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微波技术在Suzuki反应中的应用 总被引:3,自引:0,他引:3
与传统的加热方式相比,微波加热具有加热速度快、热效率高、节约能源、洁净、操作简单等优点,已成为重要的有机合成工具之一。钯催化的Suzuki反应提供了一种合成各种联芳烃的温和方法,具有较高的选择性。本文综述了近年来微波技术在Suzuki反应中的应用研究进展,涉及到各种不同的反应体系,重点讨论了KF/Al2O3负载钯和聚合物负载钯等非均相催化体系,对于均相反应则着重讨论无过渡金属和超低含量钯催化的Suzuki反应体系,还讨论了连续流动的微波反应器及Suzuki反应在有机合成中的应用。 相似文献
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通过研磨、剪切、拉伸等方式获得的机械力能促进化学反应,为合成化学开辟了新方向。机械研磨技术作为绿色无溶剂合成方法,应用前景广泛。本文综述了机械研磨技术应用于固态、黏稠状混合物等凝聚态下的有机合成反应,展望了机械研磨技术在有机反应中的发展前景。与传统液相反应相比,其不需要溶剂,具有反应效率高、反应时间短、选择性好、后处理简单、适用于溶解性差的底物等优点。通过机械研磨技术进行的凝聚态有机反应,在某些情况下,会经历与液相反应不同的反应途径,从而生成迥异的反应产物。 相似文献
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微波技术在有机化学反应中的应用 总被引:4,自引:0,他引:4
本文介绍了微波技术在干法有机反应、加速有机合成速率及合成短寿命放射性药剂中的应用,概述了微波技术中影响反应速率的因素等,说明了微波特有的能量及快速加热能力在化学反应研究中具有广泛的实际意义。 相似文献
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《有机化学》2019,(2)
近年来,微波辅助有机合成(Microwave-assisted organic synthesis, MAOS)作为新兴的绿色有机合成方法受到研究者的广泛关注.与传统加热方法相比,其反应时间更短,产物收率更高并具有良好的反应选择性.许多人名反应中,譬如Diels-Alder反应、Witting反应、Heck反应和Mannich反应,均可利用该技术实现反应的快速进行.另外,α-重氮酯类化合物作为有机合成中一类重要的活性中间体,可以应用于Wolff重排反应以及C—H,N—H,Si—H等一系列插入反应.虽然关于α-重氮酯的研究在20年前已经成为一个成熟的学科,但在一些领域仍激发着研究者浓厚的研究兴趣.基于此,借助微波技术实现了短时间内α-重氮酯类化合物的克级制备,分离收率最高可达90%,且具有良好的官能团兼容性.该方法操作简便,反应条件温和,原子利用效率高,符合绿色化学的要求,为α-重氮酯类化合物的合成及进一步衍生化研究提供极大的便利. 相似文献
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Food processors requirements met by radiation processing 总被引:1,自引:0,他引:1
Processing food using irradiation provides significant advantages to food producers by destroying harmful pathogens and extending shelf life without any detectable physical or chemical changes. It is expected that through increased public education, food irradiation will emerge as a viable commercial industry. Food production in most countries involves state of the art manufacturing, packaging, labeling, and shipping techniques that provides maximum efficiency and profit. In the United States, food sales are extremely competitive and profit margins small. Most food producers have heavily invested in equipment and are hesitant to modify their equipment. Meat and poultry producers in particular utilize sophisticated production machinery that processes enormous volumes of product on a continuous basis. It is incumbent on the food irradiation equipment suppliers to develop equipment that can easily merge with existing processes without requiring major changes to either the final food product or the process utilized to produce that product. Before a food producer can include irradiation as part of their food production process, they must be certain the available equipment meets their needs. This paper will examine several major requirements of food processors that will most likely have to be provided by the supplier of the irradiation equipment. 相似文献
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Since the US Food & Drug Administration (FDA) approved irradiation of red meats in December 1997, the irradiation industry has been focused on this potential new utilization of our technology. In February 1999, the United States Department of Agricultural (USDA) finally issued a proposed rule, which will allow processors to begin irradiating red meats for human consumption. This presentation provides a brief update of the rules, regulations and prospects for this promising application. 相似文献
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Khadijah M. Al-Zaydi 《Arabian Journal of Chemistry》2009,2(1):55-58
A variety of arylhydrazonopyridinones 6a,b were prepared via heating cyanoacetamide derivative with ethyl acetoacetate in the absence of solvent under reflux conventionally or ultrasound irradiation or in a microwave oven then coupling with heteroaromatic diazonium salts. Several attempts were made to synthesize corresponding aminothienopyridinones 7a,b from 6a,b. Also, attempts to add electron poor olefins to 6a,b have failed and only arylhydrazonopyridinones recovered. 相似文献
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T. I. Karu O. A. Tiphlova Yu. A. Matveyets A. P. Yartsev V. S. Letokhov 《Journal of photochemistry and photobiology. B, Biology》1991,10(4):339-344
To evaluate the contribution of local pulsed heating of light-absorbing microregions to biochemical activity, irradiation of Escherichia coli was carried out using femtosecond laser pulses (λ = 620 nm, τp=3 × 10−13 s, fp = 0.5 Hz, Ep = 1.1 × 10−3J cm−2, Iav = 5.5 × 10−4 W cm−2, Ip = 109 W cm−2) and continuous wave (CW) laser radiation (λ = 632.8 nm, I = 1.3 W cm−2). The irradiation dose required to produce a similar biological effect (a 160%–190% increase in the clonogenic activity of the irradiated cells compared with the non-irradiated controls) is a factor of about 103 lower for pulsed radiation than for CW radiation (3.3 × 10−1 and 7.8 × 102 J cm−2 respectively). The minimum size of the microregions transiently heated on irradiation with femtosecond laser pulses is estimated to be about 10 Å, which corresponds to the size of the chromophores of hypothetical primary photoacceptors—respiratory chain components. 相似文献
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T. I. Karu O. A. Tiphlova Yu. A. Matveyets A. P. Yartsev V. S. Letokhov 《Journal of photochemistry and photobiology. B, Biology》1991,10(4)
To evaluate the contribution of local pulsed heating of light-absorbing microregions to biochemical activity, irradiation of Escherichia coli was carried out using femtosecond laser pulses (λ = 620 nm, τp=3 × 10−13 s, fp = 0.5 Hz, Ep = 1.1 × 10−3J cm−2, Iav = 5.5 × 10−4 W cm−2, Ip = 109 W cm−2) and continuous wave (CW) laser radiation (λ = 632.8 nm, I = 1.3 W cm−2). The irradiation dose required to produce a similar biological effect (a 160%–190% increase in the clonogenic activity of the irradiated cells compared with the non-irradiated controls) is a factor of about 103 lower for pulsed radiation than for CW radiation (3.3 × 10−1 and 7.8 × 102 J cm−2 respectively). The minimum size of the microregions transiently heated on irradiation with femtosecond laser pulses is estimated to be about 10 Å, which corresponds to the size of the chromophores of hypothetical primary photoacceptors—respiratory chain components. 相似文献
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《合成通讯》2013,43(17):3049-3054
Abstract Investigation of the key step of 3-aminophenothiazine (5) synthesis, that is thiation of N-(4-phenylaminophenyl)-phthalimid (3) was carried out. The best results were achieved using microwave irradiation, when 55% of the pure thiation product 3-phalimidophenothiazine (4) were isolated in 10–20 min reaction time. 相似文献
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Henry Delince 《Radiation Physics and Chemistry》1998,52(1-6):135-139
Employing the simple microgel electrophoresis of single cells - ‘comet assay’ - on grapefruit seeds enabled a rapid identification of irradiated fruits. Fruits were exposed to radiation doses of 0, 0.1, 0.2, 0.3, 0.4 and 0.5 kGy covering the range of potential commercial irradiation for insect disinfestation and quarantine purposes. Seeds were isolated, crushed, and the cells embedded in an agarose layer. After lysis of the cells, they were subjected to microgel electrophoresis for 2.5 minutes, and then stained. Fruits irradiated with 0.2 kGy and higher doses showed typical DNA fragmentation, the DNA fragments stretching or migrating out of the cells forming a tail towards the anode, giving the damaged cells an appearance of a comet. With increasing dose a longer extension of the DNA from the nucleus towards the anode is observed. Undamaged cells will appear as intact nuclei without tails. The DNA comet assay is thus a rapid and inexpensive screening technique to detect irradiated grapefruits. Suspected samples may subsequently be analysed by officially validated methods for detection of irradiated foods. 相似文献
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To understand the different action mechanisms of space irradiation on polymers, phenolphthalein poly(ether sulfone) (PES‐C) blocks were irradiated by electrons and atomic oxygen. The changes in surface chemical structure and composition of PES‐C in different radiations were studied by attenuated total‐reflection FTIR (FTIR‐ATR) and XPS. It was found that PES‐C was prone to be influenced by space irradiation. Electron and atomic oxygen irradiation can destroy the molecular chain of PES‐C and result in changes of surface chemical composition of the polymer. But due to the different nature of the radiation sources, electron irradiation induced the carbonization of the polymer surface, while atomic oxygen irradiation resulted in the oxidation of the polymer surface. Besides this, the sulfone structure was reduced or oxidized depending on the nature of the radiation sources. So, different radiation sources might influence the surface chemical structure and composition of polymers differently. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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TheBeckInannrearrangement,theacid-mediatedisomerizationofoximestoamides,wasfirstdiscoveredinl886l.Asoneoftheoldestandmostfamiliartransformationsinorganicchemistry,ithasbeenwidelystudiedandagreatvarietyofmethodstoconductthistfansformationhavebeenreported'.However,mostofthesemethodswerecarriedoutbyusingalargeamountofsolventswithlongreactiontime.Whatismore,thepriorpreparationofthecorrespondingketoximesisusuallyrequired,whichmakestheseprocessesinconvenientandlessattractive.Bytakingadvantageofboth… 相似文献
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Spiro [3H-indole-3,2′-[4H] pyrido [3,2-e]-1,3-thiazine]-2,4′ (1H) diones, a class of previously unknown compound which does not form under conventional conditions, can be prepared by treatment of ‘in situ’ generated 3-indolylimine derivatives with 2-mercaptonicotinic acid under microwave irradiation in absence of any solvent or solid support in 85-92% yields in 3-8 min. The facile one pot reaction is generalized for a variety of ketones and amines to give pure pyrido [3,2-e] thiazine derivatives, which do not require further purification processes. 相似文献