168 research outputs found
Synthesis and characterization of novel ligands and application of their transition metal complexes as catalysts or anticancer agents
No full textIn this Thesis work, we report an innovative approach for the synthesis of 2-bromoacrylic acid and its ester derivatives that are the key intermediates in the synthesis of chiral aryloxypropionic acid an important class of herbicides. The synthesis of the bromo substitued acrylics was carried out via carbonylation of (trimethylsilyl)acetylene using as catalytic system Pd(OCOCH3)2 in combination with CH3SO3H and 2-(6-methyl)(diphenylphosphine)pyridine. When the reaction is carried out in methanol, methyl 2-(trimethylsilyl)acrylate was obtained in good yields with a branched/linear ratio 95/5. On the other hand, hydroxycarbonylation reactions give 2-(trimethylsilyl)acrylic acid with lower conversions and selectivities (ca. 53%, and 93/7 respectively). The effects of phosphine/palladium, acid/palladium, reaction time, temperature, and CO pressure on the substrate conversion and selectivity towards branched isomer have been investigated. Methyl 2,3-dibromo-2-(trimethylsilyl)propanoate is easily prepared by reaction of methyl 2-(trimethylsilyl)acrylate with bromine in dry dichloromethane. Then bromodesylilation of 2-(trimethylsilyl)acrylate in the presence of an excess of base gives 2-bromoacrylic acid in good yield (ca. 90%).
A series of triazole ligands were synthesized by the CuAAC reaction. They were employed as chelating ligands to prepare Ru(II), Pd(II), and Co(II) complexes. Ligands and metal complexes have been characterized by analytical data, ESI-MS and 1H and 13C NMR spectroscopy.
The water soluble sodium 2-(1-((pyridin-2-yl)methyl)-1H-1,2,3-triazol-4-yl)ethyl sulfate ligand
has been employed as ligand in biphasic water/organic solvent catalysis. A preformed ruthenium complex and an iridium system containing this water soluble pyridyl-triazolyl ligand were successfully employed in water/toluene biphasic catalytic hydrogenation of C=C and C=O double bonds. The hydrogenation of styrene, 2-cyclohexene-1-one, m-diisopropenylbenzene, and cinnamaldehyde has been investigated. The water soluble 2-(1-(2-(methylthio)ethyl)-1H-1,2,3-triazol-4-yl)ethanol ligand in combination with [RhCl(COD)]2 gives a system displaying good activity in olefin hydroformylation.
The above water soluble [RuCl(η6-p-cymene)(sulphated ligand)] complex has been tested in vitro against several human cancer cell lines (A375, A431, BxPC3, A549 and HCT-15.) derived from solid tumors by the MTT test. Preliminary results indicate that the ruthenium complex is less cytotoxic than cisplatin but has a potential as antimetastatic agent
The intriguing methoxycarbonylation of trimethylsilylacetylene in the presence of Drent's catalytic system
No full textThe alkoxycarbonylation of trimethylsilylacetylene has been studied in order to develop an atom economic sustainable synthesis of 2-(trimethylsilyl)acrylates, a family of valuable intermediates. Pd(OAc)2 in combination with CH3SO3H and diphenyl-(pyridin-2-yl)phosphine or diphenyl-(6-methyl-pyridin-2-yl)phosphine is an active catalyst for the reaction affording mixtures of the sought 2-(trimethylsilyl)acrylate and the isomeric 3-(trimethylsilyl)acrylate. The phosphine ligand has a dramatic effect on the reaction. When employing diphenyl-(pyridin-2-yl)phosphine, it is necessary to carry out the reaction at 80°C in order to observe a modest catalytic activity, and the product is an almost equimolecular mixture of the two isomeric esters. On the contrary, when employing diphenyl-(6-methyl-pyridin-2-yl)phosphine, the reaction proceeds under much milder conditions affording with high rate (turnover frequency [TOF] up to 1200 h−1) and selectivity (>95%) of the sought 2-(trimethylsilyl)acrylate. The reaction conditions have been optimized, and the effects of phosphine/palladium, acid/palladium, reaction time, temperature, and CO pressure have been investigated. © 2021 The Authors. Applied Organometallic Chemistry published by John Wiley & Sons Ltd
Synthesis, Characterization and Antibacterial Activity on Dinuclear Schiff-base Macrocyclic Metal Complexes
No full textSchiff-bases and their dinuclear metal complexes have been extensively received special attention because of their wide range of applications including catalysts, medicine crystal engineering, anti-corrosion agent, and biological activities [1]. Dinuclear macrocyclic lead (II) complex, Pb2L1(SCN)4 was synthesized by template condensation of pyridine-2,6-dicarboxaldehyde and 1,2-bis (2-aminoethoxy) ethane in presence of Pb(SCN)2 as the metal source, here L1 is tetra-Schiff-base macrocycle. Transmetallation treatment of Pb2L1(SCN)4 with Co(PF6)2.6H2O produced the new complex, Co2L1(SCN)4 [2]. Reduction of lead (II) complex gave new reduced tetra-Schiff-base macrocyclic ligand, L2[3]. All the metal complexes and ligand were characterized by UV-Visible, FT-IR, 1H NMR spectroscopy. The antibacterial activities against some pathogenic gram positive and gram negative bacteria were studied by cylinder disk diffusion method. The complexes were found to inhibit the growth of bacteria
Congestion control in Mobile Ad-Hoc networks (MANETs)
No full textThis thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Computer Science and Engineering, 2011.Cataloged from PDF version of thesis report.Includes bibliographical references (page 39).Md. Mahbubul AlamTanmoon Taz ShetuB. Computer Science and Engineerin
Biphase hydroformylation catalyzed by rhodium in combination with a water-soluble pyridyl- triazole ligand
No full text[RhCl(COD)]2 in combination with a water soluble sulphonated pyridyl-triazolyl N,N-bidentate ligand
efficiently catalyzes styrene and 1-hexene hydroformylation in water/organic solvent biphasic systems.
The catalyst displays a good activity affording mixtures of linear and branched aldehydes with complete
chemoselectivity. The aqueous catalytic phase may be recycled four times giving complete substrate
conversion by 18 h. Mercury-poisoning experiments and transmission electron microscopy indicate that,
after the first catalytic run, rhodium is present in the aqueous phase in nanoparticle form.[RhCl(COD)]2 in combination with a water soluble sulphonated pyridyl-triazolyl N,N-bidentate ligand efficiently catalyzes styrene and 1-hexene hydroformylation in water/organic solvent biphasic systems. The catalyst displays a good activity affording mixtures of linear and branched aldehydes with complete chemoselectivity. The aqueous catalytic phase may be recycled four times giving complete substrate conversion by 18h. Mercury-poisoning experiments and transmission electron microscopy indicate that, after the first catalytic run, rhodium is present in the aqueous phase in nanoparticle form
Synthesis of a water‐soluble thio‐triazole ligand for biphase rhodium catalyzed hydroformylation of styrene
No full textAn environmentally safe water-soluble new ligand (2-(1-(2-(methylthio)ethyl)-1H-1,2,3-triazol-4-yl)ethanol) (ligand 1) has
been synthesized by the click reaction between (2-azidoethyl)(methyl)sulfane and 3-butyn-1-ol. The structure of the novel
ligand was confirmed by NMR spectroscopy. In situ combination of ligand 1 with [Rh(COD)Cl]2 and [Rh (CO)2(acac)] (Rh:
ligand = 1: 4) successfully employed for the biphasic catalytic hydroformylation of styrene. The formation of branched
2-phenylpropanol was confirmed by gas chromatogphic analysis. The recycled catalytic aqueous phase can be used
three runs with remarkable catalytic efficiency
A water-soluble pyridyl-triazole ligand for aqueous phase palladium catalyzed Suzuki–Miyaura coupling
No full textThe alkoxycarbonylation of protected propargyl alcohols
No full textPalladium-catalyzed alkoxycarbonylation of the C≡C triple bond of propargyl alcohol is a sustainable synthetic
approach to 2-(hydroxymethyl)acrylates, a family of valuable intermediates. The developed synthetic protocol
includes protection of the alcoholic function of the alkyne before its carbonylation in the presence of Drent’s
catalytic system. Protection step effectively extends the catalyst life hence enhancing the practical applicability
of the reaction. The effectiveness of some different protecting groups (benzyl, acetyl and trimethylsilyl) has been
assessed and the influence of the reaction parameters investigated.Palladium-catalyzed alkoxycarbonylation of the C≡C triple bond of propargyl alcohol is a sustainable synthetic approach to 2-(hydroxymethyl)acrylates, a family of valuable intermediates. The developed synthetic protocol includes protection of the alcoholic function of the alkyne before its carbonylation in the presence of Drent's catalytic system. Protection step effectively extends the catalyst life hence enhancing the practical applicability of the reaction. The effectiveness of some different protecting groups (benzyl, acetyl and trimethylsilyl) has been assessed and the influence of the reaction parameters investigated
Preparation and Characterization of a Molecular Cobalt Complex Containing a Water Soluble Triazole Ligand
No full textCobalt(II) perchlorate hexahydrate, (Co(ClO4)2.6H2O) was reacted with a water soluble sulphonated pyridyl-triazole N,N-bidentate ligand (2-(1-((pyridine-2-yl)methyl)-1H-1,2,3-triazol-4-yl)ethyl sodium sulfate, `ligand 1.Na) in methanol to form [Co(ligand 1)2(H2O)2].4H2O as a microcrystalline solid. In this context, ligand 1.Na was first synthesized by the cycloaddition reaction of 2-(azidomethyl)pyridine and sodium 3-butyn-1-sulfate in 4:1 tert-BuOH/water solvents in presence of Cu(AcO)2H2O (10-15 mol %) as catalyst. The ligand 1.Na was white solid, absorbed moisture at open air, soluble in methanol and DMSO and characterized by elemental analysis, ESI-MS spectrum in the negative mode, 1H NMR and 13C NMR spectroscopy. In the 1H NMR spectrum of ligand 1.Na in CD3OD, a characteristic triazole strong singlet peak appeared at 7.97 ppm, a remarkable shift of δ value for CH2 proton of 2-(azidomethyl)pyridine was observed. In the 13C NMR spectrum, the triazole carbon resonates at 137.90 ppm. The prepared complex was characterized by physical data, FT-IR, ESI-MS and elemental analysis. The light pink crystals are fairly stable at open atmosphere even if they slowly loose the lattice solvent. The ESI-MS spectrum of [Co(ligand 1)2(H2O)2].4H2O indicates the species [Co(ligand 1.Na)(ligand 1)]+ and [Co(ligand 1.Na)]+ which corresponds to the m/z value at 648.6 and 402.6 respectively. Based on the observed data, octahedral geometry of the synthesized complex was suggested
Stereoselective synthesis of 2-substituted acrylic derivatives via carbonylation reaction
No full textThe carbonylation of 1-alkynes is a versatile tool for the synthesis of important intermediates such as α,β-unsaturated carboxylic acids [1,2]. In our recent work, we have disclosed the synthesis of the important intermediate 2-(trimethylsilyl)acrylic acid and its methyl ester, starting from commercially available trimethylsilylacetylene, in the presence of the readily available catalytic system obtained in situ from Pd(OCOCH3)2/CH3SO3H/2-methyl(diphenylphosphino)pyridine. Reactions are carried out at 80 ºC; methoxycarbonylation reactions allow to obtain methyl 2-(trimethylsilyl)acrylate in good conversions (ca. 93%) and with a branched/linear ratio 95/5, whereas hydroxycarbonylation reactions give lower conversions and selectivities (ca. 53%, and 93/7 respectively).
[1] R. Romagnoli, P.G. Baraldi, M.K. Salvador, M.E. Camacho, J. Balzarini, J. Bermejo, F. Estévez, Eur. J. Med. Chem., 2013, 63, 544–557.
[2] B.S. Sekhon, J. Pestic. Sci., 2009, 34, 1–12.
[3] E. Drent, P. Arnoldy, P.H.M. Budzelaar, J. Organomet. Chem., 1993, 455, 247–253
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