Synthesis and characterization of the novel diamine-functionalized Fe3 O4 @SiO2 nanocatalyst and its application for one-pot three-component synthesis of chromenes

Core-shell assembly of ZrO2 nanoparticles with ionic liquid: a novel and highly efficient heterogeneous catalysts for Biginelli and esterification reactions

Imidazolium sulfonic acid chloride grafted ZrO₂ nanoparticles (ZrO₂-IL) were synthesized through facile post-treatment of the nanoparticles with the imidazolium-sulfonic acid chloride ionic liquid. The immobilization of the ionic liquid over the ZrO₂ nanoparticles was evident from the XRD, SEM, TEM, Raman, BET, and XPS analysis. The results obtained from the XRD analysis clearly show that the catalyst has an orthorhombic structure and from the BET analysis it is evident that the surface is mesoporous with uniform pore sizes and pore distribution. Further evidence of immobilization of ionic liquid over the ZrO₂ NPs was obtained from the SEM, TEM, XPS, and Raman analysis. Under mild conditions, the synthesized heterostructure was used in the acid-catalyzed esterification of different acids. The ZrO₂-IL catalyst converts 99% of the acid to ester with a 98.9% yield in 1h. The material was also shown to be highly efficient as catalyst for the Biginelli reaction under solvent-free conditions, with the catalyst for dihydropyrimidin-2(1H)-one (DHPMs) in 1h with 99.2% conversion and 99% yield. The synergy between the ionic liquid catalyst and the substrates increased the catalytic efficiency and resulted in high-yield product conversion. The mechanism of both transformation reactions was investigated, as well as the synergy between ionic liquid and ZrO₂ nanoparticles for better catalytic efficiency was established.

Preparation and catalytic application of two different nanocatalysts based on hexagonal mesoporous silica (HMS) in synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives

The present study describes the synthesis, characterization, and investigation of catalytic activity of xanthine-Ni complex (Xa-Ni) and 4-phenylthiosemicarbazide-Cu complex (PTSC-Cu) incorporated into functionalized hexagonal mesoporous silica (HMS/Pr-Xa-Ni and HMS/Pr-PTSC-Cu). These useful mesoporous catalysts had been synthesized and identified using various techniques such as FT-IR, XRD, adsorption-desorption of nitrogen, SEM, TEM, EDX-Map, TGA, AAS and ICP. These spectral techniques successfully confirmed the synthesis of the mesoporous catalysts. The catalytic activity of HMS/Pr-a-Ni (Catalyst A) and HMS/Pr-PTSC-Cu (Catalyst B) were evaluated for synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives. HMS/Pr-PTSC-Cu exhibited higher efficiency in green media under milder reaction condition at room temperature. Furthermore, the synthesized nanocatalysts, exhibited appropriate recoverability that can be able to reuse for several times without significant loss of catalytic activity.

Laccase immobilized on amino-functionalized magnetic Fe3O4-SiO2 core-shell material for 2,4-dichlorophenol removal

In this study, an amino-functionalized magnetic silica microsphere material (Fe₃O₄-SiO₂-NH₂) was prepared. Using glutaraldehyde as a cross-linking agent, Trametes versicolor laccase was adsorbed-covalently bonded and immobilized on the material to prepare Laccase @ Fe₃O₄-SiO₂. In addition, the materials were characterized and analysed by SEM, TEM, XRD, FT-IR and VSM. Finally, the thermal inactivation dynamics of immobilized laccase in polar/non-polar/toxic systems and the adsorption and degradation of 2,4-DCP were studied. The results showed that Laccase @ Fe₃O₄-SiO₂ under the optimal conditions (pH 6, temperature 65°C, initial concentration of 2,4-DCP 10 mg/L), the removal rate was as high as 81.6%. Moreover, compared with free laccase, immobilized laccase had good tolerance under low pH and high-temperature conditions, and storage stability was also greatly improved. After repeated use for 7 times, Laccase @ Fe₃O₄-SiO₂ can still maintain 59% removal rate of 2,4-DCP, which gives it the potential for industrial applications.

Synthesis of 3-methyl-4H-benzo[b][1,4]thiazine-2-carboxylates using CAN as a catalyst and its conversion into guanidines

Background:

1,4-benzothiazine carboxylates show wide application in the field of medicinal chemistry. Therefore, we have designed convenient and efficient method for the synthesis of 1,4-benzothiazine carboxylates.

Objective:

Synthesis of 1,4-benzothiazine carboxylates and its guanidines by simple and facile method using efficient catalyst.

Method:

Derivatives of 1,4-benzothiazine carboxylates were synthesized by cyclocondensing β-keto esters with 2- aminobenzenethiols using CAN as a catalyst at room temperature. 1,4-benzothiazine caboxylate,condensed with guanidine hydrochloride in the presence of sodium methoxide in DMF to obtained new 3-substituted-l-4Hbenzo[b][1,4]thiazine-2-carboxyguanidines (88-91%).

Results:

All the products were obtained with good to excellent yields within 40 min. Here, CAN oxidizes aminothiophenol into disulfide and then nucleophilic attack of enolic form of β-ketoesters on the disulphide and 1, 4-benzothiazine acetates, were obtained with good yields.

Conclusion:

We have designed convenient and efficient method for the synthesis of 1,4-benzothiazine carboxylates. Most remarkable features of this cyclocondensation such as use of efficient catalyst and non-volatile solvent under mild reaction condition to obtained excellent yield.

High-performance sono/nano-catalytic system: Fe3O4@Pd/CaCO3-DTT core/shell nanostructures, a suitable alternative for traditional reducing agents for antibodies

Herein, a novel heterogeneous nanoscale reducing agent for antibody cleavage, made of iron oxide nanoparticles, silica network, palladium on calcium carbonate (10%), and dithiothreitol (Fe₃O₄@Pd/CaCO₃-DTT), is presented as a substantial alternative for traditional homogeneous analogues. Conventionally, antibody fragmentation is accomplished using reducing agents and proteases that digest or cleave certain portions of the immunoglobulin protein structure to provide active thiol sites for drug tagging aims. Then, dialysis process is needed to separate excess chemical structures and purify the reduced antibody. In this work, we have made an effort to design a suitable heterogeneous tool for protein cleavage and skip the dialysis process for purification of the reduced antibody. In this regard, firstly, various preparation methods including microwave irradiation, reflux and ultrasonication have been precisely compared, and it has been proven that the best result is obtained through 10 min ultrasound (US) irradiation using an US bath with 50 KHz frequency and 200 W L^-1 power density. Then, all the necessary structural analyses have been done and thoroughly interpreted for the final product. Afterward, the catalytic performance of Fe₃O₄@Pd/CaCO₃-DTT nanoscale system in the presence of US waves (50 KHz, 200 W) has been monitored using some disulphide derivatives. The NPs could be conveniently separated from the mixture through their substantial paramagnetic property. Thus, dialysis process in which various types of membranes are used is practically jumped after the reduction process. In this work, this is clearly demonstrated that there is a constructive synergistic effect between US waves and prepared Fe₃O₄@Pd/CaCO₃-DTT nanoscale reducing agent. Ultimately, trastuzumab (anti HER-2) antibody has been used to test the performance of the prepared Fe₃O₄@Pd/CaCO₃-DTT NPs in a real protein reduction reaction.

One-pot Multicomponent Synthesis of pyrrolo[1,2-d][1,4]benzoxazines and pyrrolo[1, 2-a]pyrazines in Water Catalyzed by Fe3O4@SiO2@L-Arginine-SA Magnetic Nanoparticles

AIMS

Synthesis of pyrrolo[1,2-d][1,4]benzoxazines and pyrrolo[1,2-a]pyrazines using magnetic nanoparticles.

BACKGROUND

One-pot, three component reaction for the synthesis of pyrrolo[1,2-d][1,4]benzoxazines and pyrrolo[1,2-a]pyrazines is reported. For the synthesis of pyrrolo[1,2-d][1,4]benzoxazines use of 2- aminophenols, dialkylacetylenedicarboxylates and β -nitrostyrene derivatives and Pyrrolo[1,2-a]pyrazines synthesized from reaction of ethylenediamine, dialkylacetylenedicarboxylates and β-nitrostyrene derivatives is discussed.

MATERIALS AND METHODS

2-aminophenol (0.5 mmol) and dimethylacetylenedicarboxylate (0.5 mmol) in water (3 ml) were stirred at room temperature for 10 min. Then, β-nitrostyrene (0.5 mmol) and Fe3O4@SiO2@LArginine- SA MNPs (0.07 g) were added and the mixture was refluxed for 5 h. After completion of the reaction, the mixture was cooled to room temperature and the catalyst was separated with external magnet and product extracted with dichloromethane. More purification of products was performed by column chromatography (nhexane/ ethyl acetate 4:1). Ethylenediamine (0.6 mmol) was added to dialkylacetylenedicarboxylate (0.6 mmol) in 3 ml water and was stirred for 10 min at room temperature. Later, β -nitrostyrene (0.5 mmol) and Fe3O4@SiO2@L-Arginine-SA MNPs (0.06 g) were added to mixture reaction and refluxed for 3 h. After completion, the mixture reaction was cooled to room temperature and the catalyst was separated by an external magnet. Then, the product was extracted with dichloromethane. For more purification column chromatography was used (n-hexane/ethylacetate 1:1).

RESULTS AND DISCUSSIONS

In this research, we have synthesized new derivatives of pyrrolo[1,2- d][1.4]benzoxazines and pyrrolo[1,2-a]pyrazines in green conditions consisting of use of water as a green solvent and magnetic nanoparticles.

CONCLUSION

In this research, we have synthesized new derivatives of pyrrolo[1,2-d][1.4]benzoxazines and pyrrolo[1,2-a]pyrazines in green conditions consisting of use of water as a green solvent and magnetic nanoparticles which were easily separated from mixture with an external magnet and had the capability to be recovered and reused. Also, in this work, the yield was good and the time of reactions was low compared with prior research.