AP Inter 1st Year Chemistry Notes Chapter 13 Organic Chemistry-Some Basic Principles and Techniques

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AP Inter 1st Year Chemistry Notes 13th Lesson Organic Chemistry-Some Basic Principles and Techniques

→ Crystallisation: (Principle)
The compound should be insoluble at low temperature but soluble at higher temperature in the given solvent, Impurities either not soluble or soluble go into filtrate.

→ Sublimation:
If the compound is sublimating the impurities should not sublimate.

→ Distillation process is useful for the purification of liquids contaminated with non-volatile impurities.

→ Nitrogen halogens and sulphur in the given organic compounds is detected by leassaigne’s test.

→ Nitrogen is estimated by Duma’s method and kjeldahl’s method.

→ Broadly hydrocarbons can be divided into Aliphatic and Aromatic.

→ A series of organic compounds with same functional group, but the consecutive members differ by a – CH₂ – group is called Homologous series.

→ Molecules with same molecular formula but differ in the properties are called Isomers.

→ Isomerism arising due to difference in structures is called structural isomerism.

→ Chain isomerism is due to the difference in carbon chain.

→ Position isomerism is due to change in the position of substitued group.

→ Change of unsaturated hydrocarbons to saturated hydrocarbons in presence of Ni catalyst is called Sabatier-Senderen’s reduction.

→ When alkyl halide is heated with sodium metal in dry ether, alkane is formed. This reaction is called Wurtz reaction.

→ Concentrated solution of sodium acetate on electrolysis gives ethane. This reaction is called Kolbe’s electrolysis.

→ Substitution of an atom or group of atoms in a molecule is called substitution reaction.

→ Removal of small molecule from a molecule is called elimination reaction.

→ Dehydro halogenation means removal of hydrogen halide.
Dehalogenation means removal of halogen molecule.
Decarboxilation means removal of CO₂ molecule.
Dehydration means removal of water molecule.

→ Ethylene on polymerisation forms polyethylene.

→ Ethylene on ozonolysis gives Formaldehyde.

→ On the electrolysis of cone, aqueous solution of potassium maleate (or fiimarate), Acetylene is formed at anode.

→ Calcium carbide on hydrolysis gives acetylene gas.

→ When acetylene gas passed through hot dil. acids in presence of Hg²⁺ ions, Acetaldehyde is formed.

→ Acetylene gas on passing through red-hot copper tube, benzene is formed.

→ Acetylene decolourises Bayer’s reagent and Br₂ in CCl₄.

→ Acetylene gives white precipitate with ammonical AgNO₃ solution and red coloured precipitate with ammonical Cu₂Cl₂ solution.

→ Benzene is obtained from the fractional distillation of coal tar.

→ Though benzene is unsaturated compound, it does not undergo addition reactions in ordinary conditions.

→ Chlorination of benzene in presence of UV- rays give benzene hexachloride.

→ Benzene on ozonolysis with three molecules of O₃ gives an ozonide and it forms three molecules of glyoxal.

→ Benzene reacts with alkyl halides in the presence of Lewis acids and gives alkyl benzenes.

→ Phenomenon of existance of more than one compound having identical structures but differing in spatial arrangements of atoms or groups due to the restricted rotation about a double bond is known as geometrical isomerism.

→ Markownikoffs rule:
The rule states that when an unsymmetrical reagent adds to a double bond, the positive part of the reagent attaches itself to a carbon of the double bond so as to yield the more stable carbocation as an intermediate.

→ In presence of peroxides, anti Markownikoffs rule takes place, which is called Kharsch effect.

→ Ethylene reacts with sulphur mono chloride (S₂Cl₂) to give mustard gas.

→ Acetylene is more acidic than ethylene is more acidic than ethane.

→ Commercially Benzene is prepared from the coal tar-Coal tar on destructive distillation produce different fractions.

→ 0 – and P – directing groups are
– OH, – NH₂, – NHR, – OCH₃, – CH₃ etc;
All those activating groups.

→ m-directing groups are
– CN, – SO₃H, – CO₂H, – CHO etc
These are deactivating groups.

→ Several poly nuclear hydrocarbons are carcinogenic.
Ex : 1, 3 – benzanthracene, 3 – methyl cholanthrene etc.

→ Alkenes of the type ab C = C ab, ab C = C ax and ab C = C bx show geometrical isomerism.