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81.
A series of piperidoimidazolinium salts which differ in the chain lengths (butyl, octyl, dodecyl, octadecyl) and their Pd–N‐heterocyclic carbene complexes with pyridine were synthesized and characterized using elemental analysis and spectroscopic methods. The effects of these ligands on catalyst activation and the performance of the complexes were studied in Suzuki–Miyaura reactions of arylboronic acid with aryl chlorides. The complex with the ligand having the longest chain length was found to be most active. The results demonstrated that the length of the alkyl chain of the piperidoimidazolin‐2‐ylidene controlled the dispersion and composition of the nanoparticles and it affected the catalytic activity. The impact of alkyl chain length of piperidoimidazolin‐2‐ylidene on the Suzuki–Miyaura reactions of arylboronic acid with aryl halides was systematically investigated. 相似文献
82.
Finn J. Geffers Florens R. Kurth Prof. Dr. Peter G. Jones Prof. Dr. Daniel B. Werz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(60):14846-14850
Alkyne aminopalladation reactions starting from tosylamides are reported. The emerging vinylic Pd species are converted either in an intramolecular Heck reaction with olefinic units or in an intermolecular Suzuki reaction by using boronic acids exhibiting broad functional group tolerance. Tetra(hetero)substituted tosylated enamines are obtained in a simple one-pot process. 相似文献
83.
Polyphenol microspheres were prepared by template polymerization of phenol in the presence of horseradish peroxidase as bio‐enzyme catalyst and aqueous 1,4‐dioxane as solvent. The morphology of polyphenol microspheres thus obtained was observed with a scanning electron microscope. Further, polyphenol microspheres as obtained were loaded with palladium to generate polyphenol microsphere‐supported Pd complex. Resultant Pd complex catalyst supported by polyphenol microspheres was characterized by means of Fourier transformation infrared spectrometry, X‐ray diffraction, X‐ray photoelectron spectroscopy and scanning electron microscopy, and its thermal stability was examined. Moreover, the catalytic activity of polyphenol microsphere‐supported Pd catalyst as synthesized for the Heck reactions of acrylic acid with aryl iodides was evaluated. Results indicate that the polyphenol microsphere as obtained has a diameter of about 500 nm. Polyphenol microsphere‐supported Pd catalyst, as synthesized, at a dosage of 0.37 mol% Pd, possesses good catalytic activity for the Heck reactions of acrylic acid with aryl iodides in air at a low temperature of 50°C, and it also exhibits catalytic activity for bromide and activated chlorobenzene. The polyphenol microsphere‐supported Pd complex has good thermal stability, and it can be readily separated and reused; the yield of the reaction of iodobenzene with acrylic acid remains at 82% after five recycle runs, showing promising potential as a catalyst for Heck reactions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
84.
《应用有机金属化学》2017,31(10)
Uniform carbon nanospheres (UCS) with well‐controlled nano‐morphologies were fabricated by hydrothermal carbonization of sucrose in the presence of kayexalate. Highly dispersed and ultrafine palladium nanoparticles were supported on the UCS through a facile co‐reduction process with NaBH4 as reducing agent. The obtained Pd@UCS exhibited efficient catalytic activity for the Suzuki coupling reaction. Moreover, the as‐prepared catalyst could be recycled and reused at least five times without significant loss of its catalytic activity. 相似文献
85.
86.
Wen Qiang Du Ze Ming Rong Yan Liang Yong Wang Xin Yi Lu Yi Fan Wang Lian Hai Lu 《中国化学快报》2012,23(7):773-776
Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corresponding saturated aldehydes was achieved under mild conditions.This protocol provides an alternative for efficient preparation of saturated aldehydes. 相似文献
87.
Hui Li Jiancheng Luo Prof. Tianbo Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):17949-17952
The dilute solutions behaviors of Pd12L24 metal–organic nanocage and its two PEGylated derivatives are explored. The basic nanocages can self‐assemble into vesicle‐like blackberry structures in polar solvents via counterion‐mediated attraction, whereas the PEGylated nanocages always stay as discrete ions under the same conditions, demonstrating that the PEGylation can improve the stability of the single nanocages. In addition, larger nanocages are found to self‐assemble in less polar solvents. 相似文献
88.
89.
The system, Pd(OAc)2/imidazolium salts (L2), was found as an efficient catalyst in the Heck coupling reaction of olefins with aryl halides and Suzuki reactions of various aryl halides with aryl boronic acids under aerobic condition. This catalytic system demonstrates great tolerance to a wide range of groups on all substrates of aryl halides, alkenes and aryl boronic acids. 相似文献
90.
以丙烯酸铵为模板剂,由油柱成型法制备了系列球形Al2O3载体,采用XRD、BET等分析测试手段对其晶体结构、比表面积、孔容和孔径分布进行了表征,结果表明,600℃焙烧的球形γ-Al2O3载体具有介孔结构,并且比表面较不使用模板剂的样品有大幅度增加。焙烧温度升至960℃得到δ-Al2O3,介孔结构消失,但由于结构记忆效应,载体的大表面特性得以保持。以δ-Al2O3为载体制备Pd/Al2O3催化剂,采用氢-氧滴定(HOT)方法测定发现,比表面的增加显著提高了Pd金属的分散度,从而大幅度提高了催化剂的蒽醌加氢活性,氢化效率最高可达10.5 g.L-1。 相似文献