Question

Compare the basic strength of compounds given:
(i) $E{t_3}N$
(ii)

(iii)

Answer 1

Hint:The basic strength of a compound depends upon its ability to accept a proton from another molecule. Now one can apply this concept in the above structures and decide which structure can have more basic strength. Factors such as bulkiness around the nitrogen atom can also be considered while deciding basic strength.

Complete answer:
1) First of all we will understand the factors which affect the basic strength of structures. The above-given structure is of amines which are bases.
2) When we are deciding the basicity of a nitrogen-containing organic we need to analyze the fact about the reactivity of the nitrogen atom in each structure.
3) The base is a species that accepts a hydrogen atom from acid to form the conjugate acid. Now in order to be a reactive base, it needs to analyze how much alone a pair is available for the hydrogen acceptance.
4) While deciding the basicity one needs to analyze its conjugate acid structure. The more stable is the conjugate acid structure the more will be its basic structure. Now, let's analyze each structure one by one.
5) The structure $E{t_3}N$ possesses three methyl groups attached to the nitrogen. So, after the formation of conjugate acid which has a positive charge on the nitrogen atom, the three ethyl groups will give ${\text{ + I}}$ effect which will give stability to the structure, Hence, this is the most basic structure.
6) The second structure has a bridge nitrogen atom. The positive charge on the bridging nitrogen is very unstable hence this structure is less basic.
7) The third structure has two nitrogen atoms at the bridge position. If there is a positive charge formed on one nitrogen then the other one will show an ${\text{ - I}}$ effect which makes the structure very unstable. Hence, this structure is the least basic.
Therefore, the order of basic strength will be (i) > (ii) > (iii).

Note:
The reactivity of nitrogen in a structure depends upon how much the lone pair on the nitrogen atom wants to break away from the nucleus of nitrogen and make a new bond with the hydrogen.