Tamilnadu Samacheer Kalvi 12th Chemistry Notes Chapter 13 Organic Nitrogen Compounds Notes

Nitro Compounds: If one of the hydrogen atom of hydrocarbon is replaced by the -NO-, group, the resultant organic compound is called nitro compound.

Tautomerism: 1° and 2° nitroalkanes, having a-H , also show as equilibrium mixture of two tautomers namely nitro and aci form. Such a isomeric form are collectively called tautomerism.

Nature of Nitro form:

  • Less acidic
  • Dissolves in NaOH slowly
  • Decolourises FeCl3 solution
  • Electrical conductivity is low

Nature of aci form:

  • More acidic and also called pseudoacids (or) nitronic acids
  • Dissolves in NaOH instantly
  • With FeCl3 gives reddish brown colour
  • Electrical conductivity is high

Nef carbonyl synthesis: Nitro alkanes are reacts with potassium hydroxide, followed by hydrolysis they form corresponding aldehyde.

Amine: An organic compound, which containing NH, functional group and they are called amines.

Mendius reaction: The reduction of alkyl or aryl cyanides reaction in which Na / C2H5OH is used as a reducing agent is called Mendius reaction.

Hoffmann’s degradation reaction: When Amides are treated with bromine in the presence of aqueous or ethanolic solution of KOH, primary amines with one carbon atom less than the parent amides are obtained.

Gabriel phthalimide synthesis: Gabriel synthesis is used for the preparation of Aliphatic primary amines. Phthalimide on treatment with ethanolic KOH forms potassium salt of phthalimide which on heating with alkyl halide followed by alkaline hydrolysis gives primary amine.

Hoffmann’s ammonolysis: When Alkyl halides (or) benzylhalides are heated with alcoholic ammonia in a sealed tube, mixtures of 1°, 2° and 3° amines and quaternary ammonium salts are obtained.

The boiling point of various amines follows the order,
Samacheer Kalvi 12th Chemistry Notes Chapter 13 Organic Nitrogen Compounds Notes 1
Order of basic strength in case of alkyl substituted amines in aqueous solution is,
Samacheer Kalvi 12th Chemistry Notes Chapter 13 Organic Nitrogen Compounds Notes 2

The relative basicity of amines follows the below mentioned order
Alkyl amines > Aralkyl amines > Ammonia > N – Aralkyl amines > Aryl amines

Schotten – Baumann reaction: Aniline reacts with benzoylchloride in the presence of NaOH to give N – phenyl benzamide. This reaction is known as Schotten – Baumann reaction.

Libermann’s nitroso test: Alkyl and aryl secondary amines react with nitrous acid to give N – nitroso amine as yellow oily liquid which is insoluble in water. This reaction is known as Libermann’s nitroso test.

Carbylamine reaction: Aliphatic (or) aromatic primary (only) amines react with chloroform and alcoholic KOH to give isocyanides (carbylamines), which has an unpleasant smell. This reaction is known as carbylamines test.

Mustard oil reaction: When primary amines are treated with carbon disulphide, N – alkyldithio carbonic acid is formed which on subsequent treatment with HgCl2, give an alkyl isothiocyanate.

Diazonium Salts: Aromatic amines on treatment with NaN02 and HC1 gives diazonium salts. They are stable only for a short time.

Sandmeyer reaction: On mixing freshly prepared solution of benzene diazonium chloride with cuprous halides, aryl halides are obtained. This reaction is called Sandmeyer reaction.

Gattermann reaction: Conversion of benzene diazonium chloride into chloro / bromo arenes can also be effected using HC1 or HBr and copper powder. This reaction is called Gattermann reaction.

Baltz – schiemann reaction: When benzene diazonium chloride is treated with fluoroboric acid, benzene diazonium tetra fluoroborate is precipitated which on heating decomposes to give fluorobenzene.

Gomberg reaction: Benzene diazonium chloride in the presence of sodium hydroxide to give
biphenyl. This reaction in known as the Gomberg reaction. , .

Coupling reactions: Benzene diazonium chloride reacts with electron rich aromatic compounds like phenol, aniline to form brightly coloured azo compounds. Coupling generally occurs at the para position. If para position is occupied then coupling occurs at the ortho position.

Thrope nitrile condensation: Self condensation of two molecules of alkyl nitrile (containing a-H atom) in the presence of sodium to form iminonitrile.

Levine and hauser acetylation: The nitriles containing a – hydrogen also undergo condensation with esters in the presence of sodamide in ether to form ketonitriles. This reaction is known as “ Levine and hauser” acetylation.

Cyanomethylation reaction: This reaction involves replacement of ethoxy (OC2H5) group by methylnitrile (-CH2 CN) group and it is called as cyanomethylation reaction.

Uses of nitroalkanes:

  • Nitromethane is used as a fuel for cars
  • Chloropicrin (CCl3 NO2) is used as an insecticide
  • Nitroethane is used as a fuel additive and precursor to explosive and they are good solvents for polymers, cellulose ester, synthetic rubber and dyes etc.,
  • 4% solution of ethylnitrite in alcohol is known as sweet spirit of nitre and in used as diuretic.

Uses of nitrobenzene:

  • Nitrobenzene is used to produce lubricating oils in motors and machinery
  • It is used in the manufacture of dyes, drugs, pesticides, synthelic rubber, aniline and explosives like TNT, TNB.

Uses of cyanides and isocyanides:

  • Alkyl cyanides are important intermediates in the organic synthesis of larger number of compounds like acids, amides, esters, amines etc.
  • Nitriles are used in textile industry in the manufacture of nitrile rubber and also as a solvent particularly in perfume industry.

Cancer Drug: Mitomycin C, and anticancer agent used to treat stomach and colon cancer, contains an aziridine ring. The aziridine functional group participates in the drug’s degradation by DNA, resulting in the death of cancerous cells.

Samacheer Kalvi 12th Chemistry Notes