DBU, a Common Base in Organic Chemistry

Which nitrogen atom is more basic in the compound DBU?

a) Label the hybridization of each nitrogen atom.

Answer:

N1, being sp3 hybridized, is more basic.

Explanation:

The compound DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) is a common base in organic chemistry. It contains two nitrogen atoms: N1 and N2.

Let's first label the hybridization of each nitrogen atom. N1, the sp3 hybridized nitrogen atom, is bonded to three hydrogen atoms and one carbon atom, whereas N2, the sp2 hybridized nitrogen atom, is solely bonded to three carbon atoms.

The basicity of an atom is determined by its ability to donate a lone pair of electrons. In DBU, the sp3 hybridized nitrogen (N1) is more basic. This is primarily due to the fact that nitrogen atom N1 has a lone pair of electrons available for bonding.

In contrast, nitrogen atom N2 is engaged in a resonance structure with the adjacent carbons, resulting in delocalization of its lone pair of electrons in the aromatic ring, which reduces its basicity.