K₃PO₄ showed superior catalytic activity to others for the carbonylation of amines.

Up to 99% of formaldehydes were produced using K₃PO₄ at mild conditions.

PO₄^3− of K₃PO₄ is capable of forming a strong hydrogen bond with an amine.

PO₄^3− functions as a proton shuttle as well as an amine activator.

Small portion of K₃PO₄ was transformed into K₂HPO₄ during the carbonylation.