Microwave heating as a new way to induce selectivity between competitive reactions. application to isomeric ratio control in sulfonation of naphthalene.

Stuerga, D.; Gonon, K.; Lallemant, M.

doi:10.1016/s0040-4020(01)87961-8

Cited by 106 publications

(52 citation statements)

References 5 publications

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“…1.20, is called ''induced selectivity''. Numerical results correspond to a values of kinetic terms which give an optimum selectivity effect; exact values could be found elsewhere [141]. Under classical heating conditions, or a very slow heating rate, a mixture of the two products P 1 and P 2 is obtained.…”

Section: 27mentioning

confidence: 71%

“…The temperature and, especially, the thermal path TðtÞ seems to be a crucial variable. The authors have shown theoretically and experimentally that strong heating rates (up to 5 s À1 ) can induce selectivity or inversion between two competitive reactions [141].…”

Section: 27mentioning

confidence: 99%

“…Sulfonation of naphthalene results in a mixture of 1-and 2-naphthalene sulfonic, di, tri, and tetrasulfonic acids and sulfones, depending on operating conditions. The reaction is first order with respect to naphthalene in concentrated aqueous sulfuric acid and the ratio of 1-to 2-sulfonic acid decreases slightly with increasing sulfuric acid concentration and temperaturethe isomer ratio is 6 for 75% sulfuric acid and 4 for 95% sulfuric acid at 25 C. The detailed operating conditions (concentrations, microwave applicator, heating rates, and analysis) can be found elsewhere [141]. Figure 1.22 shows the dependence of the percentage 1-and 2-sulfonic acids after reaction on the microwave power used.…”

Section: 27mentioning

confidence: 99%

See 2 more Smart Citations

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Stuerga¹

2006

Microwaves in Organic Synthesis

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The main focus of the revised edition of this first chapter is essentially the same as the original -to explain in a chemically intelligible fashion the physical origin of microwave-matter interactions and, especially, the theory of dielectric relaxation of polar molecules. This revised version contains approximately 60% new material to scan a large range of reaction media able to be heated by microwave heating. The accounts presented are intended to be illustrative rather than exhaustive. They are planned to serve as introductions to the different aspects of interest in comprehensive microwave heating. In this sense the treatment is selective and to some extent arbitrary. Hence the bibliography contains historical papers and valuable reviews to which the reader anxious to pursue particular aspects should certainly turn.It is the author's conviction, confirmed over many years of teaching experience, that it is much safer -at least for those who rate not trained physicists -to deal intelligently with an oversimplified model than to use sophisticated methods which require experience before becoming productive. Because of comments about the first edition, however, the author has included more technical material to enable better understanding of the concepts and ideas. These paragraphs could be omitted, depending on the level of comprehension of the reader. They are preceded by two different symbols -k for TOOLS and j for CONCEPTS.After consideration of the history and position of microwaves in the electromagnetic spectrum, notions of polarization and dielectric loss will be examined. The orienting effects of electric fields and the physical origin of dielectric loss will be analyzed, as also will transfers between rotational states and vibrational states within condensed phases.Dielectric relaxation and dielectric losses of pure liquids, ionic solutions, solids, polymers and colloids will be discussed. Effect of electrolytes, relaxation of defects within crystals lattices, adsorbed phases, interfacial relaxation, space charge polarization, and the Maxwell-Wagner effect will be analyzed. Next, a brief overview of 1 thermal conversion properties, thermodynamic aspects, and athermal effects will be given.

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Section: 27mentioning

confidence: 71%

Section: 27mentioning

confidence: 99%

Section: 27mentioning

confidence: 99%

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Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Stuerga¹

2006

Microwaves in Organic Synthesis

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“…Stuerga et al suggested that, as a result of the more rapid heating that microwaves induce, the reaction time of their chemical syntheses may be decreased by 75%. However, they suggest that this decrease in reaction time is purely due to superheating and not to any increased non-thermal molecular perturbation (Stuerga, Gonon, & Lallemant, 1993). Many experts now believe that the microwave effect is the result of the microwaves' ability to superheat solvents beyond their normal boiling points.…”

Section: Mechanism Of Catalysismentioning

confidence: 99%

Microwave‐assisted proteomics

Lill¹,

Ingle²,

Liu³

et al. 2007

Mass Spectrometry Reviews

144

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State-of-the-art proteomic analysis has recently undergone a rapid evolution; with more high-throughput analytical instrumentation and informatic tools available, sample preparation is becoming one of the rate-limiting steps in protein characterization workflows. Recently several protocols have appeared in the literature that employ microwave irradiation as a tool for the preparation of biological samples for subsequent mass spectrometric characterization. Techniques for microwave-assisted biocatalyzed reactions (including sample reduction and alkylation, enzymatic and chemical digestion, removal and analysis of posttranslational modifications and characterization of enzymes and protein-interaction sites) are described. This review summarizes the various approaches undertaken, instrumentation employed, and reduction in overall experimental time observed when microwave assistance is applied. #

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“…A sulfonação do naftaleno conduzida em um reator de microondas é considerada como o primeiro caso de seletividade induzida por microondas 35 . Assim, variando-se a potência do aparelho é possível a obtenção seletiva do ácido 2-naftaleno-sulfônico (Figura 3 e Equação 3).…”

Section: Seletividade Induzida Por Microondasunclassified

Microondas em síntese orgânica

Sanseverino¹

2002

Quím. Nova

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Recebido em 11/7/01; aceito em 17/10/01 MICROWAVES IN ORGANIC SYNTHESIS. The application of microwave heating to organic synthesis is presented in a concise manner. Issues such as the history of the microwave oven, dielectric heating, reactions techniques (dry reactions, MORE chemistry), domestic ovens, microwave reactors, microwave effect and control of selectivities are discussed. Selected examples from the literature showed faster reactions, improved yields, less thermal degradations and cleaner reactions.Keywords: microwave heating; organic synthesis; green chemistry. INTRODUÇÃOA utilização do forno de microondas de cozinha no preparo ou aquecimento de alimentos é um fato comum nos dias de hoje. O uso de microondas em química analítica já é conhecido desde a década de 70, sendo que entre as aplicações mais importantes podemos citar: a digestão de amostras para análise elementar, a extração de diversas substâncias e a desorção térmica de vários compostos 1 . O aquecimento por microondas também é largamente utilizado em escala comercial na preparação e secagem de alimentos 2 . Uma aplicação recente é a obtenção de produtos orgânicos em escala de laboratório usando o aquecimento por microondas, onde as reações são conduzidas em forno de microondas de cozinha ou em reatores especificamente desenhados para esta finalidade. Embora esta tecnologia seja parte do nosso cotidiano, como ela surgiu? Quem inventou o forno de microondas? Porque esta técnica despertou um interesse tão grande na área de síntese orgânica?Portanto, o objetivo deste trabalho é apresentar uma breve introdução sobre a utilização do aquecimento de microondas em síntese orgânica. O QUE SÃO MICROONDAS?As microondas são radiação eletromagnética não ionizante, que possuem uma freqüência que vai de 300 a 300.000 MHz e que corresponde a comprimentos de onda de 1 mm a 1 m. A região de microondas situa-se entre a região de infravermelho e ondas de rádio no espectro eletromagnético 1 (Figura 1). A INVENÇÃO DO FORNO DE MICROONDASCientistas britânicos durante a 2 a Guerra Mundial desenvolveram um dispositivo que gerava microondas chamado magnétron e que era o coração do RADAR ("Radio Detection And Ranging") usado para detectar aeronaves inimigas. O sistema funciona da seguinte forma: o objeto a ser detectado reflete o sinal emitido (as microondas) e o sistema de RADAR detecta o eco deste sinal, e com isto é possível saber a posição, forma do objeto, velocidade e direção de seu movimento.Havia uma necessidade urgente na Inglaterra de produzir o magnétron em grande quantidade e os cientistas britânicos entraram em contato com os Estados Unidos, de forma que pudessem usar o parque industrial americano para produzir este aparelho que era crucial na defesa da Inglaterra contra os ataques aéreos da Alemanha 3 . Após uma sugestão do laboratório de Radiação do M.I.T. (Massachusetts Institute of Technology), ocorreu um encontro de cientistas britânicos com um engenheiro chamado Percy L. Spencer (1894Spencer ( -1970 de uma pequena companhia americana chamada Raythe...

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Microwave heating as a new way to induce selectivity between competitive reactions. application to isomeric ratio control in sulfonation of naphthalene.

Cited by 106 publications

References 5 publications

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Microwave‐assisted proteomics

Microondas em síntese orgânica

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