Primary amine,secondary amine and amide which is more basic?
Answers
Secondary amine due to greater positive inductive effect of the alkyl group.
Answer:
Explanation:
Amines are derivatives of ammonia in which one, two, or all three hydrogen atoms are replaced by hydrocarbon groups.
When the hydrogen is replaced by one group it called primary amin[ e.g methylamine (CH3-NH2)]; by two groups, it is called secondary [e.g Dimethylamine (CH3-NH-CH3)]; and by three groups, it is called tertiary amine[e.g trimethylamine is CH3-N(CH3)-CH3].
Amines are basic in nature as they have lone pair of electrons on nitrogen. Therefore, they have a strong tendency to donate this lone pair of electrons to electron acceptors.
The basicity of amines depends on:
The electronic properties of the substituents (alkyl groups enhance the basicity, aryl groups diminish it).
The degree of solvation of the protonated amine, which includes steric hindrance by the groups on nitrogen.
And since the ammonium salts of primary and secondary amines undergo solvation effects (due to hydrogen bonding) to a much greater degree than ammonium salts of tertiary amines in water. The solvation effects increase the electron density on the amine nitrogen to a greater degree than the inductive effect of alkyl groups. Although the conjugate acid of primary amine are the most stable with the greatest number of hydrogen bonding, its basicity is the less stable because of its low electron density on the nitrogen atom and its lone pair of electrons are not readily available for protonation.
Therefore, i will say that Secondary amine is more basic than primary and tertiary because is more stable than both [ I.e the stability of the conjugate acid formed with it], has high electron density and the easy availability of electrons for protonation which balances in the two groups attached to it.