共查询到20条相似文献,搜索用时 156 毫秒
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报道双(4-甲基-7-香豆素基)氧乙酸多亚甲基二醇酯的合成、光环化反应和荧光光谱研究。结果表明,双(4-甲基-7-香豆素基)氧乙酸多亚甲基二醇酯在氯仿溶液中于光照下生成分子内环化产物,环化产物的产率随着链长的增加而逐渐降低,这与荧光光谱中观察到的相对荧光强度随链长增加而增大的整体趋势一致。 相似文献
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香豆素是一类具有重要生理活性的天然产物。本文通过4-羟基香豆素的合成,然后与醛缩合,制备了一类具有双香豆素结构的化合物,对其结构通过^1H NMR、IR及元素分析确证并对其波谱学特征予以了讨论。 相似文献
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采用多种芳香双酯作为电子给予体制备了丙烯聚合高效催化剂,该催化剂具有高活性、聚合反应平稳、产物等规度高等特征.研究了多种芳香双酯和外加各种烷基硅氧烷对丙烯聚合的作用,测定了聚合反应动力学曲线,确定了聚合动力学方程.用扫描电镜研究了催化剂的形态,表明双酯组份能使催化剂结合得较紧密;对聚合产物的结构用DSD、红外光谱进行了表征. 相似文献
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A series of polymethylenediamine bis(4-methyl-7-coumarinyl)oxyacetic amides have been synthesized and their intramolecular photochemical cyclodimerizations have been investigated It was found that only syn-HT configuration products were obtained when these bisamides were directly irradiated in dimethyl sulfoxide solution and the yields of the products decreased with the intrease of the chain length.The structures of long chain amides and their intramolecular photoryrlizatum products were determined by IR,MS,1H NMR and elemental analysis. 相似文献
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K. Barabás M. Iring S. László-Hedvig T. Kelen F. Tüdos 《European Polymer Journal》1978,14(6):405-407
In the oxidation of isotactic polypropylene, qualitative and quantitative studies were made of organic volatile products by gas chromatographic methods. Experimental results and further data have been compared. Most of the products formed during degradation are acetone, and other ketones and aldehydes. Propylene, acetic acid and 2.4-dimethyl furane have also been identified.The products are formed in an accelerating kinetic process. There was linear relationship between the volatile products measured and the amount of oxygen consumption: approximately 2% of the oxygen absorbed is built into low molecular weight organic carbonyl compounds. 相似文献
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A series of poly(ethylene glycol) biscoumarinyloxyacetatea have been synthesized and their intramolecular photochemical cyclodimerizations have been studied. It was found that only syn-HT configuration products were obtained when these bisesters were directly irradiated in chloroform, and the yields of the products decreased with the increase of the chain length. This photocyclization reaction is a convenient and effective method to synthesize macrocyclic compounds. 相似文献
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Gutch P. K. Raza S. K. Malhotra R. C. 《Journal of Thermal Analysis and Calorimetry》2003,71(2):593-599
Thermal decomposition studies have been carried out using flash vacuum thermolysis (FVT) to find out the decomposition temperature
for benzylidene malononitriles (BMNs) including 2-chlorobenzylidene malononitrile (cs), a widely used riot control agent.
The FVT studies have been carried out in a specially designed all glass assembly at various temperatures ranging from 300
to 600°C. A number of rearranged products along with hydrogen cyanide were obtained as major decomposition products. The products
were analysed and the structures were confirmed by GC/MS. the thermal behaviour of BMNs has also been investigated by TG under
nitrogen atmosphere. These studies show that the pyrotechnic mixture for tear gas munitions should not have burst temperature
above 300°C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Maillard反应的高分子产物的研究进展 总被引:3,自引:0,他引:3
Maillard反应产物由于其天然性和独特的香味,使其在食品和烟草领域的应用倍受关注.目前,对Maillard反应产物中的小分子化合物的研究已经比较透彻,但是高分子产物的结构及形成机理尚不清楚.虽然Maillard高分子产物及其复杂,但人们通过膜透析、凝胶柱层析等分离方法,对其提纯分级后,再运用凝胶渗透色谱、元素分析、放射性同位素标记、紫外-可见光谱、红外光谱、核磁共振(NMR)、热裂解等分析手段对其进行表征,对Maillard高分子产物的结构和形成机理有了一定的了解.本文对Maillard反应的高分子产物的分离提纯方法、分析表征方法和分子结构的假设模型三方面的研究进展进行了综述. 相似文献
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WANG Yong-Mei DU Da-Ming MENG Ji-Ben ZHOU Xiu-Zhong WANG LeiDepartment of Chemistry Nankai University Tianjin China College of Chemistry Shandong University Jinan Shandong China 《中国化学》1997,(2)
A series of poly(ethylene glycol) biscoumarinyloxyacetates have been synthesized and their intramolecular photochemical cyclodimerizations have been studied.It was found that only syn-HT configuration products were obtained when these bisesters were directly irradiated in chloroform,and the yields of the products decreased with the increase of the chain length.This photocyclization reaction is a convenient and effective method to synthesize macrocyclic compounds. 相似文献
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采用添加剂湿法制备了掺入不同Ce含量的Cex(CoFe)3-xO4铁氧体。对产物的物相,形貌,磁性能研究表明,所得产物均为单一的尖晶石结构,一般情况下呈颗粒状,矫顽力随溶液中Ce^4+浓度的增加而增加。当溶液中含有Ce^3+和Ce(OH)4时,产物显示有部分棒状晶体,矫顽力有明显提高,且当「Ce^3+」占(「Ce^3+」+Ce^4+「)总量的5%左右时所得产物矫顽力最大。 相似文献
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Copeland G Ghosh MV Shallcross DE Percival CJ Dyke JM 《Physical chemistry chemical physics : PCCP》2011,13(39):17461-17473
The reactions of ozone with the alkenes 2,3-dimethyl 2-butene (DMB) and 2-methyl propene (2MP) have been investigated using a flow-tube interfaced to a u.v. photoelectron spectrometer. These reactions were studied at low pressure at different reagent partial pressures, both with the alkene in excess and ozone in excess. In each case, photoelectron spectra recorded as a function of time have been used to estimate partial pressures of the reagents and products as a function of time using photoionization cross-sections of selected photoelectron bands of the reagents and products, which were measured separately. The yields of all the main products have been determined, some of which have been measured in previous studies. For each reaction, oxygen was observed as a product for the first time and its yield was measured. Kinetics simulations were performed using reaction schemes which were developed for these reactions, which are consistent with that used earlier for the ozone-ethene reaction, in order to determine the main reactions for production of the products. The experimental product yields have been used in a global model to estimate their global annual emissions in the atmosphere. For example, for the reaction of O(3) with 2MP the formaldehyde, formic acid and acetone global annual emissions are calculated as 0.4 Tg, 25.0 Gg and 0.16 Tg respectively, which are estimated as 0.02, 0.3 and 0.2% of the total annual emission respectively. For the reaction of O(3) with DMB, the acetone yield is higher at 0.9 Tg which is approximately 1% of the total annual estimated emission. 相似文献
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Herbinet O Battin-Leclerc F Bax S Le Gall H Glaude PA Fournet R Zhou Z Deng L Guo H Xie M Qi F 《Physical chemistry chemical physics : PCCP》2011,13(1):296-308
The products obtained from the low-temperature oxidation of n-butane in a jet-stirred reactor (JSR) have been analysed using two methods: gas chromatography analysis of the outlet gas and reflectron time-of-flight mass spectrometry. The mass spectrometer was combined with tunable synchrotron vacuum ultraviolet photoionization and coupled with a JSR via a molecular-beam sampling system. Experiments were performed under quasi-atmospheric pressure, for temperatures between 550 and 800 K, at a mean residence time of 6 s and with a stoichiometric n-butane/oxygen/argon mixture (composition = 4/26/70 in mol%). 36 reaction products have been quantified, including in addition to the usual oxidation products, acetic acid, hydrogen peroxide, C(1), C(2) and C(4) alkylhydroperoxides and C(4) ketohydroperoxides. Evidence of the possible formation of products (dihydrofuranes, furanones) derived from cyclic ethers has also been found. The performance of a detailed kinetic model of the literature has been assessed with the simulation of the formation of this extended range of species. These simulations have also allowed the analysis of possible pathways for the formation of some obtained products. 相似文献