Procedure for systematic identification of Organic Compounds
In the identification of organic compounds, the following steps should be followed systematically
Haphazard methods will lead to wrong results, waste of chemicals and time.
As far as possible stick to the relative amounts reagents mentioned in the procedure. Use of excess of
chemicals will not always give the desired results.
When you are using volatile and inflammable solvents like ether and benzene, keep the test-tube away
from flame.
1. Physical Examination:
a) State- Solid/liquid
b) Colour- white/colourless / yellow /red/dark
c) Odour- Characteristic odour/odourless.
2. Ignition test:
Experiment
Two or three drops of the
given liquid or a small pinch
of the given solid is taken in a
spatula and heated, till the
substance catches fire and
burns
3. Bromine Water Test:
Observation
a) The compound burns
liberating lot of smoke
b) White fumes are
liberated
c) A voluminous porous,
black residue is left
behind
Inference
The compound is aromatic
and /or unsaturated
Compound may be urea
Compound may be
carbohydrate
Compound+ 1drop of bromine
water. Shake well
Reddish brown colour of
bromine is discharged or
faded
Reddish brown colour is not
discharged
Compound may be
unsaturated or a phenol or
amine or an amide or an
aldehyde
Compound is none of the
above
OR
Compound+1-2 drops of 1%
Pink colour is discharged
KMnO4 Solution. Shake well
It is an easily oxidizable
compound like an unsaturated
compound or a phenol or an
amine or an aldehyde
Pink colour is not discharged
The Compound is none of the
above.
White ppt soluble in NH4OH
Pale yellow ppt sparingly
soluble in NH4OH
Chlorine is present
Yellow ppt insoluble in
NH4OH
Iodine is present
Test for Halogens:
(1) 2ml of stock solution
+10-15drops of conc.
HNO3 Boil, cool and
add silver nitrate
solution
(2) 2 ml of stock solution
+Cl2 water +CCI4
shake well.
(3) Beilstein’s test for
halogens:
Dip a clean and fresh
copper wire in the
substance and hold it
in the blue flame of a
Bunsen burner
6. Solubility Test:
Bromine is present
Bromine is confirmed
a) Orange red globule
b) Violet globule
A green flame is
observed
Iodine is confirmed
Halogen is present in the
compound
The Purpose of this test is to find out the correct group to which the organic compound
belongs. For this purpose different solvents are tried and the solubility of the compound is
determined. This gives the group and the probable functional groups in that group. Then
classification reactions for that particular solubility group are carried out to find out the exact
functional group.
The solute and the solvent should be used in a proper proportion to judge solubility. For this
purpose 2-3 drops of the unknown liquid or about 0.2g of the unknown solid, about 5ml of the
solvent is added and shaken well.
The unknown liquid is said to be soluble in a solvent if,
a)
b)
c)
d)
Two separate layers are not formed
Oily drops are not seen
Emulsion is not observed
A homogeneous solution is formed with or without change of colour or liberation of heat.
On mixing a liquid with a solvent (e.g. benzyl alcohol and conc. H2SO4) if a solid if formed,
that compound has reacted with the solvent and hence it belongs to that group of the solvent
The unknown solid is said to be soluble in a solvent if it dissolves completely in it to form a
homogenous solution.
Note:
1) If the compound is insoluble in water, solubility in ether should not be tested
2) To try ether and conc. H2SO4 as solvents, the test tube must be completely dry.
3) If the compound contains nitrogen, and it is insoluble in water and 5% HCI, it belongs to
VII group. Then solubility in NaOH and conc. H2SO4 should not be carried out.
Solubility Table
Soluble in
ether
Group
Compoun
ds
Insoluble in
ether (
Nitrogen
may be
present)
Soluble in Soluble In
5%
HCI 5% NaOH
(Nitrogen Is
Present)
Soluble in
cold conc
H2SO4
I
II
III
IV
V
Many low
mol wt.
compounds
and
Resorcinol
Amides and
carbohydrate
s e.g.
Urea
Glucose
Amines
e.g.
Aniline
O,m,p
Toluidines.
Monomethyl
Aniline
Dimethyl
aniline
Carboxylic
acids and
phenols
e.g.
Benzoic
alcohol,
Salicylic acid
Pehnol
O,m,pcresols
Alcohols
Aldehydes
Ketones
and esters
e.g.
Benzyl
alcohol,
Benzaldeh
yde
Acetophen
one
Methyl &
Ethyl
Benzoates
Insoluble
in cold
conc
H2SO4
(
Halogen
may be
present)
Nitrogen
is present
and
compound
is
insoluble
in water
and
5%HCI
VI
Aromatic
hydrocar
bonds
and their
halogen
derivativ
es
e.g.
Toluene
Biphenyl
Naphthal
ene,
Chlorobe
nzene,
Benzyl
Chloride
VII
Amides
and nitro
compound
s
Benzamid
em
Nitrobenzene mdinitroBenzene,
P-Nitro
toluene
4. Physical Constants:
If the given compound is a solid, determine the melting point. Note down the temperature when the
substance in the capillary tube has just melted
If the given compound is a liquid, determine the boiling point. See that the bulb of the thermometer is just
a little bit below the level of the side arm of the distillation flask. Note down the constant temperature
when about half of the liquid has distilled out. This is the observed boiling point. Since boiling point
decreases by one percent for every 1,000ft. Altitude above sea level, at Bangalore a correction of 3.5% is
to be added to the observed B.P. to get the correct B.P.
Correct B.P. = observed B.P. +3.5% correction.
5. Lessaigne’s Test (Sodium fusion test) or Elementary Analysis:
The purpose of this test is to find out the presence or absence of nitrogen, sulphur and halogens in the
given organic compound.
A piece of metallic sodium is taken on a filter paper by means of a spatula. It is pressed between the
folds of the filter paper and dried. It is then introduced into a dry sodium fusion tube. The tube is held
by a pair of tongs and waved over a flame once or twice till the sodium becomes a silvery white
button. The fusion tube is cooled in air. A small quantity of the given organic substance is introduced
into it and the tube is heated intermittently. Sodium reacts with nitrogen, sulphur and halogens to
form the respective sodium compounds, namely sodium cyanide, sodium sulphide and sodium halide.
The fusion is complete when a black fused mass is formed in the fusion tube. Now the fusion tube is
heated strongly till it becomes red hot. It is then plunged into about half a test tube of distilled water
taken in a mortar. Two more fusions are carried out similarly and these fusion tubes are also dropped
into the same mortar. Using a pestle, the fused mass with glass is crushed. The mixture as such is
taken in a small beaker and boiled. The purpose of boiling is to extract the fused mass to the
maximum extent. The hot mixture is filtered. The filtrate called ‘Stock solution’ is used as follows to
detect nitrogen sulphur and halogens.
Experiment
Test for nitrogen:
Observation
A blue or a green coloured
solution or a ppt
Inference
Nitrogen is present
2mlof stock solution+Freshly
prepared ferrous sulphate
Solution +2 drops of NaOH.
Boil, cool and add excess of dil
H2SO4
Test for sulphur
2ml of stock solution +2or 3
drops of sodium nitro prusside
indicator
Sulphur is present
Violet coloured solution
OR
Sulphur is present
2ml of stock solution +acetic
acid + lead acetate solution
Black ppt
7. Classification reactions:
Depending on the solubility group to which the organic compound belongs, classification reactions of the
particular group are carried out to detect the functional group. For example, if the compound belongs to
IV group, tests for carboxylic acid and phenolic compounds are conducted.
8. Preparation of a suitable solid derivative:
To confirm the identification of the functional group, a suitable solid derivative having a M.P. between
500 and 2500C is prepared, filtered, washed, dried and the melting point is determined.
CLASSIFICATION REACTIONS FOR I GROUPOF THE SOLUBILITY TABLE:
Compounds belonging to this group are soluble in water and also in ether. Reactions for phenolic
compounds are carried out.
Experiment
1) Compound dissolved in
water+ a few drops of
neutral ferric chloride
solution.
2) Compound + water +
bromine water dropwise.
Shake well
3) Phthalein Test:
Compound in a dry test
tube +1/2 its quantity of
phthalic anhydride + 2
drops of conc. H2SO4.
Heat till a dark red
coloured mixture is
formed. Pour the mixture
into a beaker containing
cold water.
Add excess of NaOH
solution and stir.
Observation
Inference
A violet coloured solution.
It is a phenolic compound
Reddish brown colour of
bromine water is discharged
It is a phenolic compound
Yellow coloured solution is
formed
Phenolic compound is confirmed
A double coloured (green and
red) solution is obtained
The given compound may be
resorcinol
Preparation of derivative, Dibenzoate.
Take about one gram of the given compound in a 100ml. Stoppered conical flask. Add about 15 to 20ml.
of 5% NaOH solution. Shake well. Add about 2ml. of benzoyl chloride in excess as can be recognised by
its odour and irritating action. Cool the flask if lot of heat is liberated. Pour the contents of the flask into a
beaker of cold water. Filter the dibenzoate derivative at the pump. Wash with water and dry.
CLASSIFICATION REACTIONS FOR II GROUP OF THE SOLUBILITY TABLE:
Compounds of this group are soluble in water but insoluble in ether. Such substances are
1. Amides like urea
2. Carbohydrates like glucose.
IF the elementary analysis shows the absence of nitrogen, it canbe concluded that amides are absent and
tests for carbohydrates should be directly carried out.
Reaction of amides:
Experiment
1) Compound +5ml of 4 N
NaOH solutions. Boil
and expose a wet red
limus paper to the
vapour. Expose a glass
rod dispped in HCi to the
gas
2) Biuret test:
The given compound is
heated in a dry test tube
till all ammonia is
expelled in the form of
white fumes. The solid
melts and then solidifies.
On cooling, to the white
residue a few drops of
NaOH solution and a
drop of copper sulphate
solution are added
Observation
Inference
Red litmus paper turns blue.
Dense white fumes
It is an amide
A purple or violet colour is seen
The given substance is urea.
1. Compound+Conc.
H2SO4 Heat
A black product is formed
It is a carbohydrate
2. Compd. +NaOH solution
boil well
Yellow coloured solution first
formed turns brown
It is a Carbohydrate
A violet ring is formed
It is a carbohydrate
A red ppt if formed
It is a reducing sugar
Reactions of Carbohydrates:
3. Molisch Test
Solution of compound in
water+(alpha) Naphthol colution
in alcohol+conc. H2SO4 carefully
down the sides of the test tube
4. Compound+ Fehling’s
solution ( Mix equal
volumes of Fehling’s A
and Fehling’s B
Solution)
Heat for a few minutes
5. Silver Mirror Test
Experiment
Observation
Inference
Compound+ Tollen’s Reagent
(To 2ML. of silver nitrate
solution, add a few drops of
NaOH solution. A brown ppt is
formed. Add enough NH4OH just
to dissolve the ppt to form a
colourless solution.)
Heat by placing the test tube in a
beaker containing hot water or by
direct heating without shaking
the test tube
The test tube appears silvery
white from outside
It is a reducing sugar
6. Osazone Formation:
It is a reducing sugar
Compound dissolved in
water+phenyl hydrazine.
Heat the test tube in a beaker
containing boiling water.
Preparation of derivatives:
A. For amides(ex. Urea)- nitrate derivative
Dissolve a little urea in water taken in a test tube. Add Conc. HNO3 dropwise till a white
crystalline ppt appears. Filter the ppt, wash with minimum quantity of water and dry
B. For Carbohydrates (ex. Glucose)—Osazone derivative.
The yellow crystalline solid formed inreaction(6) for Carbohydrates is the osazone of the sugar. It is
filtered, washed and dried.
CLASSIFICATION REACTIONS FOR III GROUP OF THE SOLUBILITYTABLE
Compounds belonging to this group contain nitrogen. They are insoluble in water, but dissolve in 5%
hydrochloric acid. Such compounds are
Primary amines- aniline and o,m,p- toluidines
Secondary amines- monomethyl aniline
Tertiary amines- dimethyl aniline.
Experiment
Observation
1. Compound in a dry test
tube+acetyl chloride drop
by drop
2. Compound +2ml of glacial
acetic acid +2ml of acetic
anhydride. Heat and pour
the mixture to cold water
or dil NaOH solution
taken in a beaker
A vigorous reaction takes place with the
evolution of heat
Inference
It may be ap – or a s- amine but
not a t- amine.
OR
A solid is formed
3. Compound in a dry test
tube + a few drops of
benzoyl choloride
4. Cabylamine Test:
Compound +alcoholic KOH
solution+ chloroform. Heat the
mixture and pour into water
and feel the smell
A vigorous reaction takes place with the
liberation of heat and a solid is formed
It may be p- or s-amine but not tamine
A foul smell
5. Diazotisation and coupling
reaction:
a. Compound + di HCL.
Cool the test tube in ice
water for 2 minutes
b. Cool a solution of sodium
nitrite in water, in ice
water for 2 minutes.
The compound must be a pamine
Pale blue or yellow coloured solution
Mix the two solutions(a)
and (b)
It is a p-amine
OR
Yellow oily drops
It is a s-amine
OR
Green ppt
It is a t-amine
A red dye is formed
To the above mixture of
(a) and (b) add an ice cold
solution of β naphthol in
NaOH solution
P-amine is confirmed
Derivatives:
(a) Acetyl or benzoyl derivatives of p-and s-amines:
To the compound taken in a dry test tube, add acetyl chloride or benzoyl chloride drop wise. A vigorous
reaction takes place in cold itself. Lot of heat is liberated and a solid if formed. Pour the reaction mixture
into water or dil NaOH solution. Filter the solid derivative and dry.
(b) Preparation of p-bromo derivative of t-amine:
To the compound taken in a test tube, add a solution ofbromine in glacial acetic acid and warm. Filter
the p-bromo derivative which separates out on cooling. Wash and dry.
CLASSIFICATION REACTIONS FOR IV GROUP OF THE SOLUBILITY TABLE:
Compounds belonging to this group are insoluble in water and 5% HCI. But they are soluble in 5%
NaOH. Such substances are carboxylic acids and phenolic compounds.
E.g. Benzoic acid, Phenol, o, p, m-cresols, phenolic acids ( salicylic acid)
Reactions of Carboxylic acids.
Experiment
1.
Compound+water+a piece of
blue litmus paper. Shake well.
2. Compound +5% sodium
bicarbonate solution.
3. Esterification:
Compound +3-4 drops of
ethyl alcohol +2-3 drops of
conc. H2SO4. Heat and pour
the mixture into beaker
contining water. Add a little
NaOH soln to neutralize the
solution
4. Formation of acid amides:
Compound in a dry test tube+
A small quantity of
phosphorus pentachloride.
Heat slightly. Cool. Add
liquor ammonia to the mixture
carefully.
Reactions of Phenols:
Observation
Inference
Blue limus paper turns red
It is an acidic compound
Slow effervescence takes place on the
surface of the solid.
It is a carboxylic acid
Sweet fruity odour
It is a carboxylic acid
A vigorous reaction takes place and a
white solid is formed
It is a carboxylic acid
1. Compound+ water+2-3 drops
of neutral ferric chloride
solution.
2. Compound+Bromine water
dropwise. Shake
Violet or pink or dirty green
coloured solution
It is a phenolic compound
Reddish brown colour is discharged
and a white or pale yellow ppt is
formed
It is a phenolic compound
Colour less solution turns pink or
blue in NaOH medium
It is a Phenolic compound
(Exception-p-cresol)
3. Phthalein Reaction:
Compound in a dry test tube+half its
quantity of phthalic anhydride + 2-3
drops of conc. H2SO4. Heat the test
tube till a homogeneous red coloured
mass is formed. Pour the mixture into
water taken in a beaker. Add NaOH
solution in excess
Derivative:
(a) Amide derivatives of carboxylic acids:
Take the given compound in a dry test tube and add phosphorus pentachloride. Heat and cool
the liquid product.
Add liquor ammonia dropwise carefully. A Vigorous reaction takes place with the liberation of
heat and white solid is formed.
(b) Preparation of acetyl derivative of salicylic acid(aspirin)
Take the given compound in a test tube. Add acetic anhydride (2ml) and glacial acetic acid
(2ml).
Heat and pour the mixture into dil NaOH solution taken in a beaker. Filter the white solid which
separates out, wash and dry.
(c) Preparation of benzoate derivative of phenol, m-cresol and p-cresol:
Add about one test tube of 5% NaOH to about 2ml of the phenol taken in a 100ml stoppered
conical flask. Add about 2ml of benzoyl chloride dropwise with vigorous shaking. Destroy any
excess of benzoyl chloride by the addition of excess of NaOH solution. Cool, filter the
precipitate,
wash and dry.
(d) Preparation of picrate derivative of O-cresol and m-cresol:
Prepare strong solution of cresol in about 3ml of benzene and picric acid in about 3ml of
benzene separately. Mic the two solutions and evaporate to dryness near the window. Yellow
crystalline solid separates Out.
CLASSIFICATION REACTIONS FOR V GROUP OF THE SOLUBILITY TABLE
Compounds belonging to this group do not contain nitrogen. They are insoluble in water, 5% HCI
& 5% NaOH. But they are soluble in cold con. Sulphuric acid, with the evolution of heat or
change of colour. Such compounds are.
Alcohols- Benzyl alcohol
AldehydesBenzaldehyde
Ketones _ Acetophenone.
Esters- Methyl benzoate and ethyl benzoate.
Experiments
Test for alcohols:
1. Compound (3-4 drops) in
a dry test tube + a piece
of dry sodium
2. Acetylation:
3-4 drops of the
compound +2=3 drops of
acetyl chloride or acetic
and anhydride and 2-3
drops of glacial acetic
acid. Warm the solution
and pour into water taken
in a beaker. Add NaOH
solution to neutralise the
solution
Observation
Inference
A vigorous reaction takes place
and sodium quickly dissolves
It is an alcohol
A pleasant smelling solution is
obtained
It is an alcohol
Test for aldehydes and ketones:
1. Compound +phenyl
hydrazine
2. Compound +2.4 dinitro
phenyl hydrazine
3. 2-3 drops of compound
+5ml of 40% sodium
bisulphate solution.
Shake vigorously for a
few minutes
4. Compound+2-3 drops of
Schiffs reagent. Shake
well in cold/
5. Compound + Tollen’s
reagent. Heat the test
tube in a beaker
Yellow solid is formed
It is an aldehyde or a ketone
Orange red solid is obtained
It is an aldehyde or a ketone
A crystalline think white ppt is
obtained
It is an aldehyde or a Ketone
A rose red coloured solution is
obtained
It is an aldehyde
The test tube appears silvery
white from outside
It is an aldehyde
containing hot water or
by direct heating without
shaking the test tube
6. Compound + a few
drops of sodium nitro
prusside +NaOH
solution in excess.
Shake well
7. Compound+ twise the
quantity of m-dinitrobenzene +NaOH
solution in excess.
Shake well.
8. Iodoform Reaction:
Compound +Iodine
solution + excess of
NaOH solution. Shake
well. Warm if necessary
A red coloured Solution
It is a ketone
A pink or violet colour is
developed; this fades away
gradually
It is a ketone
A yellow ppt is formed
It is a methyl ketone
Test for esters:
1. Odour of the compound
Sweet fruity Odour
2. Compound + 20%
sodium jhydroxide
A white precipitate is formed
solution. Boil for about
10 minutes. Cool and add
excess of dil H2SO4.
3. Compound + 2-3drops of
ethyl alcohol. Shake.
Add about 0.2g
hydroxylamine
hydrochloride + about
5ml of 2N NaOH
solution. Boil gently;
cool Add 1-2 drops for
neutral ferric chloride
solution and excess of dil
HCI
A violet or deep reddish brown
colour is seen
4. Compound + dil NaOH + Pink colour gradually disappears
Phenolphthalene and
warm with shaking
It may be an ester
It is an ester
It is an ester
It is an ester
Preparation of derivatives:
(A) Benzoic acid from benzyl alcohol.
Take a mixture of a few drops of benzyl alcohol and about 5ml of 10% sodium carbonate
Solution in a 100ml concial flask provided with a one holed cork carrying a long glass tube which
serves as a condenser. Heat the solution and add about 15ml of saturated solution of potassium
permanganate slowly till a light pink colour remains. Boil for a few more minutes. Filter off
brown ppt of managanese dioxide. Add dil H2SO4 to the filtrate till the solution is acidic. On
cooling benzoic acid separates out as a white solid. Filter, wash and dry.
(B) Preparation of phenyl hydrazone derivative of benzaldehyde and acetophenone:
To about 5ml of phenyl hydrazine taken in a test tube add a few drops of glacial acetic acid and a
few drops of benzaldehyde or acetophone. Shake well. Filter off the yellow ppt. of the phenyl
hydrazone. Wash and dry.
(c) Preparation of benzoic acid from methyl and ethyl benzoates:
To about 2ml of methyl or ethyl benzoate taken in 100 ml concial flask provided with a one holed
cork carrying a long glass tube, add about 25 ml of 20% NaOH solution. Boil for about 10-15
minutes. Acidify with HCI and cool. Filter off the precipitate of benzoic acid, wash and dry.
CLASSIFICATION REACTIONS FOR VI GROUP OF THE SOLUBILITY TABLE
Compounds belonging to this group do not contain nitrogen. They are insoluble in water, 5% HCI
5% NaOH and cold conc. H2SO4 such compounds are
Aromatic Hydrocarbons- Toluene, Naphthalene and biphenyl.
Aromatic Halides- Chlorobenzene and benzyl chloride.
Experiment
Observation
Inference
1. 2 to 3 drops of the liquid
or a small pinch of the
solid +5 ml. of fuming
H2SO4. Heat strongly
with carefully shaking
Compound dissolves to form a
homogeneous solution.
It is an aromatic compound
2. Small quantity of
substances as above+5
ml of dimethyl sulphate.
Heat the solution
strongly with shaking
Compound dissolves to form a
homogeneous solution
It is an aromatic compound
A white turbid mixture is formed
It is an aromatic compound
Add NH4OH to the
mixture
The following reaction is carried out only if the presence of chlorine in the given compound has been
established by elementary analysis.
Compound + silver nitrate
solution+5ml of ethyl alcohol.
Shake well.
White ppt
Chlorine atom is in the side chain
No ppt
Chlorine atom is attached to the
aromatic nucleus
Preparation of Derivatives:
A. Benzzoic acid from toluene:
For procedure, see the method of preparation of benzoic acid from benzyl alcohol in V group.
Use toluene instead of benzyl alcohol.
B. Pictrate derivative of naphthalene:
To a strong solution of naphthalene in about 3 ml of benzene add a stron solution of picric acid in
about 3ml of benzene. Mix the two solutions. Evaporate the solution to dryness near the window
to get the solid.
C. Preparation of nitro derivatives for biphenyl, chlorobenzene and benzyl chloride.
Take the compound in a test tube and add a mixture of 3ml. of fuming nitric acid and 3ml of
conc. Sulphuric acid, Boil with shaking for about 5 minutes. Add one or two drops of the mixture
to a little ice water taken in another test tube.
If a yellow solid separates out, nitration is complete. If a yellow emulsion is formed nitration is
incomplete and the mixture must be heated for a few more minutes. Finally, pour the mixture into
ice water. Filter off the yellow solid, wash and dry.
CLASSIFICATION REACTIONS FOR VII GROUP OF THE SOLUBILITY TABLE
Compounds belonging to this group contain nitrogen. They are insoluble in water and 5% HCI.
Such compounds are,
Amides- Benzamide
Nitro compounds- Nitrobenzene , mdinitrobenxene, p-nitrotoluene
Experiment
Test for amides
Compound + excess of 2N NaOH
solution. Boil well and expose a
wet red litmus paper to the vapours;
also expose the vapours to glass rod
dipped in HCI. Cool the solution
and add excess of HCI
Observation
Inference
Red Litmus paper turns blue
Dense white fumes
A white solid separates out
It is an amide
A red dye is formed
The original compound is a
nitro- compound
An ash-grey coloured ppt is
formed
It is a nitro compound
Tests for nitro compounds:
1. Compound (3-4 drops or a
small pinch of solid) + Tin
or Zinc bits + conc HCI.
Boil well with shaking till
the yellow compound has
dissolved completely to
form a colourless solution.
Filter the hot solution. Cool
the filtrate first under tap
and then in ice.
To this, add an ice cold
solution of sodium nitrite in
water and then an ice cold
solution of β-naphthol in
NaOH
2. Mullikan and Barker’s
reaction:
Compound + alcohol+
concentrated solution of
calcium chloride + zinc
dust. Boil and filter.
Filtrate +Tollent’s reagent
3. Janowsky’s reaction:
Compound+acetone+NaOH Pale yellow coloured
solution. Shake well
solution
Violet or pink coloured
solution
Preparation of derivatives:
A. Benzoic acid from benzamide:
It is a mononitro compound
It is a dinitro compound
To a little benzamide taken in a test tube, add about 5ml of 50 % H2SO4. Boil well and pour the
mixture into ice water taken in a beaker. Filter off the precipitated benzoic acid, wash and dry.
B. Preparation of M-dinitrobenzene from nitrobenzene:
To about 3ml of nitrobenzene, add about 3 ml of fuming HNO3 and 3ml of conc- H2SO4. Boil
for about 5 minutes with shaking. Pour the mixture into ice water. Filter off the yellow solid,
wash and dry.
C. Preparation of derivative from m-dinitrobezene
Prepare a strong of m-dinitrobenzene in 3ml of benzene. To this add a strong solution of
naphthalene in 3ml of benzene and mix well. Concentrate and cool the solution or evaporate the
solution to dryness near the window to get the derivative.
D. Preparation of p-nitrobenzoic acid from p-nitro toluene:
For procedure, see method of preparation of benzoic acid from benzyl alcohol in V group. Use pnitro toluene instead of benzyl alcohol.