Design and characterization of an amino acid-modified magnetic NaY zeolite as a heterogeneous catalyst for the synthesis of 2-pyrazolines

Abstract

In this study, a magnetic heterogeneous nanocatalyst was synthesized by functionalizing magnetic NaY nanozeolite with 6-aminocaproic acid (MNaY/PS/AC). The catalyst was prepared by magnetization of NaY zeolite with Fe₃O₄ nanoparticles, surface modification with 3-(chloropropyl) trimethoxysilane (CPTMS), and final grafting of 6-aminocaproic acid as an organic ligand. The physicochemical properties of the prepared nanocatalyst were characterized using FT-IR, XRD, TGA, SEM, TEM, BET, EDS mapping, CHN, ICP, and VSM techniques. It is important to note that direct surface characterization techniques, such as XPS, were not available in this study; therefore, conclusions about surface chemical states are based on cumulative indirect evidence. The catalytic performance of MNaY/PS/AC was evaluated in the synthesis of 2-pyrazoline derivatives via a cyclization of chalcones and hydrazine hydrate. Under optimized conditions (ethanol at 40 °C), the catalyst exhibited good activity, providing high to excellent yields (85–98%) in short reaction times. Key advantages include the use of a reusable catalyst, mild reaction conditions, a simple work-up, and the ability to recover the catalyst with ease using an external magnet. Furthermore, the nanocatalyst demonstrated good stability and could be reused for seven consecutive cycles without significant loss of catalytic performance.