Application of Pd(II) Complexes with Pyridines as Catalysts for the Reduction of Aromatic Nitro Compounds by CO/H<sub>2</sub>O
作者:Agnieszka Krogul、Grzegorz Litwinienko
DOI:10.1021/acs.oprd.5b00273
日期:2015.12.18
undertaken to minimize the cost of large-scale conversion of aromatic nitro compounds to amines. Toward this end, application of CO/H2O as a reducing agent instead of molecular hydrogen seems to be a promising method, and the process can be catalyzed by Pd(II) complexes. In this work, the catalyticactivity of square planar complexes of general structure PdCl2(XnPy)2 (where XnPy = pyridine derivative) was
为了使芳香族硝基化合物大规模转化为胺的成本最小化,已经进行了许多努力。为此,使用CO / H 2 O作为还原剂代替分子氢似乎是一种有前途的方法,并且该过程可以由Pd(II)配合物催化。在这项工作中,研究了具有一般结构PdCl 2(X n Py)2(其中X n Py =吡啶衍生物)的方形平面配合物的催化活性。尤其要注意X n Py(配体)的芳环和要还原的硝基化合物(YC 6 H 4 NO 2)中取代基的作用)。在YC 6 H 4 NO 2的芳香环中引入吸电子Y会提高转化率,这表明该过程的动力学类似于在不存在水的情况下用CO羰基合成硝基苯氮烯的过程(见J. Mol 。CATAL A:化学2011,337,9-16)。令人惊讶地,吸电子取代基掺入X n Py配体的芳环中也增加了YC 6 H 4 NO 2的转化率(与YC 6 H 4 NO 2底物的结构无关)。
Crystal structure, electronic properties and cytotoxic activity of palladium chloride complexes with monosubstituted pyridines
作者:Agnieszka Krogul、Jakub Cedrowski、Katarzyna Wiktorska、Wojciech P. Ozimiński、Jadwiga Skupińska、Grzegorz Litwinienko
DOI:10.1039/c1dt11412c
日期:——
Palladium(II) complexes attract great attention due to their remarkable catalytic and biological activity. In the present study X-ray characterization, UV-Vis and Time-Dependent Density Functional Theory (TD-DFT) calculations for six PdCl2(XPy)2complexes (where: Py = pyridine; X = H, CH3 or Cl) were applied in order to investigate substituent effects on their crystal structures and electronic properties
Electrocatalytic reduction of carbon dioxide by substituted pyridine and pyrazole complexes of palladium
作者:A.G.M.Mostafa Hossain、T. Nagaoka、K. Ogura
DOI:10.1016/0013-4686(96)00136-3
日期:1996.8
A series of [PdCl2L2] complexes (L = substituted pyridine and pyrazole) has been tried as an electrocatalyst for the reduction of CO2 in acetonitrile (AN) containing 0.1 M tetraethylammonium perchlorate (TEAP) at glassy carbon or Pt electrodes. The complexes working as the catalyst were [PdCl2L2] (L = Pyrazole (Pyra), 4-Methylpyridine (4-Mpy) and 3-methylpyrazole (3-Mpyra)) at an applied potential
已尝试使用一系列[PdCl 2 L 2 ]配合物(L =取代的吡啶和吡唑)作为电催化剂,以减少玻璃碳或Pt电极上含0.1 M高氯酸四乙铵(TEAP)的乙腈(AN)中的CO 2。用作催化剂的络合物为[PdCl 2 L 2 ](L =吡唑(Pyra),4-甲基吡啶(4-Mpy)和3-甲基吡唑(3-Mpyra)),相对于Ag +的施加电势为-1.10 V还原产物为甲酸和H 2Pyra,4-Mpy和3-Mpyra的Pd配合物形成甲酸的当前效率分别为10%,20%和10.2%。目前,析氢的效率为31–54%,甲酸盐质子和氢的来源来自添加的水(占体积的4%)。
Tuning of the catalytic properties of PdCl2(XnPy)2 complexes by variation of the basicity of aromatic ligands
The position and number of substituents in pyridine ligands (XnPy) were correlated with structural, physical, and chemical properties of PdCl2(XnPy)(2) complexes applied as catalysts for the carbonylation of aromatic nitrocompounds (phosgene-free method of carbamates production). Thermal stability and catalytic activity of PdCl2(XnPY)(2) complexes without steric hindrance increases with increasing XnPy's basicity whereas a decrease of thermal stability and catalytic activity of the complexes is observed for sterically crowded complexes (with the ortho-substituted XnPy). The complexes with X = Cl in meta- position of XnPy decompose to a mixture of PdCl2 and metallic Pd (similarly to complexes with MenPy) whereas complexes with ortho-chlorine (in XnPy) decompose to the organopalladium products. Therefore, two different mechanisms of thermal decomposition are proposed for PdCl2(ClnPy)(2) and PdCl2(MenPy)(2). The results of complex thermal and structural analysis of a series of PdCl2(XnPy)(2) complexes allow us to get insight into the mechanism of nitrobenzene (NB) carbonylation catalyzed by PdCl2(XnPY)(2) at 150-180 degrees C. We conclude that the electron transfer from Pd(0) to nitrobenzene is the rate determining step of catalytic cycle of NB carbonylation. (C) 2014 Elsevier B.V. All rights reserved.
Catalytic activity of PdCl2 complexes with pyridines in nitrobenzene carbonylation
Synthesis of square planar palladium(II) complexes of general structure PdCl2(XnPy)(2) (where: Py = pyridine; XnPy = 2-MePy: 3-MePy; 4-MePy; 2,4-Me2Py; 2,6-Me2Py; 2-CIPy; 3-CIPy and 3,5-Cl2Py) has been performed in order to study activity of these complexes as catalysts of nitrobenzene (NB) carbonylation - a process of industrial importance leading to production of ethyl N-phenylcarbamate (EPC). Electron withdrawing/electron donating properties of XnPy ligands (described by experimentally determined acidity parameter pK(a)) have been correlated with activities of PdCl2(X Py)2 complexes during NB carbonylation in presence of catalytic system PdCl2(XnPy)(2)/Fe/I-2/XnPy. We observed that conversions of substrates and yields of EPC increase within increasing basicity of XnPy ligand (for not sterically hindered XnPy's). On the basis of current work and our previous studies a detailed mechanism of catalytic carbonylation of NB is proposed. (C) 2011 Elsevier B.V. All rights reserved.