排序方式: 共有37条查询结果,搜索用时 15 毫秒
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四氯氧化钨或六氯化钨与不含β H的Grignard试剂在无水四氢呋喃中反应,形成钨的卡宾铬合物,可与醛、酮反应得到烯烃,具有类似于Witig试剂的功能 相似文献
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本文采用相转移卡宾法合成2-甲基-2-戊烯酸,收率为42.5‰,产品的香息较好,结果较佳. 相似文献
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WANG YongSheng SUN HongMei TAO XuePing SHEN Qi ZHANG Yong 《科学通报(英文版)》2007,52(23):3193-3199
The reaction of anhydrous FeBr2 with two equivalents of anionic N-heterocyclic carbene (NaL1 and NaL2), which are generated in situ by the reaction of the corresponding salt [4-R-C6H4COCH2{CH- (NCHCHNiPr)}Br] (R = OCH3, H2L1Br, 1; R = F, H2L2Br, 2) with two equivalents of NaN(SiMe3)2, affords bis-ligand Fe(II) complexes of L12Fe (3) and L22Fe (4) in high yield, respectively. Attempt to synthesize mono-ligand Fe(II) bromide by the 1:1 molar ratio of NaL to FeBr2 is unsuccessful, and the same com- plexes of 3 and 4 were obtained. Both 3 and 4 have been depicted by elemental analysis and X-ray structure determination. Preliminary studies show that both 3 and 4 can be used as single-component catalyst for the ring-opening polymerization of ε-caprolactone, and the catalytic activity of 3 is higher than that of 4. 相似文献
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Pyranylidene carbene complexes bearing a pyran ring carbene ligand represent a unique kind of organometallic species due to their special structures and reactivity. In this review, we present a comprehensive summary on the synthesis and reactivity of pyranylidene carbene complexes during the past four decades. 相似文献
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1991年,Arduengo等分离出第一个稳定的N杂环卡宾——咪唑-2-碳烯,之后,N杂环卡宾化学得到了迅速的发展,在多种催化反应中得到了广泛的应用.本文综述了N杂环卡宾在催化有机反应中的研究进展,如催化安息香缩合反应、Stetter反应、a3-d3极性反转反应、开环反应、酯基交换反应、开环聚合反应. 相似文献
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使用密度泛函理论B3LYP方法研究了金属Ta亚烷基化合物与Os氧化物间的亚烷基转移反应机理.使用B3LYP方法,金属原子采用LanL2DZ基组和赝势,其他原子采用6-31G(d)基组,优化得到了反应物、产物、中间体和过渡态的几何构型.对所得到的结构使用B3LYP方法,金属原子采用包含f轨道的SDDAll基组和赝势,其他原子采用6-311++G(d,p)基组计算了反应的活化Gibbs自由能.研究结果表明,金属Ta亚烷基化合物与Os氧化物间的亚烷基转移反应经由4个基元反应完成,每一基元反应的过渡态都具有四元环结构并且其活化Gibbs自由能都很小,反应在低温下容易完成.研究结果还表明,总反应是放热反应并且第1个基元反应是决速步骤. 相似文献
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Jon-Paul Griffiths M. G. Moloney 《复旦学报(自然科学版)》2005,44(5):772-773
Surface-active polymers are of substantial importance in many diverse aspects of modern technology, with applications ranging from solid phase chemical synthesis related to drug discovery and chemical catalysis to biocompatible/bioactive medical implants and prostheses, and to surface-modified fabrics. Whilst there are a number of existing physical (e. g. corona or plasma discharge, ion beam irradiation ) and chemical (e. g. silanisation, oxidation, chlorination, acylation and quaternisation ) methods for the surface modification of polymers, the frequent requirement for significant infrastructure, harsh reaction conditions, 相似文献
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用AM1方法优化了二溴卡宾与对-甲基苯乙酮环加成反应的反应物、过渡太、中间体和产物的构型,找到了反应的过渡态,从理论上论证了二溴卡宾与对-甲基苯乙酮加成反应的机理,得出了该反应为强放热反应,第二步反应为反应控制步骤的结论。 相似文献