Abstract:
Octahedral MnO2 molecular sieve (hereafter designated as OMS) was prepared in the presence of urea, and
mesoporous ZSM-5 (designated as Meso-ZSM-5) was prepared
using propyltriethoxysilane as additive under hydrothermal synthesis
condition. OMS-decorated Meso-ZSM-5 was prepared by heating a
grounded mixture of OMS and Meso-ZSM-5. Powder X-ray
diffraction, N2-sorption, SEM, TEM, thermogravimetric analysis,
FT-IR, diffuse reflectance UV−vis spectroscopy, and NH3 and CO2
temperature-programmed desorption techniques were used to
characterize the material. The catalyst was demonstrated in a onepot, one-step synthesis of pyrazoles via cyclization followed by
dehydrogenation as the key reaction steps. Synthesis of carbamates
by the reaction of cyclic and acyclic carbonates/di-tert-butyl
dicarbonate with amines was another important application of this catalyst. Catalyst exhibited efficient recyclability. No
leaching of active species took place even after five recycles. A strong interface between OMS and Meso-ZSM-5 imparts strong
acidity and distinguished activity in the synthesis of pyrazole heterocycles and organic carbamates.
