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本文报道树脂法从混合物中分离纯化邻硝基苯甲醛的方法。研究说明,通过伯胺树脂与醛的反应对邻硝基苯甲醛进行化学吸附,可以将邻硝基苯甲醛从含有邻硝基甲苯、邻硝基苯甲醛、邻硝基溴苄、邻硝基-α,α─二溴苄、以及邻硝基苄醇的混合物中有效地分离出来。 相似文献
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邻酰氧基取代苯甲醛和苯甲醇在硼氢化钠水溶液中的还原反应 总被引:1,自引:0,他引:1
邻位上含有苯甲酰氧取代基的苯甲醛化合物2,5-双[(4-甲氧基苯甲酰)氧基]苯甲醛用NaBH~4还原时,产物与体系中是否含水有重要关系.在无水的情况下,还原按正常的方式进行,并生成相应的苯甲醇化合物;在有水的情况下,醛基首先被还原成醇,接着被还原成甲基,同时发生邻位(而不是间位)苯甲酰氧基的水解,产物为邻甲基酚类化合物.模型化合物邻(对甲氧基苯甲酰)氧基苯甲醛和间(对甲氧基苯甲酰)氧基苯甲醛的反应证实了上述发现.这一特殊反应可以推广到邻位上含有酰氧取代基的基本甲醛及其相应的醇. 相似文献
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邻位上含有苯甲酰氧取代基的苯甲醛化合物2,5-双[(4-甲氧基苯甲酰)氧基]苯甲醛用NaBH_4还原时,产物与体系中是否含水有重要关系.在无水的情况下,还原按正常的方式进行,并生成相应的苯甲醇化合物;在有水的情况下,醛基首先被还原成醇,接着被还原成甲基,同时发生邻位(而不是间位)苯甲酰氧基的水解,产物为邻甲基酚类化合物.模型化合物邻(对甲氧基苯甲酰)氧基苯甲醛和间(对甲氧基苯甲酰)氧基苯甲醛的反应证实了上述发现.这一特殊反应可以推广到邻位上含有酰氧取代基的苯甲醛及其相应的醇. 相似文献
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环上取代基对苯乙酮和苯甲醛缩合反应的影响 总被引:9,自引:0,他引:9
苯乙酮衍生物与苯甲醛衍生物缩合制备各种查尔酮,报道了4种苯乙酮衍生物与9种苯甲醛之间相互缩合的结果,讨论了环上取代基对缩合反应的影响。苯甲醛环上取代基,除羟基外无论是吸电子基还是给电子基对缩合反应收率影响都不大;羟基处于醛基邻位和对位的苯甲醛与几种苯乙酮衍生物的缩合,多数没有得到预期的产物,或收率极低;苯乙酮环上的羟基对缩合反应影响很大,羟基超多,缩合越困难。提出了一种假设,试图解释羟基对缩合反应 相似文献
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邻硝基苯甲醛的间接电解合成研究 总被引:5,自引:0,他引:5
对硫酸钴(Ⅱ)电化学制备以及用其作氧化媒质合成邻硝基苯甲醛进行了研究,结果表明,在11℃以银离子作催化剂,用Pbo2/Pb作阳极,在含0.45MCoCO4的5.3M硫酸溶液中进行电解反应时,可获得较高的电流效率,在温度12℃9.2M硫酸溶液中,使用过量70倍的邻硝基甲苯进行化学合成时,邻硝基苯甲醛的收率在74.5%。 相似文献
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以混合二甲苯为原料, Mn(Ⅲ)为氧化剂, 硫酸溶液为电解质, 采用槽内式超声电合成甲基苯甲醛. 探讨了选择性电合成甲基苯甲醛的可能性, 通过径向基(RBF)神经网络和遗传算法(GA)对选择性电合成甲基苯甲醛3种异构体的比例、 电流效率与混合二甲苯的用量、 硫酸浓度和电流强度的关系建立预测模型, 并运用GA确定模型中RBF神经网络的目标均方误差(Goal)和径向基函数的分布(Spread). 然后根据预测模型, 使用GA对电合成条件进行优化, 分别获得了电合成产物中对位甲基苯甲醛占优、 邻位和对位甲基苯甲醛占优以及电流效率最高时的电合成条件. 当采用上述条件进行实验时, 模型给出的预测结果分别为: 对位甲基苯甲醛占优的质量分数可达90.01%, 邻位和对位甲基苯甲醛占优的质量分数为80.38%, 电流效率达到最高时的邻位、 间位和对位甲基苯甲醛的质量分数分别为16.80%, 8.43%和74.77%; 而与之相对应的实际实验结果分别为90.10%和79.91%, 以及17.20%, 8.49%和74.31%, 二者之间的最大相对误差小于±2.24%, 表明所建立模型的预测值与实测值基本吻合. 相似文献
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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
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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
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Aptamers: molecular tools for analytical applications 总被引:3,自引:0,他引:3
Mairal T Ozalp VC Lozano Sánchez P Mir M Katakis I O'Sullivan CK 《Analytical and bioanalytical chemistry》2008,390(4):989-1007
Aptamers are artificial nucleic acid ligands, specifically generated against certain targets, such as amino acids, drugs,
proteins or other molecules. In nature they exist as a nucleic acid based genetic regulatory element called a riboswitch.
For generation of artificial ligands, they are isolated from combinatorial libraries of synthetic nucleic acid by exponential
enrichment, via an in vitro iterative process of adsorption, recovery and reamplification known as systematic evolution of
ligands by exponential enrichment (SELEX). Thanks to their unique characteristics and chemical structure, aptamers offer themselves
as ideal candidates for use in analytical devices and techniques. Recent progress in the aptamer selection and incorporation
of aptamers into molecular beacon structures will ensure the application of aptamers for functional and quantitative proteomics
and high-throughput screening for drug discovery, as well as in various analytical applications. The properties of aptamers
as well as recent developments in improved, time-efficient methods for their selection and stabilization are outlined. The
use of these powerful molecular tools for analysis and the advantages they offer over existing affinity biocomponents are
discussed. Finally the evolving use of aptamers in specific analytical applications such as chromatography, ELISA-type assays,
biosensors and affinity PCR as well as current avenues of research and future perspectives conclude this review. 相似文献
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《印度化学会志》2023,100(1):100818
In the present paper, the heat generating and/or absorption as well as thermo-diffusion on the unsteady free convection MHD gyrating flow of radiation and chemical reactive second grade fluid past an unbounded perpendicular plate during absorbent medium have been discussed. Here, it is assumed that, the confining plate has the ramped wall temperature with ramped surface concentration and isothermal temperature with ramped surface concentration. The analytical solutions for the governing equations are found by utilization of Laplace transformation methodology. The velocity, temperature and concentration profiles are analyzed with quite few figures. It is determined that, velocity, temperature and concentration distribution sketches in case of ramped temperature as well as ramped surface concentration are not as much of as those of isothermal temperature as well as ramped surface concentration. In addition to the idioms of skin friction, Nusselt number as well as Sherwood number are achieved and characterized numerically with tabular format. 相似文献
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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
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香豆素-3-羧酸分子印迹聚合物复合膜对底物的结合及渗透选择性质的研究 总被引:9,自引:0,他引:9
在光照和引发剂的作用下, 模板分子香豆素-3-羧酸、 功能单体丙烯酰胺和交联剂乙二醇二甲基丙烯酸酯(EDMA)或三甲氧基丙烷三甲基丙烯酸(TRIM)在聚偏氟乙烯(PVDF)微孔滤膜表面聚合形成分子印迹聚合物复合膜. 用高效液相色谱仪测定了分别以TRIM和EDMA为交联剂制备的分子印迹聚合物膜在不同溶剂中对混合底物的结合和渗透选择性. 结果表明, 以TRIM为交联剂的印迹膜对模板分子具有更高的结合和渗透选择性. 另外, 以乙腈或乙腈/水作为溶剂对分子印迹膜所作的实验和讨论有助于为从复杂样品中分离模板分子奠定理论和实验基础. 相似文献