| amines salts solubility | they are soluble in water and insoluble in organic solvents live ethers |
| explain the basic nature of amines by pKb or Kb values | pKb value of ammonia is 4.75 aliphatic amines pKb values lie in the range of 3 to 4.22 |
| why are aliphatic amines stronger bases than ammonia | due to +I effect of alkyl groups leading to high electron density on the nitrogen atom |
| why then are aromatic amines weaker than ammonia | due to electron withdrawing nature of aryl group |
| what does basic character of amines depend on | it depends on the ease of formation of the cation by accepting a proton from the acid. the more stable the cation is relative to the amine more basic is the amine |
| relation of alkyl group with amines and basicity | the alkyl group causes an +I effect and hence nitrogen readily loses electrons. also due to dispersal of +ve charge due to +I effect |
| order of basicity of amines in the gaseous state | tertiary amines >secondary amines>primary amines>NH3 |
| what happens to the basicity of amines in aqueous state | the +ve charge not only gets stabalised by +I effect but also due to solvation of water molecules. hence the greater the size of the ion the less will be the solvation. |
| order of basicity in aq. medium | primary>secondary>tertiary |
| which structure has only two resonating structure in arylamines | anilinium |
| how is the basic strength of aniline increased | it is increased by stubstituting electron releasing groups like -OCH3,-CH3 |
| acylation | aliphatic and aromatic primary and secondary amines react with acid chlorides, anhydrides and ethers by nucleophilicsubstitution reaction |
| how does the reaction acylation shift the equilibrium to the right hand side | this reaction is carried out in the presence of a base stronger thanamine like pyridine which removes the HCl so formed |
| reaction of amines with benzoyl chloride | benzoylation |
| carbylamine reactions | primary amines on heating with chloroform(CHCl3) and ethanolic potassium hydroxide form isocyanides or carbylamines which are foul smelling. |
| what is special about carbylamine reaction | used to test for primary amines does not show reaction with secondary or tertiary amines |
| reaction with nitrous acid | three classes of amines react differently with nitrous acid which is prepared in situ from a mineral acid and sodium nitrite |
| primary aliphatic amines react with nitrous acid to form | aliphatic diazonium salts which being unstable liberate N2 gas |
| aromatic amines react with nitrous acid at low temp. to form | diazonium salts in presence of NaNO2+HCl |
| reaction with arylsulphonyl chloride | hisenberg's reagent reacts with primary and secondary amines to form sulphonamides |
| what is hinsberg's reagent | C6H5SO2Cl |
