Microwave-Assisted Organic Synthesis

1992 ◽  
Vol 269 ◽  
Author(s):  
Raymond J. Giguere
Keyword(s):  
Microwave Heating ◽  
Organic Synthesis ◽  
Relevant Literature ◽  
Conventional Heating ◽  
Microwave Assisted ◽  
Concise Overview ◽  
Materials Research ◽  
Heating Mode

ABSTRACTA concise overview of the use of microwave heating in organic synthesis is presented. The role of solvents and representative examples from the relevant literature are discussed to illustrate the significant impact this non-conventional heating mode continues to have in this area of materials research.

Microwave-assisted organic synthesis in Water

2021 ◽  
Vol 08 ◽  
Author(s):  
Geetanjali ◽  
Ram Singh
Keyword(s):  
Green Chemistry ◽  
Organic Synthesis ◽  
Negative Impact ◽  
Environmental Concern ◽  
Conventional Heating ◽  
Health It ◽  
Microwave Assisted ◽  
Important Principle ◽  
Environment And Health ◽  
Methods Of Synthesis

: Most of the traditional methods for organic synthesis have been associated with environmental concern. The transition from traditional to modern methods of synthesis is mainly based on principles of green chemistry to achieve better sustainability by reducing the negative impact on the environment and health. It has been found that microwaves as an energy source in organic synthesis have a great advantage over conventional heating. Microwave-assisted reactions are energy efficient and hence, brought themselves in the preview green chemistry principles. The use of safer solvents is another important principle of green chemistry. The use of water as a solvent in organic synthesis has great benefits over the use of hazardous organic solvents in terms of environment and safety. This study will cover the use of both microwave and water simultaneously in organic reactions.

Comparison of Conventional and Microwave Heating for Evaluation of Microwave Effects

2016 ◽  
Vol 69 (8) ◽  
pp. 865 ◽  
Author(s):  
Péter Bana ◽  
István Greiner
Keyword(s):  
Temperature Measurement ◽  
Microwave Heating ◽  
Organic Synthesis ◽  
Convenient Method ◽  
Thermal Effects ◽  
Fibre Optic ◽  
Organic Transformations ◽  
Microwave Assisted ◽  
Microwave Reactor ◽  
Microwave Effects

In microwave-assisted organic synthesis, the question of microwave effects is still debated. Proper examination of these hypothesized phenomena is encumbered by some specific features of microwave heating. We devise a convenient method to eliminate most of the irreproducibility observed in microwave-heated organic transformations by thermal conditioning of the microwave reactor cavity. To show the utility of this approach, we investigated a reaction of 2-chloropyridine, in which microwave conditions were shown to be beneficial by previous studies. Using our method to ensure proper reproducibility together with fibre optic temperature measurement, the observed differences were traced back to large hidden thermal differences, while non-thermal effects could not be detected in the comparison experiments.

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 Parameters Affecting the Microwave-Assisted Polyol Synthesis of Silver Nanorods

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Srichandana Nandikonda ◽  
Edward W. Davis
Keyword(s):  
Microwave Heating ◽  
Polyol Process ◽  
Polyol Synthesis ◽  
Copper Salts ◽  
Silver Nanorods ◽  
Microwave Assisted ◽  
Traditional Process ◽  
Stark Contrast ◽  
Container Shape

The effects of salt chemistry and concentration on the morphology and yield of silver nanorods produced by the microwave-assisted polyol synthesis are reported. Compared to NaCl, iron and copper salts reduced nanorod yield and length and increased diameter. This is in stark contrast to expectations based on the slower traditional polyol process. The role of the cation was further explored using MgCl2 and MnCl2 which showed different concentration dependent effects on nanorod diameter. In addition, the morphology and yield of nanomaterials was found to be significantly influenced by small variations in the procedure including container shape and the time between reactant mixing and microwave heating. These results highlight that, while the microwave-assisted process is very promising, results cannot be directly anticipated based on the traditional process, and the synthesis is very sensitive to procedural changes.

scholarly journals Microwave-assisted modifications of polysaccharides

2014 ◽  
Vol 86 (11) ◽  
pp. 1695-1706 ◽  
Author(s):  
Jacques Desbrières ◽  
Charlotte Petit ◽  
Stéphanie Reynaud
Keyword(s):  
Microwave Irradiation ◽  
High Performance ◽  
Recent Literature ◽  
Conventional Heating ◽  
Natural Polymers ◽  
Environment Friendly ◽  
Microwave Assisted ◽  
The Past ◽  
Energy Consuming

Abstract Polysaccharides are a natural and renewable feed stock for synthesizing high performance macromolecular materials. However, their structure does not allow reaching all properties required for specific applications and chemical modifications are necessary to reach such objectives. Despite the use of natural polymers, the chemistry and processes employed are not environment-friendly due to the nature of chemicals, solvents or because the conventional chemical process are energy-consuming. On the other hand, microwave assisted processes were developed in organic chemistry since the 1980s and more recently for polymer chemistry (polymer formation and modification). Within the chemistry of natural polymers, the use of microwave irradiation has been exploited in the past two decades to alleviate limitations in the synthesis of graft modified polysaccharide materials. Microwave heating is described as more homogeneous, selective and efficient as compared to conventional heating resulting in faster reactions with fewer or no side products as example. Different results reported within the recent literature will be discussed considering the role of microwave irradiation and its consequence on the reaction parameters and properties of final materials. Grafting of polysaccharides, specific modification of polysaccharides or fibers particularly for preparing smart textiles or medical products as well as reactions of polysaccharides to valuable bio-platform molecule will be discussed.

scholarly journals Microwave-Assisted Pyrolysis of Biomass Waste: A Mini Review

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1190 ◽  
Author(s):  
Saleem Ethaib ◽  
Rozita Omar ◽  
Siti Mazlina Mustapa Kamal ◽  
Dayang Radiah Awang Biak ◽  
Salah L. Zubaidi
Keyword(s):  
Microwave Heating ◽  
Complex Structure ◽  
Initial Moisture Content ◽  
Raw Material ◽  
Conventional Heating ◽  
Operating Parameters ◽  
High Heating Rate ◽  
Biomass Waste ◽  
Promising Alternative ◽  
Microwave Assisted

The utilization of biomass waste as a raw material for renewable energy is a global concern. Pyrolysis is one of the thermal treatments for biomass wastes that results in the production of liquid, solid and gaseous products. Unfortunately, the complex structure of the biomass materials matrix needs elevated heating to convert these materials into useful products. Microwave heating is a promising alternative to conventional heating approaches. Recently, it has been widely used in pyrolysis due to easy operation and its high heating rate. This review tries to identify the microwave-assisted pyrolysis treatment process fundamentals and discusses various key operating parameters which have an effect on product yield. It was found that several operating parameters govern this process such as microwave power and the degree of temperature, microwave absorber addition and its concentration, initial moisture content, initial sweep gas flow rate/residence time. Moreover, this study highlighted the most attractive products of the microwave pyrolysis process. These products include synthesis gas, bio-char, and bio-oil. The benefits and challenges of microwave heating are discussed.

scholarly journals Application of Microwave in Hydrogen Production from Methane Dry Reforming: Comparison Between the Conventional and Microwave-Assisted Catalytic Reforming on Improving the Energy Efficiency

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 618 ◽  
Author(s):  
Seyyedmajid Sharifvaghefi ◽  
Babak Shirani ◽  
Mladen Eic ◽  
Ying Zheng
Keyword(s):  
Energy Efficiency ◽  
Microwave Heating ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Conventional Heating ◽  
Feed Conversion ◽  
Methane Dry Reforming ◽  
Microwave Assisted ◽  
Reaction Conversion ◽  
Active Metal

The microwave-assisted dry reforming of methane over Ni and Ni–MgO catalysts supported on activated carbon (AC) was studied with respect to reducing reaction energy consumption. In order to optimize the reforming reaction using the microwave setup, an inclusive study was performed on the effect of operating parameters, including the type of catalysts’ active metal and their concentration in the AC support, feed flow rate, and reaction temperature on the reaction conversion and H2/CO selectivity. The methane dry reforming was also carried out using conventional heating and the results were compared to those of microwave heating. The catalysts’ activity was increased under microwave heating and as a result, the feed conversion and hydrogen selectivity were enhanced in comparison to the conventional heating method. In addition, to improve the reactants’ conversion and products’ selectivity, the thermal analysis also clarified the crucial importance of microwave heating in enhancing the energy efficiency of the reaction compared to the conventional heating.

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 L-Lactide polymerization by calix[4]arene-titanium (IV) complex using conventional heating and microwave irradiation

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Marco Frediani ◽  
David Sémeril ◽  
Dominique Matt ◽  
Fabio Rizzolo ◽  
Anna Maria Papini ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Microwave Irradiation ◽  
Organic Synthesis ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Polymerization Rate ◽  
The Other ◽  
Conventional Heating ◽  
Microwave Assisted ◽  
Microwave Effect

AbstractSince the first contributions by Gedye and Giguere in 1986, growing attention has been registered on the use of microwave heating in organic synthesis. However still many aspects need to be clarified especially about the so called “microwave effect” and the possible degradation phenomena that may be recognized during polymer synthesis. In this work the complex cone-25,27- dipropyloxy-26,28-dioxo-calix[4]arene titanium (IV) dichloride (1) has been tested for the ring opening polymerization of L-lactide, comparing the effect of conventional heating with a possible microwave assisted strategy. The polymers obtained were fully characterized (NMR, IR, HPLC-SEC, DSC, MALDI-TOF and WAXD analysis). As expected the use of microwave irradiation induced an increase of the polymerization rate. On the other side the use of microwaves resulted in a slight loss of the control over molecular weight and molecular weight distribution if compared with a conventional thermal treatment.

THE EFFECT OF CONVENTIONAL AND MICROWAVE HEATING TECHNIQUES ON TRANSESTERIFICATION OF WASTE COOKING OIL TO BIODIESEL

2016 ◽  
Vol 78 (8-3) ◽  
Author(s):  
Mohd Johari Kamaruddin ◽  
Nurulsurusiah Mohamad ◽  
Umi Aisah Asli ◽  
Muhammad Abbas Ahmad Zaini ◽  
Kamarizan Kidam ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Processing Parameters ◽  
Waste Cooking Oil ◽  
Green Technology ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Thermal Heating ◽  
Microwave Assisted ◽  
Cooking Oil

This research is focused on the effect of processing parameters such as molar ratio of sample to solvent (1:3-1:15), catalyst loading (0.5-2.5 wt %), temperature (40-80 °C) and time of reaction (5-180 min) on the transesterification yield of waste cooking oil (WCO) in conventional thermal heating and microwave heating techniques. The analysis carried out revealed that the microwave assisted transesterification produced a comparable yield to conventional heating transesterification with ~5 times faster in heating up the reaction mixture to a reaction temperature and reduced ~90% of the reaction time required. This study concludes that microwave assisted transesterification, which is a green technology, may have great potential in reducing the processing time compared to conventional thermal heating transesterification.

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