A New Microwave Reactor Suitable for Organic Synthesis and Kinetics Studies.<sup>1</sup>

Constable, D. A.; Raner, Kevin D.; Somlo, P.; Strauss, Christopher R.

doi:10.1080/08327823.1992.11688190

Cited by 20 publications

(20 citation statements)

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“…The observed differences can be explained by the fact that the reaction under MW irradiation occurs at a higher temperature than that under conventional refluxing conditions. Similarly, the research groups of Bond (46) and Strauss (47,48) also conclude that the reaction rates are identical in the presence or absence of MW irradiation, the final yield being dependent on the temperature profile and not on the mode of heating.…”

Section: Cyclization and Cycloadditionmentioning

confidence: 84%

Microwave Technology—Applications in Chemical Synthesis

Varma¹

2013

Kirk-Othmer Encyclopedia of Chemical Technology

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Microwave heating, a unique heating technique is reviewed for expeditious chemical syntheses. Specifically, the solvent‐free reactions or reactions in benign media are convenient to perform and have advantages over the conventional heating protocols as summarized in the previous editions. A wide range of selective functional group transformations have been accomplished expeditiously and efficiently using a variety of supported reagents on mineral oxides as catalysts or in benign reaction media. Further scale‐up developments on such themes will go a long way in realizing the sustainable goals in the chemical arena including the synthesis of nanomaterials and nano‐catalysts. The major limitations for MW‐assisted reactions can be overcome by translating batch microwave chemistry to continuous flow domain wherein conventionally heated and suitably equipped fluidic flow devices may help produce meaningful amounts of chemical products in a continuous mode. This is especially true for the use of magnetic nano catalysis in flow chemistry which has a great potential to grow in this sustainable endeavor as the nanoparticle‐bound magnetic catalysts can be confined and at the same time agitated in a reactor by a rotating magnetic field, thus, avoiding potential problems of clogging membranes or filters that are commonly used as barriers for immobilized catalysts.

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Section: Cyclization and Cycloadditionmentioning

confidence: 84%

Microwave Technology—Applications in Chemical Synthesis

Varma¹

2013

Kirk-Othmer Encyclopedia of Chemical Technology

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“…When such events occur, reaction mixtures are difficult to contain within the vessel and commonly, vapour is released into the atmosphere. Dedicated microwave reactors have been developed that are capable of reliable and safe operation with volatile organic solvents at elevated temperatures and pressures 13,65,[91][92][93][94][95] . Independent investigations into optimal parameters for microwave chemistry support this approach 90,96 .…”

Section: Methods Employing Solventsmentioning

confidence: 99%

Scale‐Up of Microwave‐Assisted Organic Synthesis

Roberts

Strauss

2005

Microwave Assisted Organic Synthesis

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In 1986 it was first reported that organic reactions could be conducted by heating in sealed containers in domestic microwave ovens 1,2 . Rate enhancements of up to three orders of magnitude were disclosed 3 . However, temperature and pressure measurement were technically difficult to achieve and in some instances the vessels deformed or exploded 1-3 .From these publications, workers interested in exploring the microwave technique perceived it to be simultaneously beneficial through increased rates, yet hazardous in the presence of flammable organic solvents. Subsequently, a vast body of work was carried out with domestic microwave ovens, but under solvent-free conditions and without recourse to sample mixing or temperature measurement. This continued across a broadening front on the laboratory scale. These and other developments in microwave chemistry have been reviewed extensively in journals, book chapters 4-20 and in a recent monograph 21 .Although relatively inexpensive in terms of purchase price, domestic microwave ovens are not designed to contain chemical explosions or toxic fumes and are incompatible with corrosive and inflammable compounds 13 . Flux densities within the microwave cavity can vary considerably, resulting in 'hot' and 'cold' spots. Mode stirrers and circulation of the vessel within the cavity are sometimes incorporated to assist in overcoming the non-uniformity of the energy distribution, but such measures are usually inadequate. Domestic ovens operate on duty cycles and intervals between zero and full power can be many seconds. This is not always ideal for heating common foods and beverages, let alone for performing delicate chemical manipulations. Intermittent bursts of power afford poor temperature control in chemical reactions. When these matters are considered in conjunction with the initial lack of dedicated pressure vessels for microwave-assisted organic chemistry, it is not surprising that explosions occurred 1-3 and that reactions are not necessarily reproducible in domestic microwave systems 6 .During the decade after 1986, disadvantages of domestic microwave ovens for organic chemistry became apparent to many researchers. Because of the unavailability of specifically designed commercial equipment, however, workers with volatile organic solvents, still found it necessary to adapt domestic units for reflux conditions or for operations under pressure. For reactions at reflux 22-30 , domestic microwave ovens were modified by fitting with a shielded opening to prevent microwave leakage and through which the reaction vessel within the microwave cavity could be connected to an external condenser 22,23,30 . Commercial systems adopting this approach have since appeared. When microwave-transparent coolants (chilled hydrocarbons, ice or solid carbon dioxide) are used, along with the reaction vessel, the condenser can also be located within the microwave cavity, thereby avoiding potential problems with microwave leakage 26,29,31 . 237Microwave Assisted Organic Synthesis Edited by Jason P. T...

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“…By 1995, a complementary laboratory-scale microwave batch reactor (MBR) with pressureresistant vessels had been constructed. [39] It superseded our 1992 prototype [38] and enabled rapid heating (typically 1-2 • C per second) and infinitely variable control of microwave power, as well as measurement of absorbed and reflected microwave energy. A load-matching device (cavity tuner) optimized heating efficiency.…”

Section: Beginnings Of Microwave-assisted Organic Chemistrymentioning

confidence: 99%

“…Dedicated, closed-vessel microwave reactors required to meet such objectives were designed and built. [37][38][39] For the decade up to 1998, the research domain remained ours exclusively. Proponents of solvent-free methods derided the approach, some going so far as to predict that microwave systems operating with volatile organic solvents would never be acceptable.…”

Section: Beginnings Of Microwave-assisted Organic Chemistrymentioning

confidence: 99%

“…Temperature and pressure were measured directly by optic fibre thermometry and through a transducer, respectively. Magnetic stirring of the sample, unprecedented for microwave chemistry before our work, [38,39] ensured uniform temperature by thorough mixing. Chemicals could be added and samples withdrawn while heating.…”

Section: Beginnings Of Microwave-assisted Organic Chemistrymentioning

confidence: 99%

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A Strategic, 'Green' Approach to Organic Chemistry with Microwave Assistance and Predictive Yield Optimization as Core, Enabling Technologies

Strauss¹

2009

Aust. J. Chem.

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Since 1988, we have pursued enabling technologies and methods as tools for 'green' synthetic chemistry. The developed technologies comprise hardware including catalytic membranes and continuous and batch microwave reactors that have established global markets, as well as interactive, predictive software for optimization of yields and translation of conditions. New methods include 'green' reactions such as a catalytic symmetrical etherification, Pd-catalyzed coupling processes and a multi-component cascade for aniline derivatives. Reactions and workup were facilitated through solvent-free conditions, aqueous media at high temperature and dimethylammonium dimethylcarbamate (dimcarb) as a 'distillable' protic ionic liquid, as well as by non-extractive techniques for product isolation. The technologies and methods were designed for use alone or in various combinations as desired. Consolidation of individual operations or processes into unit steps was achieved through multi-tasking: media, reactants, catalysts, and conditions were selected to serve several purposes at various stages of a reaction. The tools were used to establish a technology platform comprising structurally diverse oligomers, macrocycles, and rod-like molecules supplementary to those available through phenolformaldehyde chemistry. Dienone precursors were assembled from versatile building blocks containing complementary 'male' or 'female' fittings that were connected through inherently 'green' Claisen-Schmidt-type reactions. Isoaromatization afforded Horning-crowns, macrocyclic phenolic derivatives that were hybrids of calixarenes and crown ethers. Preliminary studies of organic substrates in salt water, with and without CO 2 , called into question proposals for disposal of anthropogenic CO 2 by deep-sea dispersal.

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A New Microwave Reactor Suitable for Organic Synthesis and Kinetics Studies.¹

Cited by 20 publications

References 1 publication

Microwave Technology—Applications in Chemical Synthesis

Microwave Technology—Applications in Chemical Synthesis

Scale‐Up of Microwave‐Assisted Organic Synthesis

A Strategic, 'Green' Approach to Organic Chemistry with Microwave Assistance and Predictive Yield Optimization as Core, Enabling Technologies

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A New Microwave Reactor Suitable for Organic Synthesis and Kinetics Studies.1

Cited by 20 publications

References 1 publication

Microwave Technology—Applications in Chemical Synthesis

Microwave Technology—Applications in Chemical Synthesis

Scale‐Up of Microwave‐Assisted Organic Synthesis

A Strategic, 'Green' Approach to Organic Chemistry with Microwave Assistance and Predictive Yield Optimization as Core, Enabling Technologies

Contact Info

Product

Resources

About

A New Microwave Reactor Suitable for Organic Synthesis and Kinetics Studies.¹