Norazzizi Nordin

Preparation and characterization of HypoGel-supported Pd nanocatalysts for Suzuki reaction under mild conditions

Abstract A new heterogeneous catalyst composed of Pd nanoparticles immobilized within a HypoGel resin has been prepared in the absence of any ligands using an extensive cross-linking method. This newly developed nanocatalyst was characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy and inductively coupled plasma-mass spectrometer (ICP-MS) techniques. TEM and XRD results revealed that the Pd nanoparticles were well dispersed with diameters in the range of 4–12 nm, and an average size of about 8 nm. The cross-linked Pd catalyst demonstrated excellent catalytic activity towards the synthesis of a series of biaryl compounds by the reaction of various aryl halides (e.g., bromides andiodides) with phenylboronic acid in the presence of tetrabutylammonium bromide. ICP-MS analysis indicated that there was only 0.25% weight loss of Pd (0.55 ± 0.02 ppm) from the supported catalyst after the first cycle reaction. Furthermore, the catalyst showed excellent reusability (up to five uses) with consistently high levels of catalytic activity following its recovery by filtration.

Controlled Release Electrochemical Synthesis and Cytotoxicity Study of Copper(II) Nanoparticles in Copper(II) Decanoate Complex

In the present study, a controlled release electrochemical (CRE) technique based on the controlled release of Cu2+ ion from Cu anode in the presence of decanoic acid (HDe) has been used to synthesize Cu(II) decanoate (CuDe2) complex. The effect of applied voltages (1–10V) and electrolyte concentrations (0.1–2.0M CH3COONH4) during the electrolysis on the nanoparticles obtained was studied using TEM. The results reveal that small-sized nanoparticles (2±1nm) were obtained by using lowest applied voltage and CH3COONH4 concentration (1V and 0.1M, respectively). The smallest nanoparticle obtained was then used in the cytotoxicity study against A549 and HeLa cells. The synthesized complex gives moderate cytotoxic effect on the selected cells (IC50=15.85μM and 20.89μM, respectively) and low cytotoxic effect on normal cells (IMR90). Apoptosis is the mode of cell death based on the apoptosis assay that has been conducted.

Effect of Applied Voltage on Slow-Release of Cu(II) Ions on the Synthesis of Copper(II) Stearate Complex by Electrochemical Technique

ion from electrochemical oxidation of a Cu anode in the presence of stearic acid (HSt) and an aqueous solution of ammonium acetate (CH 3 COONH 4 ) (0.1 mol L-1) as supporting electrolyte has been used to synthesize Cu(II) stearate (Cu(II)St) complex. Different values of applied voltages (1, 5 and 10 V) were used during the synthesis to study the effect of applied voltage on the particle size of the Cu nanoparticles and morphology of the synthesized Cu(II)St complex. By using 1 V of applied voltage, small Cu nanoparticle was produced with an average particle size of 2.49 ± 0.82 nm, followed by 5 V (3.61 ± 1.18 nm) and 10 V (6.64 ± 2.72 nm). Another advantage of using 1 V of the applied voltage is the formation of well-shaped petal-like structures of the Cu(II)St complex compared to the synthesis using 5 V and 10 V which inhibit the formation of well-shaped petal-like structure. This proves that the slow-release electrochemical synthesis using lower value of applied voltage has successfully resulted in the formation of small size Cu nanoparticles.

Electrochemical synthesis and in vitro cytotoxicity study of copper(II) carboxylates with different fatty acid alkyl chain lengths

In the present study, an electrochemical technique based on the release of Cu2+ ions from a Cu anode in the presence of unsaturated fatty acids with different alkyl chain lengths has been used to synthesize Cu(II) carboxylates. The fatty acids used in this study are lauric acid (C12 : 0) and stearic acid (C18 : 0). Optimum electrolysis conditions for the synthesis of Cu(II) laurate (CuLa2) and Cu(II) stearate (CuSt2) have been determined to maximize percentage yield and minimize energy consumption and loss of the Cu anode. We observe that both compounds (99.21%) are produced with lower energy consumption (∼21.01 W h L−1) and anode loss (∼0.57 mg L−1) by using the same optimum conditions of 10 V of applied voltage for 4 hours of electrolysis time in 0.1 M CH3COONH4 electrolyte solution. The cytotoxicity study on selected tumor cells (A549 and HeLa) shows that the synthesized compounds have moderate cytotoxic effects with IC50 in the range from 19.50 to 44.67 μM. CuLa2 with C12 alkyl chains provides better cytotoxicity effect on the selected tumor cells due to lower IC50 than CuSt2 with C18 alkyl chains. This shows that the length of alkyl chain also affects the compound toxicity towards selected tumor cells.

Ru/FTO: Heterogeneous catalyst for glycerol hydrogenolysis

An introduction of Fluorine-doped tin oxide (FTO) as new catalyst support with Ru metal had enhanced the conversion and selectivity for glycerol hydrogenolysis. A small cluster of Ru were highly dispersed and intercalated over FTO via simple chemical mixture and reduction method. In comparison with various metal (Pd, Os, Cu), Ru/FTO catalyst showed the highest conversion (100%) and highly selectivity of 1,2-propanediol (94%) in the hydrogenolysis of glycerol. The reaction was optimally conducted at 150 °C, 20 bar of H2 pressure and at 8 hours. Ru/FTO catalyst was ascribed as active catalyst due to the amphoteric sites of FTO and small size of Ru metal. This provides high surface concentration of reduction process that involves the chemical bond dissociation in the glycerol hydrogenolysis.

Synthesis, Characterization and Catalytic Performance of Prepared by Sol-Gel Technique

The purpose of this work is to study the synthesis, characterization, and catalytic performance of two types of solid heteropoly acid catalysts, namely, silicotungstic acid bulk (STAB) and STA-silica sol-gel (STA-SG) compared with sulfuric acid. From the XPS analyses, there was a significant formation of W-O-Si, W-O-W, and Si-O-Si bonding in STA-SG compared to that in STAB. The main spectra of O1s (90.74%, 531.5 eV) followed by other O1s peak (9.26%, 532.8 eV) were due to the presence of W-O-W and W-O-Si bonds, respectively. The STA-SG catalyst was found to be the more environmentally benign solid acid catalyst for the esterification reaction between oleic acid and glycerol due to its lower toxicity supported by silica via sol-gel technique. In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H2SO4 and the STAB gave high conversion of 100% and 98% but at a lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94% but with a significantly higher GME selectivity of 95%, rendering it the more efficient solid acid catalyst.

Synthesis, characterization and catalytic performance of H 3SiW 12O 40/SiO 2 prepared by sol-gel technique

The purpose of this work is to study the synthesis, characterization, and catalytic performance of two types of solid heteropoly acid catalysts, namely, silicotungstic acid bulk (STAB) and STA-silica sol-gel (STA-SG) compared with sulfuric acid. From the XPS analyses, there was a significant formation of W-O-Si, W-O-W, and Si-O-Si bonding in STA-SG compared to that in STAB. The main spectra of O1s (90.74%, 531.5 eV) followed by other O1s peak (9.26%, 532.8 eV) were due to the presence of W-O-W and W-O-Si bonds, respectively. The STA-SG catalyst was found to be the more environmentally benign solid acid catalyst for the esterification reaction between oleic acid and glycerol due to its lower toxicity supported by silica via sol-gel technique. In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H2SO4 and the STAB gave high conversion of 100% and 98% but at a lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94% but with a significantly higher GME selectivity of 95%, rendering it the more efficient solid acid catalyst.

Synthesis, Characterization and Catalytic Performance ofH3SiW12O40/SiO2Prepared by Sol-Gel Technique

The purpose of this work is to study the synthesis, characterization, and catalytic performance of two types of solid heteropoly acid catalysts, namely, silicotungstic acid bulk (STAB) and STA-silica sol-gel (STA-SG) compared with sulfuric acid. From the XPS analyses, there was a significant formation of W-O-Si, W-O-W, and Si-O-Si bonding in STA-SG compared to that in STAB. The main spectra of O1s (90.74%, 531.5 eV) followed by other O1s peak (9.26%, 532.8 eV) were due to the presence of W-O-W and W-O-Si bonds, respectively. The STA-SG catalyst was found to be the more environmentally benign solid acid catalyst for the esterification reaction between oleic acid and glycerol due to its lower toxicity supported by silica via sol-gel technique. In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H2SO4 and the STAB gave high conversion of 100% and 98% but at a lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94% but with a significantly higher GME selectivity of 95%, rendering it the more efficient solid acid catalyst.