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METHODS OF PURIFICATION (OC) - Coggle Diagram
METHODS OF PURIFICATION (OC)
Solvent Extraction / Differential Extraction
Based on different solubilities of an organic compound in different solvents
If an organic compound is soluble in water and is more soluble in an organic solvent than water, it is
seperatated by shaking it with an organic solvent.
The organic solvent and the aqueous solution should be immisicble with each other so they form discinct layers.
Higher density: Solvent Layer
Lower Density: Organic compound in aqueous layer
Example: Benzoic acid can be extracted from its aqueous sol. using benzene as a solvent.
Chromatography
Adsorption Chromatography
Column Chromatography:: Based on rate of adsorption
Thin Layer Chromatography: Taking a sample on a glass plate, immersed in solvenet, and based on solubility and rates.
basesd on the fact that different compounds are adsorbed on an adsorbent to different degrees.
Commonly used adsorbents: Silica Gel, Alumina, Magnesium Oxide, Cellulose Powder, Activated animal charcoal.
They are based on the Principle of Differential Adsorption
RF= Distance moved by substance from baseline/ distance moved by solveent from base line
NOTE: Amine acids are detected by
spraying the plate with ninhydrine solution
Partition Chormatography
Paper Chromatography
based on the principle of continuous differential partitioning of components of a mixture b/w stationary and mobile phases.
Same method as TLC: A filter paper is used
Solvent moves from bottom to top
via cappilary action,
Amine acids and sugar are used for seperation
2 phases involved
Stationary Phase
Either liquid/solid
Moving/mobile phase
one thats allowed to move slowly over the stationary phase, (gas/liquid).
Used for seperation of mixtures into their components, purification of compounds, and also to test purity.
Initially used for the seperation of coloured substances found in plants
This technique is based on the rates at which components of mixtures move through a porous(stationary) medium under the influence of some solvent.
Sublimation
convert from solid to vapor, is a reversible reaction, attains equilibrium,
Used in purification of solids
Eg: Camphor, Naphthalene, Anthracene, Benzoic Acid, Indigo, Iodine, Mercury(II) Chloride, Solid Sulphur Dioxide, phthalic anhydride
Distillation
Steam Distillation
Used to
serperate compounds that are steam volatile, and are insoluble in water.
Examples, Aniline, Nitrobenzene, Bromobenzene, Orthonitrophenol, Orthohydroxy benzaldehyde (salicylaldehyde), orthohydroxy aceto-phenone, turpenten oil, essential oil
Fractional Distillation
Used when BP difference b/w 2 liquids is
less than 40 celsius
Vapours of liquid with higher BP condense, before the vapours of liquid with the liquid with lower BP. The vapours rising up in the fractionating column is more richer and the more volatile compound.
the compound w/ lowe BP, is highly volatile, and is seperated first
Fractionating column: provides different temperature regions
Different Fractions of Crude Oil:
Acetone, Methyl Alcohol
Benzene, Toulene
Examples: Acetone, Methyl Alcohol
This method does not seperate Azeotropic Mixtures or constant boiling mixtures
Distillation under reduced Pressure/ Vaccum Distillation
Done using a vaccum pump, where the pressure of the liquid decreases, due to which the BP decreases
This method is used to
purify liquids having high BP
as if they are distilled until reaching their BP, it leads to decomposition of the substance
Examples: Glycerine, Formaldehyde, Glycerol, Hydrogren Peroxide
Simple Distillation
Used for purification of liquids that do not undergo decomposition at their BP
Definition: The vapourisation of a liquid by heating and obtaining subsequent vapours by cooling
Conditions: It is used when the liquids that have BP difference
greater than 45 Celsius
The substance with the lower BP is vapourised, and then condensed
Examples: Chloroform,Aniline| Ether, toulene| Benzene, Aniline
