scholarly journals New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

2017 ◽  
Vol 13 ◽  
pp. 1982-1993 ◽  
Author(s):  
Daily Rodríguez-Padrón ◽  
Alina M Balu ◽  
Antonio A Romero ◽  
Rafael Luque
Keyword(s):  
Benzyl Alcohol ◽  
Potential Method ◽  
Point Of View ◽  
Conventional Heating ◽  
Alkylation Reaction ◽  
Microwave Assisted ◽  
Oxidation Of Benzyl Alcohol ◽  
Valuable Product ◽  
Mechanochemical Milling ◽  
Alkylation Reactions

Polysaccharides from natural sources and iron precursors were applied to develop new bio-nanocomposites by mechanochemical milling processes. The proposed methodology was demonstrated to be advantageous in comparison with other protocols for the synthesis of iron oxide based nanostructures. Additionally, mechanochemistry has enormous potential from an environmental point-of-view since it is able to reduce solvent issues in chemical syntheses. The catalytic activity of the obtained nanocatalysts was investigated in both the oxidation of benzyl alcohol to benzaldehyde and in the alkylation of toluene with benzyl chloride. The microwave-assisted oxidation of benzyl alcohol reached 45% conversion after 10 min. The conversion of the alkylation of toluene in both microwave-assisted and conventional heating methods was higher than 99% after 3 min and 30 min, respectively. The transformation of benzyl alcohol and toluene into valuable product in both the oxidation and alkylation reaction reveals a potential method for the valorization of lignocellulosic biomass.

Size Effect of Silica-supported Gold Clusters in the Microwave-assisted Oxidation of Benzyl Alcohol with H2O2

2010 ◽  
Vol 39 (3) ◽  
pp. 159-161 ◽  
Author(s):  
Yongmei Liu ◽  
Hironori Tsunoyama ◽  
Tomoki Akita ◽  
Tatsuya Tsukuda
Keyword(s):  
Size Effect ◽  
Benzyl Alcohol ◽  
Gold Clusters ◽  
Microwave Assisted ◽  
Oxidation Of Benzyl Alcohol ◽  
Supported Gold

scholarly journals A study comparing Conventional Heating and Microwave Assistance Heating to Recover Metals from Municipal Solid Waste using Microwave-Assisted Leaching Technique

2020 ◽  
Author(s):  
Mariam Khan ◽  
Mohammad Al ghouti ◽  
Mustafa Nasser ◽  
Khalid Al Kuwari ◽  
Oon Heng
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Bottom Ash ◽  
Acid Leaching ◽  
Point Of View ◽  
Conventional Heating ◽  
Microwave Assisted ◽  
Heating Radiation ◽  
Microwave Assistance ◽  
The Cost

This study investigates and compares microwave-heating radiation with conventional heating. Incinerated municipal solid waste (IMSW) bottom ash (BA) and fly ash (FA) was utilized to recover various metals including Co, Cr, Cu, Fe, Mn, Zn,Pb, Al, Cd, Ba, Mg and V using various acid leaching agents i.e. HCl, HNO3 and H3PO4 were utilized and several parameters were altered in order to determine the most effective conditions. The current study concluded that microwave assisted leaching method is effective to recover most of the metals. In addtion, metals from MSWBA were much easier to recover in contrast with MSW-FA. 71% of Co, 75.69% of Cr, 56.19% of Cd, 35.23% of Ba and 30.2% of Pb, using 2M of HCl and 3M of H3PO4. While 1.48% of Cr, 0.93% of Fe, 1.19% of Mn, and 1.18% of Al were extracted using HCL and H3PO4 from MSWFA. It was also confirmed that higher power and longer contact time had a positive effect on metal recovery. From cost analysis point of view, microwave assisted leaching was fraction of the cost for conventional heating, making this method comparatively sustainable, energy efficient and safe.

scholarly journals A Microwave-Assisted Boudouard Reaction: A Highly Effective Reduction of the Greenhouse Gas CO2 to Useful CO Feedstock with Semi-Coke

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1507
Author(s):  
Huan Dai ◽  
Hong Zhao ◽  
Siyuan Chen ◽  
Biao Jiang
Keyword(s):  
Carbon Dioxide ◽  
Microwave Heating ◽  
Barium Carbonate ◽  
Fixed Bed ◽  
Potential Method ◽  
Fixed Bed Reactor ◽  
Conventional Heating ◽  
Boudouard Reaction ◽  
Co2 Conversion ◽  
Microwave Assisted

The conversion of CO2 into more synthetically flexible CO is an effective and potential method for CO2 remediation, utilization and carbon emission reduction. In this paper, the reaction of carbon-carbon dioxide (the Boudouard reaction) was performed in a microwave fixed bed reactor using semi-coke (SC) as both the microwave absorber and reactant and was systematically compared with that heated in a conventional thermal field. The effects of the heating source, SC particle size, CO2 flow rate and additives on CO2 conversion and CO output were investigated. By microwave heating (MWH), CO2 conversion reached more than 99% while by conventional heating (CH), the maximum conversion of CO2 was approximately 29% at 900 °C. Meanwhile, for the reaction with 5 wt% barium carbonate added as a promoter, the reaction temperature was significantly reduced to 750 °C with an almost quantitative conversion of CO2. Further kinetic calculations showed that the apparent activation energy of the reaction under microwave heating was 46.3 kJ/mol, which was only one-third of that observed under conventional heating. The microwave-assisted Boudouard reaction with catalytic barium carbonate is a promising method for carbon dioxide utilization.

Selective Oxidation of Benzyl Alcohol Catalyzed by Pd/PMO-SBA-15 Catalyst

2011 ◽  
Vol 31 (11) ◽  
pp. 1369-1373
Author(s):  
Cheng LIU ◽  
Rong TAN ◽  
Donghong YIN ◽  
Ningya YU ◽  
Yuxu ZHOU
Keyword(s):  
Benzyl Alcohol ◽  
Selective Oxidation ◽  
Oxidation Of Benzyl Alcohol

Regioselective Synthesis of Potent 4,5,6,7-Tetrahydroindazole Derivatives via Microwave-assisted Vilsmeier-Haack Reaction and their Antioxidant Activity Evaluation

2019 ◽  
Vol 16 (3) ◽  
pp. 194-201 ◽  
Author(s):  
Renu Bala ◽  
Vandana Devi ◽  
Pratibha Singh ◽  
Navjot Kaur ◽  
Pawandeep Kaur ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Microwave Irradiation ◽  
Biological Activities ◽  
Reaction Times ◽  
Conventional Heating ◽  
High Chemical ◽  
Microwave Assisted ◽  
Work Up ◽  
Active Methylene ◽  
By Products

Background: Tetrahydroindazole, a member of the fused-pyrazole system, is a least studied class of heterocyclic compounds owing to its scarcity in nature. However, a large number of synthetically prepared tetrahydroindazoles are known to show a variety of biological activities such as interleukin- 2 inducible T-Cell kinase inhibitors, AMPA receptor positive allosteric modulators, antitumor, antituberculosis, anti-inflammatory and antimicrobial activities. Vilsmeier-Haack reaction is one of the most important chemical reactions used for formylation of electron rich arenes. Even though Vilsmeier- Haack reaction was studied on a wide variety of hydrazones derived from active methylene compounds, literature lacks the examples of the use of 4-substituted cyclohexanones as a substrate for the synthesis of 4,5,6,7-tetrahydroindazoles. The study of the reaction of Vilsmeier-Haack reagent with hydrazones derived from cyclic keto compounds having active methylene has been considered the interested topic of investigation. In the present study, ethyl cyclohexanone-4-carboxylate was treated with one equivalent of various hydrazines for two hours and the resulted hydrazones were further treated with an OPC-VH reagent (Vilsmeier-Haack reagent isolated from phthaloyl dichloride and N,Ndimethylformamide) afforded 4,5,6,7-tetrahydroindazoles in excellent yields. The synthesized compounds 4a-f and 5a-f were screened for their antioxidant activities using the DPPH radical scavenging assay. The target compounds were synthesized regioselectively using 4+1 approach in excellent yields. A number of experiments using both conventional heating as well as microwave irradiation methods were tried and on comparison, microwave irradiation method was found excellent in terms of easy work up, high chemical yields, shortened reaction times, clean and, no by-products formation. Some of the synthesized compounds showed significant antioxidant activity. The microwave assisted synthesis of 4,5,6,7-tetrahydroindazoles from ethyl cyclohexanone-4-carboxylate has been reported under mild conditions in excellent yield. Easy work up, high chemical yield, shortened reaction times, clean and no by-products formation are the major advantages of this protocol. These advantages may make this method useful for chemists who are interested in developing novel 4,5,6,7-tetrahydroindazole based drugs.

Microwave-assisted Synthesis of Polymethoxychalcone Mannich Bases and Their Antiproliferative Activity

2019 ◽  
Vol 16 (2) ◽  
pp. 117-121 ◽  
Author(s):  
Peipei Han ◽  
Wenhua Zhou ◽  
Mingxia Chen ◽  
Qiuan Wang
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Antiproliferative Activity ◽  
Mannich Base ◽  
Cancer Cell Lines ◽  
Secondary Amines ◽  
Conventional Heating ◽  
Microwave Assisted ◽  
Ic50 Values ◽  
Antiproliferative Activities

A series of eight polymethoxychalcone Mannich base derivatives 2a-2h was synthesized via the microwave-assisted Mannich reaction of natural product 2'-hydroxy-3,4,4',5,6'-pentamethoxychalcone (1) with various secondary amines and formaldehyde. Compared to conventional heating method (80°C), the microwave-assisted method (700W, 65°C) is efficient with short reaction time (0.5-1 h) and good yields (74-88%). The antiproliferative activities of eight Mannich base derivatives were evaluated in vitro on a panel of three human cancer cell lines (Hela, HCC1954 and SK-OV-3) by CCK-8 assay. The results showed that all of the Mannich base derivatives exhibited potential antiproliferative activities on tested cancer cell lines with the IC50 values of 9.13-48.51 µM. Some active compounds exhibited more activity as compared to positive control cis-Platin. Among them, compound 2b revealed to have the strongest antiproliferative activity against all the three cancer cell lines with IC50 values ranging from 9.13 to 11.24 µM.

Microwave-assisted Synthesis of Benzoxazoles Derivatives

2020 ◽  
Vol 7 (3) ◽  
pp. 183-195
Author(s):  
Musa Özil ◽  
Emre Menteşe
Keyword(s):  
Microwave Irradiation ◽  
Reaction Medium ◽  
Pharmaceutical Chemistry ◽  
Conventional Heating ◽  
High Yield ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Optical Brighteners ◽  
Chemistry Research ◽  
Extensive Class

Background: Benzoxazole, containing a 1,3-oxazole system fused with a benzene ring, has a profound effect on medicinal chemistry research owing to its important pharmacological activities. On the other hand, the benzoxazole derivative has exhibited important properties in material science. Especially in recent years, microwave-assisted synthesis is a technique that can be used to increase diversity and quick research in modern chemistry. The utilization of microwave irradiation is beneficial for the synthesis of benzoxazole in recent years. In this focused review, we provide a metaanalysis of studies on benzoxazole in different reaction conditions, catalysts, and starting materials by microwave technique so far, which is different from conventional heating. Methods: Synthesis of different kind of benzoxazole derivatives have been carried out by microwave irradiation. The most used method to obtain benzoxazoles is the condensation of 2-aminophenol or its derivatives with aldehydes, carboxylic acids, nitriles, isocyanates, and aliphatic amines. Results: Benzoxazole system and its derivatives have exhibited a broad range of pharmacological properties. Thus, many scientists have remarked on the importance of the synthesis of different benzoxazole derivatives. Conventional heating is a relatively inefficient and slow method to convey energy in orientation to the reaction medium. However, the microwave-assisted heating technique is a more effective interior heating by straight coupling of microwave energy with the molecules. Conclusion: In this review, different studies were presented on the recent details accessible in the microwave- assisted techniques on the synthesis of the benzoxazole ring. It presents all examples of such compounds that have been reported from 1996 to the present. Benzoxazoles showed an extensive class of chemical substances not only in pharmaceutical chemistry but also in dyestuff, polymer industries, agrochemical, and optical brighteners. Thus the development of fast and efficient achievement of benzoxazoles with a diversity of substituents in high yield is getting more noteworthy. As shown in this review, microwave-assisted synthesis of benzoxazoles is a very effective and useful technique.

scholarly journals Microwave-Assisted Preparation of Luminescent Inorganic Materials: A Fast Route to Light Conversion and Storage Phosphors

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2882
Author(s):  
José Miranda de Carvalho ◽  
Cássio Cardoso Santos Pedroso ◽  
Matheus Salgado de Nichile Saula ◽  
Maria Claudia França Cunha Felinto ◽  
Hermi Felinto de Brito
Keyword(s):  
Rapid Heating ◽  
Inorganic Materials ◽  
Rapid Screening ◽  
Conventional Heating ◽  
Quantum Yields ◽  
Microwave Assisted Synthesis ◽  
Volumetric Heating ◽  
White Leds ◽  
Microwave Assisted ◽  
And Storage

Luminescent inorganic materials are used in several technological applications such as light-emitting displays, white LEDs for illumination, bioimaging, and photodynamic therapy. Usually, inorganic phosphors (e.g., complex oxides, silicates) need high temperatures and, in some cases, specific atmospheres to be formed or to obtain a homogeneous composition. Low ionic diffusion and high melting points of the precursors lead to long processing times in these solid-state syntheses with a cost in energy consumption when conventional heating methods are applied. Microwave-assisted synthesis relies on selective, volumetric heating attributed to the electromagnetic radiation interaction with the matter. The microwave heating allows for rapid heating rates and small temperature gradients yielding homogeneous, well-formed materials swiftly. Luminescent inorganic materials can benefit significantly from the microwave-assisted synthesis for high homogeneity, diverse morphology, and rapid screening of different compositions. The rapid screening allows for fast material investigation, whereas the benefits of enhanced homogeneity include improvement in the optical properties such as quantum yields and storage capacity.

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