Write short notes on the following:
(i) Carbylamine reaction
(ii) Diazotization
(iii) Hofmann's bromamide reaction
(iv) Coupling reaction
(v) Ammonolysis
(vi) Acetylation
(vii) Gabriel phthalimide synthesis.
Write short notes on the following:
(i) Carbylamine reaction
(ii) Diazotization
(iii) Hofmann's bromamide reaction
(iv) Coupling reaction
(v) Ammonolysis
(vi) Acetylation
(vii) Gabriel phthalimide synthesis.
Carbylamine reaction When aliphatic and aromatic primary amines are heated with chloroform and ethanolic potassium hydroxide, carbylamines or isocyanides are formed. These substances produced have foul smell. Secondary and teritary amines do not give this reaction. This reaction is used to detect primary amines.
R−NH2+CHCl3+3KOHHeat−−−→R−NC+3KCl+3H2O
Diazotization Aromatic amines react with nitrous acid at low temperatures (273-278K) to form diazonium salts. This reaction is called diazotization reaction.
NaNO2+HCl→HONO+NaCl
C6H5NH2Aniline(primary aromatic amine)+HONO+HCl273−278K−−−−−−→C6H5N2ClBenzene diazonium chloride+Nacl+2H2O
Note When primary aliphatic amines react with nitrous acid, aliphatic diazonium salts are formed (Unstable), which liberate nitrogen gas and alchols.
R−NH2+HNO2NaNO2+HCl−−−−−−−−→[R−+N2−Cl]H2O−−→ROH+N2+HCl
Hofmann's bromamide reaction This is a method used for converting primary amide into primary amine.
An amide is treated with bromine in an aqueous or ethanolic solution of sodium hydroxide. The amine so formed contains one carbon less than that present in the amide.
Couplinig reaction When diazonium salts react with phenols or aromatic amines they form azo compounds of general formula, Ar-N=N-Ar. This reaction is mcalled coupling reaction. The reaction takes place in alkaline medium (pH 9 to 10) e.g.
Ammonolysis The process of cleavage of C-X bond by ammonia molecule is known as ammonolysis.
Acetylation The process in which acetyl CH3CO− group is introudced in a molecule, is called acetylation, Reagents used for this purpose are acetyl chloride or acetic anhydride.
Gabriel phthalimide synthesis This method isused for the preparation of aliphatic primary amines. Phthalimide on reaction with ethanolic potassium hydroxide forms potassium salt of phthalimide. This potassium salt on heating with alkly halide followed by alkaline hydrolysis produces primary amine.
Carbylamine reaction When aliphatic and aromatic primary amines are heated with chloroform and ethanolic potassium hydroxide, carbylamines or isocyanides are formed. These substances produced have foul smell. Secondary and teritary amines do not give this reaction. This reaction is used to detect primary amines.
R−NH2+CHCl3+3KOHHeat−−−→R−NC+3KCl+3H2O
Diazotization Aromatic amines react with nitrous acid at low temperatures (273-278K) to form diazonium salts. This reaction is called diazotization reaction.
NaNO2+HCl→HONO+NaCl
C6H5NH2Aniline(primary aromatic amine)+HONO+HCl273−278K−−−−−−→C6H5N2ClBenzene diazonium chloride+Nacl+2H2O
Note When primary aliphatic amines react with nitrous acid, aliphatic diazonium salts are formed (Unstable), which liberate nitrogen gas and alchols.
R−NH2+HNO2NaNO2+HCl−−−−−−−−→[R−+N2−Cl]H2O−−→ROH+N2+HCl
Hofmann's bromamide reaction This is a method used for converting primary amide into primary amine.
An amide is treated with bromine in an aqueous or ethanolic solution of sodium hydroxide. The amine so formed contains one carbon less than that present in the amide.
Couplinig reaction When diazonium salts react with phenols or aromatic amines they form azo compounds of general formula, Ar-N=N-Ar. This reaction is mcalled coupling reaction. The reaction takes place in alkaline medium (pH 9 to 10) e.g.
Ammonolysis The process of cleavage of C-X bond by ammonia molecule is known as ammonolysis.
Acetylation The process in which acetyl CH3CO− group is introudced in a molecule, is called acetylation, Reagents used for this purpose are acetyl chloride or acetic anhydride.
Gabriel phthalimide synthesis This method isused for the preparation of aliphatic primary amines. Phthalimide on reaction with ethanolic potassium hydroxide forms potassium salt of phthalimide. This potassium salt on heating with alkly halide followed by alkaline hydrolysis produces primary amine.
