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 The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction.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

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200400655

Controlled microwave heating in modern organic synthesis.

Microwave assisted organic synthesis-a review

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30th April 2014), are included.

/pdf/anion-exchange-membranes-in-electrochemical-energy-systems-46uquenb56.pdf

Anion-exchange membranes in electrochemical energy systems

Anion exchange membranes for alkaline fuel cells: A review

Vinylbenzyl chloride was grafted onto PVDF and FEP polymer films using radiation-grafting methodology. Subsequent reaction with trimethylamine and ion-exchange with potassium hydroxide yields alkaline anion-exchange membranes that are capable of conducting hydroxide ions; such membranes may be suitable for use in low temperature direct methanol fuel cells for portable devices. The PVDF based materials underwent an undesirable degradation and were found to be less suitable for this class of membrane. FEP-based materials exhibited superior structural stability, conductivities up to 0.02 S cm−1 at room temperature, and good retention of ion-exchange capacities when treated in water at 60 °C.

https://epubs.surrey.ac.uk/375323/1/fulltext.pdf

Alkaline anion-exchange radiation-grafted membranes for possible electrochemical application in fuel cells

Vinylbenzyl chloride has been radiation grafted onto both PVDF and FEP fluoropolymer films; subsequent amination and ion-exchange to give the hydroxide ion forms yield anion-exchange membranes suitable for use in low temperature direct methanol fuel cells for portable applications.

Comparison of PVDF- and FEP-based radiation-grafted alkaline anion-exchange membranes for use in low temperature portable DMFCs

Microwave assisted synthesis of pyrroles

The ability of certain Fe and Mn metalloporphyrins to catalyse the H 2 O 2 epoxidation of cyclooctene is analysed. The ‘efficiency’ of epoxidation is dissected into contributions due to inherent catalyst epoxidation ability, catalyst H 2 O 2 dismutation ability, and catalyst stability towards the oxidant. It is shown that catalyst stability is a major factor contributing to apparent catalyst ability. The preparation of a sol–gel encapsulated metalloporphyrin is reported and it is shown to exhibit reduced rate of epoxidation, but a much enhanced stability.

Timothy N. Danks

Papers

Alkaline anion-exchange radiation-grafted membranes for possible electrochemical application in fuel cells

Comparison of PVDF- and FEP-based radiation-grafted alkaline anion-exchange membranes for use in low temperature portable DMFCs

Microwave assisted synthesis of pyrroles

Stability of various metalloporphyrin catalysts during hydrogen peroxide epoxidation of alkene

Thermal and microwave-assisted N-formylation using solid-supported reagents