scholarly journals Microwave Synthetic Routes for Shape-Controlled Catalyst Nanoparticles and Nanocomposites

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3647
Author(s):  
Clare Davis-Wheeler Chin ◽  
LaRico J. Treadwell ◽  
John B. Wiley
Keyword(s):  
Microwave Irradiation ◽  
Extreme Temperature ◽  
Direct Interaction ◽  
Reaction Rates ◽  
Noble Metal Nanoparticles ◽  
Reaction Conditions ◽  
Inorganic Nanomaterials ◽  
Synthetic Routes ◽  
High Degree ◽  
Nanoscale Composites

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.

Synthesis of 3,3′- Di-indolylmethanes under mild conditions by Microwave Irradiation Mediated Reactions of Indoles with C, N-Diaryl nitrones

2021 ◽  
pp. 247-254
Author(s):  
Avijit Banerji ◽  
Rina Saha ◽  
Maya Gupta ◽  
Julie Banerji ◽  
Manosi Das ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Reaction Times ◽  
Reaction Rates ◽  
Biologically Active ◽  
High Yield ◽  
Acid Catalysts ◽  
Nmr Studies ◽  
Reaction Conditions ◽  
Dichloromethane Solution ◽  
Ytterbium Triflate

3,3′-Di-indolylmethane derivatives are important biologically active compounds possessing anti-cancer properties. Hence, development of synthetic routes to these are of great interest to organic chemists. In the present communication we report a high-yield method using mild reaction conditions and short reaction times for the synthesis of 3,3′-di-indolylmethane derivatives. The method involved reactions of indole and substituted indoles with C,N-disubstituted nitrones in the presence of acid catalysts, with the utilisation of microwave irradiation techniques. Reactions of indole, 2-methyl indole and 2-phenyl indole were performed with ten different C,N-diaryl- and C-aryl-N-methyl- nitrones in dichloromethane solution in the absence and presence of acid catalysts, viz. ytterbium triflate, p-toluene sulphonic acid and Montmorillonite clay K-10. Reaction times varied between 2 to 18 minutes. In general, yields of the catalysed reactions were above 75%. The products were characterised spectroscopically, including two-dimensional NMR studies. The microwave irradiation technique enhanced reaction rates by a significant amount. Ytterbium triflate proved to be the best catalyst, giving clean reactions, without formation of by-products, in high yields. The structure and conformation of 3,3′-di-indolyl-phenylmethane were computed. GRAPHICAL ABSTRACT: We report a high-yield method using mild reaction conditions and short reaction times for the synthesis of 3,3′-di-indolylmethane derivatives, involving reactions of indole and substituted indoles with C, N-disubstituted nitrones in the presence of acid catalysts using microwave irradiation.

scholarly journals Microwave-Assisted Asinger Synthesis of Thiazolines

2020 ◽  
Vol 3 (1) ◽  
pp. 27
Author(s):  
Raúl Eduardo Gordillo-Cruz ◽  
Liliana Gonzalez-Reyes ◽  
Milton Coporo-Reyes ◽  
Nieves Zavala-Segovia ◽  
Bernardo A. Frontana-Uribe ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Reaction Times ◽  
Reaction Conditions ◽  
Microwave Assisted

An array of 2,4-disubstituted thiazolines was obtained through Asinger reaction approach from the straightforward treatment of diverse aldehydes/ketones with 1-mercaptopropan-2-one, in the presence of NH3 assisted by microwave irradiation, displaying similar and sometimes higher yields, as well as shorter reaction times that traditional Asinger reaction conditions at room and lower temperatures.

scholarly journals Antibacterial and Photocatalytic Properties of ZnO Nanoparticles Obtained from Chemical versus Saponaria officinalis Extract-Mediated Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2072
Author(s):  
Maria Antonia Tănase ◽  
Maria Marinescu ◽  
Petruta Oancea ◽  
Adina Răducan ◽  
Catalin Ionut Mihaescu ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Zno Nanoparticles ◽  
Model Compound ◽  
Size Composition ◽  
Inorganic Nanoparticles ◽  
Bacterial Strains ◽  
X Ray Diffraction ◽  
Zno Nps ◽  
Reaction Conditions ◽  
Saponaria Officinalis

In the present work, the properties of ZnO nanoparticles obtained using an eco-friendly synthesis (biomediated methods in microwave irradiation) were studied. Saponaria officinalis extracts were used as both reducing and capping agents in the green nanochemistry synthesis of ZnO. Inorganic zinc oxide nanopowders were successfully prepared by a modified hydrothermal method and plant extract-mediated method. The influence of microwave irradiation was studied in both cases. The size, composition, crystallinity and morphology of inorganic nanoparticles (NPs) were investigated using dynamic light scattering (DLS), powder X-ray diffraction (XRD), SEM-EDX microscopy. Tunings of the nanochemistry reaction conditions (Zn precursor, structuring agent), ZnO NPs with various shapes were obtained, from quasi-spherical to flower-like. The optical properties and photocatalytic activity (degradation of methylene blue as model compound) were also investigated. ZnO nanopowders’ antibacterial activity was tested against Gram-positive and Gram-negative bacterial strains to evidence the influence of the vegetal extract-mediated synthesis on the biological activity.

scholarly journals Rate Dependence on Inductive and Resonance Effects for the Organocatalyzed Enantioselective Conjugate Addition of Alkenyl and Alkynyl Boronic Acids to β-Indolyl Enones and β-Pyrrolyl Enones

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1615
Author(s):  
Amy Boylan ◽  
Thien S. Nguyen ◽  
Brian J. Lundy ◽  
Jian-Yuan Li ◽  
Ravikrishna Vallakati ◽  
...  
Keyword(s):  
Positive Charge ◽  
Bond Formation ◽  
Conjugate Addition ◽  
Reaction Rates ◽  
Boronic Acids ◽  
Key Factors ◽  
Resonance Contribution ◽  
Reaction Conditions ◽  
Resonance Effects ◽  
Resonance Stabilization

Two key factors bear on reaction rates for the conjugate addition of alkenyl boronic acids to heteroaryl-appended enones: the proximity of inductively electron-withdrawing heteroatoms to the site of bond formation and the resonance contribution of available heteroatom lone pairs to stabilize the developing positive charge at the enone β-position. For the former, the closer the heteroatom is to the enone β-carbon, the faster the reaction. For the latter, greater resonance stabilization of the benzylic cationic charge accelerates the reaction. Thus, reaction rates are increased by the closer proximity of inductive electron-withdrawing elements, but if resonance effects are involved, then increased rates are observed with electron-donating ability. Evidence for these trends in isomeric substrates is presented, and the application of these insights has allowed for reaction conditions that provide improved reactivity with previously problematic substrates.

Optimization of biodiesel synthesis under simultaneous ultrasound-microwave irradiation using response surface methodology (RSM)

2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Teymor Tavakoli Hashjin ◽  
Barat Ghobadian ◽  
Gholamhasan Najafi ◽  
Stefano Mantegna ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Microwave Irradiation ◽  
Response Surface ◽  
Palm Oil ◽  
Catalyst Concentration ◽  
Irradiation Time ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Biodiesel Synthesis

AbstractThis work investigates the effect of simultaneous ultrasound-microwave irradiation on palm oil transesterification and uncovers optimal operating conditions. Response surface methodology (RSM) has been used to analyze the influence of reaction conditions, including methanol/palm oil molar ratio, catalyst concentration, reaction temperature and irradiation time on biodiesel yield. RSM analyses indicate 136 s and 129 s as the optimal sonication and microwave irradiation times, respectively. Optimized parameters for full conversion (97.53%) are 1.09% catalyst concentration and a 7:3.1 methanol/oil molar ratio at 58.4°C. Simultaneous ultrasound-microwave irradiation dramatically accelerates the palm oil transesterification reaction. Pure biodiesel was obtained after only 2.2 min while the conventional method requires about 1 h.

Reaction de méthanation du gaz de synthèse: Influence de la température de calcination des catalyseurs à base de nickel

1993 ◽  
Vol 71 (1) ◽  
pp. 107-111
Author(s):  
M. Ghazi ◽  
J. Barrault
Keyword(s):  
Nickel Content ◽  
Great Part ◽  
Extreme Temperature ◽  
Nickel Catalysts ◽  
Economic Situation ◽  
Reaction Conditions ◽  
Methanation Reaction ◽  
Different Temperatures ◽  
Usual Process ◽  
Important Activity

Due to their important activity and selectivity, nickel catalysts are often used to realize the methanation reaction; however, the usual process based on these catalysts is not fitted for the present economic situation. To raise their stability, three catalysts with similar nickel content but calcinated at different temperatures have been studied for the reaction of methanation. The results obtained show that the catalyst calcinated at the highest temperature (973 K) shows the greatest promise because a great part of its activity and of its stability is preserved even when the reaction conditions are extreme (temperature of 773 K).

scholarly journals Microwave Assisted Synthesis of 1,5-Benzothiazepines Using Greener Reaction Medium

2019 ◽  
Vol 31 (5) ◽  
pp. 993-996 ◽  
Author(s):  
Sanjay S. Kotalwar ◽  
Amol D. Kale ◽  
Ram B. Kohire ◽  
Vasant B. Jagrut
Keyword(s):  
Reaction Time ◽  
Microwave Irradiation ◽  
Reaction Medium ◽  
Microwave Assisted Synthesis ◽  
Reaction Conditions ◽  
Renewable Sources ◽  
Microwave Assisted ◽  
High Yields

An efficient and eco-friendly synthesis of 1,5-benzothiazepines has been developed by the reaction of various 2-propen-1-ones with 2-aminothiophenol using microwave irradiation in greener reaction medium, glycerol. The clean reaction conditions, shorter reaction time, high yields and non-toxic, biodegradable reaction medium manufactured from renewable sources are unique features of this method.

scholarly journals Microwave Assisted Three Component Reaction Conditions to Obtain New Thiazolidinones with Different Heterocyclic Skeletons

Proceedings ◽  
2019 ◽  
Vol 41 (1) ◽  
pp. 38
Author(s):  
Fernando J. Lorenzo ◽  
Romina A. Ocampo ◽  
Sandra D. Mandolesi
Keyword(s):  
Microwave Irradiation ◽  
Thioglycolic Acid ◽  
Aldehyde Group ◽  
Green Solvent ◽  
Reaction Products ◽  
Reaction Conditions ◽  
One Pot ◽  
Microwave Assisted ◽  
Three Component Reaction ◽  
The One

We present here a new proposal for the “one pot” generation of new 4-thiazolidinones (9a–e) through a multicomponent reaction under microwave irradiation conditions, using aromatic and heteroaromatic amines (8a–e), absolute ethanol as a “green” solvent and modifying the aldehyde group in the glycosidic residue, synthesized from D-mannitol. The study is focused in the variation of the irradiation times and the concentration of thioglycolic acid in order to study the possibility of controlling the structure and/or stereochemistry of the products formed in the reaction. Thiazolidinones 9a–d were obtained with a 69–82% The generation of the corresponding reaction products were monitored by TLC and CG-MS, taking reaction aliquots. The conditions reaction proved to be chemoselective depending on the excess of acid and irradiation times.

scholarly journals Old Molecule, New Chemistry: Exploring Silicon Phthalocyanines as Emerging N-Type Materials in Organic Electronics

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1334 ◽  
Author(s):  
Nathan J. Yutronkie ◽  
Trevor M. Grant ◽  
Owen A. Melville ◽  
Benoît H. Lessard ◽  
Jaclyn L. Brusso
Keyword(s):  
Organic Thin Film Transistors ◽  
Organic Thin Film ◽  
Field Effect Mobility ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
High Performing ◽  
Silicon Phthalocyanines ◽  
Electron Field ◽  
Synthetic Routes ◽  
Average Electron

Efficient synthesis of silicon phthalocyanines (SiPc) eliminating the strenuous reaction conditions and hazardous reagents required by classical methods is described. Implementation into organic thin-film transistors (OTFTs) affords average electron field-effect mobility of 3.1 × 10−3 cm2 V−1 s−1 and threshold voltage of 25.6 V for all synthetic routes. These results demonstrate that our novel chemistry can lead to high performing SiPc-based n-type OTFTs.

scholarly journals Characterization and purification of a novel dATP-binding protein in eukaryotes

1992 ◽  
Vol 287 (3) ◽  
pp. 871-879 ◽  
Author(s):  
A Dalton ◽  
D P Hornby ◽  
S P Langston ◽  
G M Blackburn
Keyword(s):  
Binding Protein ◽  
Active Form ◽  
Direct Interaction ◽  
Nuclear Fraction ◽  
Yeast Saccharomyces Cerevisiae ◽  
Naturally Occurring ◽  
Sds Page ◽  
Marked Preference ◽  
High Degree ◽  
Page Electrophoresis

We characterized and purified an acidic dATP-binding protein, which, in its active form, resides in the nuclear fraction of a range of cells from mammals (including pig liver) and baker's yeast (Saccharomyces cerevisiae). This protein exhibits a high degree of specificity for the deoxy form of the naturally occurring nucleoside triphosphates and shows a marked preference for the purine deoxynucleoside triphosphates dATP and dGTP. The protein cleaves the terminal phosphate of dATP and appears to retain the dADP moiety of the nucleotide in a reaction that is resistant to both SDS and 8 M-urea. Fractionation of the nuclear preparation followed by non-denaturing PAGE and SDS/PAGE electrophoresis was sufficient to produce pure protein. The occurrence of this activity in all nuclei tested suggests that it plays an important role in nuclear metabolism. The specificity of the enzyme for deoxynucleoside triphosphates further suggests a role for this enzyme in DNA replication or repair, but the acidity of the protein argues against a direct interaction with DNA, and, indeed, the catalytic activity is not modulated by the inclusion of DNA in a variety of physical forms.

Sign in / Sign up

Export Citation Format

Share Document