Intermittent microwave irradiation

Kitayama Y, Igarashi H, Sugimura H. Amplification of FISH signals using intermittent microwave irradiation for analysis of chromosomal instability in gastric cancer. Mol. Pathol. 1999 52 357-359. 

Kitayama, Y., Igarashi, H., and Sugimura, H. 2000. Initial intermittent microwave irradiation for fluorescence irradiation for fluorescence in situ hybridization analysis in paraffin-embedded tissue sections of gastrointestinal neoplasia. Lab. Invest. 50 779-781. 

Li, W., Murai, Y., Okada, E., Matsui, K., Hayashi S., Horie, M., and Takano, Y. (2002) Modified and simplified western blotting protocol use of intermittent microwave irradiation (IMWI) and 5% skim milk to improve binding specificity. Pathol. Int. 52, 234-238. 

Tian ZQ, Jiang SP, Liang YM, Shen PK. Synthesis and characterization of platinum catalysts on muldwaUed carbon nanotubes by intermittent microwave irradiation for fuel cell appUcations. J Phys Chem B 2006 110 5343-50. 

Also, comparison of preparation method on the catalytic behavior of perovskite oxides for liquid reaction was investigated. Kulkami et al [56, 57] prepared a series of Lai-xSrxFeOs catalyst for reduction of nitrobenzene to aniline by microwave irradiation method, finding that the activity is similar to that prepared by conventional methods. The advantage in using microwave method is that it does not involve intermittent grindings and calcinations at elevated temperatures. 

A solvent-free strategy for the synthesis of thiazoles involved mixing of thioamides with a-tosyloxy ketones in a clay-catalyzed reaction (Scheme 7). The typical procedure entailed mixing of thioamides and in situ produced a-tosyloxy ketones with montmorillonite K-10 clay in an open glass container. The reaction mixture was irradiated in a microwave oven for 2-5 min with intermittent irradiation and the product was extracted into ethyl acetate to afford 2-substituted thiazoles in 88-96% yields [8]. 

We have also tried the trapping reactor system, in which ammonia is trapped on the catalyst/adsorbent and microwave is irradiated intermittently. However, due to the small specific surface area and the small ammonia adsorption capacity on the employed CuO, the trapping system was not effective compared to the continuous irradiation. Further study should be made to develop a material having high ammonia adsorption capacity and high efficiency for microwave absorption. Supported CuO on high surface area material or preparation of high surface area CuO can be effective. 

In a typical experiment, benzaldehyde (106 mg, 1 mmol) was added to the finely powdered paraformaldehyde (60 mg, 2 mmol). To this mixture, powdered barium hydroxide octahydrate (631 mg, 2 mmol) was added in a glass test tube and the reaction mixture was placed in an alumina bath (neutral alumina 125 g, mesh 150, Aldrich bath 5.7 cm diameter) inside a household microwave oven and irradiated for the specified time at its full power of 900 W intermittently or heated in an oil bath at 100-110 °C. On completion of the reaction, as indicated by TLC (hexane-EtOAc, 4 1, v/v), the reaction mixture was neutralized with dilute HC1 and the product extracted into ethyl acetate. The combined organic extracts were dried over anhydrous sodium sulfate and the solvent removed under reduced pressure. The pure benzyl alcohol (99 mg, 91%), however, is obtained by extracting the reaction mixture with ethyl acetate prior to neutralization and subsequent removal of the solvent under reduced pressure. 

Salicylaldehyde 3 (0.122 mg, 1 mmol), KF-alumina (0.620 g, 2 mmol of KF) and a-tosyloxyketone 2 (1 mmol) were placed in a glass tube and mixed thoroughly on a vortex mixer. The glass tube was then placed in an alumina bath inside the microwave oven and irradiated (intermittently at 1.5-min intervals 130 °C) for a specified time. On completion of the reaction, followed by TLC examination (hexane-EtOAc, 9 1), the product was extracted into methylene chloride (3xl0mL). The solvent was then removed under reduced pressure and the residue was crystallized from ethanol to afford a nearly quantitative yield of 2-ar-oylbenzo[/ ]furans 4a-h. 

In an extremely simple approach, an unmodified household microwave oven has been used in this study with excellent results. The generation of higher temperatures is avoided simply by intermittent irradiation [38]. 

The foremost result of this experiment is the agreement of the empirical distribution U q)/U l) with the (q — l)-fold conditional survival probability. The latter one has been calculated under the precondition that the coherent evolution of the microwave-driven ion s wave function is broken by just the possibility of observation during the intermittent irradiation of probe light. If such breaks were not to happen, the evolution of the ion s wave function should continue during the subsequent intervals of driving. An uninterrupted evolution would require a different calculation of the conditional probabilities of survival [44], namely... 

It has been reported that thionations with CR can be effected in the absence of solvent by the use of microwave radiation. Yields appear to be comparable to or in some cases better than those obtained in solution, while reaction times are very much shorter. Difficulties with charring during the reaction were overcome by using intermittent irradiation accompanied by periodic remixing. 

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