Efficient Synthesis of Benzyl-Protected Cyclic Lysine on Pt/M-Al2o3 Catalysts and its Application in Functional Nylon-6 Copolymers Production

Abstract

Functional nylon-6 polymers, especially those with special properties such as antibacterial, flame retardant, and specific thermal properties, have a wide range of applications. However, the efficient synthesis of these polymer monomers has long remained a challenge. Benzyl-protected cyclic lysine (BCL) is a potentially functional monomer, and an efficient method for the synthesis of benzyl-protected cyclic lysine on a supported platinum catalyst is proposed in this article. Compared to existing techniques, this approach offers higher synthesis efficiency and sustainability. Pt/ m-Al2O3 catalysts were prepared using a vacuum impregnation method and showed excellent activity and selectivity in the production of benzyl-protected cyclic lysine. The conversion rate of α-amino-ε-caprolactam (α-ACL) was 100%, and the selectivity of BCL was 96.0%. The Pt/ m-Al2O3 catalyst maintained good stability over multiple reaction cycles. The reaction mechanism and thermodynamics of functionalized α-ACL were also investigated. The copolymer synthesized with the prepared BCL showed similar structure and thermal stability to pure nylon-6, indicating possible unique functional properties. This study provides a route for the synthesis of cyclic lysine protected with various groups and its potential applications in the field of polymer chemistry.

Keywords: Benzyl-protected cyclic lysine, Pt/m-Al2O3 catalysts, Nylon-6 Polymers, functional nylon-6 copolymers