Pd-HPW/SiO2 Bi-Functional Catalyst: Sonochemical Synthesis, Characterization, and Effect on Octahydroquinazolinone Synthesis

Abstract

A Palladium-doped silica-supported heteropoly acid (HPW) (1%Pd-HPW/SiO2) bi-functional catalyst was produced using ultrasonic and conventional procedures. Both forms of catalyst were characterized with distinct analytical approaches in order to access the advantages of each one. The presence of the required functional groups in the catalyst was confirmed using FT-IR. The crystallinity of ultrasonically generated 1%Pd-HPW/SiO2 was confirmed with XRD. The existence of necessary elements in the catalyst was also suggested by XPS and EDX data. BET was used to calculate the surface area of the ultrasonically synthesized catalyst (395 m2 g−1), and it was found to be greater than that of the non-ultrasonic synthesized catalyst (382 m2 g−1). The N2 adsorption-desorption isotherm indicated mesoporous structures. The SEM morphology at a similar magnification exhibited quite different shapes. In comparison to traditional methods, ultrasonic approaches produce higher yields in less time and use less energy. Furthermore, the effect of the preparation method of the 1%Pd-HPW/SiO2 catalyst was extensively studied with respect to the synthesis of octahydroquinazolinones. Excellent product yields, a fast reaction time, and simple work-up methods are some peculiarities associated with the ultrasonically synthesized catalyst. The recycling study was also investigated and found suitable for up to four reaction cycles.

Synthesis and Biological Evaluation of Octahydroquinazolinones as Phospholipase A2, and Protease Inhibitors: Experimental and Theoretical Exploration

“…The frequencies at 3477 and 3363, and 3390 and 3380 cm −1 in FT-IR symmetric stretching N–H vibrations are for compounds 4a and 4b , respectively. Peaks at 3191 and 3305 cm −1 are attributed to broad OH [ 26 , 27 ]. The C=O ring has a peak between 1683 and 1685 cm −1 for both compounds.…”

“…Approximately, 2.96 g of 25% HPW/SiO 2 powder and 0.02 M Pd(OAc) 2 were added to a 200 mL beaker. The mixture was then poured with 14 mL of benzene and agitated gently for 1 h at room temperature on a magnetic stirrer, followed by progressive evaporation of the benzene in a rotary evaporator [ 26 ]. The catalyst must be calcined under vacuum at 150 °C/0.1 kPa after drying, and then reduced in an oven for 2 h by a hydrogen flow at 250 °C.…”

“…A combination of dimedone ( 1 ) (1 mmol), urea/thiourea ( 2 ) (1.5 mmol), and substituted aldehydes ( 3 ) (1 mmol) were agitated at 100 °C in a 100 mL round bottom flask in the presence of an optimal amount (0.1 g) of Pd-HPW/SiO 2 catalyst in 10 mL of water [ 26 ]. The course of the reaction was continually monitored in a solvent system of ethyl acetate and acetone (3:7).…”

“…Compounds 4a and 4b were optimized using Gaussian-09 software [ 26 , 40 ] with the DFT- B3LYP [ 41 , 42 , 43 , 44 , 45 , 46 ], method, and cc-pVDZ [ 47 , 48 , 49 , 50 , 51 ] as a basis set, while the frontier molecular orbitals and nature bonding orbital analysis were performed at the same level. Compounds 4a and 4b have more than two reaction sites, for example, methoxy-, hydroxyl-, azolin-, and carbonyl/thiocarbonyl groups.…”

Solar-Driven Thermocatalytic Synthesis of Octahydroquinazolinone Using Novel Polyvinylchloride (PVC)-Supported Aluminum Oxide (Al2O3) Catalysts

“…To date, several photo-assisted mechanistic approaches for the synthesis of quinazoline/octahydroquinazolinone have been proposed, such as photocatalysis, energy transfer, proton-coupled electron-transfer system, and hydrogen atom transfer [ 38 ]. We have envisaged with our previous efforts using recyclable catalysts and conventional heating methods for the synthesis of octahydroquinazolinone/quinazoline synthesis [ 39 , 40 ]. To contribute to this ongoing endeavor, in this work, we report on a novel three-component reaction for solar irradiation-induced octahydroquinazolinone synthesis based on aluminum oxide supported by PVC as a thermocatalyst, as shown in Figure 1 .…”