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METHODS OF SEPERATION OF MONOFUNCTIONAL ORGANIC
COMPOUNDS .
I) Seperation based on differences
In chemical properties of the
Compounds:
1. Toluene and Aniline :
Extraction with dil. HCl ; Aniline passes into the aqueous
layer as salt and may be recovered by neutralization.
2. Phenol and Toluene :
Seperated by treatment with dil. NaOH.
3. Dibutyl Ether and Chlorobenzene :
i) treated with conc. H2SO4 which dissolves Dibutyl ether.
ii) it may be recovered from soln. by dilution with water.
4. Phenols and any compd. containing –COOH grp. :
Treated with dil. soln. of NaHCO3 –
i) weakly acidic phenols (also enols) are not converted into
salts and removed by ether extraction.
ii) acid pass into soln. as the sodium salts and may be
recovered after acidification.
5. Seperation of mix. of amines :
i) Hinsberg test :
substrate : amines
reagent : NaOH + p-tosyl chloride + dil. HCl
product :
a) filtered -ppt.(sulphonamide of primary and sec.amine) +
filterate (tert. amine).
b) ppt. + alkali----- ppt. (sulphonamide of sec. amine) +
filterate (sulphonamide of primary amine)
filterate acidified with dil. HCl to ppt. primary amine.
6. Aldehydes and Ketones from other liq. hydrocarbons :
Shaken with a soln. of NaHCO3--ppt. (bisulphite of carbonyl compds.)
which is decomposed with dil. acid to recover aldehyde or ketone.
II) Seperation based on differences in the volatilities of the
components in aqueous solutions :
1. Diethylamine and butan-1-ol :
i) sufficient dil. H2SO4 added to neutralize the base.
ii) steam distillation to remove the alcohol.
iii) amine can be recovered by adding NaOH to the residue and
repeating the distillation.
2. Diethyl ketone and acetic acid :
i)treated with sufficient dilute NaOH to form sod. acetate and distilling
the aqueous mixture;ketone will pass over in the steam and the
non-volatile stable salt will remain in the flask.
ii)acidification with dilute H2SO4 liberates acetic acid which can be
isolated by steam distillation or by extraction.
DETECTION OF ELEMENTS
SODIUM FUSION TEST:
Organic compound is fused with metallic sodium(Lassaignes
test) to form NaCN,Na2S,sod.halides if the above elements are
present.
(i)Test for Nitrogen:
FeSO4 + 6NaCN  Na4[Fe(CN)6] + Na2SO4
3Na4[Fe(CN)6] + 2Fe2(SO4)3  Fe4[Fe(CN)6]3 + 6Na2SO4
(ii)Test for Sulphur:
1)dil. acetic acid + lead acetate soln. black ppt. of Pb2S
2)2-3 drops of freshly prepared dil. soln. of sod.nitropruside
is addedPurple colouration (slowly fades on standing)
(iii)Test for Halogens(Nitrogen and sulphur absent):
Fusion soln.+dil. nitric acid +AgNO3 Soln.(excess)ppt.
ppt. + dil. aq. ammonia soln.-->ppt.
1)If ppt. is white and readily soluble chlorine is present.
2)If ppt. is pale yellow and difficultly soluble bromine is
present.
3)If ppt. is yellow and insoluble iodine is present.
Functional
Groups
Test(s)
Reagent(s)
Inference
10-No ppt.
Lucas test
conc.HCl+ZnCl2 20-Turbidity within
5 mins.
0
3 -Turbidity at once
Victor Meyers (i)P/I2(ii)AgNO2 10-red colour
Alcohols (-OH)
Test
(iii)HNO2(iv)NaOH 20-blue colour
30-colourless
sod. metal
Na
effervescence
test
occurs
Acetylchloride (i)CH3COCl
white fumes
test
(ii)NH4OH
Ester test
ester
Exception Protecting Removal
Groups
of
(by forming Protecting
group
(i)ether
(ii)esters
H+
pleasant smell
Cerric amm.
CAN
pink or red colour
nitrate test [(NH4)2Ce(NO3)6] (ROH)2Ce(NO3)4
Litmus Test
Phenols
red colour
Neutral FeCl3 Neutral FeCl3
purple or violet
(i)ether
Test
coloured complex
(ii)esters
Libermann’s NaNO2 , H2SO4 red ,blue(when alkali nitrophenol
Test
is added)
& p-sub.phenols.
Tollens test
Aldehyde
litmus paper
Ag(NH3)2+
H+
silver mirror(Ag )
Fehling’s test CuSO4+ sod.pot.
tartarate red colour of Cu20
(equal amounts)
H+
Shiff’s test
Aldehyde &
Ketones
shiff’s reagent deep colour
aromatic
(magenta + water (pink, violet or red) aldehydes
+ SO2)
Hydrazone
DNP
bright orange
test
(or Yellow) ppt.
Haloform
NaOH / I2
Yellow ppt of(CHI3)
test
Iodoform
(methyl
ketone)
Acetals
using
ethylene
glycol
-do-
H+