Question

Explain why propylamine is stronger base than ammonia

Answer 1

Ответ:

Yes methylamine a stronger base than ammonia since it as a election donating group (methyl). Therefore electron density on Nitrogen atom increase. Hence it is stronger base,whereas in ammonia electron donating group is absent.So it is weak base when compared to methylamine. 

Answer 2

Propylamine (C3H9N) is a primary aliphatic amine, while ammonia (NH3) is a simple inorganic compound. The basicity of amines is determined by their ability to donate a lone pair of electrons to accept a proton (H+) from a surrounding medium. In this context, propylamine is generally considered a stronger base compared to ammonia due to several factors:

1. Steric Effects: Propylamine has three alkyl groups (propyl groups) attached to the central nitrogen atom. These alkyl groups can provide steric hindrance, which makes it harder for a proton to approach the nitrogen lone pair. As a result, propylamine is less likely to form a hydrogen bond with a proton and is more reluctant to accept a proton, exhibiting weaker basicity compared to ammonia.

2. Electron-Donating Nature of Alkyl Groups: The alkyl groups in propylamine donate electron density to the nitrogen atom, reducing the availability of the lone pair for proton acceptance. This electron-donating effect decreases the basicity of propylamine.

3. Resonance Effects: In ammonia, the lone pair on nitrogen is in a sp3 hybridized orbital. In propylamine, due to the presence of alkyl groups, the lone pair on nitrogen can have a greater degree of resonance stabilization involving adjacent carbon atoms. This resonance can further reduce the basicity of propylamine compared to ammonia.

4. Inductive Effects: The alkyl groups in propylamine can have an inductive electron-withdrawing effect, which can partially offset the electron-donating effect mentioned earlier. This also contributes to reducing the basicity of propylamine.

5. Solubility Effects: Propylamine, being a larger molecule than ammonia, is less soluble in water. Basicity is often related to solubility, as the ability to form hydrogen bonds with water affects the availability of lone pairs for proton acceptance. Since propylamine is less soluble in water, its basicity may appear stronger in a non-aqueous environment, but in water, it might be less effective as a base due to limited solubility.

In summary, while propylamine's larger size and the presence of alkyl groups might suggest it could be a stronger base, its steric hindrance, electron-donating and electron-withdrawing effects from alkyl groups, resonance effects, and solubility considerations collectively lead to it being a weaker base compared to the simpler ammonia molecule.