Microwave-enhanced radiochemistry

Elander, Nils; Jones, John R.; Lu, Shuiyu; Stone‐Elander, Sharon

doi:10.1039/a901713e

Cited by 220 publications

(106 citation statements)

References 29 publications

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“…Earlier examples of controlled MAOS are limited and can be found in previous review articles and books. [4][5][6][7][8][9][10][11][12][13][14][15][16] 2.2. Transition-Metal-Catalyzed C À C Bond Formations…”

Section: Scope and Organization Of The Reviewmentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11][12][13][14][15][16] Conventional cycloaddition reactions require, in many cases, the use of harsh conditions such as high temperatures and long reaction times, but they can be performed with great success with the aid of Scheme 29. Synthesis of benzoxazoles, [167] oxazolidines, [168,169] and benzothiazoles, [170] 1,3-dipolar cycloaddition reaction to form triazoles, [171] and [3 + 2] cycloadditions of azomethine ylides and maleimide.…”

Section: Cycloaddition Reactionsmentioning

confidence: 99%

“…Therefore, many academic and industrial research groups are already using MAOS as a forefront technology for rapid optimization of reactions, for the efficient synthesis of new chemical entities, and for discovering and probing new chemical reactivity. A large number of review articles [4][5][6][7][8][9][10][11][12][13] and several books [14][15][16] provide extensive coverage of the subject. The aim of this Review is to highlight some of the most recent applications and trends in microwave synthesis, and to discuss the impact and future potential of this technology.…”

Section: Introductionmentioning

confidence: 99%

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Controlled Microwave Heating in Modern Organic Synthesis

2004

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Although fire is now rarely used in synthetic chemistry, it was not until Robert Bunsen invented the burner in 1855 that the energy from this heat source could be applied to a reaction vessel in a focused manner. The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction. In the past few years, heating and driving chemical reactions by microwave energy has been an increasingly popular theme in the scientific community. This nonclassical heating technique is slowly moving from a laboratory curiosity to an established technique that is heavily used in both academia and industry. The efficiency of “microwave flash heating” in dramatically reducing reaction times (from days and hours to minutes and seconds) is just one of the many advantages. This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.

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Section: Scope and Organization Of The Reviewmentioning

confidence: 99%

Section: Cycloaddition Reactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Controlled Microwave Heating in Modern Organic Synthesis

2004

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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.…”

mentioning

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.…”

mentioning

confidence: 99%

Microwave-assisted enzyme-catalyzed reactions in various solvent systems

Lin

Sun

et al. 2005

J. Am. Soc. Mass Spectrom.

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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 Technology—Chemical Synthesis Applications

Varma¹

2003

Kirk-Othmer Encyclopedia of Chemical Technology

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Microwave‐accelerated chemical syntheses in various solvents as well as under solvent‐free conditions have witnessed an explosive growth. This technology, which is still in its growth phase, has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although the use of dedicated MW equipment has been rapidly gaining ground. Of special interest is the environmentally friendlier solventless approach that often involves exposure of neat reactants to MW irradiation or employs supported reagents on recyclable inorganic oxides or catalysts and has been adequately demonstrated in several MW‐assisted condensation, deprotection, rearrangement, cyclization, reduction, and oxidation reactions. The rapid one‐pot preparation of heterocyclic compounds from in situ generated reactive intermediates and the general application to multicomponent reactions, that are adaptable for building a library of compounds, have been accomplished using this MW technique. More recently, the strategy has been extended to combinatorial chemistry and the synthesis of a newer class of solvents, ionic liquids that are essentially molten salts with barely measurable vapor pressure. The salient features of these high yield protocols, namely, the selectivity, experimental ease of manipulation, and the enhanced reaction rates are discussed.

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Microwave-enhanced radiochemistry

Cited by 220 publications

References 29 publications

Controlled Microwave Heating in Modern Organic Synthesis

Controlled Microwave Heating in Modern Organic Synthesis

Microwave-assisted enzyme-catalyzed reactions in various solvent systems

Microwave Technology—Chemical Synthesis Applications

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