Synthesis of anti-inflammatory 2,3-unsaturated O-glycosides using conventional and microwave heating techniques

2017 ◽  
Vol 23 (3) ◽  
pp. 205-211
Author(s):  
Adriana Cristina N. de Melo ◽  
Ronaldo N. de Oliveira ◽  
João R. de Freitas Filho ◽  
Teresinha G. da Silva ◽  
Rajendra M. Srivastava
Keyword(s):  
Reaction Time ◽  
Microwave Irradiation ◽  
Microwave Heating ◽  
Acid Catalyst ◽  
Conventional Heating ◽  
Microwave Exposure ◽  
Ferrier Rearrangement ◽  
Acetyl Group ◽  
Anti Inflammatory

AbstractThe preparation of eight 2,3-unsaturated O-glycosides from D-glycals and alcohols, using montmorillonite K-10 as an acid catalyst, is described. The Ferrier rearrangement products were obtained in good yields using conventional heating and microwave irradiation but the reaction time was substantially reduced employing the latter procedure. The yields were slightly lower under microwave exposure. Five of the di-O-acetylated products were deacetylated to the glycosides in excellent yields. The acetylated products possess good anti-inflammatory property suggesting that the acetyl group plays an important role in reducing the inflammation. Among the compounds tested, glycosides containing thiophene as an aglycone present much better inflammation reducing characteristics than the analogues without this function.

scholarly journals Intensification and optimization of biodiesel production using microwave-assisted acid-organo catalyzed transesterification process

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Moina Athar ◽  
Sadaf Zaidi ◽  
Saeikh Zaffar Hassan
Keyword(s):  
Reaction Time ◽  
Organic Acid ◽  
Microwave Heating ◽  
Low Cost ◽  
Acid Catalyst ◽  
Operating Conditions ◽  
Biodiesel Production ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Inorganic Acid

AbstractTo produce biodiesel cost-effective, low-cost, high free fatty acid (FFA) oil feedstock is desirable. But high FFA creates difficulty during the base-catalyzed transesterification process by yield loss due to the formation of soap. However, these problems are overcome by the use of an acid catalyst. The acid catalysts can directly convert both triglycerides and FFAs into biodiesel without the formation of soaps or emulsions. The shortcomings of mostly used inorganic acids are that they work well for esterification of FFA present in low-cost oil, but their kinetics for transesterification of triglycerides present in oils is considerably slower. Corrosion of equipment is another major problem associated with an inorganic acid catalyst. The usage of an organic acid catalyst of the alkyl benzene sulfonic type, like 4-dodecyl benzene sulfonic acid (DBSA) minimizes these disadvantages of inorganic acid-catalyzed transesterification. The aim of the present investigation was to reduce the reaction time of transesterification of triglycerides further by using microwaves as a heating source in the presence of DBSA catalyst to achieve higher conversions under mild operating conditions. To optimize the transesterification variables for the higher conversion of biodiesel, the response surface methodology was employed to design the experiment. By using the DBSA catalyst under microwave heating at a temperature of 76 °C, conversion close to 100% in only 30 min of reaction time was obtained using a 0.09 molar ratio of catalyst to oil and 9.0 molar ratio of methanol to oil. A modified polynomial model was developed and was adequately fitted with the experimental data and could be used for understanding the effect of various process parameters. The catalyst to oil molar ratio and reaction temperature created a stronger effect on the biodiesel production than that exhibited by the methanol to oil molar ratio. It was observed that the microwave heating process outperformed conventional heating, providing a rapid, easy method for biodiesel synthesis from triglycerides in the presence of DBSA, an organic acid catalyst. The produced biodiesel was of good quality, as all the properties were within the prescribed limits of the ASTM D6751 standard.

First Sustainable Aziridination of Olefins Using Recyclable Copper-Immobilized Magnetic Nanoparticles

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 563-566 ◽  
Author(s):  
Sylvestre Toumieux ◽  
Mohamad Khodadadi ◽  
Gwladys Pourceau ◽  
Matthieu Becuwe ◽  
Anne Wadouachi
Keyword(s):  
Magnetic Nanoparticles ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Significant Loss ◽  
Conventional Heating ◽  
Heating Method ◽  
Magnetic Extraction

The first copper-catalyzed aziridination of olefins using re­cyclable magnetic nanoparticles is described. Magnetic nanoparticles were modified with dopamine and used as a support to coordinate copper. The methodology was optimized with styrene as olefin and using [N-(p-toluenesulfonyl)imino]phenyliodinane (PhI=NTs) as nitrene source. A microwave irradiation decreased the reaction time by 4-fold compared to conventional heating method. The catalyst was recovered by simple magnetic extraction and could be reused successfully up to five times without significant loss of activity. The methodology was ­applied to a range of different olefins leading to moderate to excellent yields in the formation of the expected aziridine.

Lewis Acid Promoted, One-Pot Synthesis of Fluoroquinolone Clubbed 1,3,4-Thiadiazole Motifs under Microwave Irradiation: Their Biological Activities

2020 ◽  
Vol 7 (1) ◽  
pp. 60-66
Author(s):  
Navin B. Patel ◽  
Rahul B. Parmar ◽  
Hetal I. Soni
Keyword(s):  
Reaction Time ◽  
Microwave Irradiation ◽  
Lewis Acid ◽  
Acid Catalyst ◽  
Antitubercular Activity ◽  
Biologically Active ◽  
High Yield ◽  
One Pot ◽  
One Pot Synthesis ◽  
Lewis Acid Catalyst

Background: A Lewis acid promoted efficient and facile procedure for one-pot synthesis of a novel series of fluoroquinolone clubbed with thiadiazoles motifs under microwave irradiation is described here. This technique has more advantages such as high yield, a clean procedure, low reaction time, simple work-up and use of Lewis acid catalyst. Objective: Our aim is to generate a biologically active 1,3,4- thiadiazole ring system by using a onepot synthesis method and microwave-assisted heating. High yield and low reaction time were the main purposes to synthesize bioactive fluoroquinolone clubbed 1,3,4- thiadiazole moiety. Methods: Fluoroquinolone Clubbed 1,3,4-Thiadiazole Motifs was prepared by Lewis acid promoted, one-pot synthesis, under microwave irradiation. All the synthesized molecules were determined by IR, 1H NMR, 13C NMR, and Mass spectra. The antimicrobial activity of synthesized compounds was examined against two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), two Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), and three fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using the MIC (Minimal Inhibitory Concentration) method and antitubercular activity H37Rv using L. J. Slope Method. Results: Lewis acid promoted, one-pot synthesis of Fluoroquinolone clubbed 1,3,4-Thiadiazole motifs under microwave irradiation is an extremely beneficial method because of its low reaction time and good yield. Some of these novel derivatives showed moderate to good in vitro antibacterial, antifungal, and antitubercular activity. Conclusion: One-pot synthesis of 1,3,4-Thiadiazole by using Lewis acid catalyst gives a good result for saving time and also getting more production of novel heterocyclic compounds with good antimicrobial properties via microwave heating method.

A high-yield microwave heating method for the preparation of (phthalocyaninato)bis(chloro)silicon(IV)

2001 ◽  
Vol 05 (04) ◽  
pp. 376-380 ◽  
Author(s):  
DOMINIC A. DAVIES ◽  
CHRISTINA SCHNIK ◽  
JACK SILVER ◽  
JOSE L. SOSA-SANCHEZ ◽  
PHILIP G. RIBY
Keyword(s):  
Reaction Time ◽  
Microwave Heating ◽  
Silicon Tetrachloride ◽  
Conventional Heating ◽  
High Yield ◽  
Thermal Heating ◽  
Heating Method ◽  
Purification Time

The microwave heating synthesis of (phthalocyaninato)bis(chloro)silicon(IV) prepared from diiminoisoindolene and silicon tetrachloride in quinoline has been shown to be rapid (5 min reaction time compared to 30 min with thermal heating) and results in a high yield (91% compared to 71% using thermal heating). A modified microwave ashing furnace was used to heat the reaction mixture. The high yield has led to a reduction in the purification time to 1 h (compared to 4 h or more using conventional heating).

Microwave-assisted Al-substituted Tobermorite Synthesis

2000 ◽  
Vol 15 (4) ◽  
pp. 850-853 ◽  
Author(s):  
Michihiro Miyake ◽  
Shigeto Niiya ◽  
Motohide Matsuda
Keyword(s):  
Reaction Time ◽  
Hydrothermal Synthesis ◽  
Microwave Heating ◽  
Conventional Heating ◽  
Crystallization Time ◽  
Short Reaction Time ◽  
Microwave Assisted

The effect of microwave heating on the hydrothermal synthesis of Al-substituted tobermorite and the removal characteristics of resulting materials were examined and compared with the effect of conventional heating. The microwave heating reduced the crystallization time of Al-substituted tobermorite—i.e., Al-substituted tobermorite was synthesized within 80 min at around 140 °C—and produced smaller crystallites than the conventional heating. The minute crystallites were found to promote the removal characteristics for Cs+ ions in short reaction time.

scholarly journals The Impact of Microwave Irradiation Reaction in Medicinal Chemistry: A Review

2021 ◽  
Vol 37 (1) ◽  
pp. 01-24
Author(s):  
Ashutosh Pal ◽  
Krishnanka Shekhar Gayen
Keyword(s):  
Drug Discovery ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Medicinal Chemistry ◽  
Rapid Evolution ◽  
Therapeutic Agents ◽  
Conventional Heating ◽  
Compound Libraries ◽  
The Impact ◽  
Better Than

The present review collects an update of the reactions in the area of medicinal chemistry using microwave irradiation. This review come up with an overview of most salient reactions performed under microwave irradiation in the field of drug discovery. Moreover, chemists are preferring to use this reaction rapidly in the academic as well as pharmaceutical laboratory during their drug discovery and making library of compounds. This reaction is much greener using less amount and readily recyclable solvents or sometimes reaction process without solvents and product become much cleaner, often yields are better than the conventional heating. Microwave irradiation is now very robust instrument used in company in the field of drug discovery, due to reduce the reaction time from hour to minute or even second and efficiently creation of compound libraries through combinatorial methodology associated with drug discovery so that new therapeutic agents bring to the market quicker. Hopefully, we will observe in the future the use of microwave irradiation drugs for the patients and this technology will utilize increase in number extensively in the field of medicinal chemistry. As this is an exceedingly rapid evolution area, this review offers significant expertise to the interested readers.

scholarly journals High efficiency extractions of V, Cr, Ti, Fe and Mn from vanadium slag by microwave heating

2021 ◽  
pp. 23-23
Author(s):  
B. Tan ◽  
S. Wu ◽  
L.-J. Wang ◽  
K.-C. Chou
Keyword(s):  
High Temperature ◽  
Reaction Time ◽  
Diffusion Process ◽  
Microwave Heating ◽  
High Efficiency ◽  
Conventional Heating ◽  
Vanadium Slag ◽  
Reduction Processes ◽  
Fe And Mn ◽  
Speed Up

The vanadium slag (V-slag) is generated from smelting vanadium titanomagnetite ore, which contains valuable elements, such as V, Ti, Cr, Fe and Mn. The traditional methods were mainly focused on the extractions of V and Cr by oxidation or reduction processes. In the present work, chlorination method was adopted to keep the valence state of each elements as original state. In order to speed up the diffusion of elements and reduce volatility of molten salt, microwave heating has been examined in the current paper. The results indicated that it only took 30 min to chlorinate V-slag at 800 ?C, and the chlorination ratios of V, Cr, Mn, Fe and Ti could reach to 82.67%, 75.82%, 92.96%, 91.66% and 63.14%, respectively. Compared with the results by conventional heating for 8 h, this extraction rate by microwave heating shows greater advantages. In addition, microwave heating can reduce effectively volatilization of AlCl3 by shortening the reaction time. The volatilization ratio of AlCl3 in this microwave heating was 3.92% instead of 8.97% in conventional heating (1h). The mechanism of efficient chlorination can be summarized as the enhancement of ions diffusion process and enhanced chemical reaction due to local high temperature.

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.

scholarly journals In Situ Transesterification of Spirulina Microalgae to Produce Biodiesel Using Microwave Irradiation

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Alex K. Koech ◽  
Anil Kumar ◽  
Zachary O. Siagi
Keyword(s):  
Fatty Acid ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Spirulina Platensis ◽  
Reaction System ◽  
Conventional Heating ◽  
Process Conditions ◽  
In Situ Transesterification ◽  
Algae Biomass

The present technology of transesterification of vegetable oils to produce biodiesel, which is suited to replace petrodiesel, has economic challenges, and therefore, alternative sources are being explored. Microalgae, a renewable, third-generation biofuel resource, have the potential to become a viable feedstock due to their high oil content and environmentally friendly nature. The present study investigates the effect of microwave irradiation on the simultaneous extraction and transesterification of algae lipids to produce fatty acid methyl ester (FAME), in a batch reaction system using sulphuric acid catalyst. In situ transesterification combines the two steps of lipid extraction and transesterification into a single step. The microwave synthesis unit comprised of a 3-neck round bottom flask inside a 1300-Watt microwave oven, fitted with a quick-fit condenser and having an external stirrer. Response surface methodology (RSM) was used to analyse the influence of process variables, dry algae to methanol ratio 1 : 4 − 1 : 14   g / ml , algae biomass to catalyst ratio 1 : 0.0032 − 1 : 0.0368   wt % , and reaction time 1 − 11   min , at 500  rpm stirring rate for in situ reaction. FAME was analysed using gas chromatography (GC). The total lipid content of Arthrospira Spirulina platensis microalgae biomass was found to be 10.7 % by weight. The algae biomass also contained proteins at   51.83 % , moisture content at 7.8 % , and ash content 14.30 % by weight. RSM gave the optimum process conditions as dry algae biomass feed to methanol wt / vol ratio of 1 : 9, catalyst concentration of 2   wt % , and reaction time of   7   minutes   for a maximum FAME yield of 83.43   wt % . The major fatty acid composition of FAME was palmitic 43.83 % , linoleic   38.83 % , and linolenic 19.41 % . FAME properties obtained according to European Standards (EN 14214) and American Society for Testing and Materials (ASTM D 6751) standards were as follows: flash point 16 4 o C calorific value 32,911   kJ / kg , acid value 0.475 KOH / g , viscosity 4.45   m m 2 / s , and specific gravity   0.868 . The study showed that Arthrospira Spirulina platensis microalgae lipid FAME met the biodiesel standards (EN 14214 and ASTM D 6751) and has the potential to replace petrodiesel. Microwave irradiation increased the reaction rate resulting in a reduced reaction time of 7 minutes (as compared to 8 hours for conventional heating) and therefore was found to be a superior heating mode as compared to conventional heating.

scholarly journals A Green Synthesis of a Novel Calix[4]Resorcinarene from 7-Hydroxycitronellal Using Microwave Irradiation

2018 ◽  
Vol 18 (1) ◽  
pp. 53
Author(s):  
Ratnaningsih Eko Sardjono ◽  
Iqbal Musthapa ◽  
Iis Rosliana ◽  
Fitri Khoerunnisa ◽  
Galuh Yuliani
Keyword(s):  
Energy Consumption ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Irradiation Time ◽  
Microwave Oven ◽  
Conventional Heating ◽  
Heating Method ◽  
Microwave Assisted ◽  
Domestic Microwave Oven ◽  
Waste Production

A new versatile macromolecule cyclic C-3,7-dimethyl-7-hydroxycalix[4]resorcinarene (CDHHK4R) has been synthesized from a fragrance agent, 7-hydroxycitronellal, via microwave irradiation. The reaction utilized a domestic microwave oven at various irradiation time and power to yield an optimum condition. As a comparison, the conventional heating method was also employed for the synthesis of the same calix[4]resorcinarene. Compared to the conventional method, microwave-assisted reaction effectively reduced the reaction time, the amount of energy consumption and the waste production. It is found that the synthesis of CDHHK4R by microwave irradiation yielded 77.55% of product, higher than by conventional heating which was only 62.17%.

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