O-Carboxymethyl Chitosan Supported Heterogeneous Palladium and Ni Catalysts for Heck Reaction

Abstract

Two polymer catalysts (Pd-OCMCS and Ni-OCMCS) with good reusability were synthesized by coordinating Pd and Ni onto O-carboxymethyl chitosan (OCMCS). The chemical structure and thermal stability of prepared catalysts were determined by Fourier transform infrared (FT-IR) spectra, Energy Dispersive Spectrometer (EDS)analysis, X-ray diffraction (XRD), and thermogravimetric analyzer (TG-DTG), and the analysis results showed that the Pd and Ni ions coordinated onto the OCMCS and formed a ligand with the –COOH group, amino groups, and –OH group on the OCMCS, and the EDS and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) analysis results showed that the loading amounts of Pd and Ni were approximately 8.3% and 8.9%, respectively. In the Heck reaction between aryl halides and n-butyl acrylate catalyzed by the prepared catalyst, the test results showed that the product yield followed the order of aryl iodide > aryl bromide > aryl chloride. Additionally, the product yield for the aryl iodide and aryl bromide could reach up to 99% and 96%, respectively. Moreover, the electron-withdrawing and electron-donating property of the group on the aryl also affected the product yield, and the product yield for aryl halides with electron-withdrawing group p-NO2, p-CH3CO, and p-CHO was higher than that with electron-donating group p-CH3.

Chitosan: A Natural Biopolymer with a Wide and Varied Range of Applications

“…O -Carboxymethyl chitosan has been used as support to graft PdCl 2 or Ni(OAc) 2 , obtaining high yields in the Heck coupling [ 224 ]. In another research, chitosan was cross-linked with glutaraldehyde to the immobilization of Pd 2+ -species in its structure, reaching yields very close to 100% ( Figure 15 ) [ 225 ].…”

SYNTHESIS AND PHYSICOCHEMICAL PROPERTIES OF MAGNETITE NANOPARTICLES (Fe3O4) AS POTENTIAL SOLID SUPPORT FOR HOMOGENEOUS CATALYSTS

“…Limitations on the catalyst separation becoming one of the drawbacks of homogeneous reaction systems, various approaches using solid materials as catalyst support have been extensively studied [1]. To date, considerable research attention has been paid to the usage of supported catalysts for organic synthesis.…”

Palladium Supported on Bioinspired Materials as Catalysts for C–C Coupling Reactions

“…O-carboxymethyl chitosan is more commonly used as a support for palladium catalysts: it can be easily synthesized by the reaction of pristine chitosan with monochloroacetic acid, although it is also commercially available from various suppliers in light of its wide use for several applications. In this context, Zhang and Lv described, in 2017, the preparation of palladium supported on O-carboxymethyl chitosan (named Pd-OCMCS, Scheme 33): the modified biopolymer was first treated with a KOH aqueous solution (60 • C, 1 h), then a PdCl 2 aqueous solution was dropped and mixed for further 12 h at 60 • C [105].…”

“…O-carboxymethyl chitosan is more commonly used as a support for palladium catalysts: it can be easily synthesized by the reaction of pristine chitosan with monochloroacetic acid, although it is also commercially available from various suppliers in light of its wide use for several applications. In this context, Zhang and Lv described, in 2017, the preparation of palladium supported on O-carboxymethyl chitosan (named Pd-OCMCS, Scheme 33): the modified biopolymer was first treated with a KOH aqueous solution (60 °C, 1 h), then a PdCl2 aqueous solution was dropped and mixed for further 12 h at 60 °C [105]. FT-IR analysis of Pd-OCMCS showed a shift of the asymmetric C=O stretching vibration peak from 1644 cm −1 to 1654 cm −1 , suggesting that Pd ions were coordinated by the carboxylate groups of O-carboxymethyl chitosan; this indication was then further confirmed by the XRD patterns of the catalyst.…”