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The Application of Microwave Technology in Chemistry

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Microwave Chemistry".

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 25346

Special Issue Editor

Laboratory of Organic Chemistry, Department of Chemistry, National and University of Athens, Zografou, 157 84 Athens, Greece
Interests: enzyme inhibitors; N-heterocyclic carbenes; medicinal chemistry; microwave-assisted reactions; antimycobacterial agents; antituberculosis; synthetic methodology

Special Issue Information

Dear Colleagues,

The chemical industry in recent decades has contributed in the pollution of our planet and the use of nonrenewable resources of energy. It is essential that new methodologies emerge—methodologies that are cleaner and abide by the principles of green chemistry and sustainable development. The use of microwave technology can assist in this direction through the application of more sustainable methodologies in the benefit of the environment.

The scope of this Special Issue is to offer a platform where new developments in microwave-assisted reactions in chemistry will be published. The focus of these developments may relate to medicinal chemistry, industrial uses, and synthetic methodologies. The synthesis of bioactive compounds, commercial chemicals, APIs and novel materials assisted by microwave technology may be presented. I kindly invite any researcher that wants to contribute in this area to submit their work in this Special Issue on “The Application of Microwave Technology in Chemistry”.

Dr. Magrioti Victoria
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Microwave technology
  • Applications in chemistry
  • Synthetic methodology
  • Green chemistry
  • Medicinal chemistry
  • Industrial applications
  • Bioactive compounds
  • Heterocycles

Published Papers (8 papers)

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Research

Jump to: Review

10 pages, 3013 KiB  
Article
Effect of Microwave and Conventional Modes of Heating on Sintering Behavior, Microstructural Evolution and Mechanical Properties of Al-Cu-Mn Alloys
by A. Muthuchamy, Muthe Srikanth, Dinesh K. Agrawal and A. Raja Annamalai
Molecules 2021, 26(12), 3675; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26123675 - 16 Jun 2021
Cited by 5 | Viewed by 1640
Abstract
In this research, we intended to examine the effect of heating mode on the densification, microstructure, mechanical properties, and corrosion resistance of sintered aluminum alloys. The compacts were sintered in conventional (radiation-heated) and microwave (2.45 GHz, multimode) sintering furnaces followed by aging. Detailed [...] Read more.
In this research, we intended to examine the effect of heating mode on the densification, microstructure, mechanical properties, and corrosion resistance of sintered aluminum alloys. The compacts were sintered in conventional (radiation-heated) and microwave (2.45 GHz, multimode) sintering furnaces followed by aging. Detailed analysis of the final sintered aluminum alloys was done using optical and scanning electron microscopes. The observations revealed that the microwave sintered sample has a relatively finer microstructure compared to its conventionally sintered counterparts. The experimental results also show that microwave sintered alloy has the best mechanical properties over conventionally sintered compacts. Similarly, the microwave sintered samples showed better corrosion resistance than conventionally sintered ones. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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11 pages, 1210 KiB  
Article
Microwave-Assisted Sequential One-Pot Synthesis of 8-Substituted Pyrazolo[1,5-a][1,3,5]triazines
by Jonathan Elie, Corinne Fruit and Thierry Besson
Molecules 2021, 26(12), 3540; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26123540 - 10 Jun 2021
Cited by 2 | Viewed by 2112
Abstract
This paper reports a convenient sequential one-pot approach for the synthesis of an array of 14 pyrazolo[1,5-a][1,3,5]triazines, substituted in C8 by halogen (Br), various functions (CN and CO2Et) and alkyl or (het)aryl groups. This study confirms the interest of [...] Read more.
This paper reports a convenient sequential one-pot approach for the synthesis of an array of 14 pyrazolo[1,5-a][1,3,5]triazines, substituted in C8 by halogen (Br), various functions (CN and CO2Et) and alkyl or (het)aryl groups. This study confirms the interest of combining the efficient heating obtained under dielectric microwave heating and the achievement of sequential one-pot reactions, avoiding the tedious work-up and purification of intermediate compounds, achieving sustainable synthesis processes. Considering usual conventional methods, this microwave protocol is featured by advantages in terms of yields, reaction times, and convenient gram scale synthesis. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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24 pages, 7705 KiB  
Article
Synthesis of Isothiocyanates Using DMT/NMM/TsO as a New Desulfurization Reagent
by Łukasz Janczewski, Dorota Kręgiel and Beata Kolesińska
Molecules 2021, 26(9), 2740; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26092740 - 06 May 2021
Cited by 8 | Viewed by 3718
Abstract
Thirty-three alkyl and aryl isothiocyanates, as well as isothiocyanate derivatives from esters of coded amino acids and from esters of unnatural amino acids (6-aminocaproic, 4-(aminomethyl)benzoic, and tranexamic acids), were synthesized with satisfactory or very good yields (25–97%). Synthesis was performed in a “one-pot”, [...] Read more.
Thirty-three alkyl and aryl isothiocyanates, as well as isothiocyanate derivatives from esters of coded amino acids and from esters of unnatural amino acids (6-aminocaproic, 4-(aminomethyl)benzoic, and tranexamic acids), were synthesized with satisfactory or very good yields (25–97%). Synthesis was performed in a “one-pot”, two-step procedure, in the presence of organic base (Et3N, DBU or NMM), and carbon disulfide via dithiocarbamates, with 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate (DMT/NMM/TsO) as a desulfurization reagent. For the synthesis of aliphatic and aromatic isothiocyanates, reactions were carried out in a microwave reactor, and selected alkyl isothiocyanates were also synthesized in aqueous medium with high yields (72–96%). Isothiocyanate derivatives of L- and D-amino acid methyl esters were synthesized, under conditions without microwave radiation assistance, with low racemization (er 99 > 1), and their absolute configuration was confirmed by circular dichroism. Isothiocyanate derivatives of natural and unnatural amino acids were evaluated for antibacterial activity on E. coli and S. aureus bacterial strains, where the most active was ITC 9e. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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17 pages, 3730 KiB  
Article
In Search of the Driving Factor for the Microwave Curing of Epoxy Adhesives and for the Protection of the Base Substrate against Thermal Damage
by Satoshi Horikoshi, Yuhei Arai and Nick Serpone
Molecules 2021, 26(8), 2240; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26082240 - 13 Apr 2021
Cited by 6 | Viewed by 1567
Abstract
This study used controlled microwaves to elucidate the response of adhesive components to microwaves and examined the advantages of microwave radiation in curing epoxy adhesives. Curing of adhesives with microwaves proceeded very rapidly, even though each component of the adhesive was not efficiently [...] Read more.
This study used controlled microwaves to elucidate the response of adhesive components to microwaves and examined the advantages of microwave radiation in curing epoxy adhesives. Curing of adhesives with microwaves proceeded very rapidly, even though each component of the adhesive was not efficiently heated by the microwaves. The reason the adhesive cured rapidly is that microwave heating was enhanced by the electrically charged (ionic) intermediates produced by the curing reaction. In contrast, the cured adhesive displayed lower microwave absorption and lower heating efficiency, suggesting that the cured adhesive stopped heating even if it continued to be exposed to microwaves. This is a definite advantage in the curing of adhesives with microwaves, as, for example, adhesives dropped onto polystyrene could be cured using microwave heating without degrading the polystyrene base substrate. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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Review

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16 pages, 2606 KiB  
Review
Microwave Synthetic Routes for Shape-Controlled Catalyst Nanoparticles and Nanocomposites
by Clare Davis-Wheeler Chin, LaRico J. Treadwell and John B. Wiley
Molecules 2021, 26(12), 3647; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26123647 - 15 Jun 2021
Cited by 15 | Viewed by 3033
Abstract
The use of microwave irradiation for the synthesis of inorganic nanomaterials has recently become a widespread area of research that continues to expand in scope and specialization. The growing demand for nanoscale materials with composition and morphology tailored to specific applications requires the [...] Read more.
The use of microwave irradiation for the synthesis of inorganic nanomaterials has recently become a widespread area of research that continues to expand in scope and specialization. The growing demand for nanoscale materials with composition and morphology tailored to specific applications requires the development of facile, repeatable, and scalable synthetic routes that offer a high degree of control over the reaction environment. Microwave irradiation provides unique advantages for developing such routes through its direct interaction with active reaction species, which promotes homogeneous heat distribution, increased reaction rates, greater product quality and yield, and use of mild reaction conditions. Many catalytic nanomaterials such as noble metal nanoparticles and intricate nanocomposites have very limited synthetic routes due to their extreme temperature sensitivity and difficulty achieving homogeneous growth. This work presents recent advances in the use of MW irradiation methods to produce high-quality nanoscale composites with controlled size, morphology, and architecture. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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28 pages, 4830 KiB  
Review
Microwave-Assisted Preparation of Luminescent Inorganic Materials: A Fast Route to Light Conversion and Storage Phosphors
by José Miranda de Carvalho, Cássio Cardoso Santos Pedroso, Matheus Salgado de Nichile Saula, Maria Claudia França Cunha Felinto and Hermi Felinto de Brito
Molecules 2021, 26(10), 2882; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26102882 - 13 May 2021
Cited by 9 | Viewed by 4755
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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23 pages, 6829 KiB  
Review
Green Synthetic Approach: An Efficient Eco-Friendly Tool for Synthesis of Biologically Active Oxadiazole Derivatives
by Bimal Krishna Banik, Biswa Mohan Sahoo, Bera Venkata Varaha Ravi Kumar, Krishna Chandra Panda, Jasma Jena, Manoj Kumar Mahapatra and Preetismita Borah
Molecules 2021, 26(4), 1163; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26041163 - 22 Feb 2021
Cited by 19 | Viewed by 4325
Abstract
Green synthetic protocol refers to the development of processes for the sustainable production of chemicals and materials. For the synthesis of various biologically active compounds, energy-efficient and environmentally benign processes are applied, such as microwave irradiation technology, ultrasound-mediated synthesis, photo-catalysis (ultraviolet, visible and [...] Read more.
Green synthetic protocol refers to the development of processes for the sustainable production of chemicals and materials. For the synthesis of various biologically active compounds, energy-efficient and environmentally benign processes are applied, such as microwave irradiation technology, ultrasound-mediated synthesis, photo-catalysis (ultraviolet, visible and infrared irradiation), molecular sieving, grinding and milling techniques, etc. Thesemethods are considered sustainable technology and become valuable green protocol to synthesize new drug molecules as theyprovidenumerous benefits over conventional synthetic methods.Based on this concept, oxadiazole derivatives are synthesized under microwave irradiation technique to reduce the formation of byproduct so that the product yield can be increased quantitatively in less reaction time. Hence, the synthesis of drug molecules under microwave irradiation follows a green chemistry approach that employs a set of principles to minimize or remove the utilization and production of hazardous toxic materials during the design, manufacture and application of chemical substances.This approach plays a major role in controlling environmental pollution by utilizing safer solvents, catalysts, suitable reaction conditions and thereby increases the atom economy and energy efficiency. Oxadiazole is a five-membered heterocyclic compound that possesses one oxygen and two nitrogen atoms in the ring system.Oxadiazole moiety is drawing considerable interest for the development of new drug candidates with potential therapeutic activities including antibacterial, antifungal, antiviral, anticonvulsant, anticancer, antimalarial, antitubercular, anti-asthmatic, antidepressant, antidiabetic, antioxidant, antiparkinsonian, analgesic and antiinflammatory, etc. This review focuses on different synthetic approaches of oxadiazole derivatives under microwave heating method and study of their various biological activities. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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21 pages, 2527 KiB  
Review
Prospects and Challenges of Microwave-Combined Technology for Biodiesel and Biolubricant Production through a Transesterification: A Review
by Nur Atiqah Mohamad Aziz, Robiah Yunus, Dina Kania and Hamidah Abd Hamid
Molecules 2021, 26(4), 788; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26040788 - 03 Feb 2021
Cited by 18 | Viewed by 3220
Abstract
Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part [...] Read more.
Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products. Full article
(This article belongs to the Special Issue The Application of Microwave Technology in Chemistry)
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