A tentative rationalization of microwave effects in organic synthesis according to the reaction medium, and mechanistic considerations

Perreux, Laurence; Loupy, André

doi:10.1016/s0040-4020(01)00905-x

Cited by 1,266 publications

(600 citation statements)

References 87 publications

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“…[21,22] A similar effect should be observed for polar reaction mechanisms, where the polarity is increased going from the ground state to the transition state, thus resulting in an enhancement of reactivity by lowering the activation energy. [22] Microwave effects are the subject of considerable current debate and controversy, [21][22][23] and it is evident that extensive research efforts will be necessary to truly understand these and related phenomena. [29] Since the issue of microwave effects is not the primary focus of this Review, the interested reader is referred to more detailed surveys and essays covering this topic.…”

Section: Microwave Effectsmentioning

confidence: 54%

“…It has been argued that the presence of an electric field leads to orientation effects of dipolar molecules and hence changes the pre-exponential factor A or the activation energy (entropy term) in the Arrhenius equation. [21,22] A similar effect should be observed for polar reaction mechanisms, where the polarity is increased going from the ground state to the transition state, thus resulting in an enhancement of reactivity by lowering the activation energy. [22] Microwave effects are the subject of considerable current debate and controversy, [21][22][23] and it is evident that extensive research efforts will be necessary to truly understand these and related phenomena.…”

Section: Microwave Effectsmentioning

confidence: 62%

“…[29] Since the issue of microwave effects is not the primary focus of this Review, the interested reader is referred to more detailed surveys and essays covering this topic. [21][22][23] …”

Section: Microwave Effectsmentioning

confidence: 99%

See 2 more Smart Citations

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 The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction.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: Microwave Effectsmentioning

confidence: 54%

Section: Microwave Effectsmentioning

confidence: 62%

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Controlled Microwave Heating in Modern Organic Synthesis

2004

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“…The application of microwave irradiation allows reducing reaction times from hours to minutes or seconds, increasing reaction yield and the purity of the final product as compared to the conventional methods [7][8][9]. In addition, the solvent-free, microwave-assisted reactions are considered to be an ecofriendly approach [2,10]. Due to this, microwave-assisted processes have become a great attention in recent years.…”

Section: Introductionmentioning

confidence: 99%

Thermal properties of neryl long-chain esters obtained under microwave irradiation

Worzakowska

2015

J Therm Anal Calorim

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Thermal properties of novel, neryl long-chain esters obtained through the esterification process of nerol, different chain lengths acidic components such as succinic anhydride, glutaric anhydride, adipic acid or sebacic acid and diol components such as ethylene glycol or diethylene glycol in solvent-free conditions under microwave irradiation were studied by TG/FTIR-coupled method. The studies confirmed that the use of microwave irradiation allowed obtaining flavor esters in absolutely shorter reaction time (only minutes) with high purity and yield compared to conventional method. The prepared novel, neryl long-chain esters were high thermal stable compounds and decomposed at three stages under air conditions including the breaking of ester bonds, oxidation and decarboxylation processes of formed intermediate products in a gaseous phase and thus the emission of various gaseous products. It was indicated on the same, complex and parallel decomposition mechanism under oxidative conditions for the present and previously studied long-chain esters of primary order terpene alcohols showing it independence on the type of alcohol used for their synthesis.

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“…Various discussions continue to appear in the literature about the elusive microwave-specific non-caloric or non-thermal effect s in organic synthesis 16 involving surfactants, besides the utilization of microwaves as a simple heat source. In many examples, specific microwave effects claimed in the past could easily be attributed to thermal caloric effects.…”

Section: Reactionmentioning

confidence: 99%