FeNP-loaded coal-bearing kaolin catalysts for the direct esterification of benzoic acid with cyclic ether via C(sp³)-H bond activation

ABSTRACT

The abundant and inexpensive transition metal iron was loaded onto the abundant nonmetal minerals of coal-bearing kaolin (CK) to synthesize cost-effective iron nanoparticle (FeNP)-loaded kaolin heterogeneous catalysts. Various characterization techniques were performed, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic activity was screened for the direct esterification of benzoic acid with cyclic ether via activation of the C(sp³)-H bond in a cross-dehydrogenative-coupling reaction, and the corresponding α-acyloxy ether products were obtained in good yield. Notably, the FeNP-loaded CK solid catalysts were relatively stable and could be reused at least five times while retaining good catalytic activity.

GRAPHICAL ABSTRACT

Highlights

• Iron nanoparticle-loaded kaolin was successfully synthesized as a cost-effective heterogeneous catalyst.

• The catalytic activity for the direct esterification of benzoic acid with cyclic ether via the C(sp³)-H bond activation CDC reaction was investigated.

• The recycling test showed that good catalytic activity remained after 5 cycles.

KEYWORDS:

• Iron nanoparticle-loaded kaolin
• heterogeneous catalytic activity
• CDC reaction
• recyclable

Acknowledgement

This research was financially supported by the National Science Foundation of China (22061034), the Research Program of Science and Technology at University of Inner Mongolia Autonomous Region (NJZZ21010), and the Collaborative Innovation Center for Water Environmental Security of Inner Mongolia Autonomous Region (XTCX003).

Supporting information

Details of experimental section, spectra of the KIE experiment and ¹H and ¹³C NMR spectra are given in supporting information.

Disclosure statement

No potential conflict of interest was reported by the author(s).