13869-79-9Relevant articles and documents
Catalytic activity of PdCl2 complexes with pyridines in nitrobenzene carbonylation
Krogul, Agnieszka,Skupińska, Jadwiga,Litwinienko, Grzegorz
, p. 9 - 16 (2011)
Synthesis of square planar palladium(II) complexes of general structure PdCl2(XnPy)2 (where: Py = pyridine; X nPy = 2-MePy; 3-MePy; 4-MePy; 2,4-Me2Py; 2,6-Me 2Py; 2-ClPy; 3-ClPy 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 pKa) have been correlated with activities of PdCl 2(XnPy)2 complexes during NB carbonylation in presence of catalytic system PdCl2(XnPy) 2/Fe/I2/XnPy. We observed that conversions of substrates and yields of EPC increase within increasing basicity of X nPy 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.
Synthesis and catalytic application of Pd complex catalysts: Atom-efficient cross-coupling of triarylbismuthines with haloarenes and acid chlorides under mild conditions
Jadhav,Pardeshi
, (2017/03/24)
Palladium-catalysed cross-coupling reactions are some of the most frequently used synthetic tools for the construction of new carbon–carbon bonds in organic synthesis. In the work presented, Pd(II) complex catalysts were synthesized from palladium chloride and nitrogen donor ligands as the precursors. Infrared and 1H NMR spectroscopic analyses showed that the palladium complexes were formed in the bidentate mode to the palladium centre. The resultant Pd(II) complexes were tested as catalysts for the coupling of organobismuth(III) compounds with aryl and acid halides leading to excellent yields with high turnover frequency values. The catalysts were stable under the reaction conditions and no degradation was noticed even at 150°C for one of the catalysts. The reaction proceeds via an aryl palladium complex formed by transmetallation reaction between catalyst and Ar3Bi. The whole synthetic transformation has high atom economy as all three aryl groups attached to bismuth are efficiently transferred to the electrophilic partner.
One pot synthesis of ureas and carbamates via oxidative carbonylation of aniline-type substrates by CO/O2 mixture catalyzed by Pd-complexes
Krogul, Agnieszka,Litwinienko, Grzegorz
, p. 204 - 211 (2015/07/27)
Abstract Carbonylation of aromatic amines by direct insertion of carbon monoxide is catalyzed by PdCl2(XnPy)2 complexes (where Py = pyridine, X = -CH3, -Cl; n = 0-2) and gives, depending on the conditions, ethyl N-phenylcarbamates or N,N′-diphenylureas. For carbonylation of aniline, a proper choice of XnPy ligands in PdCl2(XnPy)2 catalyst and application of molecular oxygen instead of nitrobenzene (conventionally used oxidant for carbonylations) allow to carry out the process under mild conditions with high yield and selectivity. The best results (75% yield of the main product with selectivity of catalyst above 90%) were obtained for the process catalyzed by PdCl2(2,4-Cl2Py)2 complex at 100°C and they were greatly improved in comparison to 41% yield and 68% selectivity obtained for CO/nitrobenzene used at 180°C.
Pd(II) catalyzed transformation of Schiff bases in complexes of the type trans-[PdCl2(NH2Ar-X)2] (X = H, CH3, Cl): Reactivity with aldehydes and Heck coupling reaction
Kumari, Niraj,Yadav, Vinod Kumar,Zalis, Stanislav,Mishra, Lallan
, p. 554 - 563 (2012/06/30)
Schiff bases of type (R-Ph-N=CH-Ph-CH=N-Ph-R), where, R = H (L 1), CH3 (L2) and Cl (L3), in presence of cis-[Pd(en)Cl2] or [Pd(DMSO)2Cl2] (en = 1,2-diaminoethane, DMSO = dimethylsulphoxide) give trans-[PdCl 2(NH2Ph)2] (1), trans-[PdCl2(NH 2PhCH3)2] (2) and trans-[PdCl 2(NH2PhCl)2] (3). The complexes are characterized using spectroscopic (IR, UV-vis and NMR) and X-diffraction techniques. The H-bonding interaction generates multinuclear supramolecular structure in complex (2) and (3). Complex (1) on reaction with benzaldehyde, salicylaldehyde and 4-carboxybenzaldehyde yields complexes of the type [PdCl2(PhN=CHPh)2] (4), [Pd(PhN=CHPhO)2] (5) and [PdCl2(PhN=CHPhCOOH)2] (6) respectively. The structures have been optimized using density functional theory at B3LYP level. Heck coupling reactions of bromobenzene with acrylonitrile and bromobenzene with ethyl acrylate in the presence of complexes (1), (2) and (3) have been carried out separately.
Cyclopalladation of meta -(diphenylthiophosphoryloxy)benzaldimines: NCS and unexpected NCO 5,6-membered pincer palladium complexes
Kozlov,Aleksanyan,Nelyubina, Yu. V.,Lyssenko,Vasilev,Petrovskii,Odinets
, p. 2054 - 2062 (2010/06/18)
Unsymmetrical NCS-pincer ligands of a new type, namely, m-(diphenylthiophosphoryloxy)benzaldimines 3 (1-[Ph2P(S)O]-3-[CH - NR]-C6H4, R = OMe (3a), Ph (3b), tBu (3c)), were obtained in two steps starting from commercially available 3-hydroxybenzaldehyde. These ligands easily underwent cyclopalladation at the C-2 position of the central benzene ring in the reaction with PdCl 2(PhCN)2 in benzene or benzene-methanol solutions to afford the corresponding hybrid pincer complexes 4a-c with five- and six-membered fused metallacycles in moderate to good yields. The same reaction in dichloromethane followed by treatment with alcohol resulted in unexpected formation of the related NCO-palladacycles 5a,b, along with the above NCS-complexes. Complexes 5 present the products of formal oxidation of the P - S group in the starting ligand, which apparently proceeds in the metal ion coordination sphere. Realization of κ3-NCS and κ3-NCO coordination in 4a-c and 5a,b, respectively, was unambiguously confirmed by X-ray diffraction analysis as well as multinuclear (1H, 13C, 31P) NMR, IR, and Raman spectroscopy. The NCS-pincer complexes 4a-c demonstrated excellent catalytic activity for the Suzuki cross-coupling reactions of aryl halides with phenylboronic acid.
Oxidative alkoxycarbonylation of aniline using homogeneous catalysts
Mulla,Gupte,Chaudhari
, p. L7-L10 (2008/10/08)
In this communication, preliminary data on the homogeneously catalyzed oxidative alkoxycarbonylation of aniline to N,N-diphenyl urea and N-phenyl carbamate has been reported. The aim of this work was to evaluate performance of a variety of Pd, Ru and Rh complex catalysts for the above reaction. The activity and selectivity of the catalyst are highest with iodine-containing ligands and depend on the ease with which the catalyst precusor can be converted into an active catalytic intermediate.
Palladium-catalysed N,N'-disubstituted urea synthesis by oxidative carbonylation of amines under CO and O2 at atmospheric pressure
Giannoccaro, Potenzo
, p. 271 - 278 (2007/10/02)
N,N'-disubstituted ureas have been obtained in good yields by reaction of aromatic and aliphatic primary amines in alcohol solution with CO and O2 under mild conditions (70-90 deg C, 1 atm) and in the presence of catalytic amounts of PdCl2 or a palladium(II) complex.Under more drastic temperature and pressure conditions carbamate esters were obtained instead.In the aniline carbonylation, the catalysis involves the following reactions: .Reaction (1) occurs at room temperature but more drastic conditions (70-90 deg C) are necessary for reaction (2).The influence of onium salts, such as PhNH3+X- (X=Cl, I) or CuCl2, on the catalytic activity has also been studied and the best results obtained with CuCl2.A side reaction involving carbon monoxide oxidation was almost suppressed when the reactions were carried out in alcohol, but enhanced when THF or dimethoxypropane was used as solvent.
MECHANISM OF THE FORMATION OF PALLADIUM COMPLEXES SERVING AS CATALYSTS IN HYDROGENATION REACTIONS. II. REACTIVITY OF PALLADIUM PHOSPHINE HALIDES TOWARDS MOLECULAR HYDROGEN
Berenblyum, A. S.,Aseeva, A. P.,Lakhman, L. I.,Moiseev, I. I.
, p. 237 - 248 (2007/10/02)
Cl, benzene and aniline hydrochloride were isolated as products of the reactions of (PPh3)2PdCl2 or 2 with H2 in organic amines (Am).Similar products were obtained when (Ph3P)2Pd(Ph)Br was treated with H2 both in amines and aromatic solvents.The reaction between H2 and 2 resulted in the formation of 2*2Am.The kinetic data for H2 absorption by solutions of palladium(II) complexes are consistent with the heterolytic mechanism of cleavage of the H-H bond in the coordination sphere of palladium(II); the function of the H+ acceptor being performed by the bases (e.g.Am or Ph).The reaction between the palladium complexes and H2 is autocatalytic.Reduction of the initial PdII complexes leads to lower oxidation state palladium complexes, which catalyse the reduction of PdII complexes.In the coordination sphere of the lower oxidation state palladium complexes, the oxidative addition of PR3 to Pd takes place with formation of compounds containing a Pd-R bond.It is the reaction between these complexes and H2 that yields palladium compounds with PR2 ligands.
