New chiral half-sandwich Ru hydride enantiomers with asymmetric disubstitution on the Cp ligand have been successfully synthesized and resolved. An enantiopure thiolate ligand was installed on the Ru center to form a pair of diastereomers, which were separated by crystallization via vapor diffusion of pentane into their saturated Et2O solution. Racemization occurred at elevated temperatures, but a room temperature conversion pathway was developed to remove the chiral thiolate ligand and generate the enantiopure hydride complex. Two new Rh(III) hydride complexes and their Ir analogues have been synthesized and characterized. The hydride complexes readily transfer H– to the N-carbophenoxypyridinium cation at room temperature, giving mixtures of 1,2- and 1,4-dihydropyridine products. In CD3CN, all four hydrides give nearly the same product ratio, demonstrating that the hydride transfer mechanism is outer sphere. In weak or non-coordinating solvents, the resulting 16-electron cations catalyze the isomerization of 1,2- to 1,4-dihydropyridine at rates that depend upon the cation and the solvent. The fastest isomerization was observed with the Rh(III) cation [Cp*Rh(2-(2-pyridyl)phenyl)]+, Acetonitrile can trap the 16-electron cations resulting from hydride transfer, dramatically slowing the isomerization process. The thermodynamics and kinetics of hydride, hydrogen atom and proton transfer reactions of the Rh(III) hydride, Cp*Rh(2-(2-pyridyl)phenyl)H, were studied both thermodynamically and kinetically. This hydride is both a good hydride and hydrogen atom donor, but a poor proton donor. This previously unobserved combination of properties is due to the high energy of the hydride’s conjugate base, [Cp*Rh(2-(2-pyridyl)phenyl)]−. Its exceptional hydride donor ability makes Cp*Rh(2-(2-pyridyl)phenyl)H a very efficient catalyst for the ionic hydrogenation of iminium cations.

Research described herein seeks to study the reactivity of CpRu(P-P)H with pyridinium and azetidinium cations. For the former, we wish to determine if a previously established methodology for the regioselective reduction of a particular pyridinium cation may be extended to other pyridinium cations and if the methodology may be improved with the introduction of a pendant amine in the diphosphine. Our studies have shown that this methodology could not be extended to pyridinium cations having substituents on the pyridinium ring. For the latter, we seek to establish the reactivity of CpRu(P-P)H with azetidinium cations and compare these results to what the Norton Group has previously established in studies concerning aziridinium cations. Our studies have shown that opening of azetidinium is about six orders of magnitude slower compared to the opening of aziridinium.

The research described in this thesis focuses on the catalytic asymmetric hydrogenation of prochiral olefins using N, P – chelated iridium catalysts. This catalytic system is tolerant to a wide range of substrates and performs better than the well-known ruthenium- and rhodium-catalytic systems for substrates devoid of coordinating groups in proximity of the olefin. Low catalytic loadings (often <1 %) and the high atom efficiency of this reaction make it a synthetically useful method of chiral molecule synthesis. The primary aim of this thesis was to develop new catalysts that rapidly and efficiently hydrogenate a broad range of alkenes asymmetrically. Papers I and II describe the synthesis and evaluation of new, highly efficient, chiral N, P – ligated iridium complexes. These catalysts were obtained in relatively few steps, while leaving open possibilities to modify and fine-tune their structure. Their versatility is ideally suited to both industrial uses and to equip any catalyst box. Paper III deals with a common problem of defluorination of vinylic fluorides during the hydrogenation. The catalyst designed in that work performs well for several substrates giving very low defluorination rates making it a good starting point for further improvements to cover a broader scope of vinyl fluorides. The structures of the catalysts from papers I and III also offers an easy approach to attach the catalyst ligands to a solid support. Paper IV explores hydrogenation of vinyl boronates, which gives synthetically interesting borane compounds with high enantioselectivities. Taking into account the rich chemistry of organic boranes, these compounds are very important. Paper V deals with hydrogenation of diphenylvinylphosphine oxides and vinyl phosphonates, another important classes of substrates that give chiral phosphorous containing compounds of interest in many fields of chemistry: such as medicinal chemistry and organocatalysis. In papers VI and VII we explore the Birch reaction as a source of prochiral olefins. By combining asymmetric hydrogenation with it, we obtain a powerful method to create chiral compounds with excellent enantioselectivities that are next to impossible to make by other routes. The products of the asymmetric hydrogenation are further modified by other well-known transformation to create other induced stereogenic centres.

Hydrogenation of "largely unfunctionalized" alkenes has been an active area of research for about a decade. Many catalysts have been prepared but we noticed that comparatively few substrates have been studied and none of these hydrogenations provided useful chirons for the organic synthesis area. That motivated us to investigate asymmetric hydrogenations of chiral acyclic alkenes, which are seldom used for hydrogenations and usually the reactions are fully substrate controlled. It emerged that such reactions could provide a concise entry points into chirons that can be used to prepare many natural products. Asymmetric hydrogenations of functionalized, but not coordinatively functionalized, alkenes have been used to prepare several chirons for syntheses ofpolyketide natural products using our N,carbene Crabtree's catalyst analog. Starting from optically active starting materials (eg Roche esters, lactic acid, glyceraldehyde dimethyl ketals, amino acids), highly optically active chiral alkenes can be made in several steps with high yield. With the iridium catalyzed asymmetric hydrogenations, chiral ethers, 1,3-hydroxymethyl chiron, alpha-methyl-beta-hydroxy-gamma-methyl chiron, alpha-methyl-gamma-alkyl-gamma-amino acid can be obtained with high stereoselectivities. With those well developed methodologies, (-)-dihydromyoporone, (-)-spongidepsin, (-)-invictolide have been prepared with high efficiency. Not like the vinyl acetate, which can be hydrogenated quite well with many Rh catalysts, the alkyl vinyl ether does not have a coordination functional group nearby, hence it is a difficult substrate for asymmetric hydrogenation and there are relatively few iv reports. Also the simple alkyl enol ether is quite acid sensitive and the Pfatlz's type N,PIr catalysts cannot hydrogenate the simple alkyl enol ethers well under the standard hydrogenation conditions. We explored many alkyl enol ethers and found some of them can be hydrogenated efficiently (50 bar H2, 1 mol percent N,carbene-Ir catalyst, 25 degree C) with high enantioselectivities (up to 98 percent ee). This study led us to suspect that more protons were produced when N,P-Ir catalyst precursors were used relative to the corresponding carbene catalyst since the former only gave complex mixture when being used. DF calculations and several other experiments supported this postulation.

The present project is related to two aspects of research (i) to develop a new technique to synthesize fine nano-size polymer particles with unique and controllable properties; (ii) to synthesize novel functional polymer nanoparticles aiming to overcome the central challenge that has limited the commercialization of green latex hydrogenation, i.e. the optimal interplay of accelerating the hydrogenation rate, decreasing the required quantity of catalyst, and eliminating the need for an organic solvent. Focusing on these two objectives stated above, the following studies were carried out. (1) Development of Micellar Nucleation Mechanism for Preparation of Fine Polymer Nanoparticles. Polymer nanoparticles below 20 nm with a solid content of more than 13 wt% and a narrow molecular weight polydispersity (~1.1) were prepared using a micellar nucleation semibatch microemulsion polymerization system emulsified by sodium dodecyl sulfate (SDS), with SDS/monomer (methyl methacrylate) and SDS/H2O weight ratios of up to 1:16 and 1:100, respectively. It was found that for benzoyl peroxide (BPO), micellar nucleation is more favorable for the synthesis of smaller polymer nanoparticles than ammonium persulfate (APS), which gives rise to homogeneous nucleation and 2,2'-azobisisobutyronitrile (AIBN), which involves partially heterogeneous nucleation. In the polymerization process, there exists a critical stability concentration (CSC) for SDS, above which the size of the nanoparticles is to be minimized and stabilized. With an increase in the monomer addition rate, the polymerization system changes from a microemulsion system to an emulsion system. A mechanism was proposed to describe the micellar nucleation process of semibatch microemulsion polymerization. This technique will pioneer a significant new way to use a simple but practical method to synthesize narrow PDI polymers, which is a very meaningful new development. (2) Diene-Based Polymer Nanoparticles: Preparation and Direct Catalytic Latex Hydrogenation. At the first stage of this study, poly(butadiene-co-acrylonitrile) nanoparticles were synthesized in a semibatch microemulsion polymerization system using Gemini surfactant trimethylene-1,3-bis (dodecyldimethylammonium bromide), referred to as GS 12-3-12, as the emulsifier. The main characteristic of this GS emulsified system lies in that the decomposition rate of initiator was increased considerably at a low reaction temperature of 50 °C because of the acidic initiation environment induced by GS 12-3-12. The particle size can be controlled by the surfactant concentration and monomer/water ratio and a particle size below 20 nm can be realized. The obtained latex particles exhibit a spherical morphology. The microstructure and copolymer composition of the polymer nanoparticles was characterized by FT-IR and 1H NMR spectroscopy. The effects of the surfactant concentration on the particle size, Zeta-potential, polymerization conversion, copolymer composition, molecular weight, and glass transition temperature (Tg) were investigated. The kinetic study of the copolymerization reaction was carried out, which indicated that an azeotropic composition was produced. The relationship between Tg and number-average molecular weight can be well represented by the Fox-Flory equation. Finally, the semibatch process using conventional single-tail surfactant SDS was compared. In the second stage of this study, the prepared unsaturated nanoparticles were employed as the substrates for latex hydrogenation in the presence of Wilkinson’s catalyst, i.e., RhCl(P(C6H5)3)3. The direct catalytic hydrogenation of poly(butadiene-co-acrylonitrile) nanoparticles in latex form was carried out under various experimental conditions in the presence of Wilkinson’s catalyst without the addition of any organic solvents. In order to appreciate the important factors which influence the nature and extent of this type of hydrogenation, the effects of particle size within the range from 17.5 to 42.2 nm, temperature from 90 to 130 °C, and catalyst concentration from 0.1 to 1.0 wt% (based on the weight of polymer) on the hydrogenation rate were fully investigated. The kinetics study shows that the reaction is chemically controlled with a fairly high apparent activation energy, which is calculated to be between 100 and 110 kJ/mol under the experimental conditions employed. Mass transfer of both hydrogen and catalyst involved in the reaction system was discussed. The analysis of mass transfer of reactants coupled with the reaction kinetics indicated that the catalysis of hydrogenation proceeds at the molecular level. The competitive coordination of the active catalyst species RhH2Cl(PPh3)2 between the carbon-carbon unsaturation and the acrylonitrile moiety within the copolymer was elucidated based on the reaction kinetics of the hydrogenation. (3) Poly(methyl methacrylate)-poly(acrylonitrile-co-butadiene) (PMMA-NBR) Core-Shell Polymer Nanoparticles: Preparation and Direct Catalytic Latex Hydrogenation. PMMA-NBR core-shell structured nanoparticles were prepared using a two stage semibatch microemulsion polymerization system with PMMA and NBR as the core and shell respectively. The GS 12-3-12 was employed as the emulsifier and found to impose a pronounced influence on the formation of the core-shell nanoparticles. A spherical morphology of the core-shell nanoparticles was observed. It was found that there exists an optimal MMA addition amount which can result in the minimized size of PMMA-NBR core-shell nanoparticles. The formation mechanism of the core-shell structure and the interaction between the core and shell domains was illustrated. The PMMA-NBR nano-size latex can be used as the substrate for the following direct latex hydrogenation catalyzed by Wilkinson’s catalyst to prepare the PMMA-HNBR core-shell nanoparticles. The hydrogenation rate is rapid. In the absence of any organic solvent, the PMMA-HNBR nanoparticles with a size of 30.6 nm were obtained within 3 h using 0.9 wt% Wilkinson’s catalyst at 130 °C under 1000 psi of H2. This study provides a new perspective in the chemical modification of NBR and shows promise in the realization of a "green" process for the commercial hydrogenation of unsaturated elastomers.

The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity. This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.

In this research, two-stage hydrotreating of bitumen-derived light gas oil (LGO) from Athabasca oil sands was studied. The objective was to catalytically upgrade the LGO by reducing the aromatics content and enhancing the cetane content via inter-stage removal of hydrogen sulfide. The impact of hydrogen sulfide inhibition on aromatics hydrogenation (HDA), hydrodenitrogenation (HDN) and hydrodesulfirization (HDS) activities was investigated. Experiments for this study were carried out in a trickle-bed reactor loaded with commercial NiMo/Al2O3 and lab-prepared NiW/Al2O3 in the stage I and stage II reactors, respectively. Temperature was varied from 350 to 390 oC at the optimum LHSV and pressure conditions of 0.6 h-1 and 11.0 MPa, respectively. The results from two-stage process showed significant improvement in HDA, cetane rating and HDS activities compared to the single-stage process after the inter-stage removal of hydrogen sulfide. Hence, the presence of hydrogen sulfide in the reaction retarded both the HDA and HDS processes in the single-stage operation. Negligible hydrogen sulfide inhibition was however, observed in the HDN process. <p>Prior to the two-stage hydrotreating study, single-stage hydrotreating reactions were carried out over commercial NiMo/Al2O3 catalyst to determine the optimum operating conditions for maximizing hydrogenation of aromatics. A statistical approach via the Analysis of Variance (ANOVA) technique was used to develop regression models for predicting the conversion of aromatics, sulfur and nitrogen in the LGO feed. Experiments were performed at the following operating conditions: temperature (340-390 oC); pressure (6.9-12.4 MPa) and liquid hourly space velocity, LHSV (0.5-2.0 h-1). Hydrogen-to-oil ratio was maintained constant at 550 ml/ml. The results showed that the two-level interaction between temperature and pressure was the only significant interaction parameter affecting HDA while interaction between temperature and LHSV was the most important parameter affecting both HDS and HDN activities. A maximum 63 % HDA was obtained at 379 oC, 11.0 MPa and 0.6 h-1. Experiments with NiW/Al2O3 were also performed in a single-stage reactor with LGO blend feedstock by varying temperature from 340-390 oC at the optimum pressure and space velocity of 11.0 MPa and 0.6 h-1, respectively. The following order of ease of hydrogenation was observed: poly- > di- >> monoaromatics. The order of ease of hydrogenation in other LGO feedstocks (atmospheric light gas oil, ALGO; hydrocrack light gas oil, HLGO; and vacuum light gas oil, VLGO) was studied and found to follow the order: VLGO > ALHO > HLGO. Studies on mild hydrocracking (MHC) in the gas oil feedstocks showed a net increase in gasoline with a corresponding decrease in diesel with increasing temperature. <p>Both the single and two-stage HDA and HDS kinetics were modeled using Langmuir-Hinshelwood rate equations. These models predicted the experimental data with reasonable accuracy. The degree of conversion of the gas oil fractions in ALGO, HLGO and VLGO via mild hydrocracking was best described by a pseudo-first order kinetic model based on a parallel conversion scheme.

Diimide generated from the hydrazine/hydrogen peroxide/catalyst system can be used to hydrogenate unsaturated polymers in latex form. As an economical and environmentally benign alternative to the commercial processes based on hydrogen/transition metal catalysts, this method is of special interest to industry. This thesis provides a detailed description of the diimide hydrogenation process. Reaction kinetics, catalysts and gel formation mechanism have been investigated. <br /> <br /> Four main reactions and a mass transfer process form three parallel processes in this system: diimide is generated at the interface of the latex particles; diimide diffuses into the organic phase to saturate carbon-carbon double bonds; diimide may be consumed at the interface by hydrogen peroxide, and may also be consumed by the disproportionation reaction in the organic phase. The two side reactions contribute to the low hydrogenation efficiency of hydrogen peroxide. Slowing down hydrogen peroxide addition and using stable interfacial catalysts may totally suppress the side reaction in the aqueous phase. The actual catalytic activity of metal ions in the latex depends on the hydrogen peroxide concentration and the addition procedure of reactants. Cupric ion provides better selectivity for hydrogenation than ferric ion and silver ion do. Boric acid as a promoter provides improved selectivity for hydrogenation and faster diimide generation rate. The side reaction in the rubber phase results in low efficiency and gel formation. The rate constants of the four reactions in this system are estimated. <br /> <br />It is shown that the hydrogenation of nitrile rubber latex with an average particle diameter of 72 nm is mainly a reaction-controlled process. Diimide diffusion presents limitation upon hydrogenation at high hydrogenation degree range. Antioxidants can not effectively inhibit gel formation during hydrogenation. Hydrogenation of a core-shell latex with NBR as the shell layer should be able to achieve a higher efficiency, a higher degree of hydrogenation and a lower level of crosslinking.

In this research, two-stage hydrotreating of bitumen-derived light gas oil (LGO) from Athabasca oil sands was studied. The objective was to catalytically upgrade the LGO by reducing the aromatics content and enhancing the cetane content via inter-stage removal of hydrogen sulfide. The impact of hydrogen sulfide inhibition on aromatics hydrogenation (HDA), hydrodenitrogenation (HDN) and hydrodesulfirization (HDS) activities was investigated. Experiments for this study were carried out in a trickle-bed reactor loaded with commercial NiMo/Al2O3 and lab-prepared NiW/Al2O3 in the stage I and stage II reactors, respectively. Temperature was varied from 350 to 390 oC at the optimum LHSV and pressure conditions of 0.6 h-1 and 11.0 MPa, respectively. The results from two-stage process showed significant improvement in HDA, cetane rating and HDS activities compared to the single-stage process after the inter-stage removal of hydrogen sulfide. Hence, the presence of hydrogen sulfide in the reaction retarded both the HDA and HDS processes in the single-stage operation. Negligible hydrogen sulfide inhibition was however, observed in the HDN process. <p>Prior to the two-stage hydrotreating study, single-stage hydrotreating reactions were carried out over commercial NiMo/Al2O3 catalyst to determine the optimum operating conditions for maximizing hydrogenation of aromatics. A statistical approach via the Analysis of Variance (ANOVA) technique was used to develop regression models for predicting the conversion of aromatics, sulfur and nitrogen in the LGO feed. Experiments were performed at the following operating conditions: temperature (340-390 oC); pressure (6.9-12.4 MPa) and liquid hourly space velocity, LHSV (0.5-2.0 h-1). Hydrogen-to-oil ratio was maintained constant at 550 ml/ml. The results showed that the two-level interaction between temperature and pressure was the only significant interaction parameter affecting HDA while interaction between temperature and LHSV was the most important parameter affecting both HDS and HDN activities. A maximum 63 % HDA was obtained at 379 oC, 11.0 MPa and 0.6 h-1. Experiments with NiW/Al2O3 were also performed in a single-stage reactor with LGO blend feedstock by varying temperature from 340-390 oC at the optimum pressure and space velocity of 11.0 MPa and 0.6 h-1, respectively. The following order of ease of hydrogenation was observed: poly- > di- >> monoaromatics. The order of ease of hydrogenation in other LGO feedstocks (atmospheric light gas oil, ALGO; hydrocrack light gas oil, HLGO; and vacuum light gas oil, VLGO) was studied and found to follow the order: VLGO > ALHO > HLGO. Studies on mild hydrocracking (MHC) in the gas oil feedstocks showed a net increase in gasoline with a corresponding decrease in diesel with increasing temperature. <p>Both the single and two-stage HDA and HDS kinetics were modeled using Langmuir-Hinshelwood rate equations. These models predicted the experimental data with reasonable accuracy. The degree of conversion of the gas oil fractions in ALGO, HLGO and VLGO via mild hydrocracking was best described by a pseudo-first order kinetic model based on a parallel conversion scheme.

In this article, we examined different synthetic approaches with varying adding starting materials for the thiol containg schiff-base complex [ZnL1]2(L1=o-C6H4(SH)(CH=NC6H4SH-o)). We found that the key step for successful synthesis of [ZnL1]2 is the formation of zinc aldehyde intermediate. We also break the [ZnL2]2 dimer by adding chelating agent, TMEDA, to obtain the Zn(L1)(TMEDA) monomer. It¡¦s single crystal X-ray structure confirmed, the structure of the target ligand L1. We also synthesized [NiL1]2 by transmetalation of [ZnL1]2 - an easier synthetic approach. We further reduced the imine part on L1 of [ZnL1]2 and Zn(L1)(TMEDA) to get [ZnL2]2(L2=o-C6H4(SH)(CH2NHC6H4SH-o)) and Zn(L2)(TMEDA) respectively for future reactivity studies.