Microwave assisted organic synthesis—a review

Lidström, Pelle; Tierney, Jason; Wathey, Bernard; Westman, Jacob

doi:10.1016/s0040-4020(01)00906-1

Cited by 2,631 publications

(1,260 citation statements)

References 515 publications

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“…Formation of a fivemember-ring from cleavage of a six-member ring during degradation is feasible but not very common. Under continuous microwave irradiation, the selective heating was believed to create steady state microscale hot spots at the organic−mineral interface in micropores, 26 resulting in pyrolysis of the sorbed organic molecules. With continued input of microwave energy, 3,5-diamino-1,2,4-triazole underwent further ring cleavage and eventually degraded into small organic fragments, such as guanidine and cyanamide.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

“…25 Dipolar polarization (heat is generated in polar molecules) and conduction (heat is generated through resistance to an electric current) are the two major mechanisms for microwave dielectric heating. 26 The enhancement of reaction rates by microwaves has been attributed to the heating effect and the lowering of the overall activation energy for a kinetic process. 27 Although microwave irradiation might be able to excite specific molecules or functional groups within the molecules in a homogeneous system, the oscillations produced by the radiation in these target molecules would be instantaneously transferred by collisions with the adjacent molecules, precluding the formation of "molecular hot spots".…”

Section: ■ Introductionmentioning

confidence: 99%

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Microwave-Induced Degradation of Atrazine Sorbed in Mineral Micropores

Cheng

2012

Environ. Sci. Technol.

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ABSTRACT:The herbicide atrazine is a common pollutant in reservoirs and other sources of drinking water worldwide. The adsorption of atrazine from water onto zeolites CBV-720 and 4A, mesoporous silica MCM-41, quartz sand, and diatomite, and its microwave-induced degradation when sorbed on these minerals, were studied. Dealuminated HY zeolite CBV-720 exhibited the highest atrazine sorption capacity among the mineral sorbents because of its high micropore volume, suitable pore sizes, and surface hydrophobicity. Atrazine sorbed on the minerals degraded under microwave irradiation due to interfacial selective heating by the microwave, while atrazine in aqueous solution and associated with PTFE powder was not affected. Atrazine degraded rapidly in the micropores of CBV-720 under microwave irradiation and its degradation intermediates also decomposed with further irradiation, suggesting atrazine could be fully mineralized. Two new degradation intermediates of atrazine, 3,5-diamino-1,2,4-triazole and guanidine, were first identified in this study. The evolution of degradation intermediates and changes in infrared spectra of CBV-720 after microwave irradiation consistently indicate the creation of microscale hot spots in the micropores and the degradation of atrazine following a pyrolysis mechanism. These results indicate that microporous mineral sorption coupled with microwave-induced degradation could serve as an efficient treatment technology for removing atrazine from drinking water.

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Section: Environmental Science and Technologymentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Microwave-Induced Degradation of Atrazine Sorbed in Mineral Micropores

Cheng

2012

Environ. Sci. Technol.

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“…Recently, Gilar et al reported that a novel acid-labile anionic surfactant solubilizes proteins and improves digestion rates without inhibiting the activity of trypsin or other common endopeptidases [13]. An alternative approach to improving the digestion efficiency is the use of microwave irradiation.Microwave irradiation was recognized in the mid1980s to be an efficient heating source for chemical reactions, where reactions that require several hours under conventional conditions can often be completed in a few minutes with very high yields and reaction selectivities [15][16][17]. To avoid the risk of potential explosions, reactions can be performed in open flasks by using solvents that have relatively high boiling points, such as acetonitrile and dimethyl formamide.…”

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confidence: 99%

“…Microwave irradiation was recognized in the mid1980s to be an efficient heating source for chemical reactions, where reactions that require several hours under conventional conditions can often be completed in a few minutes with very high yields and reaction selectivities [15][16][17]. To avoid the risk of potential explosions, reactions can be performed in open flasks by using solvents that have relatively high boiling points, such as acetonitrile and dimethyl formamide.…”

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confidence: 99%

Microwave-assisted enzyme-catalyzed reactions in various solvent systems

Lin

Sun

et al. 2005

J. Am. Soc. Mass Spectrom.

101

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The work describes the accelerated enzymatic digestion of several proteins in various solvent systems under microwave irradiation. The tryptic fragments of the proteins were analyzed by matrix-assisted laser desorption/ionization mass spectrometry. Under the influence of rapid microwave heating, these enzymatic reactions can proceed in a solvent such as chloroform, which, under traditional digestion conditions, renders the enzyme inactive. The digestion efficiencies and sequence coverages were increased when the trypsin digestions occurred in acetonitrile-, methanol-and chloroform-containing solutions that were heated under microwave irradiation for 10 min using a commercial microwave applicator. The percentage of the protein digested under microwave irradiation increased with the relative acetonitrile content, but decreased as the methanol content was increased. These observations suggest that acetonitrile does not deactivate the enzyme during the irradiation period; in contrast, methanol does deactivate it. In all cases, the digestion efficiencies under microwave irradiation exceed those under conventional conditions. A dvances in mass spectrometric ionization methods, such as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI), make it possible to analyze complex biomolecules quite readily [1][2][3][4][5]. Tandem mass spectrometry (MS/MS) allows fragment ions to be generated from mass-selected precursor peptide ions, which, in turn, reveal sequence information for the peptide. The protein databases that are available in the public domain allow rapid identification of proteins by partial sequence analysis using tandem mass spectrometry; this process eliminates the need for complete protein sequence analysis [6 -12]. The enzymatic cleavage of proteins into smaller peptide fragments is an important step to undertake before MS analysis for the characterization of protein structures.To obtain detailed structural information, proteins are first subjected to proteolytic cleavage and then subjected to MS analysis of the resulting peptide mixture. This method of protein analysis is known as peptide mass fingerprinting. For a mass spectrometer capable of performing MS/MS analysis, the peptides are further sequenced by tandem MS before the identities of the proteins are analyzed. Efficient protein digestion requires production of peptides with a high coverage of protein sequence as well as fast digestion times. Generally, enzymatic digestions of proteins are carried out for several hours, or overnight, to generate sufficient amounts of peptides for analysis. To improve the efficiency of protein digestion, additives such as surfactants, organic solvents, and urea are often used to increase the proteins' solubilities and, thus, facilitate more-complete digestion [13,14]. Recently, Gilar et al. reported that a novel acid-labile anionic surfactant solubilizes proteins and improves digestion rates without inhibiting the activity of trypsin or other common endopeptidases [13]. An alternative ...

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“…Microwave irradiation as a powerful and controlled heating source has been widely employed in organic synthesis to reduce the reaction time, improve yield or selectivity, and reduce the amount of solvent used for reactions [17][18][19][20][21]. The blending of microwave heating and polymersupported reactions to simplify purification is a logical consequence to address the separation issue.…”

Section: Integrated Reaction and Separation Systemmentioning

confidence: 99%

Microwave-Enhanced High-Speed Fluorous Synthesis

Zhang

Microwave Methods in Organic Synthesis

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Increasing reaction speed and simplifying product purification are two major ways to improve the efficiency of organic synthesis. A new technology for high-speed solution-phase synthesis has been developed by combination of microwave heating and fluorous purification. This review describes different techniques for microwave-enhanced fluorous synthesis and their applications in Pdcatalyzed cross-coupling reactions, free-radical reactions, multicomponent reactions, and compound library synthesis.

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Microwave assisted organic synthesis—a review

Cited by 2,631 publications

References 515 publications

Microwave-Induced Degradation of Atrazine Sorbed in Mineral Micropores

Microwave-Induced Degradation of Atrazine Sorbed in Mineral Micropores

Microwave-assisted enzyme-catalyzed reactions in various solvent systems

Microwave-Enhanced High-Speed Fluorous Synthesis

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