Cobalt-catalyzed synthesis of ε-caprolactam and nylon-6 from aminopentene and carbon monoxide

ε-Caprolactam and nylon-6 oligomers were synthesized from 4-pentene-1-amine and/or 3-pentene-1-amine and carbon monoxide using Co ₂(CO)₈ as catalyst. The results show that the volatile fraction of the product mixture is composed of ε-caprolactam, 3-methyl-2-piperidinone and 3-ethyl-2-pyrrolidinone, while the solid residue mainly consists of nylon-6 oligomers. The addition of excess PEt₃ as ligand can significantly improve the regioselectivity to ε-caprolactam. Using 3-pentene-1-amine as starting material leads to the same results as 4-pentene-1-amine due to rapid C=C bond isomerization.