Green revolution in chemistry by microwave assisted synthesis A review (original) (raw)
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Microwave Synthesis-A Potential Tool for Green Chemistry
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Microwave radiation, an electromagnetic radiation, is widely use as a source of heating in organic synthesis. The basic mechanisms observed in microwave assisted synthesis are dipolar polarization and conduction. Microwave assisted organic synthesis (MAOS) has emerged as a new "lead" in organic synthesis. The technique offers simple, clean, fast, efficient, and economic for the synthesis of a large number of organic molecules, have provided the momentum for many chemists to switch from traditional heating method to microwave assisted chemistry. In the recent year microwave assisted organic reaction has emerged as new tool in organic synthesis. In the present article an attempt was made to focus on what is microwave, how is it generated and what importance may it have.
ChemInform Abstract: Microwave-Assisted Organic Synthesis: An Alternative Synthetic Strategy
ChemInform, 2011
Pharmaceutical companies have made major investments in high-throughput technologies for genomic and proteomic research, combinatorial chemistry and biological screening in order to identify more potential drug candidates at a faster pace. However, synthesis and lead compound optimisation remain the bottlenecks in the drug discovery process. Developing chemical compounds with the desired biological properties is time-consuming and expensive. Consequently, increasing interest is being directed towards technologies that allow more rapid synthesis and screening of chemical substances to identify compounds with functional qualities. Microwave heating is a process within a family of electroheat techniques, such as induction, radio frequency, direct resistance or infra-red heating, all of which utilise specific parts of the electromagnetic spectrum. These processes supplement, and in specific cases totally replace, conventional heating or drying systems used in industry. There is hardly any reaction type or name reaction that has not yet been tested in the microwave field. This is because some conventional systems are very bulky, not easy to operate, can pollute the environment due to harmful omissions and above all can be very inefficient. The major advantages of using microwaves are rapid heat transfer, volumetric and selective heating, compactness of equipment, speed of switching on and off and pollution-free environment as there are no products of combustion. Microwave leakage can certainly be kept well below government recommended levels. It has long been established that a dielectric material can be processed with energy in the form of high-frequency electromagnetic waves. The present review article describes the mechanism of microwave heating and comparison of the conventional and microwave assisted organic synthesis to improve the synthesis of the organic molecules.
A SIGNIFICANCE OF MICROWAVE ASSIST TECHNIQUE IN GREEN CHEMISTRY
International Journal of …, 2011
Microwave Assisted Synthesis is rapidly becoming the method of choice in modern synthesis and discovery chemistry laboratories. Microwave-assisted synthesis improves both throughput and turnaround time for chemists by offering the benefits of drastically reduced reaction times, increased yields, and purer products. In this type of synthesis we applying microwave irradiation to chemical reactions. The fundamental mechanism of microwave heating involves agitation of polar molecules or ions that oscillate under the effect of an oscillating electric or magnetic field. In the presence of an oscillating field, particles try to orient themselves or be in phase with the field. Only materials that absorb microwave radiation are relevant to microwave chemistry. These materials can be categorized according to the three main mechanisms of heating, namely. Dipolar polarization, Conduction mechanism, Interfacial polarization. Microwave chemistry apparatus are classified: Single-mode apparatus and Multi-mode apparatus. Although occasionally known by such acronyms as 'MEC' (Microwave-Enhanced Chemistry) or 'MORE' synthesis (Microwave-organic Reaction Enhancement), these acronyms have had little acceptance outside a small number of groups. The ability to combine microwave technology with in-situ reaction monitoring as an analytical tools will offer opportunities for chemists to optimize the reaction conditions. Different compounds convert microwave radiation to heat by different amounts. This selectivity allows some parts of the object being heated to heat more quickly or more slowly than others (particularly the reaction vessel).
A Review on: A significance of microwave assist technique in green chemistry
Microwave Assisted Synthesis is rapidly becoming the method of choice in modern synthesis and discovery chemistry laboratories. Microwave-assisted synthesis improves both throughput and turnaround time for chemists by offering the benefits of drastically reduced reaction times, increased yields, and purer products. In this type of synthesis we applying microwave irradiation to chemical reactions. The fundamental mechanism of microwave heating involves agitation of polar molecules or ions that oscillate under the effect of an oscillating electric or magnetic field. In the presence of an oscillating field, particles try to orient themselves or be in phase with the field. Only materials that absorb microwave radiation are relevant to microwave chemistry. These materials can be categorized according to the three main mechanisms of heating, namely. Dipolar polarization, Conduction mechanism, Interfacial polarization. Microwave chemistry apparatus are classified: Single-mode apparatus and Multi-mode apparatus. Although occasionally known by such acronyms as 'MEC' (Microwave-Enhanced Chemistry) or 'MORE' synthesis (Microwave-organic Reaction Enhancement), these acronyms have had little acceptance outside a small number of groups. The ability to combine microwave technology with in-situ reaction monitoring as an analytical tools will offer opportunities for chemists to optimize the reaction conditions. Different compounds convert microwave radiation to heat by different amounts. This selectivity allows some parts of the object being heated to heat more quickly or more slowly than others (particularly the reaction vessel).
Australian Journal of Chemistry, 2009
The use of emerging microwave (MW)-assisted chemistry techniques in conjunction with benign reaction media is dramatically reducing chemical waste and reaction times in several organic syntheses and chemical transformations. The present review summarizes recent developments in MW-assisted synthesis, name reactions and organic transformations, and rapid generation of nanoparticles with uniform size distribution. Greener protocols have been developed for the synthesis of various bio-active heterocycles, namely 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, 1,3-dioxanes, pyrazoles, hydrazones and 3,4-dihydropyrimidin-2(1H)-ones, which proceed under the influence of microwaves and using eco-friendly conditions. These high-yielding methods were catalyzed efficiently by solid-supported Nafion NR50 under solvent-free conditions and polystyrene sulfonic acid in aqueous media. The eco-friendly nucleophilic substitution chemistry in water to generate cyclic amines via double N-alkylation of primary a...
General characteristics and applications of microwaves in organic synthesis
2009
This review focusses upon the key achievements made in organic synthesis using microwave-assisted reactions in the solid phase, with neat reactants and under solvent-free conditions. It also highlights the general characteristics of microwave applications in organic synthesis. It shows that reactions under microwaves are fast, with often increased reaction rates and lead to better selectivity. Some of the microwave-assisted reactions can even be carried out under neat conditions therefore leading to the area of green chemistry.
Bringing Together Microwave Assisted Synthesis and Chemical Engineering Principles
Proceedings 17th International Conference on Microwave and High Frequency Heating, 2019
It is nowadays admitted that microwaves are frequently used in organic chemistry labs [1] (even if not as much as it was predicted 20 years ago, one must say [2]). On the other side it is also certain that this technology has not yet found its place in chemical industry: application at a production scale are very scarce [3][4] and this despite the potential advantages of the technology (selective heating, high heating rate, low thermal inertia…). The point is that mastering all the aspects of microwaves assisted synthesis at industrial scale demands a lot of different skills to work together: chemistry, process engineering, microwave engineering, materials science. This is so challenging that tools and methodologies for quantification of industrial microwave interest and scaling-up of lab results are missing. In this work we present our contributions to the deployment of microwaves for synthesis in the chemical industry which are mainly The development of small pilot reactors (1 ...
Importance of Microwave Heating In Organic Synthesis
Advanced Journal of Chemistry-Section A, 2019
Microwave heating is widely used as a convenient source of heating in organic synthesis. The heating is instantaneous and very specific. Nowadays, Microwave-assisted organic synthesis could be considered in which all of the previously heated reactions could be performed using this technique. The benefits of microwave-assisted organic synthesis are increasingly making the technique more widely established. The technique offers simple, clean, fast, efficient, and economic features for the synthesis of a large number of organic molecules. In the present article, an attempt was made to focus on the importance of the microwave heating. Microwave heating Organic synthesis Chemical reactions