Thesis (Ph. D.)--University of Toledo, 2005. / Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Includes bibliographical references (leaves 196-217).

ChapterI contains a review of phosphoniteisn asymmetric catalysis and recent developments in asymmetric hydrogenation and a symmetric hydroformylation catalysis. Chapter2 is concerned with new phosphonite ligands f r asymmetric catalysis. A new three-steps ynthesiso f 9,9'-biphenanthryl-10,10'-dio(lb iphenanthrol') in 36% yield from phenanthrene is reported. The ligands PhP(OR)2, PhP(OR')2, (RO)2PCH2CH2P(OR)2a nd Ph2PCH2CH2P(OR)2 derived from 'biphenanthrol' (HOR)2 and dimethyl-1,1'-binaphthyl-2,2'-dihydroxy-3,3'-dicarboxylate( HOR')2 have been synthesised and their Pt(O,I I) and R h(I) chemistry is discussed The crystal structures of two complexes of the type [PtC12(phosphonite)h2a] ve been determined. The monoPhosphonite, diphosphonite and phosphinophosphonite complexes [Rh(cod)P2]BF4 derived from (S)-'biphenanthroal'r e described. In Chapter 3, the chemistry of some new diphosphites is described. The diastereomeric mixture of (RO)2P(ORRO)P(OR)2( 'biphenanthrite') is formed by reacting (±)-'biphenanthrol' with PC13- Optically pure (R, R, R)-'biphenanthrite' is similarly prepared from (R)-biphenanthrol'.The side-products and intermediates in this reaction are identified by their independent syntheses C: IP(OR)2,H (O)P(OR)2, (RO)2POP(OR)a2n d (HORRO)P(OR)2 Dehydration of 'biphenanthrola' lso occurs to give a furan, which was characterisedb y X-ray crystallography. Two equivalents of (R)-CIP(OR)2 react with (R)- or (S)-'binaphthol' (HOR")2 to give (R, R, R)- and (R, S, R)-(RO)2P(OR"R"O)P(OR)2 ('pnp'). The disodium salt of (±)-'biphenanthrol' reacts with two equivalents of (±)-CIP(OR)2 to yield the single ((R, SR) / (SR, S))- diastereomeor f 'biphenanthriteT. he Pt(II), Pd(11aI)n dR h(I) coordinationc hemistry of these new diphosphitesis reported. The complexes[ MC12(diphosphite)a] re fluxional due to the conformational flexibility of the nine-memberech delate ring and the crystal structures of (R,R ,R )- and (SR,S )-[PtC12('biphenanthrite)s]h ow very different ring conformations T.he hydroformylation of styrenes catalysed by rhodium(I) complexes of (R, R, R)-'biphenanthrite', (R, S, R)-'pnp' and (R, R, R)-pnp' is reported. The 'biphenanthritec' complex gives 50% branched aldehyde and no asymmetric induction. The complex of (R, SR)-'pnp' gives 91-96% branched aldehyde and up to 72% ee. The differences in the catalytic properties of the diastereomer is discussed. In Chapter4 , the asymmetric hydrogenation of oc-enamides with rhodium(I) complexes of the new phosphonites and diphosphitesa s catalysts is discussed The diphosphonite complex shows low activity and a modest ee (up to 41%) but the analogousp hosphinophosphonitceo mplex is highly active and gives high ee's (up to 88%).T his is the first phosphinophosphonittoe be used in asymmetric hydrogenation. The monophosphonitceo mplexi s very activea ndt he ee's of up to 92% aret he highest obtained with a monodentatleig and in asymmetric cc-enamide hydrogenation. Chapter5 gives the experimental details for the chemistry reported in this thesis.

M.Sc. / The main objective of the research described in this dissertation, was the optimisation of the palladium catalysed hydroformylation of a-olefms. An evaluation of the efficiency of the palladium catalysed hydroformylation process required a comparison with the hydroformylation processes based on cobalt and rhodium. Variation of ligands (diphosphines of the size R2P(CH2)nPR2), solvents, acids, etc. had a dramatic effect on the products and the rate of the reaction. Trifluoroacetic acid was used to yield C-6 aldehydes from 1-pentene while trifluoromethanesulfonic acid yields C-11 ketones. Corresponding results were obtained with 1-octene as substrate. The length of the carbon bridge between the two phosphorous atoms has an optimum length of two in the case of alkylphosphine ligands, while an optimum length of three was found in the case of arylphosphine ligands. One disadvantage of the palladium catalysed hydroformylation reaction is that this reaction requires the use of bidentate phosphine ligands. These ligands are relatively expensive and also difficult to synthesise. The instability of the palladium complex and thus the precipitation of palladium were one of the major obstacles that had to be overcome. The use of additives not only increased the rate of hydroformylation but also increased catalyst stability, which in turn allowed an increase in the reaction temperature. This further increased the rate of the palladium catalysed hydroformylation reaction. These palladium catalysts were found to affect isomerisation of the a-olefin, but isomerisation was not a rate limiting process with respect to the hydroformylation reaction. Palladium catalysed isomerisation reactions occurred at a slower rate than the corresponding cobalt catalysed isomerisation process. However, with rhodium no isomerisation occurred. The comparison between cobalt, rhodium and palladium showed that rhodium is the best catalyst for the hydroformylation of a-olefins. The pressures and temperatures required for this process are much slower than that required for palladium and cobalt. The ligand used is triphenylphosphine, which is relatively inexpensive and non-toxic, in contrast with the more expensive ligands required for the cobalt and palladium hydroformylation processes. The use of palladium opens up the unique possibility of converting a-olefins into "dimeric" ketones, which show promise as precursors for the new class of geminidetergent

M.Sc. / The main objective of the research described in this dissertation was to prepare a range of triaryl phosphine ligands having systematically changing stereo-electronic properties using Grignard reagents and P-Cl derivatives. These ligands were utilised in the Rh-catalysed hydroformylation reaction in order to determine the effects of stereo-electronic properties of these ligands on the outcome of the reaction. Initially, a first series of tri-aryl phosphine ligands having methyl or ethyl groups substituted on the ortho or para position of the phenyl rings was successfully synthesised. The stereoelectronic properties of these ligands were probed by determining the P=Se coupling constants of the Se-phosphine derivatives and the CO vibrational frequencies of the Vaskatype complexes of these ligands. It was shown that the substitution of alkyl groups on the phenyl rings of the phosphine ligands resulted in the formation of more electron-rich ligands. In the Rh-catalysed hydroformylation reaction a systematic decrease in the yields of aldehydes were observed as the basicity of the phosphine ligand increased. Inspired by the outcome of the first series, a second series of tri-aryl phosphine ligands having both methyl and fluoro groups variously substituted (ortho, meta and para positions) on the phenyl rings was successfully synthesised. It was observed that the group substituted on the ortho position electronically dominated over the group substituted in the meta and para position of the phenyl rings. Substitution of fluorine atoms on the ortho position and methyl on the para position of the phenyl rings resulted in the formation of less electron-rich phosphine ligands, while the opposite substitution pattern (p-F-o-Me) resulted in the formation of more electron-rich ligands. The former caused an increase in the yields of aldehydes obtained in the Rh-catalysed hydroformylation reaction compared to triphenylphosphine. viii A third series of tri-aryl phosphine ligands having trifluoromethyl groups substituted on the ortho, meta or para positions of the phenyl rings was successfully synthesised. It was observed that substitution of the trifluoromethyl groups on the meta and para positions of the phenyl rings resulted in the formation of less electron-rich phosphine ligands, while substitution on the ortho position resulted in the formation of more electron-rich ligands. The hydroformylation reaction with these ligands followed the same trend as with the first and second series of tri-aryl phosphine ligands. A series of tri-aryl phosphine-borane adducts of the first series of phosphine ligands was also successfully synthesised using BH3·THF. These ligands were employed in the Rh-catalysed hydroformylation reaction with the aim to determine whether in situ deprotection of the phosphine-borane adducts with CO was possible. The hydroformylation results with these adducts provided yields of aldehydes similar to those of the free phosphines. This suggested that deprotection had occurred to release the free phosphine which complexed to the Rh catalyst. This indicated that phosphine-borane complexes can be directly applied to carbonylation reactions eliminating the use of common deprotection methods and provides an opening for more research in this regard.

Triacetyl-D-glucal, an unsaturated sugar has been prepared and submitted to the hydroformylation reaction, which is the addition of carbon monoxide and hydrogen to an unsaturated compound at high pressure and temperature. A cobalt catalyst is generally used, in this case, cobalt acetate tetrahydrate. The mixture of products obtained was separated by column chromatography and distillation. The main products are probably triacetyl-D-deoxyglucose obtained by the addition of water to the starting material, 1,2-hydroglucal obtained by hydrogenation of the starting material, a small amount of the theoretical hydroformylation compound and varying amounts of the starting material. / Science, Faculty of / Chemistry, Department of / Graduate

The hydroformylation of oct-1-ene is investigated under fluorous biphasic conditions, utilising the facile catalyst recovery that is provided by the temperature dependent miscibility of the perfluorinated solvent with normal organic solvents. High conversions and selectivities have been obtained in the batch process and the system is now described under continuous-flow conditions in a custom built reactor. The continuous-flow reactor was successfully run for 46 hours, with conversions to nonanal of 60% and l:b ratios of approximately 10. To understand the mechanism of this reaction more fully, a spectroscopic study of the catalyst formation and hydroformylation reaction was undertaken, using high-pressure infrared (HPIR) and nuclear magnetic resonance (HPNMR) techniques. The results of this study showed that although there is some effect of the strongly electron withdrawing nature of the perfluorinated ligand, the species formed under reaction conditions are very similar to those formed under the analogous triphenylphosphine system. It was found that under reaction conditions the perfluorinated ligand formed both the bis- and tris- phosphine complexes, compared to triphenylphosphine, which only formed the bis-phosphine complexes. The equatorial-equatorial and equatorial-axial isomers of [RhH(CO)₂(P(C₆H₄C₆F₁₃)₃)₂] were identified by means of a deuterium study in the HPIR spectrometer. The low levels of phosphorus and rhodium leaching to the organic phase were attributed to the predominant formation of [RhH(CO)(P(C₆H₄C₆F₁₃)₃)₃] under ambient pressure and temperature (separator conditions) indicated by a well defined quartet in the metal hydride region of the ¹H NMR spectrum.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This project entailed the synthesis and characterization of mono- and multi-nuclear rhodium and ruthenium iminopyridyl complexes and their application in the hydroformylation of 1- octene. The multi-nuclear complexes were synthesized in order to investigate whether it could produce catalysts with higher activity than their mononuclear analogues. Four novel iminopyridyl ligands, ranging from mono- to tetra-functional compounds, were synthesized. The synthesis was a two-step process initially involving a Schiff base condensation reaction between 2-pyridinecarboxaldehyde and 4-aminophenol to produce a hydroxy functionalized pyridine-imine. The latter was then subjected to a nucleophilic substitution reaction with an appropriate benzyl bromide derivative to yield the target ligands. All these ligands were isolated in moderate to good yields and characterized using a range of analytical techniques. These ligands, together with the hydroxy functionalized pyridine imine, were then complexed to both Rh(I) and Ru(II) metal precursors, yielding ten novel metal complexes. The characterization of some of the complexes, especially the multi-nuclear complexes, were slightly more difficult due to their low solubility. However, all these complexes could be isolated in good to high yields as stable green-brown (in the case of Rh(I)) and yellow-orange (in the case of Ru(II)) solids. Finally, these complexes were applied as catalyst precursors in the hydroformylation of 1- octene. In the case of the Rh(I) complexes, relatively high activities were observed, with conversions ranging between 50 – 90 % in all cases, when tested at 30 bar, 75 °C and a 0.05 mol% catalyst loading. The activity was found to increase when going from the mono- to the bi-nuclear catalyst. However, solubility in the reaction medium was a major issue for the trinuclear catalyst, as it contributed to the lower activity observed. High chemoselectivity towards aldehydes was observed for all catalysts, which increased with reaction times. During shorter reaction time, linear regioselectivity was also relatively high. This however, decreased with increasing reaction time as the internal octenes formed initially, were converted to branched aldehydes. When the Ru(II) complexes were tested under the same conditions as the Rh(I) complexes, very low activity was observed. Under more stringent conditions (45 bar, 120 °C, 0.5 mol%) the ruthenium catalysts performed relatively well, compared to other complexes in the literature. The same trend in terms of the chemo- and regioselectivity for the Ru(II) complexes were observed. The Rh(I) complexes were far more active than the Ru(II) complexes. / AFRIKAANSE OPSOMMING: Hierdie projek behels die sintese en karakterisering van mono- en multi-kernige rhodium en ruthenium iminopiridiel komplekse en hul toepassing in the hidroformulering van 1-okteen. Die multi-kernige komplekse is gesintetiseer met die doel om vas te stel of hulle katalisatore wat meer aktief is as hul monokernige eweknieë, kan produseer. Vier nuwe iminopiridiel ligande, wat strek vanaf mono- tot tetra-funksionele verbindings, is gesintetiseer. Die sintese was ‘n twee-stap proses wat aanvanklik ‘n Schiff basis kondensasie reaksie tussen 2-piridienaldehied en 4-aminofenol behels, om ‘n fenol gefunksioneerde piridien-imien te vorm. Die laasgenoemde was gevolglik aan ‘n nukleofiliese substitusie reaksie met ‘n gepaste bensiel bromied derivaat onderhewig. Al hierdie ligande is geisoleer in matige tot goeie opbrengste en gekarakteriseer met ‘n reeks analitiese tegnieke. Hierdie ligande, tesame met die fenol gefunksioneerde piridien imien, is dan met Rh(I) en Ru(II) metaal uitgangstowwe gekomplekseer, wat tien nuwe metaal komplekse tot gevolg gehad het. Die karakterisering van sommige van die kompekse, spesifiek die multi-kernige komplekse, was effens moeiliker as gevolg van hul swak oplosbaarheid. Al hierdie komplekse kon egter in goeie tot hoë opbrengste as stabiele groen-bruin (in die geval van Rh(I)) en geel-oranje (in die geval van Ru(II)) vastestowwe geisoleer word. Laastens is die komplekse as katalisator-voorlopers in die hidroformulering van 1-okteen gebruik. In die geval van die Rh(I) komplekse is redelike hoë aktiwiteite waargeneem, met omsettings tussen 50 – 90 % in alle gevalle, wanneer hulle by 30 bar, 75 °C en ‘n katalisator lading van 0.05 mol% getoets is. Die aktiwiteit neem toe vanaf die mono- na die bi-kernige katalisator. Oplosbaarheid in die reaksie medium was egter ‘n probleem vir die tri-kernige katalisator, wat ‘n laer aktiwiteit tot gevolg gehad het. Hoë chemoselektiwiteit na aldehiede is waargeneem vir al die katalisatore en dit neem toe met reaksietyd. Gedurende korter reaksietye was die liniêre regioselektiwiteit ook redelik hoog, maar neem af met toenemende reaksietyd soos die interne okteen wat aanvanklik vorm na vertakte aldehiede omgeskakel word. Toe die Ru(II) komplekse onder dieselfde toestande as die Rh(I) komplekse getoets is, was baie lae aktiwiteite waargeneem. Onder hoër temperatuur en druk (45 bar, 120 °C, 0.5 mol%) toon die ruthenium katalisatore redelik goeie aktiwiteite in vergelyking met ander komplekse wat in die literatuur gerapporteer is. Dieselfde tendense in terme van die chemoen regioselektiwiteit is vir die Ru(II) komplekse waargeneem. Die Rh(I) kompleks was baie meer aktief as die Ru(II) komplekse.

No description available.

Ph.D. (Chemistry) / Rhodium-catalyzed hydroformylation is one of the most important industrial processes for the production of linear and branch aldehydes. Aldehydes serve as intermediates in the production of various fine chemicals. Rh-based homogeneous catalysts for aldehydes production have demonstrated high yields and selectivity. Catalyst separation and recovery of expensive Rh-metal from reaction mixtures is a challenge to this process. With increasing industrial demand for highly selective processes, homogeneous catalysis could well be extensively employed if catalyst recovery from products and recyclability could be accomplished more efficiently and economically. The above problems justify the investigation of immobilized (heterogenized) catalysts by both academia and industry. This would solve the separation problem by making it possible to separate the catalyst from the reaction medium with simple filtration techniques and to regenerate the catalyst for reuse. Moreover, the ease of recovery of catalyst from products and reusability can minimize the impact of the process on the environment. Immobilization of metal complexes on solid supports is an effective approach to overcome the limitations of homogeneous catalysis. Support materials such as Mobil Composite Material (MCM-41) and Santa Barbara Amorphous type material (SBA-15) are attractive candidates for immobilizing metal complexes because of their high surface area, adjustable pore sizes, large pore volumes and high surface silanol groups. In the present work, mesoporous silica supports, MCM-41 and SBA-15 were synthesized. Rhodium(I) complex species, trans-aquacarbonyl bis(triphenylphosphine) [Rh(CO)(OH2)(PPh3)2]OTf and trans-aquacarbonyl bis{tris-(m-sulfonphenyl)-phosphine} [Rh(CO)(OH2)(TPPTS)2]OTf were synthesized as catalyst precursors and anchored onto the mesoporous MCM-41 and SBA-15 framework structure via an electrostatic method to form immobilized (heterogenized) catalysts. The support and catalyst were characterized using a range of solid-state techniques. Results showed that the structural integrity of the catalyst supports was maintained after immobilization. Results also revealed a strong interaction between rhodium complex species and the inner walls of the ordered mesoporous materials, thus leading to the formation of stable heterogenized catalysts. In addition, immobilized catalysts constrained the pores, thus leading to a confinement effect, which enhanced activity and regioselectivity in the hydroformylation process. Selected immobilized catalysts were...

Thesis advisor: Kian L. Tan / General and efficient methods for the selective hydroformylation of allylic alcohols and amines utilizing a directing group approach. / Thesis (MS) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.