不饱和烃杂钯化反应在有机合成中的应用

不饱和烃杂钯化反应是合成高活性反应中间体烷基钯(II)和烯丙基钯(II)重要的途径.这些钯的络合物,在合适的条件下能被各种亲核试剂例如烯丙基卤、一氧化碳、不饱和烃、有机硼、有机锡等捕获.经过一系列插入及消除反应,能够有效地构建多种生理活性药物、有机功能分子以及重要合成骨架.近年来,引起了有机合成工作者的兴趣.在这里,对杂钯化最新进展进行综述.

Hydrothermal synthesis of titanium-supported nanoporous palladium-copper electrocatalysts for formic acid oxidation and oxygen reduction reaction

Nanoporous Pd and binary Pd-Cu particles were prepared by a hydrothermal method using ethylene glycol as a reduction agent and they were directly immobilized on Ti substrates named as Ti-supported Pd-based catalysts. Their electrocatalytic activity for formic acid oxidation and oxygen reduction reaction （ORR） in alkaline media was examined by voltammetric techniques. Among the as-prepared catalysts, nanoPdslCu19/Ti catalyst presents the highest current density of 39.8 mA/cm2 at -0.5 V or 66.4 mA/cm2 at -0.3 V for formic acid oxidation. The onset potential of ORR on the nanoPdslCU19/Ti catalyst presents an about 70 mV positive shift compared to that on the nanoPd/Ti, and the current density of ORR at -0.3 V is 2.12 mA/cm2, which is 3.7 times larger than that on the nanoPd/Ti.

Role of Periodic Input Composition and Sweeping Gas for Improvement of Hydrogen Production in a Palladium Membrane Reactor by Partial Oxidation of Methane

The partial oxidation of methane under periodic operation over Ni/y/-Al2O3 catalyst was investigated in a Pd-membrane reactor. The effects of key parameters such as the inlet composition and the sweeping, gas on methane conversion and the hydrogen recovery are numerically estalallshed with two penodtc input ttmctlons. In order to analyze the effect of the inputs modulation, the reaction was performed under low steam to methane ratio at a mod-erate temperature and pressure. It was obtained that to achieve process intensification is to operate the process in a periodic way. The main results show that the periodic input functions can improve the performance of the process compared to the optimal steady state operation. Moreover, there is an optimum amplitude of manipulated inputs leads to a maximum of hydrogen recovery. It is noteworthy that the comparison between the predicted performancevia the sinusoidal and the＇square ways show that the better＇average performance was obtainedwith the square way.

Core/shell FePd/Pd catalyst with a superior activity to Pt in oxygen reduction reaction

Developing high-efficient non-platinum （Pt） catalysts for oxygen reduction reaction （ORR） is the key to reduce the usage of Pt and the palladium （Pd）-based cata- lyst is a promising alternative. Here, we presented a facile approach to core/shell FePd/Pd nanoparticle （NP） catalyst with the FePd core in chemically ordered face-centered tetragonal （fct-） structure and the shell in controlled thickness from 0.32 to 0.81 nm via the thermal annealing of FePd NP followed by an electro-anodization process. With a 0.71 nm-thick Pd shell, the fct-FePd/Pd shows a robust catalytic activity and durability for ORR with the mass activities at 0.85 and 0.90 V reaching 453 and 96.7 A/mgpd, respectively, which are about 3.0 and 2.1 times higher than those of commercial Pt in alkaline media. This work presents a new class of non-Pt catalyst with superior performance to Pt for ORR catalysis, and the strategy demonstrated here can be extended to design highefficient catalysts for other chemical reactions.

Mechanistic aspects of oxidation of palladium with O_2

Palladium-catalyzed aerobic transformation has been one of the most challenging topics within organometallics chemistry. Recently, the corresponding methodology has been developed rapidly, involving alcohol oxidation, alkene oxidation, oxidative coupling and so on, which stimulated considerable interests in mechanistic investigation of the oxidation of Pd with O2 . This review summarizes most of the mechanistic studies on this topic during the past ten years. Moreover, the future of the mechanistic investigation for aerobic oxidation of Pd is also discussed.