hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustratedLewispairs interface formed by the combination of gold
1,10-菲咯啉在TiO 2上热解Au(OAc)3提供了一种高活性和选择性的Au纳米颗粒(NP)催化剂,该催化剂嵌入氮掺杂的碳载体中,[受电子邮件保护]碳/ TiO 2催化剂。系统研究了热解温度,载体类型和氮配体以及Au /配体摩尔比等参数。在温和条件下,许多结构多样的炔烃的高选择性加氢以中等至极好的收率进行。对工业上重要的烯烃底物的高选择性,官能团耐受性和高可回收性使催化体系独树一帜。高活性和选择性都与由N掺杂碳的金和氮原子的组合形成的沮丧的Lewis对界面有关,根据密度泛函理论计算,该界面可以充当促进H 2杂化活化的基本位点在非常温和的条件下。这种“完全非均相”且可循环利用的金催化剂使选择性加氢工艺在环境和经济上都具有吸引力。
Ni-Catalyzed Homocoupling of 3-Halopropenoates in the Presence of Water: Formation of Hexendioates
Homocoupling of (Z)-3-halopropenoates using a catalytic amount of NiCl2 and Zn in the presence of water in pyridine afforded a mixture of (Z)- and (E)-3-hexenedioates.
Low Temperature Photolysis of<i>o</i>-Benzoquinones. Spectroscopic Detection of Cyclopentadienones and Bis-Ketenes
作者:Hideo Tomioka、Hiroshi Fukao、Yasuji Izawa
DOI:10.1246/bcsj.51.540
日期:1978.2
The photodecarbonylation of o-benzoquinone to cyclopentadienone at low temperature was monitored by infrared and ultraviolet spectra which showed that the reaction is highly sensitive to substituents. 3,5-Di-t-butyl-o-benzoquinone undergoes clean decarbonylation to give cyclopentadienone under irradiation at −170 °C. Similar irradiation of 4-t-butyl-, 4-methyl-, 3-methyl-, and unsubstituted o-benzoquinones also leads to decarbonylation to cyclopentadienones. However, competitive α-cleavage to bis-ketene becomes important in these systems. Direct spectroscopic observation of the elusive cyclopentadienone was unsuccessful because of the overlapping absorption of the by-product. The infrared spectrum of bis-ketene from 4-t-butyl-o-benzoquinone shows that it exists as a mixture of rotamers, not undergoing thermal interconversion even at −170 °C.
通过红外和紫外光谱监测了邻苯醌在低温下光脱羰生成环戊二烯酮的过程,结果表明该反应对取代基高度敏感。 3,5-二叔丁基邻苯醌在-170 °C 照射下进行清洁脱羰得到环戊二烯酮。 4-叔丁基-、4-甲基-、3-甲基-和未取代的邻苯醌的类似照射也会导致脱羰生成环戊二烯酮。然而,在这些系统中,竞争性 α-裂解为双烯酮变得很重要。由于副产物的重叠吸收,对难以捉摸的环戊二烯酮的直接光谱观察并不成功。 4-叔丁基邻苯醌的双乙烯酮的红外光谱表明,它以旋转异构体的混合物形式存在,即使在-170℃下也不会发生热互变。
Piperazine-promoted gold-catalyzed hydrogenation: the influence of capping ligands
作者:Jhonatan L. Fiorio、Eduardo C. M. Barbosa、Danielle K. Kikuchi、Pedro H. C. Camargo、Matthias Rudolph、A. Stephen K. Hashmi、Liane M. Rossi
DOI:10.1039/c9cy02016k
日期:——
Goldnanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since goldnanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold–ligand interface