Question

Rank the following nitrogen containing compounds from least to most basic, Explain?  The order is `"(2) < (3) < (1)"`. >

Answer 1

You need data.....

Explanation:

Specifically, you need the `pK_a` values of the conjugate acids of these bases.... It is unreasonable even for a 1st year or 2nd year inorganic student to know these values. Clearly the weakest acid is the conjugate species to the strongest base....

Answer 2

Rank the following nitrogen containing compounds from least to most basic, Explain?

The order is `"(2) < (3) < (1)"`.

A base is an electron pair donor, so the basicity depends on the availability of the lone pair electrons.

1,3,5-Triazine (1)

The lone pairs on `"N"` are in `"sp"^2` orbitals in the plane of the ring.

They cannot interact with the aromatic π system, so they are all available for bonding.

1,3,5-Triazine is the strongest base.

Aniline (3)

Aniline has a lone pair of electrons, but they are partially involved in resonance delocalization into the aromatic ring.

Aniline is less basic than 1,3,5-triazine.

Indole (2)

The lone pair on `"N"` is part of the aromatic 10 π system.

They are not available for bonding, so indole is the weakest base.

The order of basicity is `"(2) < (3) < (1)"`.