ORGANIC ANALYSIS
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A SYSTEMATIC PROCEDURE FOR ORGANIC QUALITIVE ANALYSIS
EXPERIMENT
OBSERVATION
i) yellow solid or liquid.
I. Preliminary Tests
INFERENCE
Presence of aromatic
nitro compounds.
i) Brown or dark coloured solid
or liquid.
May be phenols or
aromatic amines.
The colour and appearance of the
substance is noted.
ii) Colorless solid or liquid.
May be carboxylic
acids, esters,
aldehydes, ketones .
2. Odour of the substance
i) Phenolic smell.
May be phenols.
The odour of the substance is noted.
ii) Pleasant smell.
May be esters,
ketones,
nitrocompounds.
iii) Fishy smell.
May be aromatic
amines.
i) Soluble in cold condition.
May be carbohydrates
or aliphatic diamide.
ii) Soluble in hot condition.
May be aromatic or
aliphatic acids.
a) Blue litmus turns red.
May be acids or
phenols.
b) Red litmus turns blue.
May be aromatic
amines.
c) Neutral to litmus.
May be amides, esters,
adehydes, ketones,
amines, carbohydrates.
The substance is soluble.
May be aromatic
amines.
1.Colour and appearance
3.Solubility Test
Solubility of the substance is
tested in the following solvents.
a) In water
A small amount of the substance is
shaken up with 1 ml of water and the
mixture is tested with litmus paper.
b) In dil. HCl solution
A small amount of the substance is
shaken up with 1 ml of dil. HCl.
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c) In dil. NaOH solution
A small amount of the substance is
shaken up with 1 ml of dil. NaOH.
4. Litmus Test
A little of the substance is brought in
contact with a moistened litmus paper.
The substance is soluble.
i)
Blue litmus turned red.
ii) Red litmus turned blue.
iii) No change of colour takes
place
May be aromatic or
aliphatic acids or
phenols.
Presence of acids or
phenols.
Presence of amines.
Presence of
carbohydrates, ketones,
esters.
5. Test for Special Elements
Preparation of Sodium Fusion Extract ( Lassaigne’s test)
A small piece of dry sodium metal is fused in a fusion tube by heating gently. To this, little of
the solid substance or 2 drops of liquid substance is added and the tube is heated gently until the reaction
subsides and then heated to redness. The red hot end of the tube is plunged into 10ml of distilled water
in a mortar. The contents are ground well, boiled in a china dish and filtered. The filtrate is used for
following tests.
a) Test for Nitrogen
To about 2 ml of the filtrate, equal i) A blue or green precipitate or
volume of strong solution of freshly solution is obtained.
Presence of Nitrogen.
prepared ferrous sulphate (FeSO4) is
added. The solution is boiled, cooled and ii) No blue or green precipitate
or solution is obtained.
then dil. H2SO4 is added drop by
Absence of Nitrogen.
drop with constant shaking.
b) Test for Sulphur
To about 2ml of the filtrate is
treated with equal volume of freshly
prepared sodium nitroprusside.
c) Test for Halogens
A purple or violet colour is
obtained.
Presence of sulphur.
No purple or violet colour is
obtained.
Absence of sulphur.
(i) A curdy white precipitate,
Presence of chlorine.
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completely soluble in NH4OH
To about 2ml of the filtrate, equal
is obtained.
volume of dil.HNO3 is added the solution
is boiled, cooled and then silver nitrate
(ii) A pale yellow precipitate,
(AgNO3) solution is added.
sparingly soluble in NH4OH
is obtained.
Presence of bromine.
(iii) A yellow precipitate,
insoluble in NH4OH is obtained.
Presence of Iodine.
(iv) No characteristic precipitate
is obtained.
Absence of halogens
(chlorine, bromine and
iodine).
6. Test for Aliphatic or Aromatic Character
a) A little of the substance is taken in a
nickel spatula and heated in the free
flame of the Bunsen burner.
b) 1 ml conc. HNO3 and 1 ml of conc.
H2SO4 is mixed in a dry test tube. To this
a little of the substance is heated for 10
mins in a boiling water bath and then
poured into a beaker containing 20 ml of
water.
i) Burns with a smoky sooty
flame.
The substance is
aromatic.
ii) Does not burn with a smoky
sooty flame but burns with a nonluminous flame.
The substance is
aliphatic.
iii) The substance chars and
burns slowly.
The substance is
carbohydrates.
i) A yellow precipitate or
solution is obtained.
The substance is
aromatic.
ii) No yellow precipitate or
solution is obtained.
The substance is
aliphatic.
7. Test for Saturation or Unsaturation
a) A little of the substance is shaken with i) Bromine water decolourised
1ml of bromine water added drop by readily.
drop.
ii) Bromine water is
decolourised with the formation
of a white precipitate.
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Presence of
unsaturated substance.
Presence of saturated
compounds like
amines and phenols
which are readily
brominated.
iii) The solution remains brown
on adding bromine water.
b) A small amount of the substance is i) Pink colour decolourised.
shaken with 1 ml of water or acetone and
1ml of 2 % aq. KMnO4 is added drop by
drop with constant shaking.
ii) No decolourisation takes
place.
8. A little of the substance is added to 1 i) Vigorous effervescence takes
ml of a strong solution of sodium place and substance dissolves.
bicarbonate (NaHCO3) without shaking;
the changes are observed and shaken iii) Slow effervescence takes
place.
well.
iii) Slow effervescence and the
solution turn yellow.
9. A little of the substance is added to 2
ml of aq. NaOH solution, shaken well,
the changes are observed and then
heated to boiing.
The substance is
saturated.
May be unsaturated
compound or easily
oxidisable compounds
like aldehydes,
phenols or amines.
May be presence of
saturated compound.
May be presence of
carboxylic acids.
May be presence of
polyhydric phenols.
May be presence of
nitrophenol.
i) Dissolves readily in
cold. When the solution is
acidified with drops of
conc. HCl and cooled, the
substance is regenerated.
May be acids, phenols.
ii) Solution turns yellow or
brown and finally dark on
shaking in cold condition.
Polyhydric phenols
present.
iii)
Substance dissolves
gradually on warming.
May be esters.
iv)
Solution turns
yellow or brown when
boiled.
May be carbohydrates,
aliphatic aldehydes.
v) Ammonia gas is
evolved on continued
boiling.
vi) Substance is unaffected
in the cold and on boiling.
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May be amides.
May be nitro
compounds, ketones,
amines.
10. A little of the substance is heated
gently with soda lime and then more
strongly.
i) Ammonia gas is evolved.
11. A little of the substance is warmed
with 2 ml of conc. H2SO4 solution.
i) Charring or blacking takes
place with effervescence.
May be amides.
ii) Vapours with a phenolic smell Phenols are present.
and condensing to oily globules of
a liquid are evolved.
May be aromatic
amines, polyhydric
phenols, carbohydrates.
ii) White precipitate is formed
which dissolves in water.
May be aromatic
amines.
12. A little of the substance is dissolved A violet or blue or green colour
in water or alcohol and neutral FeCl3 is obtained.
solution is added drop by drop.
Presence of phenols.
13. A small amount of the substance is
added to 2 ml of Tollen’s reagent and
heated in a water bath for 10 mins.
May be presence of
polyhydric phenols,
aromatic primary
amine and reducing
sugar like
glucose.
A bright silver mirror or black
precipitate is obtained.
II. Test for Functional Groups ( Confirmative tests )
Note: It is necessary to do all the preliminary tests [from 1-12] to fix functional group. After
identifying functional group the test for the particular group alone is performed.
1. Test for Carboxylic acids
Presence of carboxylic
a) A pinch of the substance is shaken Pink colour is produced after
adding
a
number
drops
of
NaOH.
acids.
up with about 1 ml of water. One drop
of phenolphthalein is added and then very A pink colour is got even with the Absence of carboxylic
acids.
dilute sodium hydroxide solution is addedfirst drop of NaOH.
drop by drop with shaking.
b) A little of substance is mixed with a 2
ml of alcohol in a dry test tube, two drops A pleasant ester smell is noted.
of conc. H2SO4 are added, shaken well
and warmed and poured into a 30 ml of a
dilute solution of sodium carbonate
(Na2CO3) , stirred well and the smell is
noted.
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Presence of carboxylic
acids.
c) Fluorescein Test: A little of substance
is mixed with pinch of resorcinol in a dry
test tube and 1 ml of conc. H2SO4 are
added, shaken well, gently warmed and
poured into a beaker containing water,
stirred well. To this excess of NaOH
solution is
added and stirred well.
i) The mixture turns deep red on
heating, forms a red solution
with water and on adding NaOH,
an intense greenish yellow
fluorescence is obtained.
Presence of
dicarboxylic acids.
ii) No intense greenish yellow
fluorescence is obtained.
Presence of
monocarboxylic acids.
2. Test for Phenols
a) Libermann’s Test: A little of substance
is heated with a few crystals of sodium A red solution is obtained, which Presence of phenolic
nitrite in a dry test tube, cooled and 3 or turns blue or green on adding group.
4 drops of conc.H2SO4 are added, shaken NaOH solution.
well and poured into 50 ml of water in a
100 ml beaker, stirred well. To this
All phenols do not give
NaOH is added in excess and stirred well.
this test.
b) Phthalein Fusion Test: A little of
substance is mixed with pinch of phthalic
anhydride in a dry test tube and 1 ml of
conc. H2SO4 are added. The mixture is
gently warmed and poured into 50 ml of
water in a 100 ml beaker. To this NaOH
is added in slight excess and stirred well.
i) A pink or red colour is
obtained.
Presence of simple
phenols, salicylic acid.
ii) An intense yellowish green
fluorescence is obtained.
Presence of dihydric
phenols like
resorcinol.
c) Azo-Dye Test: A few drops of aniline A scarlet red or brownish red or
are dissolved in about 5 ml of dil.HCl. To orange red precipitate of a dye is
this 5 ml of a strong solution of sodium obtained.
nitrite is added in drops with constant
shaking and cooled in ice cold water. To
the above diazotized solution, a solution
of the substance dissolved in 3 ml of
10%NaOH is added.
d) About 1 ml of Fehling’s solution A is A red brown
mixed with 1 ml of Fehling’s solution B. obtained.
The mixture is added to a
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precipitate
Presence of phenols
such as resorcinol or
naphthol.
is Presence of polyhydric
phenols.
little of the substance shaken well and
heated in a water bath.
3. Test for Carbohydrates
a) Molisch’s Test: To a little of the
substance is dissolved in 2 ml of water, a
few drops of an alcoholic solution of 1naphthol are added, shaken well and 2 ml
of conc. H2SO4 is added along the sides
of the test tube without shaking.
A violet or purple or red coloured Presence of
ring is obtained at the junction of carbohydrates is
the two layers and the colour confirmed.
slowly spreads throughout the
solution.
b) Fehling’s Test: A small amount of
substance is shaken up with 1 ml of A red brown
water. The solution is added to about 2 ml obtained.
of Fehling’s solution A and Fehling
solution B and heated on a water bath for
15 mins.
precipitate
is Presence of
carbohydrates.
(reducing sugars)
c) A small amount of the substance is A bright yellow crystalline
dissolved in 5 ml of water, then added 2 precipitate is obtained.
ml of phenyl hydrazine hydrochloride
and 2 ml of glacial acetic acid. The
contents are heated in a water bath for 15
mins with occasional shaking and
cooled.
Presence of reducing
sugars like glucose,
fructose etc.
d) Barfoed’s Test: To a little of the i) A red brown precipitate is
substance in water, Barfoed’s reagent is obtained.
added and heated in a water bath.
ii) No red brown precipitate is
obtained.
Presence of
monosaccharides.
Presence of
polysaccharides.
4. Test for Aldehydes and Ketones
a) About 3 drops of the substance are
added to a saturated solution of sodium
bisulphite solution and shaken well.
A white crystalline precipitate is
obtained.
b)A small amount of the substance is
A yellow or red-brown crystalline
added to about 3 ml of Borsche’s reagent, precipitate is obtained.
a drop of conc. HCl is added, gently
heated for about 2 mins and then cooled
well.
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Aldehydes and certain
ketones are present.
Ketones with keto group
directly attached to
benzene ring does not
answer this test.
Presence of aldehydes
and ketones.
c)A mixture of 5 drops of phenylhydrazine a) A yellow or yellowish white
and 5 drops of glacial acetic acid are taken precipitate is obtained.
in a dry test tube. A small amount of the
substance is added, gently heated for a
b) A bright yellow crystalline
minute. Excess of cold water is added and precipitate
shaken well.
Presence of aldehydes
and ketones.
Presence of reducing
sugars.
d)About 0.3 g of semicarbazide
A white crystalline precipitate of Presence of aldehydes
hydrochloride is dissolved in water. About the semicarbazone is obtained.
and ketones.
0.5 g of sodium acetate crystals are added,
shaken well to dissolve the solid and to
this 2 ml of an alcoholic solution of the
substance is added, heated in a water bath
for 15 mins and cooled.
e)A small amount of the substance is
A violet colour is produced quickly. Presence of aldehydes is
added to about 3 ml of Schiff’s reagent
confirmed.
and shaken well.
f)A small amount of the substance is added A reddish brown precipitate is
to 2 ml of Fehling’s solution A & B and obtained
heated gently.
Presence of aliphatic
aldehydes.
Reducing sugars and
polyhydric phenols also
answer this test.
5. Test for Esters
a)Hydroxamic Acid Test
A violet or deep red brown colour is Presence of esters.
About 3 drops of the liquid and a pinch of obtained.
hydroxylamine hydrochloride are added to
about 5 ml of 10 % NaOH solution. The
contents are gently boiled for 3 mins,
cooled, acidified with conc. HCl, added
drop by drop and then about 5 drops of
FeCl3 solution are added and shaken well.
b) The liquid is refluxed with 10 % NaOH A white precipitate is obtained.
Ester of an aromatic acid
solution. The residue is acidified with con
is present.
HCl and cooled.
6.Test for Amides
a) A little of substance is heated with
5 ml of 10 % NaOH solution and
acidified with conc. HCl and cooled.
i) Ammonia is evolved while
heating.
Presence of aliphatic
or aromatic amide.
ii) On adding HCl, a white
precipitate is obtained.
Presence of aromatic
amide.
iii) On adding HCl, no white
precipitate is obtained.
Presence of amides of
lower aliphatic acids
and urea.
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b) Biuret Test: A small amount of the Ammonia is evolved on heating.
substance is gently heated in a dry test A violet or red colour
tube for few miutes, cooled, the residue solution is obtained.
is shaken up with 2 ml water, a few drops
of CuSO4 are added and then 10 %
NaOH is added drop by drop.
Presence of diamides
like urea.
7.Test for Amines
i) A little of the substance is dissolved in A clear solution is obtained.
about 1 ml of conc. HCl, diluted to 4 ml
and cooled in ice cold water. To this a few
drops of aq. sodium nitrite (NaNO2) A yellow or yellowish brown oily
[already cooled in ice water] is added liquid separates.
drop wise with constant shaking.
A yellowish brown crystalline
precipitate is obtained. The
precipitate is removed, dissolved
in water and when treated with
NaOH gives a green solid.
Presence of aromatic
primary amine.
ii) If a clear solution is obtained, a A scarlet red dye is obtained.
solution of 2-naphthol in NaOH is added.
Presence of aromatic
primary amine.
Presence of secondary
amine.
Presence of tertiary
amine.
iii) The yellow oily liquid obtained above The mixture added to water gives a Presence of secondary
is mixed with 2 drops of phenol, heated red solution which becomes green amine.
gently, 2 drops of conc. Sulphuric acid
or blue on adding NaOH.
added, again warmed, added to 20 ml of
water and then NaOH solution added in
excess.
b) A small amount of the substance I
A characteristic offensive smell of
mixed with a few drops of chloroform, 2cc isocyanide is obtained.
of alcoholic potash added and warmed
gently.
Presence of primary
amine.
c) About 0.5 g of the substance is shaken A white crystalline precipitate of
up with 2 ml of acetic acid. About 5 drops the acetyl derivative is obtained.
of acetic anhydride are added, shaken well
for some time and then diluted with water.
Presence of primary or
secondary amine.
8.Test for Nitro compounds
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a) Mulliken Barker’s Reaction: A
A bright silver mirror or a black
small amount of the substance is precipitate of silver is obtained.
dissolved in about 2 ml of alcohol.
About 1 ml of a strong solution of
calcium chloride is added, a pinch
of Zn dust is added, contents
shaken well for a few minutes and
filtered. The filtrate is added to
Tollen’s reagent and heated in a
water bath.
b) A small amount of the substance is
mixed with a few granules of tin
and 2 ml of con HCl, gently
heated, shaken well and again
heated. The contents are filtered
and the following tests are carried
on
i) A few drops of the filtrate are
A characteristic offensive smell of
treated with a few drops of
isocyanide is obtained.
chloroform and 2 to 3 ml of
alcoholic potash and gently
heated.
ii) About 2 to 3 drops of the filtrate A scarlet- red dye is obtained.
are diazotized with sodium nitrite
solution and the diazotized
solution is added to a solution of
β-naphthol in sodium hydroxide.
Presence of nitro group.
Presence of nitro group.
Presence of aromatic
nitro group.
REPORT:
The given organic substance is
i.
aliphatic /aromatic
ii.
unsaturated /not unsaturated
iii.
Contains / does not contain the elements sulphur, nitrogen, and halogens
iv.
Contains the functional group
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