scholarly journals Microwave-Assisted Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones Using Acid-Functionalized Mesoporous Polymer

2021 ◽  
Author(s):  
Bishwajit Changmai ◽  
Kalyani Rajkumari ◽  
diparjun das ◽  
Samuel Lalthazuala Rokhum
Keyword(s):  
Microwave Irradiation ◽  
Condensation Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Analytical Techniques ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Microwave Assisted Synthesis ◽  
Mesoporous Polymer

Synthesis and application of acid-functionalized mesoporous polymer catalyst for the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli condensation reaction under microwave irradiation is investigated. Several analytical techniques such as FT-IR, BET, TEM, SEM and EDX were employed to characterize the synthesized polymeric catalyst. High acidity (1.15 mmol g-1 ), high surface area (90.44 m2 g -1 ) and mesoporous nature of the catalyst effectively promoted the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones. Microwave irradiation shows higher yield (89-98 %) as compared to conventional heating (15-25 % yield) under our optimized reaction conditions such as 1:1:1.2 molar ratio of aldehyde/ethylacetoacetate/urea, catalyst loading of 6 wt.% (with respect to aldehyde), the temperature of 80 °C and microwave power of 50 W. The synthesized Biginelli products were fully characterized by 1H and 13C NMR. The reusability of the catalyst was investigated up to 5 successive cycles and it showed great stability towards the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones without any significant depreciation in yields.

scholarly journals Microwave-Assisted Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones Using Acid-Functionalized Mesoporous Polymer

2021 ◽  
Author(s):  
Bishwajit Changmai ◽  
Kalyani Rajkumari ◽  
diparjun das ◽  
Samuel Lalthazuala Rokhum
Keyword(s):  
Microwave Irradiation ◽  
Condensation Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Analytical Techniques ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Microwave Assisted Synthesis ◽  
Mesoporous Polymer

Synthesis and application of acid-functionalized mesoporous polymer catalyst for the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli condensation reaction under microwave irradiation is investigated. Several analytical techniques such as FT-IR, BET, TEM, SEM and EDX were employed to characterize the synthesized polymeric catalyst. High acidity (1.15 mmol g-1 ), high surface area (90.44 m2 g -1 ) and mesoporous nature of the catalyst effectively promoted the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones. Microwave irradiation shows higher yield (89-98 %) as compared to conventional heating (15-25 % yield) under our optimized reaction conditions such as 1:1:1.2 molar ratio of aldehyde/ethylacetoacetate/urea, catalyst loading of 6 wt.% (with respect to aldehyde), the temperature of 80 °C and microwave power of 50 W. The synthesized Biginelli products were fully characterized by 1H and 13C NMR. The reusability of the catalyst was investigated up to 5 successive cycles and it showed great stability towards the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones without any significant depreciation in yields.

scholarly journals Microwave-Assisted Synthesis of Arylidene Acetophenones

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Sheauly Khatun ◽  
M. Z. H. Khan ◽  
Khodeza Khatun ◽  
M. A. Sattar
Keyword(s):  
Microwave Irradiation ◽  
Microwave Heating ◽  
Spectral Data ◽  
Condensation Reaction ◽  
Aromatic Aldehydes ◽  
Conventional Heating ◽  
Microwave Assisted Synthesis ◽  
Efficient Synthesis ◽  
H Nmr ◽  
Microwave Assisted

An efficient synthesis of arylidene acetophenones have been achieved by using the microwave heating in comparison to the conventional heating. In this work compound 1-phenyle-3-(4-droxyphenyle)-2-propen-1-one, 1-(4-chlorophenyle)-3-phenyle-2-propen-1-one, and 1-(4-chlorophenyle)-3-(4-hydroxyphenyle)-2-propen-1-one have been synthesized by the condensation reaction between aromatic aldehydes and substituted acetophenones under microwave irradiation. The compounds of aldehydes and acetophenones were used as benzaldehyde, parahydroxybenzaldehyde, acetophenone, and parachloroacetophenone. The result shows that the time taken for the reaction was reduced from the conventional 1-2 hours to 60–120 seconds. The yield of the compounds in the conventional heating was moderate while the highest yield of 90–98% was observed in MWI method. The structure of the compounds was characterized by their IR,1H-NMR spectral data.

Microwave assisted synthesis of high-surface area WO3 particles decorated with mosaic patterns via hydrochloric acid treatment of Bi2W2O9

RSC Advances ◽  
2015 ◽  
Vol 5 (95) ◽  
pp. 77839-77846 ◽  
Author(s):  
Fuminao Kishimoto ◽  
Dai Mochizuki ◽  
Masato M. Maitani ◽  
Eiichi Suzuki ◽  
Yuji Wada
Keyword(s):  
Hydrochloric Acid ◽  
Microwave Irradiation ◽  
Surface Area ◽  
Acid Treatment ◽  
High Surface ◽  
High Surface Area ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Patterned Structures ◽  
Hydrochloric Acid Treatment

High surface area WO3 particles with mosaic patterned-structures were obtained under microwave irradiation.

Zinc-Modified MCM-22 as Potential Solid acid Catalyst for Friedel–Crafts Alkylation Reaction

2013 ◽  
Vol 11 (1) ◽  
pp. 407-415 ◽  
Author(s):  
Sharad V. Lande ◽  
A. Sakthivel, ◽  
K. V. V. S. B. S. R. Murthy ◽  
Unnikrishnan Sreedharan ◽  
Jagannath Das ◽  
...  
Keyword(s):  
Solid Acid Catalyst ◽  
High Surface ◽  
High Surface Area ◽  
Acid Catalyst ◽  
Systematic Investigation ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Alkylation Reaction ◽  
Phase Medium ◽  
Alkylation Of Benzene

Abstract In this paper, we report loading of ZnCl2 on microporous medium pore high surface area zeolite, which was achieved by incipient wetness method. The zinc-modified mobil composite material -22 (Zn-MCM-22) was systematically characterized by powder X-ray diffraction, N2 adsorption-desorption analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The acidity of the materials was studied by temperature programmed desorption of ammonia analysis. The well-characterized Zn-MCM-22 catalyst was investigated for the Friedel–Crafts alkylation of benzene by benzyl chloride in liquid phase medium. A systematic investigation of various operating parameters like effect of different temperature, catalyst loading and reactant molar ratio was carried out. The Zn-MCM-22 found to be promising, further the catalytic activity remains stable over several recycles.

scholarly journals An acceleration of microwave-assisted transesterification of palm oil-based methyl ester into trimethylolpropane ester

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nur Atiqah Mohamad Aziz ◽  
Robiah Yunus ◽  
Hamidah Abd Hamid ◽  
Alsultan Abdul Kareem Ghassan ◽  
Rozita Omar ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Microwave Irradiation ◽  
Palm Oil ◽  
Energy Requirement ◽  
Reaction System ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Sodium Methoxide Solution

AbstractMicrowave-assisted synthesis is known to accelerate the transesterification process and address the issues associated with the conventional thermal process, such as the processing time and the energy input requirement. Herein, the effect of microwave irradiation on the transesterification of palm oil methyl ester (PME) with trimethylolpropane (TMP) was evaluated. The reaction system was investigated through five process parameters, which were reaction temperature, catalyst, time, molar ratio of TMP to PME and vacuum pressure. The yield of TMP triester at 66.9 wt.% and undesirable fatty soap at 17.4% were obtained at 130 °C, 10 mbar, sodium methoxide solution at 0.6 wt.%, 10 min reaction time and molar ratio of TMP to PME at 1:4. The transesterification of palm oil-based methyl ester to trimethylolpropane ester was 3.1 folds faster in the presence of microwave irradiation. The total energy requirement was markedly reduced as compared to the conventional heating method. The findings indicate that microwave-assisted transesterification could probably be an answer to the quest for a cheaper biodegradable biolubricant.

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.

Microwave Assisted Synthesis of Schiff Bases: A Green Approach

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Mousumi Chakraborty ◽  
Sanjay Baweja ◽  
Sunita Bhagat ◽  
TejpalSingh Chundawat
Keyword(s):  
Microwave Irradiation ◽  
Microwave Power ◽  
Mass Spectra ◽  
Molar Ratio ◽  
Microwave Assisted Synthesis ◽  
Schiff’S Bases ◽  
Microwave Assisted ◽  
Green Approach ◽  
Schiff's Bases ◽  
Effects Of Temperature

Abstract In the present study Schiff’s bases are synthesized by the conventional as well as by microwave irradiation. Excellent yield within short reaction time is obtained using microwave irradiation along with other advantages like mild reaction condition, non-hazardous and safer environmental conditions. The effects of temperature, reactant molar ratio, and microwave power variation on yield are observed. Mathematical model has been developed using matlab software to obtain the yield as a function of microwave power. Kinetic study of the reaction has also been attempted. Schiff’s bases structures are confirmed by IR, 1HNMR, Mass Spectra and elemental analysis.

scholarly journals Sol-Gel Immobilisation of Lipases: Towards Active and Stable Biocatalysts for the Esterification of Valeric Acid

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2283 ◽  
Author(s):  
Soledad Cebrián-García ◽  
Alina Balu ◽  
Araceli García ◽  
Rafael Luque
Keyword(s):  
Microwave Irradiation ◽  
Sol Gel ◽  
Valeric Acid ◽  
Added Value ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Highly Active ◽  
Industrial Sectors ◽  
Wide Range ◽  
Acid Esterification

Alkyl esters are high added value products useful in a wide range of industrial sectors. A methodology based on a simple sol-gel approach (biosilicification) is herein proposed to encapsulate enzymes in order to design highly active and stable biocatalysts. Their performance was assessed through the optimization of valeric acid esterification evaluating the effect of different parameters (biocatalyst load, presence of water, reaction temperature and stirring rate) in different alcoholic media, and comparing two different methodologies: conventional heating and microwave irradiation. Ethyl valerate yields were in the 80–85% range under optimum conditions (15 min, 12% m/v biocatalyst, molar ratio 1:2 of valeric acid to alcohol). Comparatively, the biocatalysts were slightly deactivated under microwave irradiation due to enzyme denaturalisation. Biocatalyst reuse was attempted to prove that good reusability of these sol-gel immobilised enzymes could be achieved under conventional heating.

A Green and Sustainable Approach for Acetalization of Benzaldehyde Using Tungstophosphoric Acid Loaded on Metal Oxide Catalysts

2019 ◽  
Vol 41 (5) ◽  
pp. 805-805
Author(s):  
Li Fanghao Li Fanghao ◽  
Li Chenjie Li Chenjie ◽  
Chen Junyi Chen Junyi ◽  
Wang Kuiwu Wang Kuiwu ◽  
Zhang Haijiang Zhang Haijiang ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Condensation Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Synergetic Effect ◽  
Reaction Model ◽  
Oxide Catalysts ◽  
Tungstophosphoric Acid ◽  
Impregnation Method ◽  
Metal Oxide Catalysts

A series of tungstophosphoric acid (H3PW12O40; HPW) loaded on metal oxide catalysts, namely H3PW12O40/M (M= TiO2, CeO2, ZrO2) was prepared by initial wetting impregnation method and their catalytic performances were also investigated during the condensation reaction of benzaldehyde with glycol. Among them, the 20 wt% H3PW12O40/TiO2 catalyst demonstrated highly active with superior acetal yield (90.1 %) and excellent durability. The high activity of the catalyst derived from high surface area, ultra-strong Brand#248;nsted acidity and synergetic effect of Brand#248;nsted-Lewis acid. Response surface methodology (RSM) based on Box-Behnken design (BBD) was used to optimize the course of the condensation reaction of benzaldehyde with glycol, and the optimal benzaldehyde glycol acetal yield (93.4 %) could be obtained. The optimized yield and the experimental results are similar. Moreover, under optimal reaction conditions, the activation energy (Ea) of reaction could be obtained through the kinetic study of the irreversible parallel reaction model, and the Ea was 23.24 kJ/mol.

Optimization of COD Removal from an Aqueous Lignin Solution Using Photo-Fenton Reaction over Fe-Ce-Zn Catalysts

2014 ◽  
Vol 931-932 ◽  
pp. 7-11
Author(s):  
Sutasinee Neramittagapong ◽  
Arthit Neramittagapong ◽  
Siwaporn Choorueang
Keyword(s):  
Optimal Condition ◽  
Fenton Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Catalyst Loading ◽  
Statistical Experiment ◽  
Pulp Processing ◽  
Co Precipitation

This work is an investigation of the effectiveness of chemical oxygen demand (COD) removal from synthesized lignin wastewater using photo-Fenton reaction over Fe-Ce-Zn catalysts. The synthesized lignin wastewater had the same COD concentration as the pulp processing wastewater. The treatment was done using photo-Fenton reaction with the metal catalysts (Fe-Ce-Zn). They were prepared by co-precipitation. The catalysts efficacies in reducing COD were tested. It was found that the addition of zinc influenced its reaction due to the increasing of semiconductor property to the light. Moreover, the high surface area of Fe-Ce-Zn catalyst enhanced the COD removal due to the synergy of the high adsorption capacity. Therefore, the Fe-Ce-Zn catalyst was studied to obtain the optimal condition for COD reduction. The conditions and parameters investigated were: pH, the concentration of hydrogen peroxide (H2O2), and the concentration of catalyst. The optimal condition was obtained using the Box-Behnken statistical experiment design (BBD) and the response surface methodology (RSM). It has been found that the pH and the concentration of catalyst had the significant effects on the reduction of COD. The concentration of H2O2 has no effect on the COD removal. The maximum COD removal (60%) was achieved at the pH of 5.2, 4 g/L of catalyst loading, and 366 mg/L of H2O2.

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