Polysubstituted pyridines and 1,4-dihydropyridines were prepared in a three-component reaction of aromatic aldehyde, malononitrile and aliphatic amine in a mixed solvent of methanol and water.
The addition of methyl amine to ethanolamine solution can significantly increase the absorption rate of CO2, and the best mixed concentration ratio of ethanolamine and methyl a-mine is 5:1.