Extraction:

Alkaloids,essential oils of flowers, leaves & vegetables, colouring matter of leaves and soluble constituents of some roots are extracted by heating with suitable solvent(either water,alcohol or benzene) in Soxhlet apparatus

Purification:

Sublimation is used for sublimable compounds
Crystallisation is used for Benzanoic acid
Simple distillation is used for chloroform,aniline mixture
Fractional distillation is used in petroleum industry
Distillation under reduced pressure is used in spentyle soap industry
Steam distillation is used for aniline water mixture
Sugars are separated using BAW in chromatography and detected using aniline hydrogen phthalate
Amino acids are separated using either BAW or BEW in chromatography and detected using ninhydrin solution
Gas chromatography can be used to separate amino acid mixtures in very low concentrations (up-to nanograms)

4:1:3 volume ratio of n-butanol,acetic acid,water is called BAW
6:4:3 volume ratio of n-butanal, ethanal, water is called BEW

Qualitative analysis:

Detection of carbon and hydrogen:

Heat substance with Dry CuO and funnel the gas through a tube containing anhydrous CuSO₄ into lime water
Evolution of blue color in CuSO₄ confirms presence of hydrogen and lime water turning milky confirms presence of carbon

Fusing a compound with sodium metal and boiling it with distilled water gives an extract called Lassaigne's extract(LE).

Detection of nitrogen:

LE is boiled with FeSO₄ and acidified with concentrated H₂SO₄
Evolution of Prussian blue confirms presence of nitrogen
In case of blood red colour, both sulphur and nitrogen are confirmed, but evolution of Prussian blue doesn't mean there is no sulphur{it maybe present but excess Na could have been used}
This test is not given by diazonium salts or compounds with no carbon

Detection of sulphur:

1.LE is treated with sodium nitroprusside(Na₂[Fe(CN)₅NO])
Evolution of violet indicates presence of sulphur

2.LE is acidified with acetic acid and lead acetate, evolution of black precipitate confirms existence of sulphur

Detection of halogens:

1.LE is acidified with HNO₃ and treated with AgNO₃
White precipitate soluble in NH₄OH indicates presence of Cl
Yellow precipitate sparingly soluble in NH₄OH indicates presence of Br
Yellow precipitate insoluble in NH₄OH indicates presence of I
In case of presence of N or S, LE is boiled with HNO₃ before the test

2.Add CS₂ or CCl₄ to LE Then add Cl₂ water or KMnO₄ and shake & allow to rest
Orange color in organic layer confirms Br and violet color confirms I

3.Beilstein test:

Organic compound is heated on a copper wire in Bunsen flame.
Blue or green color indicates possibility of halogen

Detection of phosphorus:

Organic compound is heated with sodium peroxide
Solution is boiled with concentrated HNO₃ and treated with ammonium molybdate{(NH₄)₂MoO₄}
Yellow color indicates presence of phosphorus

Quantitative analysis:

Estimation of carbon and hydrogen(Leibig's method):

Compound of known mass is heated with CuO
CO₂ and H₂O are formed
CO₂ is absorbed in KOH and H₂O is absorbed in CaCl₂ and both are weighed

Estimation of halogens(Carius method):

Compound of known mass is heated with concentrated HNO₃ in presence of AgNO₃ in a hard glass tube(carius tube).
The halogens form AgX , carbon forms CO₂ and hydrogen forms H₂O
AgX is filtered, dried and weighed

Estimation of sulphur:

Compound of known mass is heated with fuming HNO₃ or Na₂O₂ in presence of BaCl₂.
Sulphur turns to H₂SO₄ and precipitates as BaSO₄
BaSO₄ is formed, filtered , dried and weighed

Estimation of Phosphorus:

1.Compound of known mass is heated with HNO₃ in carius tube.
NH₃ and (NH₄)₂MoO₄ are added
P turns into H₃PO₄ and precipitates as ammonium phospho molybdate.
(NH₄)₃PO₄.12MoO₃ is formed ,filtered , dried and weighed (MW = 1877)

2.Compound of known mass is heated with fuming HNO₃ or Na₂O₂ in carius tube.
Magnesia(MgCl₂ + NH₄Cl) is added.
P turns into MgNH₄.PO₄ which is heated into Mg₂P₂O₇
Mg₂P₂O₇ is filtered, dried and weighed (MW = 222)

Estimation of nitrogen:

1.Dumas method:

Compound of known mass is heated with CuO in an atmosphere of CO₂
The mixture of gases produced is passed over a heated copper gauze, turning the nitrous oxides to N₂
The mixture is collected over aqueous solution of KOH which absorbs CO₂ and nitrogen is collected in the upper part of the graduated tube.
Volume of nitrogen at STP is calculated using V = p1v1*273/(760*T1)
Where, p1= pressure of nitrogen-aqueous tension , v1 = volume of nitrogen, T1 = temperature of nitrogen
number of moles of nitrogen = V/22.4L
N₂ is obtained

2.Kjeldahl's method:

0.5g of organic compound is mixed with 10g K₂SO₄ and (1g CuSO₄ or 1 drop of mercury) and 25ml of H₂SO₄ and heated in Kjeldahl's flask
The nitrogen gets converted into ammonium sulphate and is distilled with excess NaOH.
Ammonia is evolved and passed into a known and excess amount of standard HCl or H₂SO₄.
The amount of unused acid is estimated by titration with alkali.
This method is not applicable for compounds containing nitro group, azo(-N=N-) group and nitrogen in ring
Number of mEq used to neutralise NH₃ = molarity of H₂SO₄ taken *(Volume of H₂SO₄ - volume of NaOH used for titration)

Estimation of oxygen:

1.Percentage of O = 100-(percent sum of all the other elements in the compound)

2.Aluise's method:

Compound of known mass is decomposed by heating in presence of nitrogen gas.
Mixture of gaseous products is passed over red hot coke, turning the O₂ produced in the previous step to CO.
This mixture is heated with I₂O₅ and CO turns to CO₂
CO₂ is obtained

Modern day:

Estimation of elements is an organic compound is done using instruments which use micro quantities of the compound
Quantities of C,H,N are determined using CHN elemental analyser which uses very small amount of compound(1-3mg) and quickly displays the amounts

Determination of molecular mass:

1.Victor Meyer’s method:

Volatile compound of known mass is vapourised in a Victor meyer tube
Vapours displace equal volume of air into a graduated tube
The volume is converted to volume at STP

2.For non-volatile compounds:

Compound of known mass is added to a solvent of known mass Either the elevation in boiling point of the solvent is noted or the depression in freezing point of the solvent is noted

3.Silver salt method for carboxylic acids:

Organic acid is neutralised with NH₄OH and heated to boil off excess NH₃
This is treated with AgNO₃ solution
The precipitated silver salt is filtered,washed and dried
The dry silver salt is weighed and heated in a crucible
The silver residue left is weighed

Note: Most organic acids form sparingly soluble silver salts and on ignition leave silver residue

4.Chloroplatinate method for organic bases:

Organic base reacts with dibasic chloroplatinic acid(H₂PtCl₆) and form double salts called chloroplatinates
The salts are filtered, washed, dried and weighed.
These salts are heated and leave platinum residue in the crucible.
Platinum residue is weighed

5.Volumetric method for organic acids and bases:

Organic acid

Known mass of organic acid is dissolved in water or alcohol and titrated against standard NaOH or KOH solution

Organic base

Known mass of organic base is titrated against standard solution of HCl or oxalic acid

Eudiometry(gas analysis):

Gas reactions are carried out in a tube called an eudiometer tube, graduated in mm.
Reacting gases are exploded by sparks produced by passing electricity through platinum terminals.
The volumes of gaseous products are determined by absorbing into suitable reagents

Detection and identification of functional groups:

Flame test:

Heat organic compound in a flame with the help of a clean glass rod and observe the flame

Solubility test:

Dissolve compound in H₂O, dilute NaOH, concentrated H₂SO₄

Detection of extra elements:

Refer to detection of Nitrogen,Sulphur,Halogen,Phosphorus

Confirmation of functional group if no extra elements are present:

For alkene/alkyne

They decolorize Br_2/CCl_4 or Br_2 water or Baeyer's reagent(alkaline KMnO_4)

Alkenes can be distinguished from terminal alkynes by Tollen's reagent([Ag(NH_3)_2]OH) or Fehling's solution (Cu_2Cl_2 + NH_4OH){Ammonical Cu_2Cl_2}
Terminal alkynes give white precipitate with Tollen's reagent and red precipitate with Fehling's solution

Confirmation of functional group is N is present:

Methods of separation of Mono-functional organic compounds from binary mixtures:

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