scholarly journals Microwave-assisted synthesis and antimicrobial evaluation of 6-[3-aryl-1-phenyl-4’,5’-dihydro[4,5’-bi-1H-pyrazol]-3’-yl]-2H-chromen-5-ols

2019 ◽  
Vol 84 (3) ◽  
pp. 237-244
Author(s):  
Dongamanti Ashok ◽  
Rangu Kavitha ◽  
Srinivas Gundu ◽  
Madderla Sarasija

A new series of 6-[3-aryl-1-phenyl-4?,5?-dihydro[4,5?-bi-1H-pyrazol]-3?-yl]-2H-chromen-5-ol derivatives was synthesized by Michael addition of chalcones 5a?j with hydrazine hydrate in presence of sodium acetate under conventional heating and microwave irradiation. Structural assignment of the products was confirmed based on IR, 1H-NMR, 13C-NMR, MS and analytical data. All the synthesized compounds 6a?j were screened for their antimicrobial activity against various bacterial and fungal strains. Most of the compounds exhibited variable range of antimicrobial activity and compounds 6c?f and 6i showed promising antimicrobial potency.

2016 ◽  
Vol 81 (8) ◽  
pp. 851-858 ◽  
Author(s):  
Dongamanti Ashok ◽  
Velagapuri Rao ◽  
Rangu Kavitha

A series of new benzodiazepines 4a-h have been synthesized by Michael addition of chalcones 3a-h with o-phenylenediamine (OPDA) in presence of sodium acetate under conventional heating and microwave irradiation. Structures of the newly synthesized benzodiazepines 4a-h have been established on the basis of IR, 1H & 13C NMR and mass spectral data and tested for antimicrobial activity.


2015 ◽  
Vol 80 (3) ◽  
pp. 305-313 ◽  
Author(s):  
Dongamanti Ashok ◽  
Bommidi Lakshmi ◽  
Sidda Ravi ◽  
Arram Ganesh

A series of pyrazolines 4a-g have been synthesized by Michael addition of chalcones 3a-g with hydrazine hydrate in presence of sodium acetate under conventional heating and microwave irradiation. Structures of the newly synthesized chalcones 3a-g and pyrazolines 4a-g have been established on the basis of IR, 1H & 13C NMR and mass spectral data. All the synthesized compounds were screened for their antimicrobial activity. Some of the compounds shown very good activity compared to standard drugs against all pathogenic bacteria and fungi.


2016 ◽  
Vol 22 (5) ◽  
Author(s):  
Ashok Dongamanti ◽  
Hayder Hasan Naji ◽  
Vijaya Lakshmi Bommidi ◽  
Sarasija Madderla

AbstractNew hybrid compounds containing flavanone and pyrazoline motifs were synthesized by microwave irradiation and conventional heating methods using one-pot synthetic strategy. The products were evaluated for their antimicrobial activity.


2020 ◽  
Vol 7 (3) ◽  
pp. 183-195
Author(s):  
Musa Özil ◽  
Emre Menteşe

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.


2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Sheauly Khatun ◽  
M. Z. H. Khan ◽  
Khodeza Khatun ◽  
M. A. Sattar

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.


2020 ◽  
Vol 32 (4) ◽  
pp. 839-844
Author(s):  
D. Ashok ◽  
K. Ramakrishna ◽  
Nalaparaju. Nagaraju ◽  
Ravinder Dharavath ◽  
M. Ram Reddy ◽  
...  

A method for the synthesis of several imidazoles containing isoquinoline scaffolds under conventional and microwave irradiation methods. In the microwave irradiation method gives higher yields with in shorter reaction time as compared to conventional heating method, using green solvents and eco-friendly reaction conditions. All the synthesized derivatives were characterized by IR, NMR and Mass spectral analysis. Furthermore, the title compounds were screened for their in vitro antimicrobial activity against bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumonia as well as fungi such as Aspergillus niger, Aspergillus flavus and Fusarium oxysporum. The compounds 8a, 8d, 8e and 8h exhibited better antimicrobial activity against all organisms.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nur Atiqah Mohamad Aziz ◽  
Robiah Yunus ◽  
Hamidah Abd Hamid ◽  
Alsultan Abdul Kareem Ghassan ◽  
Rozita Omar ◽  
...  

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.


2019 ◽  
Vol 84 (4) ◽  
pp. 355-364
Author(s):  
Rupireddy Venkataramana ◽  
Venkata Chittireddy ◽  
Dongamanti Ashok ◽  
Kudle Rao

A series of 2,8-di(alkyl/aryl)-substituted bischromanone derivatives were synthesized in one pot from 4,6-diacetylresorcinol and aliphatic/aromatic aldehydes in the presence of pyrrolidine/piperidine under conventional heating and microwave irradiation. The 2,8-di(alkyl/aryl)-substituted bischromanones were converted into a new series of 4,6-dichloro-3,7-diformyl-2,8-di(alkyl/aryl)-substituted bischromenes using the Vilsmeier?Haack reagent. The structures of the compounds were established based on elemental analysis, IR, 1H-NMR, 13C- -NMR and LC?MS spectral data. All the synthesized compounds were evaluated for their antimicrobial activity. Some of the compounds showed very good activity compared to standard drugs against all the tested pathogenic bacteria and fungi.


2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
L. Achutha ◽  
R. Parameshwar ◽  
B. Madhava Reddy ◽  
V. Harinadha Babu

Quinoxaline-incorporated Schiff bases(4a–j)were synthesized by the condensation of 2-[(3-methylquinoxalin-2-yl)oxy]acetohydrazide(3)with indole-3-carbaldehyde, furfuraldehyde, 5-(4-nitrophenyl)-2-furfuraldehyde, and substituted benzaldehydes under conventional and microwave irradiation methods. The microwave method was found to be remarkably successful with higher yields, less reaction time, and environmentally friendly compared to conventional heating method. The chemical structures of the synthesized compounds have been confirmed by analytical and spectral data. All the compounds have been evaluated for antitubercular and anti-inflammatory activities.


Author(s):  
Norlin Pauzi ◽  
Norashikin Mat Zain ◽  
Nurul Amira Ahmad Yusof

The conventional heating methods of nanoparticle synthesis regularly depend on the energy inputs from outer heat sources that resulted high energy intake and low reaction competences. In this paper ZnO nanoparticles stabilized with gum arabic are synthesized using precipitating method assisted by simple and cost effective microwave heating technique. The objective of this work is to investigate the effect of microwave irradiation time towards ZnO nanoparticles morphology and size. The effect of microwave irradiation time has been investigated at 2, 4, 6, and 10 minutes. Dynamic Light Scattering (DLS) was employed to measure the size of ZnO nanoparticles. Ultraviolet–Visible spectroscopy (UV-vis), Fourier-Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) were used for the characterization of the ZnO nanoparticles. UV-vis absorption spectrum was found in the range of 350 nm indicating the absorption peak of ZnO nanoparticles. FTIR spectra showed peaks range from 424 to 475 cm–1 which indicating standard of Zn–O stretching. The presence of (100), (002), and (101) planes were apparent in the XRD result, indicating the crystalline phase of ZnO nanoparticles. The increase in the microwave irradiation time affected the processes of nucleation and crystal growth promoted larger ZnO nanoparticles size. Microwave irradiation time at 2 minutes was selected as the best microwave irradiation time for smallest ZnO nanoparticles averaging about 168 nm sizes based on DLS analysis. Copyright © 2019 BCREC Group. All rights reservedReceived: 1st October 2018; Revised: 22nd November 2018; Accepted: 12nd December 2018; Available online: 25th January 2019; Published regularly: April 2019How to Cite: Pauzi, N., Zain, N.M., Yusof, N.A.A. (2019). Microwave-assisted Synthesis of ZnO Nanoparticles Stabilized with Gum Arabic: Effect of Microwave Irradiation Time on ZnO Nanoparticles Size and Morphology. Bulletin of Chemical Reaction Engineering & Catalysis, 14 (1): 182-188 (doi:10.9767/bcrec.14.1.3320.182-188)Permalink/DOI: https://doi.org/10.9767/bcrec.14.1.3320.182-188 


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