Thiolate-capped Palladium Nanoparticles for Selective Catalytic Hydrogenation of Alkenes in the Presence of Another Reactive Functional Group PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Thiolate-capped Palladium Nanoparticles for Selective Catalytic Hydrogenation of Alkenes in the Presence of Another Reactive Functional Group PDF full book. Access full book title Thiolate-capped Palladium Nanoparticles for Selective Catalytic Hydrogenation of Alkenes in the Presence of Another Reactive Functional Group by Mohammed Mahdaly. Download full books in PDF and EPUB format.
Author: Mohammed Mahdaly
Publisher:
ISBN: 9781085570886
Category : Alkenes
Languages : en
Pages : 47
Get Book Here
Book Description
This thesis presents the preparation and catalysis of octanethiolate-capped palladium nanoparticles (C8 PdNP) and phenylethanethiolate-capped palladium nanoparticles (PhC2 PdNP) for chemoselective catalytic hydrogenation reactions of alkene groups in the presence of other reducible functionalities. Kinetic studies are performed and analyzed by 1H NMR spectroscopy to obtain clearer understandings of the catalytic activity. The noncovalent interactions between surface phenyl ligands and aromatic substrates are found to hinder the hydrogenation activity of PhC2 PdNP. In comparison, the C8 PdNP is discovered to be highly active and selective for hydrogenating alkene and alkyne groups without the reduction of other reactive functional groups such as nitro, halo, carbonyls, etc. under the mild reaction condition (room temperature and atmospheric pressure).
Author: Mohammed Mahdaly
Publisher:
ISBN: 9781085570886
Category : Alkenes
Languages : en
Pages : 47
Get Book Here
Book Description
This thesis presents the preparation and catalysis of octanethiolate-capped palladium nanoparticles (C8 PdNP) and phenylethanethiolate-capped palladium nanoparticles (PhC2 PdNP) for chemoselective catalytic hydrogenation reactions of alkene groups in the presence of other reducible functionalities. Kinetic studies are performed and analyzed by 1H NMR spectroscopy to obtain clearer understandings of the catalytic activity. The noncovalent interactions between surface phenyl ligands and aromatic substrates are found to hinder the hydrogenation activity of PhC2 PdNP. In comparison, the C8 PdNP is discovered to be highly active and selective for hydrogenating alkene and alkyne groups without the reduction of other reactive functional groups such as nitro, halo, carbonyls, etc. under the mild reaction condition (room temperature and atmospheric pressure).
Author: Jie S. Zhu
Publisher:
ISBN: 9781085564441
Category : Alkenes
Languages : en
Pages : 45
Get Book Here
Book Description
Abstract: The reactions of palladium are invaluable to modern academic and industrial research, and nanotechnology is the foundation on which the next generation of materials is built upon. Unsupported thiolate-capped palladium nanoparticles were found to be highly substrate selective for alkene hydrogenation and isomerization. A modified Brust-Schiffrin reaction enabled the facile and convenient synthesis of a diverse set of ultra-small thiolate-capped nanoparticles. The physical properties of these nanoparticles were highly tunable due to the widespread availability of ligand precursors. Mechanistic evidence and insights reveal that steric and electronic effects from the ligand environment on the nanoparticle surface controlled reactivity by influencing alkene adsorption via [pi] bond coordination or di-[sigma] bond formation. Only alkenes close enough to the metal surface of the nanoparticles underwent reaction. Dienes with good overlapping p orbitals could overcome these steric effects on the deactivated palladium nanoparticle surfaces. A mechanistic model was built from these completed studies, and this model can be used to predict the selectivity of hydrogenation or isomerization in multiple classes of alkenes with varied substitution patterns. These palladium nanoparticles were also found to be capable of chemoselective alkene hydrogenation in the presence of functional groups that are known to be labile towards reduction by palladium.
Author: May Maung
Publisher:
ISBN: 9781339826233
Category : Allyl alcohol
Languages : en
Pages : 48
Get Book Here
Book Description
Abstract: This thesis presents the systematic evaluation of palladium nanoparticles functionalized with well-defined small organic ligands that can provide a spatial control in the surrounding environment of nanoparticle catalyst surfaces. Various thiolate ligand-capped palladium nanoparticles are produced by using different S-alkylthiosufate ligand precursors in a two-phase system composed of toluene and water. These palladium nanoparticles are then characterized using transmission electron microscopy, thermogravimetric analysis, NMR, FT-IR, and UV-vis spectroscopy. The catalysis studies on alkanethiolate-capped palladium nanoparticles with different ligand structures (linear alkyl vs cyclohexyl vs phenyl) show that the chemical and structural composition of a monolayer surrounding the palladium nanoparticles greatly influences the overall activity and selectivity of nanoparticle catalysts for the hydrogenation, isomerization, and hydrogenolysis of allylic alcohols. Especially, the effect of non-covalent interactions between surface ligands and incoming substrates in the near-surface environment is observed. Furthermore, the catalytic properties of & ohgr;-carboxylate-functionalized alkanethiolate-capped palladium nanoparticles are studied for the biphasic reactions of hydrophobic allylic alcohols that are immiscible in aqueous solution. The systematic investigations on the influence of pH and substrate size are performed to check the utility of structurally stable and water-soluble palladium nanoparticles as new micellar catalysts.
Author: Elham Sadeghmoghaddam
Publisher:
ISBN: 9781267703231
Category : Allyl alcohol
Languages : en
Pages : 124
Get Book Here
Book Description
Abstract: This thesis presents a synthetic method for alkanethiolate-functionalized Pd nanoparticles that are efficient catalysts for the isomerization of various allyl alcohols to their corresponding carbonyl compounds. Pd nanoparticles are produced by the borohydride reduction of K 2 PdCl4 in toluene/H2 O using sodium S -dodecylthiosulfate as a source for the stabilizing ligands. The monolayer-capped Pd nanoparticles from sodium S -dodecylthiosulfate are quite comparable in composition (dodecylthiolate) and core size with those previously prepared from dodecanethiol. However, the catalytic activity of Pd nanoparticles generated from S -dodecylthiosulfate is found to be significantly greater than that of Pd nanoparticles prepared from dodecanethiol. Furthermore, the mechanism of the catalytic reactions and the regioselectivity of Pd nanoparticles in different environments are studied by changing the amount of H 2 gas, the type of solvent used for the catalytic reactions and the use of ligands with different chain length. Lastly, the high stability of homogeneous nanocatalysts is demonstrated by recycling dodecanethiolate-capped Pd nanoparticles over ten times for the isomerization reaction of allyl alcohol.
Author: Edwin G. Avila (Graduate student)
Publisher:
ISBN:
Category : Alkenes
Languages : en
Pages : 52
Get Book Here
Book Description
Conventionally, the Tsuji-Wacker oxidation has been used to promote the Markovnikov oxidation of terminal alkenes to their respective ketones in the presence of dioxygen. Recently, the regioselective formation of the aldehyde via an anti-Markovnikov addition, which is of substantial importance to the chemistry community, has been demonstrated using a palladium/nitrite catalyst. Herein, we demonstrate the potential for the regioselective transformation of allylbenzene derivatives to their respective aldehydes under green catalytic conditions via the use of palladium nanoparticles in water. The same Pd nanoparticle catalysts were also investigated for the homocoupling of phenyl boronic acids under aerobic conditions. Catalysis results were examined using 1H NMR and/or GC-MS analyses.
Author: Christos Nixarlidis
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 55
Get Book Here
Book Description
Abstract: The field of nanomaterials has been getting more attention the last few decades because of their unique optical, electrical and physical properties compared to those of bulk materials of the same type. One of the most studied nanomaterials is colloidal metal nanoparticles (NP) because of the tunability to control their structural parameters such as core size, shape, and chemical functionality using organic capping ligands. The head group of these ligands interacts with the surface of the metal nanoparticle whereas the organic chain of the ligand prevents aggregation and the terminal group controls the chemical properties such as solubility and chemical interactions. The synthesis of water-soluble alkanethiolate-capped palladium nanoparticle (PdNP) was achieved using the thiosulfate protocol developed by our group. The produced PdNP is characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), 1H NMR and UV-Vis Spectroscopy.
Author: Khin Aye San
Publisher:
ISBN: 9780355097511
Category : Catalysis
Languages : en
Pages : 64
Get Book Here
Book Description
Abstract: Stable and isolable alkanethiolate-stabilized Pt nanoparticles (PtNP) were synthesized using the two-phase thiosulfate method with sodium S-alkylthiosulfate as ligand precursor. The mechanistic formation of octanethiolate-capped PtNP (Pt-SC8) from both sodium S-octylthiosulfate and 1-octanethiol ligands was investigated by using 1H NMR and UV-vis spectroscopy, which revealed the formation of different Pt complexes as the reaction intermediates. The partially poisoned PtNP with thiolate monolayer ligands was further investigated for the hydrogenation of various alkynes to understand the organic ligands-induced geometric and electronic surface properties of colloidal Pt nanoparticle catalysts. In addition, alkanethiolate-capped Pd nanoparticles (PdNP) were prepared using reversed thiosulfate addition method with S-octylthiosulfate as ligand precursor. Various synthetic conditions were applied to the modified two-phase method in order to control the average core size and surface ligand density. The obtained nanoparticles were characterized by 1H NMR, UV-vis spectroscopy, infrared spectroscopy (IR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM).
Author: Ayda Elhage
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Over the past decade, heterogeneous photocatalysis have gained lots of interest and attention among the organic chemistry community due to its applicability as an alternative to its homogeneous counterpart. Heterogeneous catalysis offers the advantages of easy separation and reusability of the catalyst. Several studies showed that under optimized conditions, efficient and highly selective catalytic systems could be developed using supported metal/metal oxide nanoparticles. In this dissertation, we summarize the progress in the development of supported palladium nanoparticles for different types of organic reactions. Palladium-decorated TiO2 is a moisture, air-tolerant, and versatile catalyst. The direct excitation of Pd nanoparticles selectively isomerized the benzyl-substituted alkenes to phenyl-substituted alkenes (E-isomer) with complete conversion over Pd@TiO2 under H2-free conditions. Likewise, light excited Pd nanoparticles catalyzed Sonogashira coupling, a C-C coupling reaction between different aryl iodides and acetylenes under very mild conditions in short reaction times. On the other hand, UV irradiation of Pd@TiO2 in alcoholic solutions promotes alkenes hydrogenation at room temperature under Argon. Thus, The photocatalytic activity of Pd@TiO2 can be easily tuned by changing the irradiation wavelength. Nevertheless, some of these systems suffer from catalyst deactivation, one of the main challenges faced in heterogeneous catalysis that decreases the reusability potential of the materials. In order to overcome this problem, we developed an innovative method called "Catalytic Farming". Our reactivation strategy is based on the crop rotation system used in agriculture. Thus, alternating different catalytic reactions using the same catalyst can reactivate the catalyst surface by restoring its oxidation states and extend the catalyst lifetime along with its selectivity and efficiency. In this work, the rotation strategy is illustrated by Sonogashira coupling -problem reaction that depletes the catalyst- and Ullmann homocoupling -plausible recovery reaction that restores the oxidation state of the catalyst (Pd@TiO2). The selection of the reactions in this approach is based on mechanistic studies that include the role of the solvent and evaluation of the palladium oxidation state after each reaction. In a more exploratory analysis, we successfully demonstrated that Pd nanoparticles could be supported in a wide range of materials, including inert ones such as nanodiamonds or glass fibers. The study of the action spectrum shows that direct excitation of the Pd nanoparticles is a requisite for Sonogashira coupling reactions. The main advantages of heterogeneous catalysis compared to its homogeneous counterpart are easy separation and reusability of the catalyst. Finally in order to facilitate catalyst separation from batch reaction and develop a suitable catalytic system for continuous flow chemistry, we employed glass fibers as catalyst support for a wide variety of thermal and photochemical organic reactions including C-C coupling, dehalogenation and cycloaddition. Different metal/metal oxide nanoparticles, namely Pd, Co, Cu, Au, and Ru were deposited on glass wool and fully characterized. As a proof of concept, Pd decorated glass fibers were employed in heterogeneous flow photocatalysis for Sonogashira coupling and reductive de-halogenation of aryl iodides.
Author: Meng Zhou (Chemistry professor)
Publisher:
ISBN: 9780841234376
Category : Catalysis
Languages : en
Pages :
Get Book Here
Book Description
"Catalysis is truly an interdisciplinary field to which chemists, biologists, physicists, and engineers have made seminal contributions. This book aims to address the notably diverse topic of transition-metal catalysis in a single volume. The first half of the book is dedicated to the discrete and atomically precise metal complexes for homogeneous catalysis. Bimetallic, organometallic, and coordination complexes of early, late, and post-transition metals are described. Catalytic hydrogenation, oxidation, and coupling reactions are presented. The second half of the book focuses on three distinct types of nanomaterials: (1) zero- valent metallic nanoparticles, (2) titanium dioxide semiconductors, and (3) the porous coordination polymer known as the metal-organic framework. The chapters illustrate how deeply catalysis is influenced by other disciplines (e.g., coordination chemistry, bioinorganic chemistry, organometallic chemistry, computational chemistry, organic synthesis, photochemistry, materials science, environmental chemistry, green chemistry, and renewable energy). Advancements in these areas fuel the rapid growth of catalysis science. This book allows readers to reach a high-level of understanding in catalysis by learning from the perspectives of active practitioners. Unlike a textbook that provides a systematic, comprehensive, and historical education on the general topics of catalysis, this book offers critical case studies on select topics. Substantial emphasis is placed on the structural and fundamental properties that dictate catalyst performance, enabling readers to quickly understand and apply knowledge from cutting-edge studies and applications detailed within. This book can be utilized as a handbook, a textbook or textbook supplement, or a reference to guide future work"--
Author: Dominick Damian Ortega (Graduate student)
Publisher:
ISBN:
Category : Alkenes
Languages : en
Pages : 46
Get Book Here
Book Description
Abstract: Despite the availability of many water-soluble organometallic and nanoparticulate catalysts, the direct application of water-soluble catalysts for the reaction of immiscible and hydrophobic substrates has been hindered by the low solubility of nonpolar reactants in water. Our research group has shown that alkanethiolate-capped palladium nanoparticles (PdNP) exhibit excellent catalytic activity and selectivity for hydrogenation of unsaturated compounds in organic solvents. This PdNP was synthesized using the thiosulfate protocol using sodium S-dodecylthiosulfate as ligand precursor. The purpose of this study is to examine the catalytic activity of PdNP encapsulated in 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) lipids in water. After the liposome film assembly of PdNP with PC in chloroform, the solvent was removed under vacuum and the hybrid was hydrated with phosphate buffered saline (PBS) solution. The resulting liposome- PdNP hybrids dissolved in water were characterized by 1H NMR, dynamic light scattering (DLS), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). During the catalysis reaction, the bilayer characteristics of liposome-PdNP hybrid would allow the hydrophobic substrate such as 1-octene and its isomers to momentarily enter the hydrophobic region of the catalysts with adequate stirring force. After the reaction, the resulting products from bi-phasic system were subsequently extracted with organic solvents and analyzed using gas chromatography (GC). The results suggested that the transformation of 1-octene to trans-2-octene and cis-2-octene occur after 1 h of reaction time. Transformation of trans-2-octene and cis-2-octene to octane appears to take place after the completion of a 24 h reaction time. Phase transition study was also done to evaluate the effects of temperature on the fluidity of the bilayer and on the catalytic activity of the system. Temperature study results indicate a significant increase in conversion percentage of substrate into product below the phase transition temperature while no further increase was observed at the phase transition temperature of DSPC. Further investigation using differential scanning calorimetry (DSC) showed that the phase transition temperature of DSPC slightly increased with the incorporation of the PdNP into the bilayer. Substrate effects were explored by using a longer alkyl substrate, 1-tetradecene, which lead to overall lower conversion after 24 h due to its larger and bulkier size.
