SYSTEMATIC ANALYSIS OF ORGANIC COMPOUNDS Compiled By: Dr.K.Kesavan M.Sc., Ph.D.,
Former Professor and Head, Presidency College, Chennai.
S.No EXPERIMENT OBSERVATION INFERENCE
1. Colour Pink or dark brown
solid or liquid Phenol or aromaticamines Yellow liquid or solid Nitro compound
Colorless liquid or
white solid. Absence of phenolsor aromatic amines.
2. Odour Phenolioc odour Phenols
Fishy or aniline like
odour. Aromatic amines. Pleasant fruity odour Aromatic esters
Smell of bitter almonds Aromatic aldehydes.
No characteristic odour Absence of \u2026\u2026.. 3. Solubility
In cold water Soluble Carbohydrates,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
Insoluble Absence of\u2026.. II. TEST FOR UNSATURATION.
1. To a little of the substance in water/alcohol add 1 ml of Bromine water.
Decolourised. Unsaturated compound Decolourised with the
formation of a white precipitate.
Saturated compound like Phenol or aromatic amine. Not decolourised. Saturated.
2. To a little of substance in water/Alcohol add dil. alkaline KMnO4
Decolourised Unsaturated Not Decolourised Saturated III. TEST FOR AROMATICITY.
1. A little of the substance is taken in the nickel spatula and introduce into the Bunsen flame.
Burns with sooty
Burns with a non-luminous, non-sooty flame.
Aliphatic compound. 2. Nitration Test: 0.5ml of on
HNO3 and 1ml of Con H2SO4 are mixed in a test tube. A little of the substance is added warmed cautiously poured into a beaker containing water.
Yellow precipitate or
solution Aromatic compound No yellow precipitate or
solution Aliphatic
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 To 1ml of the extract add a little FeSO4,boil,cool and add dil. HCl. A blue or green precipitate or solution is obtained. Presence of Nitrogen. No blue or green precipitate or solution is obtained. Absence of Nitrogen. 2. To 1ml of extract add 2 drops
of lead acetate solution. A black precipitate isobtained. Presence of sulphur. No black precipitate is
obtained. Absence of Sulphur. 3. To 1ml of the extract add 1ml
of dil NO3,boil,cool and then add 1ml of AgNO3. A Curdy white precipitate soluble in NH4OH is obtained. Presence of chlorine. No curdy white
precipitate. Absence of chlorine. V. TEST FOR FUNCTIONAL GROUPS.
1. Test for Carboxylic acids: To a little of the compound in water/alcohol add 1ml of sodium bicarbonate solution.
A quick effervescence
is noted PresenceCarboxylic acids.of No effervescence. Absence of
Carboxylic acids. 2. Test for phenols: To a 1ml of
neutral ferric chloride add a little of the compound.(Dilute if necessary).
A blue, violet or green
colour is noted. Presence of Phenols. No characteristic
colour. Absence of phenols. 3. Test for Esters: To 1mlof
water add a drop of NaOH and a drop of Phenolphalein.To the pink solution add a little of the substance.
The pink colour disappears on shaking or on slight heating.
Presence of Ester. The colour does not
disappear. Absence of ester.
(Note: If the colour disappears immediately it could be due to acids. Amides may also answer this test.)
4. Test for aldehydes/Ketones: To a little of the compound in water/alcohol add 1ml of the
Borsche\u2019s reagent. Boil add a drop of con.HCl, cool and
dilute the water.
An yellow or orange
precipitate s formed. PresenceAldehydes, Ketonesof or Carbohydrates.
5. Test for Aldehydes: To a little of the substance in water/alcohol add 1ml of Schiff\u2019s reagent.
A deep pink or red colour is formed immediately.
Presence of
Aldehydes. A pink or red colour is
not immediately formed.
Absence of
Aldehydes. 6. Test for ketones: To a little of
the substance in water/alcohol add 5 drops of Sodium nitroprusside,5 drops of NaOH and 5 drops of glacial acetic acid.
An orange colour is formed that turns to purple.
Presence of ketones. No characteristic colour
is developed. Absence of Ketones. 7. Test for Carbohydrates: To a
little of the substance in a dry test tube add 5 drops of con.H2SO4.Heat gently.
The substance chars with a characteristic smell of burnt sugar.
Presence of
carbohydrates. The substance does not
char. Absencecarbohydrates. of 8. Test for Primary amines: To a
little of the substance in dil.HCl, add 1ml of strong NaNO2 solution followed by
1mlof \u03b2-naphthol in sodium hydroxide.
A red brown dye is
obtained. Presence of aromaticprimary amines. No characteristic dye is
formed. Absence of aromaticprimary amines. 9. Test for Amides: To a little of
the substance add 2mlof strong NaOH solution, Heat.
Ammonia is evolved. Presence of amides. No evolution of
ammonia. Absence of amides. 10. Test for Diamide: A little of
the substance is heated in a dry test tube. The compound melts and again solidifies. Cool and add 2 drops of CuSO4 solution followed by 2 drops of NaOH.
A violet colour is
formed. Presence of Diamide. No violet colour Absence of Diamide.
11. Test for Nitro compounds: To a little of the substance in water/ethanol add NH4Cl and zinc dust.Heat, filter.Add ml of Tollons solution.
A silver mirror or black
precipitate is obtained.Presence of Nitrocompounds. No silver mirror or
black precipitate is obtained.
Absence of Nitro compounds.
VI. CONFORMATORY TEST FOR FUNCTIONAL GROUPS. 1. For Carboxylic acids. Fruity
odour test: To a little of the substance add 1ml of alcohol,5 drops of con.H2SO4.Boil and pour in 10ml of sodium carbonate solution in a beaker.
Fruity odour is
produced. Carboxylic acid isconfirmed.
2. Test for Phenols:
a. Phalein fusion test: To a 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.
Pink colour is formed Phenol is confirmed.
b. Libermann’s Test: To a little of the substance in a dry test tube add a little NaNO2,5 drops of con.H2SO4 and heat. Pour into a beaker containing water.
A red solution is formed, it turns deep blue on adding NaOH.
Phenol is confirmed.
c. Azodye Test: Dissolve 3 drops of aniline in 1ml of dil.HCl. Add 1mlof saturated NaNO2 solution followed by 1mlof the substance in NaOH.
An orange dye is
formed. Presence of Phenol isconfirmed.
3 Test for Aldehydes:
a. Tollen’s Test: To 1ml of Tollen’s reagent add a little of the substance and heat on a water bath.
A bright silver mirror or black precipitate is obtained.
Aldehyde is
confirmed. b. Fehling’s Test: Mix 0.5ml
each of fehling’s A and B solutions in a test tube and add a little of the substance and heat on a water bath.
A red precipitate is
obtained. Aldehydeconfirmed. is
4. Test For Carbohydrates: a. Molische’s Test: To 1ml
of the substance in water add 1ml of -naphthol inα alcohol mix well. Add con H2SO4 through the sides of the test tube.
A violet ring is formed at the junction of the two liquids.
Carbohydrate is confirmed.
b. Tollen’s Test: Add a little of the substance to 1ml of tollens reagent. Heat on a water bath.
A silver mirror is
formed. Presence of reducingsugar. c. Fehling’s Test: Add a
little of the substance to 1ml of a mixture of fehling’s A and B solutions. Heat on a water bath.
A red precipitate is
formed Presence of reducingsugar.
5. Test For Primary Amines: a. Carbylamine Test: To a
little of the Substance add 3 drops of chloroform and 1 ml of alcoholic KOH and heat.
Offensive smelling gas
is evolved. Primary amine isconfirmed.
6. Test For Aromatic amides: To a little of the substance add 1mlof 20% NaOH solution and boil. Cool and acidify with dil. HCl.
NH3 is evolved Presence of amide confirmed.
A white precipitate is
formed. Presence of aromaticamide confirmed. 7. Test For Diamide:
a. Oxalate Test: To a little f the substance in 1ml of water add 1ml of saturated solution of oxalic acid.
A white crystalline
precipitate is formed. Diamideconfirmed. is b. Nitrate Test: To a little of
the substance in 1ml of water, add 1ml of con.HNO3.
A white crystalline
precipitate is formed. Diamideconfirmed. is 8. Test For Dicarboxylic acids.
Fluorescein Test: To a little of the Substance add a little resorcinol and 5 drops con H2SO4.Heat and pour it in NaOH in a beaker.
A greenish yellow
fluorescence is formed.Dicarboxilic acid isconfirmed.
REPORT: The Given Organic Compound i. is acidic/basic/neutral ii. is saturated/unsaturated iii. is aromatic/aliphatic
iv. has nitrogen/sulphur/halogen
