aromatic amines. 2. Odour Phenolioc odour Phenols Fishy or aniline likeAromatic amines. odour. Pleasant fruity odour Aromatic esters Smell of bitter almonds Aromatic aldehydes. No characteristic odour Absence of \u2026\u2026.. 3. Solubility Soluble Carbohydrates, In cold water diamide, aliphatic aldehydes, ketones and acids. insoluble Absence of \u2026\u2026 If the compound is insoluble in cold water, test its solubility in NaOH and HCl. In NaOH Soluble Phenols or aromatic carboxylic acids. Insoluble Absence of \u2026. In HCl Soluble Aromatic amines Absence of\u2026.. Insoluble II. TEST FOR UNSATURATION. To a little of the substance in Decolourised. Unsaturated 1. water/alcohol add 1 ml of compound Bromine water. Decolourised with the Saturated compound Phenol or formation of a white like aromatic amine. precipitate. Not decolourised. Saturated. 2. Unsaturated To a little of substance in Decolourised water/Alcohol add dil. alkalineNot Decolourised Saturated KMnO4 III. TEST FOR AROMATICITY. 1. with sooty Aromatic compound. A little of the substance is Burns taken in the nickel spatula andluminous flame. introduce into the Bunsen flame.

Burns with a non-Aliphatic compound. luminous, non-sooty flame. 2. Nitration Test: 0.5ml of on Yellow precipitate orAromatic compound HNO3 and 1ml of Con H2SO4 solution are mixed in a test tube. A No yellow precipitate or Aliphatic little of the substance is addedsolution warmed cautiously poured into a beaker containing water. IV.TEST FOR ELEMENTS (N, S, Cl). Preparation of Sodium fusion extract: A small piece of sodium, dried with a filter paper is taken in a fusion tube. It is heated in a Bunsen flame to give a silvery globule. A small piece of organic compound is added, heated till the bottom becomes red hot. The hot tube is plunged into about 10ml of water into a mortar. It is ground well and boiled and then filtered. The filtrate is tested for the elements N,S and Cl. 1 blue or green Presence of Nitrogen. To 1ml of the extract add a A little FeSO4,boil,cool and add precipitate or solution is dil. HCl. obtained. No blue or green Absence of Nitrogen. precipitate or solution is obtained. 2. To 1ml of extract add 2 drops A black precipitate isPresence of sulphur. of lead acetate solution. obtained. No black precipitate is Absence of Sulphur. obtained. 3. Curdy To 1ml of the extract add 1ml A white Presence of chlorine. of dil NO3,boil,cool and then precipitate soluble in add 1ml of AgNO3. NH4OH is obtained. No curdy white Absence of chlorine. precipitate. V. TEST FOR FUNCTIONAL GROUPS. Test for Carboxylic acids: To a A quick effervescencePresence 1. of little of the compound in is noted Carboxylic acids. water/alcohol add 1ml of No effervescence. Absence of sodium bicarbonate solution. Carboxylic acids. 2. Test for phenols: To a 1ml of A blue, violet or greenPresence of Phenols. neutral ferric chloride add a colour is noted. little of the compound.(Dilute No characteristicAbsence of phenols. if necessary). colour. 3. pink Test for Esters: To 1mlof The colour Presence of Ester. water add a drop of NaOH anddisappears on shaking a drop of Phenolphalein.To theor on slight heating. pink solution add a little of theThe colour does notAbsence of ester. substance. disappear. (Note: If the colour disappears immediately it could be due to acids. Amides may also answer this test.)

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of Test for aldehydes/Ketones: An yellow or orangePresence To a little of the compound in precipitate s formed. Aldehydes, Ketones or Carbohydrates. water/alcohol add 1ml of the Borsche\u2019s reagent. Boil add a drop of con.HCl, cool and dilute the water. Test for Aldehydes: To a little A deep pink or redPresence of of the substance in colour is formed Aldehydes. water/alcohol add 1ml of immediately. Schiff\u2019s reagent. A pink or red colour isAbsence of not immediately Aldehydes. formed. Test for ketones: To a little of An orange colour is Presence of ketones. the substance in water/alcoholformed that turns to add 5 drops of Sodium purple. nitroprusside,5 drops of NaOH No characteristic colour Absence of Ketones. and 5 drops of glacial acetic is developed. acid. Test for Carbohydrates: To a The substance chars Presence of little of the substance in a dry with a characteristic carbohydrates. test tube add 5 drops of smell of burnt sugar. con.H2SO4.Heat gently. The substance does not Absence of char. carbohydrates. Test for Primary amines: To a A red brown dye isPresence of aromatic little of the substance in obtained. primary amines. dil.HCl, add 1ml of strong No characteristic dye is Absence of aromatic NaNO2 solution followed by formed. primary amines. 1mlof \u03b2-naphthol in sodium hydroxide. Test for Amides: To a little of Ammonia is evolved. Presence of amides. the substance add 2mlof strong No evolution of Absence of amides. NaOH solution, Heat. ammonia. Test for Diamide: A little of A violet colour is Presence of Diamide. formed. the substance is heated in a dry test tube. The compound meltsNo violet colour Absence of Diamide. and again solidifies. Cool and add 2 drops of CuSO4 solution followed by 2 drops of NaOH. Test for Nitro compounds: To A silver mirror or blackPresence of Nitro a little of the substance in precipitate is obtained. compounds. water/ethanol add NH4Cl andNo silver mirror orAbsence of Nitro zinc dust.Heat, filter.Add ml black precipitate is compounds. of Tollons solution. obtained.

VI. CONFORMATORY TEST FOR FUNCTIONAL GROUPS. For Carboxylic acids. Fruity Fruity 1. odour is Carboxylic acid is odour test: To a little of the produced. confirmed. substance add 1ml of alcohol,5 drops of con.H2SO4.Boil and pour in 10ml of sodium carbonate solution in a beaker. 2. Test for Phenols: a. Phalein fusion test: To a Pink colour is formed Phenol is confirmed. little of the substance add a little pthalic anhydrie,5 drops of con.H2SO4.Heat and pour into a beaker of water containing a few drops of NaOH. b. Libermann’s Test: To a A red solution is Phenol is confirmed. little of the substance in aformed, it turns deep dry test tube add a little blue on adding NaOH. of NaNO2,5 drops con.H2SO4 and heat. Pour into a beaker containing water. c. Azodye Test: Dissolve 3 An orange dye isPresence of Phenol is confirmed. drops of aniline in 1ml of formed. 1mlof dil.HCl. Add saturated NaNO2 solution followed by 1mlof the substance in NaOH. 3 Test for Aldehydes: Aldehyde is a. Tollen’s Test: To 1ml of A bright silver mirror or Tollen’s reagent add a black precipitate is confirmed. little of the substance andobtained. heat on a water bath. b. Fehling’s Test: Mix 0.5ml A red precipitate isAldehyde is each of fehling’s A and B obtained. confirmed. solutions in a test tube and add a little of the substance and heat on a water bath. 4. Test For Carbohydrates: a. Molische’s Test: To 1ml A violet ring is formed Carbohydrate is of the substance in water at the junction of the confirmed. add 1ml of α-naphthol in two liquids. alcohol mix well. Add con H2SO4 through the sides of the test tube.

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Tollen’s Test: Add a little A silver mirror isPresence of reducing sugar. of the substance to 1ml of formed. tollens reagent. Heat on a water bath. c. Fehling’s Test: Add a A red precipitate isPresence of reducing sugar. little of the substance to formed 1ml of a mixture of and B fehling’s A solutions. Heat on a water bath. Test For Primary Amines: a. Carbylamine Test: To a Offensive smelling gasPrimary amine is confirmed. little of the Substance addis evolved. 3 drops of chloroform and 1 ml of alcoholic KOH and heat. Presence of amide Test For Aromatic amides: To NH3 is evolved confirmed. a little of the substance add 1mlof 20% NaOH solution A white precipitate isPresence of aromatic and boil. Cool and acidify withformed. amide confirmed. dil. HCl. Test For Diamide: white crystallineDiamide is a. Oxalate Test: To a little f A the substance in 1ml of precipitate is formed. confirmed. water add 1ml of saturated solution of oxalic acid. b. Nitrate Test: To a little of A white crystallineDiamide is the substance in 1ml of precipitate is formed. confirmed. water, add 1ml of con.HNO3. Test For Dicarboxylic acids. A greenish yellow Dicarboxilic acid is Fluorescein Test: To a little of fluorescence is formed.confirmed. the Substance add a little resorcinol and 5 drops con H2SO4.Heat and pour it in NaOH in a beaker.

REPORT:

The Given Organic Compound i. is acidic/basic/neutral ii. is saturated/unsaturated iii. is aromatic/aliphatic iv. has nitrogen/sulphur/halogen v. has _________as the functional group.