共查询到20条相似文献,搜索用时 732 毫秒
1.
对聚N-乙烯咔唑(PVK)和四溴化碳体系的电荷转移复合物在紫外光照射下光解的化学过程反应进行了研究。顺磁共振谱证明,这种光化学反应是属自由基反应过程。这种光解反应生成聚N-乙烯咔唑阳离子自由基和四溴化碳阴离子自由基,同时放出质子酸H+·聚N-乙烯咔唑阳离子自由基与四溴化碳进一步反应产生3-溴代聚N-乙烯咔唑。利用这些光化学反应,我们以聚N-乙烯咔唑为主要原料研制出一种光敏显示材料——PVK光敏片,其中PVK是经过改性的,成本比较便宜。采用不同的酸敏指示剂可获得多种变色片。 相似文献
2.
含氮给体结构对丙烯腈电荷转移光聚合的影响 总被引:1,自引:0,他引:1
<正> 对于正性烯类单体,主要是乙烯基咔唑的电荷转移聚合,诚田已作过详细综述。负性烯类单体的电荷转移聚合主要研究的单体是丙烯腈(AN)及甲基丙烯酸甲酯(MMA)。Barton等研究了芳烃为引发剂的MMA光聚合。我们研究了芳胺为引发剂的光聚合。 芳胺,尤其是芳叔胺,是较强的电子给体,与负性单体在光照下经激基复合物而引发聚合,我们的实验表明,吡啶及其同系物(喹啉与吖啶)并不象吡咯及其同系物(吲哚与咔唑)那样有效地引发AN等负性单体的光聚合(见表1)。从图1所示的结构看,它们有 相似文献
3.
4.
N-乙烯基咔唑的三氯甲烷溶液经光照后可以获得聚N-乙烯基咔唑,这一结论已经通过荧光光谱和NMR谱得到证实,产率很高可达70%。又通过荧光淬灭实验证实:这一反应首先在光照下形成激基复合物,由激基复合物分解产生自由基而引发N-乙烯基咔唑的聚合,此外,本文还研究了光强、N-乙烯基咔唑的浓度和光照时间对产率的影响。 相似文献
5.
本文是含咔唑化合物及其聚合物系列研究的一部分,以对-溴苯酚为原料,经过乙烯基醚化,再同咔唑反应、合成了新的单体,N-(p-乙烯氧基苯基)咔唑(NEOPC),经过元素分析、NMR和IR等对NEOPC进行分析鉴定,研究了它的聚合行为。 相似文献
6.
7.
8.
二、聚合反应与共聚合聚合反应与共聚合反应一直是高分子合成与改性的重要内容与手段,近年仍有重要发展。下面就自由基聚合、共聚合、正负离子聚合等方面的研究概况进行简要地阐述。1.自由基聚合近年的研究主要在开发含功能基的烯类单体、新型自由基引发体系和引发机理、聚合动力学尤其高转化的聚合动力学等。李笃信等研究了 N-乙烯基咔唑在 znO 为分散 相似文献
9.
<正> 为了深入认识含咔唑基单体的光敏性与聚合性的关系,在本系列含咔唑基化合物的基础上,合成了两个新单体:N-(p-羟甲基苯基)咔唑丙烯酸酯和N-(P-羟甲基苯基)咔唑甲基丙烯酸酯,并研究了其聚合行为。 化合物Ⅰ、Ⅱ、Ⅲ和聚合物的合成,反应式如下: 相似文献
10.
11.
12.
13.
Herrmann A 《Angewandte Chemie (International ed. in English)》2007,46(31):5836-5863
Volatile organic compounds serve in nature as semiochemicals for communication between species, and are often used as flavors and fragrances in our everyday life. The quite limited longevity of olfactive perception has led to the development of pro-perfumes or pro-fragrances--ideally nonvolatile and odorless fragrance precursors which release the active volatiles by bond cleavage. Only a limited amount of reaction conditions, such as hydrolysis, temperature changes, as well as the action of light, oxygen, enzymes, or microorganisms, can be used to liberate the many different chemical functionalities. This Review describes the controlled chemical release of fragrances and discusses additional challenges such as precursor stability during product storage as well as some aspects concerning toxicity and biodegradability. As the same systems can be applied in different areas of research, the scope of this Review covers fragrance delivery as well as the controlled release of volatiles in general. 相似文献
14.
G W Hasting 《Angewandte Chemie (International ed. in English)》1970,9(5):332-344
Macromolecular substances are used in medicine both as materials and as reagents. In the former category polymers serve as replacements for soft tissue, as cardiovascular and orthopedic implants, and as adhesives. When employed as reagents, macromolecules interact with living tissue and play an active part in bodily repair processes. 相似文献
15.
A general overview of the development of the uses of light-emitting diodes in analytical instrumentation is given. Fundamental aspects of light-emitting diodes, as far as relevant for this usage, are covered in the first part. The measurement of light intensity is also discussed, as this is an essential part of any device based on light-emitting diodes as well. In the second part, applications are discussed, which cover liquid and gas-phase absorbance measurements, flow-through detectors for chromatography and capillary electrophoresis, sensors, as well as some less often reported methods such as photoacoustic spectroscopy. 相似文献
16.
Entesar A. Hassan Salem E. Zayed 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):300-323
Abstract Organic dithiocarbamates have received great attention due to their interesting chemistry and wide utility as radical precursors and intermediates in organic synthesis. They also have found many of applications, that is, in agriculture and medicine. They are in use as pesticides, as well as in the rubber industries as vulcanization accelerators; and as antioxidants. Because they exhibit strong metal-binding capacity, they can act as in inhibitors of enzymes and have a profound effect on biological systems. Moreover, they have found application in the treatment of cancer and HIV. 相似文献
17.
Kirschning A Solodenko W Mennecke K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(23):5972-5990
The concepts article describes enabling techniques (solid-phase assisted synthesis, new reactor design, microwave irradiation and new solvents) in organic chemistry and emphasizes the combination of several of them for creating new synthetic technology platforms. Particular focus is put on the combination of immobilized catalysts as well as biocatalysts with continuous flow processes. In this context, the PASSflow continuous flow technique fulfils both chemical as well as chemical engineering requirements. It combines reactor design with optimized, monolithic solid phases as well as reversible immobilization techniques for performing small as well as large scale synthesis with heterogenized catalysts under continuous flow conditions. 相似文献
18.
Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review. 相似文献
19.
Enzyme-based biocatalysis is emerging as an advanced technique to develop green processes that help to maintain the sustainability of the environment. The bioremediation of toxic organic pollutants and waste to bioenergy production using enzymes as biocatalysts is rapidly growing due to its eco-friendly and sustainable nature. Additionally, a range of microbial species that typically grow on organic wastes can be used to produce these enzymes in an efficient manner. This is seen as a potential strategy for the development of cost-effective manufacturing for a number of biotechnological applications. The present study discusses biocatalysis as a promising and sustainable method toward the bioremediation of hazardous organic pollutants as well as for bioenergy production, based on the immense potential of enzymes as biocatalysts. Emphasis has been placed on evaluating the critical elements that can enhance the production of enzymes used as biocatalysts, as well as their functional effectiveness and stability. 相似文献