A new normal form x2 + y2 = c2(1 + x2y2) of elliptic curves was introduced by M. Harold Edwards in 2007 over the field k having characteristic different than 2. This new form has very special and important properties such that addition operation is strongly unified and complete for properly chosen parameter c . In other words, doubling can be done by using the addition formula and any two points on the curve can be added by the addition formula without exception. D. Bernstein and T. Lange added one more parameter d to the normal form to cover a large class of elliptic curves, x2 + y2 = c2(1 + dx2y2) over the same field. In this thesis, an expository overview of the literature on Edwards curves is given. First, the types of Edwards curves over the nonbinary field k are introduced, addition and doubling over the curves are derived and efficient algorithms for addition and doubling are stated with their costs. Finally, known elliptic curves and Edwards curves are compared according to their cryptographic applications. The way to choose the Edwards curve which is most appropriate for cryptographic applications is also explained.

Le glycérol est une molécule bio-sourcée, abondamment disponible, issue de la saponification des corps gras et de la transestérification des huiles végétales. Les travaux portent sur l'utilisation du glycérol comme base structurale de cœurs de dendrimère, en particulier par addition d'oxa-Michael sur des dérivés acryliques. La fonctionnalisation en surface de dendrimères par des motifs imidazolium est explorée afin d’obtenir un dendrimère liquide ionique (DLI) aux propriétés thermosensibles. Le chapitre bibliographique est consacré dans une première partie, aux méthodes de synthèse de dendrimère mettant en jeu des dérivés acryliques et à leurs applications et dans une seconde partie, aux travaux consacrés à l'addition oxa-Michael d'alcools sur des dérivés acryliques. Le deuxième chapitre porte sur les synthèses, à partir du glycérol, de la base structurale du cœur de dendrimère. La réaction d’acylation du glycérol par le chlorure d’acryloyle est présentée ainsi que les différentes constructions de dendrimères poly(estersulfure) à partir du triacrylate de glycérol. L’addition nucléophile du glycérol sur l’acroléine, l’acrylamide, des acrylates et l’acrylonitrile a été étudiée. Avec les acrylates, la réaction d'addition nucléophile est en compétition avec la réaction de transestérification, à l’exception de l'acrylate de t-butyle résistant en milieu basique. Avec l’acrylonitrile, la synthèse du 1,2,3-tricyanoéthylglycéryléther a pu être menée sans solvant, en 5 heures à température ambiante, en présence d’un catalyseur peu coûteux (la soude 4 mol %) avec un rendement de 88% et une pureté de 99% sans méthode de purification. Les intermédiaires de réaction mono- et di-cyanoéthylglycéryléther ont été caractérisés et ont permis un suivi cinétique de la réaction. La synthèse de dendrimères poly(amidoamine) à partir du 1,2,3-tricyanoéthylglycéryl éther fait l’objet du troisième chapitre : synthèse des générations G0 à G2,5, caractérisation des dendrimères. Des défauts de structure dus à une cyclisation intramoléculaire ont été mis en évidence par HRMS pour les générations entières et les dendrimères de demi-génération Gn+5 (n entier) sont purifiés par colonne chromatographique. Différentes voies de synthèse pour l’obtention d’un DLI à termini imidazolium sont présentées / Glycerol is a bio-based molecule, abundantly available, from the saponification of triglyceride and the transesterification of vegetable oils. The work described in this PhD thesis concerns the use of glycerol as structural base of dendrimer's core, in particular by oxa-Michael addition on acrylic derivatives. The surface functionalization of dendrimers by imidazolium units is explored in order to obtain an ionic liquid dendrimer (DLI) with thermosensitive properties. In the first part, the bibliographic chapter presents the methods of dendrimers synthesis involving acrylic derivatives and their applications and, in a second part, the work introduces the oxa-Michael addition of alcohols to acrylic derivatives. The second chapter deals with the synthesis of the structural base of the dendrimer core from glycerol. The reaction of acylation of glycerol with acryloyl chloride is presented as well as the various constructions of poly(estersulfide) dendrimers from glycerol triacrylate. The nucleophilic addition of glycerol to acrolein, acrylamide, acrylates and acrylonitrile has been studied. With the acrylates, the nucleophilic addition reaction is in competition with the transesterification reaction, with the exception of t-butyl acrylate, resistant in basic medium. With acrylonitrile, the synthesis of 1,2,3-tricyanoethylglycerylether was carried out without solvent in 5 hours at room temperature in the presence of an inexpensive catalyst (4 mol% sodium hydroxide) in a yield of 88% and purity of 99% without purification method. The mono- and di-cyanoethylglycerylether reaction intermediates were characterized and allowed kinetic monitoring of the reaction. The synthesis of poly(amidoamine) dendrimers from 1,2,3-tricyanoethylglycerylether is the subject of the third chapter: synthesis of generations G0 to G2,5 and characterization of dendrimers. The defects in the structure due to intramolecular cyclization have been demonstrated by HRMS for generations Gn and the half-generation dendrimers Gn+5 (n=0, 1, 2) were purified by chromatographic column. Several routes of synthesis for the synthesis of DLI with imidazolium termini are presented

The Morita-Baylis-Hillman (MBH) reaction is a very versatile synthetic protocol to synthesize various useful compounds containing several functional groups. MBH acetates and carbonates are highly valued compounds as they have good potential to be precursors for organic synthesis reactions due to their ease of modification and synthesis. This thesis utilizes Density Functional Theory (DFT) calculations to understand the mechanism and selectivity of an unexpected tandem conjugate addition-elimination (CA-E) reaction of allylic alkylated Morita-Baylis-Hillman C- adducts. This synthetic protocol was developed by Prof. Zhi-Yong Jiang and co-workers from Henan University, China. The reaction required the use of sub-stoichiometric amounts of an organic or inorganic Brøndst base as a catalyst and was achieved with excellent yields (96%) in neat conditions. TBD gave the highest yield amongst the organocatalysts and Cs2CO3 gave the highest yield amongst all screened bases. A possible mechanistic pathway was proposed and three different energy profiles were modeled using 1,5,7-triaza-bicyclo-[4.4.0]-dec-5-ene (TBD), Cs2CO3 and CO32- as catalysts. All three models were able to explain the experimental observations, revealing both kinetic and thermodynamic factors influencing the selectivity of the CA-E reaction. CO32- model gave the most promising result, revealing a significant energy difference of 17.9 kcal/mol between the transition states of the two differing pathways and an energy difference of 20.9 kcal/mol between the two possible products. Although TBD modeling did not show significant difference in the transition states of the differing pathways, it revealed an unexpected secondary non-covalent electrostatic interaction, involving the electron deficient C atom of the triaza CN3 moiety of the TBD catalyst and the O atom of a neighboring NO2- group in the intermediate. Subsequent modeling using a similar substrate proved the possibility of this non-covalent electrostatic interaction, as there was significant overlap of the orbital cloud present in both the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) of the molecule between the C atom of the triaza moiety belonging to the TBD catalyst and the O atom of the nitro group of the substrate. The Mayer bond order was of the C-O interaction was determined to be 0.138.

La présence conjointe de plusieurs fonctions confère aux allylphosphonates β-éthoxycarbonylés une réactivité particulière. Ces derniers sont considérés comme d’excellents précurseurs pour l’accès à de nouveaux composés organophosphorés. Dans le présent travail, nous avons décrit, dans un premier temps, l’utilisation de ces adduits entant qu’accepteurs de Michael. En effet, nous avons effectué des additions conjuguées d ethiols, d’amines et d’anions énolates dans des conditions réactionnelles douces. Ces allylphosphonates ont été également utilisés pour la préparation d’une nouvelle famille de γ-lactames α,β-instaurés phosphono-méthylés.L’étape clé de cette synthèse est une addition conjuguée de nitroalcanes sur les allylphosphonates suivie d’une réaction de Nef..Les cétoesters ainsi obtenus sont convertis en lactames par action d’amines primaires. Des réactions d’arylations pallado-catalysées sur les allyphosphonates ont permis l’accès à des hétérocycles phosphonatés dérivant de lacoumarine, de la quinoléine et de la benzoxépinone. La synthèse de P-hétérocyclesde différentes tailles à partir des allylphosphonates a été aussi possible par la conversion du groupe phosphonate en phosphorochloridate. La réactivité de ce dernier vis-à-vis de différentes amines, a permis d’isoler une nouvelle famille de N,Phétérocyclesà 5, 7, 8 et 9 chaînons. La synthèse de P-hétérocycles à 6 chainons a été également décrite en réalisant des cyclisations dans les conditions de métathèse cyclisante (RCM) à partir d’un bisallylphosphonate et d’un bisallylphosphoramidate issus des mêmes précurseurs. / Due to the joint presence of several functional groups, β-ethoxycarbonylatedallylphosphonates are considered as excellent precursors for the preparation of neworganophosphorus compounds. In the presentwork, we first described the use of suchphosphonates as Michael acceptors. Indeed, weperformed conjugated additions of thiols,amines and enolate-anion under mild reactionconditions. Allylphosphonates were also usedfor the preparation of a new family of phosphonomethyl α,β-unsaturated γ-lactams.The key step of this sequence is a conjugateaddition of nitroalkanes on allylphosphonates followed by a Nef reaction. Ketoester intermediaites were then convertedinto lactams by reaction with primary amines.Pd-catalyzed arylations on allylphosphonates allowed preparing phosphonated heterocyclesderived from coumarin, quinolinone andbenzoxepinone skeletons. The synthesis of Pheterocyclesof various sizes fromallylphosphonates was explored by theconversion of phosphonate inphosphorochloridate. The reactivity of the latterwith amines, allowed isolation of a new familyof 5-,7-, 8- and 9-membered N,P-heterocycles.The synthesis of 6-membered P-heterocycleshas also been described by performingcyclization under the conditions of a ringclosing metathesis (RCM) starting from bisallylphosphonates and bisallylphosphoramidates.

Studies of aging processes were conducted on pyrolysis oils produced from pine and cottonwood biomass (clear wood, whole tree, bark and needles/leaves). Accelerated aging at 80 °C for up to 504 h was employed to investigate the short and long-term effects of feedstock, phase separation, char particulates, and solvent addition on pyrolysis oil properties. Feedstock containing forestry residue was found to increase water content of neat pyrolysis oil and the collection method (total vs. fractionated) affects all of the properties with the largest impact on viscosity and as produced molecular weight. Post-condensation liquid filtration did not prevent aging-related water content or molecular weight increases during aging but did retard aging reactions in pine clear wood and pine bark pyrolysis oils. Methanol addition retarded the aging reactions in pine needle fractionated pyrolysis oil; at 15 wt% phase separation was prevented and molecular weight increased 11 % after 504 h of aging.

Dissertation (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Polymers prepared via radical techniques are very common in our every day environment. The technique is however limited by a lack of control over the polymerization and an inability to produce block copolymers. Block copolymers have a significant number of potential applications in advanced materials and as a result are a field in which significant research is being conducted. Reversible Addition-Fragmentation chain transfer (RAFT) is a living free radical process that overcomes the disadvantages inherent in the traditional process. In this study the mediation behaviour of two inherently different RAFT agents was investigated by the “living” free radical polymerization of model monomers via the RAFT process in homogeneous and aqueous dispersed media with the focus on differentiating between the two types of agents. To ensure that the agents were comparable a new RAFT agent had to be prepared which has not previously been documented. The efficiency of the RAFT agents was compared in terms of rate effects, the predictability of the molecular weights of the polymers, the polydispersities of the polymers and their ability to allow block copolymer formation via sequential addition of monomers. Block copolymerizations were conducted by the addition of new monomer to the already existing RAFT end-capped chains. Monomer addition was done via three different approaches; namely shot addition, feed addition and pre-swelling (in the case of emulsions). Chromatographic analysis was conducted on the resulting block copolymers via liquid chromatography at critical conditions (LCCC), and its online coupling with size-exclusion chromatography (SEC) to obtain two-dimensional information on the differences in heterogeneity of their molecular distributions. Other analyses included dynamic light scattering analysis (DLS) and transmission electron microscopy (TEM). The detailed analysis enabled the understanding of the different products that are produced via the two different classes of RAFT agent. Potential causes for the differences are discussed and possible areas for future research are highlighted. The work presented here is the most detailed investigation of this class of polymerization to date and will provide new insight for researchers working in this vibrant and important research field. / AFRIKAANSE OPSOMMING: Polimere gesintetiseer deur die gebruik van radikaal tegnieke is algemeen in ons daaglikse omgewing. Die tegniek is egter beperk deur die gebrek aan beheer oor die polimerisasie en die onvermoë om blokkopolimere te sintetiseer. Blokkopolimere beskik oor ‘n aansienlike hoeveelheid potensiele aanwendinge in gevorderde materiale en is gevolglik ‘n belangrike navorsingsgebied. Omkeerbare addisie fragmentasie ketting oordrag (OAFO) is ‘n lewende vrye radikaal proses wat die inherente nadele van die tradisionele proses oorkom. In die betrokke studie is die mediasie gedrag van twee verskillende OAFO agente bestudeer deur die lewende vrye radikaal polimerisasie van model monomere deur die OAFO proses in homogene en waterig dispersie media met die fokus op differensiering tussen die twee tipes agente. Om te verseker dat die twee agente vergelykbaar is, is ‘n nuwe OAFO agent voorberei wat tot op hede nog nie gedokumenteer is nie. Die effektiwiteit van die OAFO agente is vergelyk in terme van tempo effekte, die voorspelbaarheid van die molekulêre massa van die polimere, die polidispersiteit van die polimere en die moontlikheid om blokkopolimerisasie deur kronologiese byvoeging van monomere te fasiliteer. Blokkopolimerisasie is uitgevoer deur die byvoeging van nuwe monomeer tot die alreeds bestaande OAFO eind-groep kettings. Monomeer byvoegings is uitgevoer deur drie verskillende metodes; naamlik vulskoot addisie, voer addisie en vooraf swelling (in die geval van emulsies). Chromatografiese analise is uitgevoer op die resulterende blokkopolimere deur vloeistof chromatografie by kritieke kondisie (LC-CC) en die aanlyn koppeling met grootte-uitsluiting vloeistof chromatografie, om twee-dimensionele informasie omtrent die verskille in heterogeniteit van hul molekulere verdeling te bepaal. Verdere analise sluit dinamiese verstrooing mikroskopie en transmissie elektron mikroskopie in. Die detaileerde analise onthul die samestelling van die verskillende produkte wat geproduseer is deur die verskillende klasse van OAFO agent. Potensiele oorsake vir die verskille is bespreek en moontlike areas vir toekomstige navorsing is benadruk. Die werk hier voorgestel is die mees gedetaileerde navorsing van hierdie tipe klas van polymerisasie tot op hede en beloof nuwe insig vir navorsers betrokke in hierdie dinamiese en belangrike navorsingsveld.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Synthetic polymers are complex compounds that have multiple distributions with regard to molar mass, chemical composition, functionality and molecular architecture. Therefore, the molecular complexity of these compounds can only be analysed using a combination of analytical techniques. Well-defined complex polymers can be prepared by different types of living radical polymerisation, including reversible addition–fragmentation chain transfer polymerisation (RAFT) and reverse iodine transfer polymerisation (RITP). Using these techniques, several different homopolymers and copolymers have been prepared. However, there is still space for some more extended research. Many different types of multifunctional RAFT agents have been reported in literature. A tetrafunctional RAFT agent was prepared in our laboratory and used for the first time in the polymerisation of styrene. The polymerisation reaction was followed using in situ 1H nuclear magnetic resonance (NMR) and the molar masses of the resultant polymers were determined using size exclusion chromatography (SEC). The molar masses of the star-shaped polystyrenes (PS) were found to be less than the theoretical molar masses. This was due to the fact that SEC was calibrated with linear PS standards, while the samples under investigation are branched. Linear and branched polymers have different hydrodynamic volumes at similar molar masses. In order to prove that the star-shaped polymers were in fact four-armed, the samples were cleaved by aminolysis to yield the linear PS arms. The molar masses of the arms were in agreement with the theoretical arm molar masses based in the fourarmed structure. RITP is a relatively new living radical polymerisation technique. Various monomers have been prepared using RITP, including acrylates, methacrylates and styrene. The polymers formed using this technique have been characterised by techniques such as SEC, NMR and mass spectrometry (MS). However, very little advanced characterisation work has been done on polymers synthesised via RITP. Polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers were prepared via RITP and the microstructure analysed by in situ NMR and other advanced analytical techniques. The chromatograms from gradient HPLC of the PS-b-PBA block copolymers showed a separation based on chemical composition. The preparation of deuterated polymers via RITP has not been reported in literature. Hydrogenous-polystyrene-block-deuterated-polystyrene (hPS-b-dPS) was synthesised via RITP and analysed using liquid chromatography at critical conditions. An isotopic separation was achieved when critical conditions were established for hydrogenous PS (h-PS). A separation of the block copolymer from the first block was also achieved under chromatographic conditions where the block copolymer eluted in SEC mode while the first block eluted in LAC mode. The separation according to the block structure was confirmed by two-dimensional liquid chromatography. / AFRIKAANSE OPSOMMING: Sintetiese polimere is komplekse verbindings wat meervoudige verspreidings ten opsigte van molêre massa, chemiese samestelling, funksionaliteit en molekulêre argitektuur. Daarom kan die molekulêre kompleksiteit van hierdie verbindings net ontleed word met behulp van 'n kombinasie van analitiese tegnieke. Goed-gedefinieerde komplekse polimere kan voorberei word deur verskillende soorte lewende radikaal polimerisasie, insluitend omkeerbare addisie-fragmentasie kettingoordrag polimerisasie (OAFO) en omgekeerde jodium oordrag polimerisasie (OJOP). Met behulp van hierdie tegnieke, was verskeie homopolimere en kopolimeer opgestel. Maar daar is nog plek vir nog uitgebreide navorsing. Baie verskillende tipes multifunksionele OAFO agente is aangemeld in die letterkunde. Ons het 'n nuwe vier-armige OAFO agent in ons laboratorium voorberei en dit was vir die eerste keer in die polimerisasie van stireen gebruik. Die polimerisasie reaksie is gevolg met behulp van in situ 1H kernmagnetieseresonans (KMR) en die molêre massas van die gevolglike polimere was bepaal deur grootteuitsluitings chromatografie (SEC). Die molêre massas van die ster-polistireen (PS) is bevind as minder as teoretiese molêre massas. Dit is omdat SEC instrumente gekalibreer word met lineêre PS standaarde, terwyl die monsters wat tans ondersoek word vertakte polimere is. Lineêre en vertakte polimere het verskillende hidrodinamiese volumes by soortgelyke molêre massas. Ten einde te bewys dat die ster polimere in werklikheid vier-armig is, is die monsters gesny deur ‘n aminolisasiereaksie om die lineêre PS arms te lewer. Die molêre massas van die arms was ooreenkomstig met die teoretiese arm molêre massas gebaseer op die vier-armige struktuur. OJOP is 'n relatiewe nuuts lewende radikaal polimerisasie tegniek. Verskeie monomere is opgestel deur OJOP, insluitend akrilate, metakrilate en stireen. Die polimere wat gevorm is deur middel van die tegniek is al gekenmerk deur tegnieke soos SEC, KMR en massaspektrometrie (MS). Tog is daar baie min gevorderde karakterisering werk gedoen oor polimere gesintetiseer deur middel van OJOP. Polistireen-blok-poli(n-butylacrylaat) (PS-b-PBA) blokkopolimere was voorberei deur middel van OJOP en die mikrostruktuur ontleed met behulp van gevorderde analitiese tegnieke. Die chromatogramme van gradiënt HPLC van die PS-b-PBA blokkopolimere het 'n skeiding ondergaan gebaseer op die chemiese samestelling. Die voorbereiding van gedeutereerde polimere deur middel van OJOP word nie in die letterkunde gevind nie. Gehidrogeneerde-polistireen-blok-gedeutereerde-polistireen (hPS-b-dPS) is gesintetiseer deur middel van OJOP en ontleed met behulp van vloeistofchromatografie onder kritiese kondisies. 'n Isotopiese skeiding was bereik wanneer kritiese kondisies gestig is vir gehidrogeneerde PS (h-PS).'n Skeiding van die blok kopolimeer van die eerste blok was ook bereik onder chromatografiese omstandighede waar die blok kopolimeer elueer in SEC terwyl die eerste blok elueer in LAC. Die skeiding volgens die blok struktuur was bevestig deur twee-dimensionele vloeistofchromatografie.

Studien utgår från en kvalitativt inriktad analys och metod, där syftet är att undersöka vilka huvudräkningsstrategier som 3 svenska respektive 3 engelska lärare undervisar i, inom addition. Det empiriska materialet består av intervjuer som sedan har transkriberats och analyserats. Studien har låtit sig inspireras av ett hermeneutiskt perspektiv kombinerat med Grounded Theory. Hermeneutiskt perspektiv innebär att all data som finns i studien har tolkats och analyserats. Grounded Theory är ett vanligt sätt att analysera kvalitativ data och genom denna teori har kategorier skapats utifrån det resultat som framkommit. Resultatet av studien visar att de svenska lärarnas vanligaste val av strategier är: talsorter var för sig och algoritmer. De engelska lärarnas vanligaste val av strategier är: tiokamrater, additionstabellen och algoritmer. Av resultatet framkommer även de skillnader som finns mellan de intervjuade lärarnas val av strategier. / The study is based on a qualitatively directed method and the main aim is to investigate, and examine the mental arithmetic strategies of both Swedish and English teachers. In particular, the methods they use, to teach addition. The empirical data within this research is based on first hand interviews with six teachers; three from Sweden, and three from England. The study is inspired by a Hermeneutic Perspective in combination with Grounded Theory. The word hermeneutic, means that all of the data contained in the study has been interpreted and analyzed by the researcher. Grounded Theory is a common method used to analyze qualitative data. With this theory, categories have been created on the basis of the results obtained within this study. The results of the study show that Swedish teachers' most common choices of strategies are; partitioning method, and algorithms. In contrast, the English teachers’ strategies are the following; number bonds, the additiontable and algorithms. The results of this study also illustrate the differences between the Swedish and the English teachers’ choices of strategies.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: A novel approach to conducting controlled free radical polymerization in aqueous systems using Reversible Addition-Fragmentation Chain Transfer (RAFT) has been studied. When conducting RAFT in aqueous systems, reaction conditions must be chosen such that monomer transport across the aqueous-phase is either eliminated or facilitated. This is to prevent the formation of the red layer associated with RAFT in emulsions. The formation of the red layer is ascribed to the inability of waterinsoluble, dithiobenzoate-endcapped oligomers to be sufficiently transported across the aqueous phase. The novel approach in this study focussed on eliminating monomer transport and comprises two fundamental steps: the synthesis of dithiobenzoate-encapped oligomers in bulk followed by miniemulsification of these oligomers to yield a polymerizable miniemulsion. Dithioesters that act as chain transfer agents in the RAFT -process were synthesized in situ, thereby eliminating laborious and time-consuming organic purification procedures of dithioesters. In situ formation of the RAFT-agents involved conducting the reaction between di(thiobenzoyl) disulfide and conventional azo-initiators of differing structures in the presence of monomer. The structure of the chosen azo-initiator played a role in the efficiency of the RAFT process when the reaction was conducted in the presence of monomer to control the free radical polymerization process. Synthesis of the oligomers was performed by heating di(thiobenzoyl) disulfide and a selected azo-initiator, in the presence of monomer for a specific reaction duration in bulk. After the reaction was stopped, these oligomers were then miniemulsified by adding water, surfactant and cosurfactant, followed by the application of shear to form the resulting mini emulsion. The free radical polymerization of the dithiobenzoate-endcapped oligomers in the miniemulsion proceeded in a controlled manner with molecular weight increasing in a linear fashion with increasing conversion, while polydispersities remained low. The familiar red layer formation associated with RAFT polymerization in conventional emulsions was not observed under these conditions. The effects of changing the cosurfactant (hydrophobe) as well as changing the degree of polymerization of the emulsified oligomers were also investigated and described. / AFRIKAANSE OPSOMMING: Hierdie studie is geloods om 'n nuwe benadering tot die beheerde vry-radikaal polimerisasie in water gebaseerde sisteme te ondersoek. Daar is spesifiek gekyk na die uitvoer van die RAFT (Reversible Addition-Fragmentation Chain Transfer) proses in emulsies. Wanneer RAFT in emulsies toegepas word, moet die toestande waaronder die reaksie uitgevoer word, versigtig opgestel word. Die toestande moet so gekies word dat die vervoer van monomere deur die waterfase óf geëlimineer word óf gefasiliteer word. Dit word gedoen om die faseskeiding in die vorm van 'n rooi laag, wat so kenmerkend van RAFT -polimerisasie in emulsies is, te voorkom. Hierdie faseskeiding vind plaas omdat die vervoer van ditiobensoaat endgroep-bevattende oligomere deur die waterfase tydens interval II, moeilik is a.g.v. hulle oplosbaarheid in water. Die nuwe benadering wat hier bestudeer is, het twee basiese stappe. Eerstens word die ditiobensoaat endgroep-bevattende oligomere in bulk gesintetiseer. Dit word gevolg deur die emulsifisering van die oligomere. Hierna vind verdere polimerisasie van die oligomere plaas deur die dormante oligomere te heraktiveer. Die ditio-esters wat as kettingoordrag agente optree in die RAFT proses, word in situ gesintetiseer. Hierdie modifikasie sny tydrowende organiese suiweringsmetodes uit. Die in situ RAFT agente word gesintetiseer deur di(tiobensoïel) disulfied met verskillende konvensionele azo-inisieerders te laat reageer. Die struktuur van die spesifieke azoinisieerder het wel 'n rol gespeel in die effektiwiteit van die RAFT proses om molekulêre massa te beheer as bg. reaksie in die teenwoordigheid van monomere uitgevoer is. Die sintese van die oligomere is gedoen deur di(tiobensoïel) en 'n azo-inisieerder te verhit in die teenwoordigheid van monomere. Die reaksie is gedoen in bulk en die graad van polimerisasie van die oligomere is beheer deur die reaksie te stop by verskillende tydstippe. Nadat die bulk reaksie gestop is, is hierdie oligomere ge-emulsifiseer deur die oligomere te meng met 'n seep, hidrofoob en water. Hierdie mengsel word dan onderwerp aan 'n vermengingskrag om 'n polimeriseerbare mini-emulsie te vorm. Die voortsetting van die polimerisasie van die oligomere in die mini-emulsie het op 'n beheerde wyse verloop, m.a.w. molekulêre massa wat linieêr toeneem met stygende omsetting. Polidispersiteit indekse van die polimere het deurentyd laag gebly in die stabielste sisteme. Onder hierdie toestande was daar geen kenmerkende rooi laagvorming te bespeur nie. Die effekte wat die verandering van die hidrofoob, asook die verandering van die graad van polimerisasie van die oligomere op die sisteem gehad het, is onder andere ook ondersoek en beskryf.

This report details the discovery of a method for rhodium catalyzed asymmetric conjugate additions of heteroaryl nucleophiles to α,β-unsaturated carbonyl compounds. This work has successfully employed heteraryl titanates in enantioselective conjugate addition to α,β-unsaturated carbonyl compounds for the first time. Moreover, the utility of benzofuranyl, benzothiophenyl, and pyrrolo zinc reagents has been exemplified in enantioselective conjugate additions. We have found that the precatalyst [Rh(COD)acac]/OMeBIPHEP is broadly effective for enantioselective conjugate additions. Each heterocycle tested exhibited unique reactivity with respect to both conversion and enantioselectivity; reactivities of heteroaryl zinc reagents and heteroaryl titanates in enantioselective conjugate additions to α,β-unsaturated carbonyl compounds are sometimes complementary. Efforts directed towards the development of a method for rhodium-free enantioselective conjugate addition of furan to α,β-unsaturated carbonyl compounds are also described. / text