The basicity of tertiary amine depends on the quantity. The more alkyl groups attached, the less basic the amine is. This is because the alkyl group sterically blocks the lone pair of electrons on the nitrogen atom, making it more difficult for the nitrogen atom to donate the lone pair of electrons to the proton.

The pKa of N-methylmorpholine is 7.4, while triethylamine The pKa is 10.5. This means that N-methylmorpholine is a weaker base than triethylamine. This is because there are two alkyl groups on the nitrogen atom of N-methylmorpholine, while there is only one alkyl group on the nitrogen atom of triethylamine. The two alkyl groups on N-methylmorpholine sterically hinder the lone pair of electrons on the nitrogen atom, making it more difficult for the nitrogen atom to donate the lone pair of electrons to the proton.

N-methylmorpholine and triethylamine are both used as various Bases in applications, including:

as a catalyst for organic reactions

As a pH buffer

As Corrosion inhibitor

As a flotation agent

N-Methylmorpholine is also used as a solvent for organic compounds.