Photokontrolle von Eigenschaften einzelner Moleküle und größerer Molekülvereinigungen ist ein faszinierendes Feld aktueller chemischer Forschung. Das schlichte Potential der genauen Adressierbarkeit von chemischer Reaktivität sowie die Möglichkeit durch Ausnutzen des katalytischen Zyklus einen Lichtstimulus in ein verstärktes chemisches Signal zu übersetzen, machen die Photokontrolle über katalytische Aktivität zu einem besonders attraktiven Ziel. Daher wurde im Rahmen dieser Dissertation ein allgemeines Konzept zur Realisierung von photoschaltbaren Katalysatoren entwickelt, das auf der reversiblen sterischen Abschirmung eines katalytisch aktiven Zentrums durch eine photochrome Abschirmungsgruppe beruht. Durch Vorgabe des Schaltzustandes des Photochromes kann die Aktivität des Katalysators bestimmt werden. Das Konzept wurde durch die Entwicklung von konformativ eingeschränkten, photoschaltbaren Piperidinbasen umgesetzt, die synthetisch leicht durch einen in hohem Maße modularen Zugang erhalten werden konnten. Die Piperidinbasen erlaubten die Photokontrolle der Katalysatoraktivität in der Nitroaldol-Reaktion (Henry-Reaktion). Durch die Optimierung der Substituenten konnten bemerkenswerte katalytische AN/AUS-Verhältnisse erreicht werden. Die Reaktivitätsunterschiede konnten mit Änderungen der Basizität in Abhängigkeit vom Schaltzustand korreliert werden. Systematische NMR-spektroskopische und theoretische Untersuchungen der strukturellen Dynamik des Katalysators in Lösung ermöglichten die Formulierung von detaillierten Struktur-Reaktivitäts-Beziehungen. Eine Erweiterung des Konzepts auf intrinsisch reaktivere Katalysatoren sollte zu einer verbesserten Anwendbarkeit beitragen. Daher wurde das Konzept der reversiblen sterischen Abschirmung auf katalytisch aktive N-heterozyklische Carbene übertragen. Eine erfolgreiche Synthese wurde durch ungünstige sterische Wechselwirkungen zwischen den abschirmenden Gruppen an den Stickstoffatomen des Carbens verhindert. / Photocontrol over properties of single molecules and assemblies thereof is an appealing area of current chemical research. The mere potential to selectively address chemical reactivity as well as the possibility to transform an incoming light stimulus into an amplified chemical signal by exploiting the associated catalytic cycle renders photocontrol of catalytic activity a particularly attractive goal. In this dissertation, a general concept for the realization of photoswitchable catalysts was developed, based on reversible steric shielding of a catalyst’s active site by a photochromic blocking group. Dictating the photochrome’s switching state enables gated access to the active site, thereby photocontrolling the catalyst’s chemical reactivity. The concept was realized by designing conformationally restricted, photoswitchable piperidine bases, which were easily synthesized exploiting a highly modular approach. Indeed, the developed piperidine bases allowed to photocontrol the catalysts’ activities in the nitroaldol reaction (Henry reaction) and by tuning of the substituents significant catalytic ON/OFF-ratios were achieved. The reactivity differences could be correlated with changes of basicity depending on the photochrome’s switching state. Systematic NMR-spectroscopic and computational studies of the catalysts’ structural dynamics in solution enabled the formulation of detailed structure-reactivity relationships. Strategies for the implementation of the concept of reversible steric shielding into the N-heterocyclic carbene (NHC) motif were devised to exploit the high reactivity of NHCs in numerous catalytic processes, which is expected to greatly enhance the utility of the concept. However, profound steric shielding of the active site to suppress unwanted OFF-state reactivity prevented the synthetic realization of the concept due to unfavorable steric interactions upon formation of the heterocyclic carbene from suitable precursors.

L’hydrosilylation d’alcènes est une réaction clé pour la synthèse d’huiles silicones fonctionnelles et d’élastomères silicones nécessite un catalyseur. Industriellement, le platine est utilisé or le coût important de ce métal motive la recherche de catalyseurs alternatifs plus compétitifs, notamment à base de métaux non précieux. Les travaux ont débuté sur des systèmes développés précédemment au laboratoire à base de cobalt et de nickel à haut degré d’oxydation et de ligands dicétones. Les cinétiques de réticulation ont été également suivies aussi bien par des mesures qualitatives d’arrêt d’agitation que par des mesures de rhéologie ou de chaleur de réaction par DSC. Ces catalyseurs sont actifs et robustes pour la réticulation. A la suite, des catalyseurs à base de cobalt portant en particulier des ligands amidures ont été étudiés. Associés à un ligand bidentate (P,N), les systèmes catalytiques sont compétitifs au platine de Karstedt pour l’hydrosilylation sélective d’alcènes. Ces catalyseurs réalisent également la réticulation d’huiles silicones à relativement basse température (20 min à 90°C). Un homologue au fer s’est également montré actif pour la réticulation d’huiles silicones démontrant la faisabilité d’une voie catalytique d’hydrosilylation à partir de complexes de fer non toxiques et robustes / Alkene hydrosilylation is a major tool for the synthesis of functionalized silicone oils and silicone elastomers and is catalyzed by transition metal complexes. Industrially, Platinum complexes are used. However, high and volatile cost and rarity of precious metals lead to the development of competitive alternative systems, especially catalysts based on non-precious transition metals. First, Nickel and Cobalt high-oxidation-state complexes bearing diketone ligands were studied. Those systems had been previously developed in the laboratory and the study has been completed. Crosslinking kinetics were followed by qualitative measures of “stop-stirring” time and by rheology and thermal analysis (DSC). Those catalysts are active over oxygen and stable for silicone-oil crosslinking. Then, Cobalt Catalysts bearing amido-based ligands were studied. When associated with a ligand (phosphino pyridine P,N), those systems are competitive with the Karstedt catalyst (Pt) for selective alkene hydrosilylation. They also allow for silicone-oil crosslinking at relatively low temperature (20 min at 90 °C). Finally, a homologous complex based on Iron was synthesized and showed activity for silicones’ crosslinking evidencing the feasibility of a catalytic hydrosilylation pathway from non-toxic and robust iron complexes.

Fossils fuels are highly demanded in everyday life domestically or industrially. Fossil fuels are finite resources and they are rapidly depleting, as such alternative renewable feedstocks are sought to replace fossil fuels. Tall oil from paper processing and cashew nut shell liquid from the cashew nut industry are the two major renewable sources we studied, they are both waste byproducts, and have the potential to be converted into value-added materials. Tall oil from the paper industry mainly contained tall oil fatty acid, and under isomerising methoxycarbonylation with palladium catalyst, dimethyl 1,19-dimethyl nonadecanedioate can be obtained. This difunctional ester, dimethyl 1,19-dimethyl nonadecanedioate, is converted to diols, secondary and primary diamines by a hydrogenation reaction with ruthenium complexes of 1,1,1-tris(diphenylphosphinometyl)ethane (triphos) as catalysts in the presence of water, amine or aqueous ammonia respectively. In the case of aqueous ammonia it is necessary to use a two step reaction via diol to obtain 1,19-diaminononadecane. Diesters, diols and diamines are useful precursors for the synthesis of polyesters and polyamides. Difunctional substrates with 8-19 carbon chains are all tolerated under the reaction conditions and are successfully converted to the corresponding diols and diamines in high yields. Under similar hydrogenation conditions with the same ruthenium catalyst, cyclic products were predominantly produced with decreased chain length. N-heterocycles, which are important building blocks for the synthesis of drug molecules, were formed from the hydrogenation of diesters with 4-7 carbon chains in the presence of an amine. Another polymer precursor, ε-caprolactam, which is the precursor for Nylon 6, is obtained in a reasonable yield from both adipic acid and adipate esters together with aqueous ammonia in the presence of ruthenium catalyst. Cashew nut shell liquid was also converted into useful medical drugs, such as norfenefrine, rac-phenylephrine, etilefrine and fenoprofene in reasonable yields. Most of these drug molecules have been formed from 3-vinylphenol by catalytic hydroxyamination followed by methylation or ethylation. 3-Vinylphenol was synthesised from cardanol by ethenolysis to 3-non-8-enylphenol followed by isomerising ethenolysis, whilst the N-alkylation reactions used methyl or ethyl triflate to avoid dialkylation. Fenoprofene was formed by firstly O-phenylating cardanol then ethenolysis followed by isomerising ethenolysis to form 1-phenoxy-3-vinylbenzene. Methoxycarbonyation followed by hydrolysis formed the final product in good yield. Our methods start from renewable waste materials and avoid unpleasant reagents in the original stoichiometric synthesis of those drugs, for example, cyanide is no longer essential for the synthesis of fenoprofene.

Durante anos, o lixo da cidade de Guaratinguetá foi aterrado e o seu produto recalcitrante não passou por nenhum tratamento físico ou mesmo químico, percolando diretamente sob o aterro. Mesmo tendo sido desativado e transformado em Parque Ecológico, o material depositado no local ao longo dos anos, continuará a ser decomposto por microrganismos e continuará a ser produzido o lixiviado como fonte de poluição ambiental. Inicialmente, fez-se a caracterização do chorume \"in natura\", demonstrando-se como fonte de matéria orgânica recalcitrante, com massa molar característica de macromoléculas (5,58 kDa e polidispersidade de 1,16), DBO não determinável pela recalcitrância molecular e/ou pela ação tóxica e DQO característica de lixiviado estabilizado (1.013 mg L-1). A fração inorgânica total, dada pela quantidade de sólidos fixos, foi de 3.670 mg L-1, valor esse 3,6 vezes maior que a fração orgânica. O estudo de tratamento do chorume, por ozonização catalítica homogênea foi desenvolvido, principalmente, pelo uso seqüencial de dois arranjos ortogonais de Taguchi, sendo o primeiro, matriz L16, para estudo exploratório dos fatores mais importantes na redução percentual da DQO. Os fatores estudados foram vazão de ozônio, concentração dos íons Fe2+, Fe3+, Zn2+, Mn2+, Ni2+ e Cr3+, pH do meio reacional e presença/ausência de fonte de radiação UV (254 nm). Dentre os metais de transição, os íons Fe2+ e Fe3+ demonstraram-se como mais viáveis como catalisadores na geração de radicais livres hidroxilas devido à sua significância estatística (p = 0,005), e por terem maior tolerância ao descarte no meio ambiente (menor toxicidade) frente aos demais íons. Com a utilização do arranjo ortogonal L8 de Taguchi, foi possível atingir degradação máxima de DQO da ordem de 50 %. A melhor configuração dos fatores, visando aumentar o percentual de redução da DQO foi: vazão de ozônio igual a 5 L h-1 (589,9 mg h-1 O3), concentração de íon de íon ferroso igual a 10 mg L-1, concentração de íon férrico igual a 5 mg L-1 e pH 5. / During many years, the garbage of Guaratinguetá city was landfilled and its recalcitrant product was not submitted to any physical or chemical treatment, leaching directly through the area. After deactivating and transforming the landfill into an Ecological Park, the material deposited in the place by the past years, will continue being decomposed by microorganisms and will continue producing the leached one as a mean of environment pollution. Initially, the leachate \"in natura\" was characterized, demonstrating itself as a source of recalcitrant organic substance with a higher molecular size characteristic of 5,58 kDa and polidispersity of 1,16 and stabilized effluent (not determinable DBO due to molecular recalcitrance and/or toxicity and DQO of 1,013 mg L-1). The total inorganic fraction, given by the amount of total fixed solids was 3,670 mg L-1, which means 3,6 times bigger than the organic fraction. The study of leachate treatment by homogeneous catalytic ozonation was given, mainly, for the sequential use of two Taguchi\'s orthogonal arrangements, being the first, L16 design, for exploratory studies of the most important factors in the percentual reduction of DQO. The factors studied were the ozone outflow, the Fe2+, Fe3+, Zn2+, Mn2+, Ni2+ and Cr3+ ions concentration, the reaction medium pH and the presence/absence of UV radiation source UV (254 nm). Amongst the transition metals, Fe2+ and Fe3+ ions have demonstrated to be as more viable as free hydroxyl radicals catalyst due to its statistics significance (p = 0,005) and also because they have a greater tolerance to the environment discarding (less toxicity) compared to the other ions. The use of L8 Taguchi\'s orthogonal arrays gives the possibility to reach 50 % maximum COD depletion. The best factors configuration, using COD percentage reduction as experimental design response was: 5 L h-1 (589,9 mg h-1 O3) ozone outflow, 10 mg L-1 ferrous concentration, 5 mg L-1 ferric ion concentration and pH 5.

Chemical modification is an important way to improve the properties of existing polymers, and one of the important examples is the hydrogenation of nitrile butadiene rubber (NBR) in organic solvent by homogeneous catalysis in order to extend its application. This process has been industrialized for many years to provide high performance elastomers (HNBR) for the automotive industry, especially those used to produce components in engine compartments. In the current commercial process, a batch reactor is employed for the hydrogenation step, which is labor intensive and not suitable for large volume of production. Thus, novel hydrogenation devices such as a continuous process are being developed in our research group to overcome these drawbacks. In order to make the process more practical for industrial application, high concentration polymer solutions should be targeted for the continuous hydrogenation. However, many problems are encountered due to the viscosity of the high concentration polymer solution, which increases tremendously as the reaction goes on, resulting in severe mass transfer and heat transfer problems. So, hydrogenation kinetics in high concentration NBR solution, as well as the rheological properties of this viscous solution are very essential and fundamental for the design of novel hydrogenation processes and reactor scale up. In the present work, hydrogenation of NBR in high concentration solution was carried out in a batch reactor. A commercial rhodium catalyst, Wilkinson’s catalyst, was used with triphenylphosphine as the co-catalyst and chlorobenzene as the solvent. The reactor was modified and a PID controller was tuned to fit this strong exothermic reaction. It was observed that when NBR solution is in a high concentration the kinetic behavior was greatly affected by mass transfer processes, especially the gas-liquid mass transfer. Reactor internals were designed and various agitators were investigated to improve the mechanical mixing. Experimental results show that the turbine-anchor combined agitator could provide superior mixing for this viscous reaction system. The kinetic behavior of NBR hydrogenation under low catalyst concentration was also studied. It was observed that the hydrogenation degree of the polymer could not reach 95% if less than 0.1%wt catalyst (based on polymer mass) was used, deviating from the behavior under a normal catalyst concentration. The viscosity of the NBR-MCB solutions was measured in a rotational rheometer that has a cylinder sensor under both room conditions and reaction conditions. Parameters that might affect the viscosity of the solutions were studied, especially the hydrogenation degree of polymer. Rheological properties of NBR-MEK solutions, as well as NBR melts were also studied for relevant information. It is concluded that the hydrogenation kinetics deviates from that reported by Parent et al. [6] when polymer is in high concentration and/or catalyst is in low concentration; and that the reaction solution (HNBR/NBR-MCB solution) deviates from Newtonian behavior when polymer concentration and hydrogenation degree are high.

The focus of this research was to improve the sustainability of various processes by employing tunable solvents, switchable solvents, and catalysis. In Chapter 2, we report applications of tunable solvents to metal and enzyme catalyzed reactions of hydrophobic substrates. Tunable solvents are defined as solvent that change properties rapidly but continuously upon the application of an external physical stimulus and we utilize these solvents to couple homogeneous reactions with heterogeneous separations. We developed organic-aqueous tunable solvents that utilize propane for efficient phase separation at moderate pressures around 1 MPa; for example the water contents in the propane-expanded THF is 3 wt% at 0.8MPa at 30°C. Also, we extended the use of CO2-organic-aqueous tunable solvents to a pharmaceutically-relevant reaction--the hydroformylation of p-methylstyrene. The homogeneous reactions provide fast rates with excellent yields. At 60°C, the reaction reaches completion after 180 minutes with 95% branched aldehyde yield. The CO2-induced heterogeneous separation of the product from the catalyst provides an efficient and simple way to remove 99% of the product, to retain 99.9% of catalyst, and to recycle the Rh-TPPMS catalyst for five consecutive reactions. In chapter 3, we investigated the use of reversible ionic liquids (RevILs) for synthesis of nanoparticles. RevILs are formed by the reversible reaction of compounds with basic nitrogen functionalities (molecular liquid) with CO2 at ambient pressure to form a liquid salt (ionic liquid). We demonstrated that RevILs form microemulsions that can be switched-on by bubbling CO2 and switched-off by heating. These microemulsions solubilize ionic compounds such as chloroauric acid. We utilized these microemulsions as a template for controlled synthesis of gold nanoparticles. With 2-component RevILs, [TMBGH]+[O2COCH3]-/N-propyl-octylsulfonamide/hexane were used to form particles in the size range of 6-20 nm with an average particles size of 11.4±3.3. With 1-component RevILs, (3-aminopropyl)-tripropylsilane was used to prepare semi-spherical gold particles with an average size of about 20nm. The 1-component RevILs systems provide a simpler method to form microemulsions when compared to the 2-componenet RevILs systems since they eliminate the need for alcohols and surfactants. In chapter 4, we developed a catalyst that efficiently decomposes hydrazine to selectively produce ammonia. This enables the use of the chemical propulsion hydrazine for electric propulsion as well. We prepared nickel, copper, cobalt, ruthenium, rhodium, and iridium nanoparticles that were supported on silica and we tested these silica-supported metals for the decomposition of hydrazine. To study the catalytic activity, we designed and constructed a continuous flow reactor. The results show that nano-nickel supported on silica is the most active and selective catalyst with 100% conversion of hydrazine and 94±3% yield of ammonia.

No description available.

Chemical modification is an important way to improve the properties of existing polymers, and one of the important examples is the hydrogenation of nitrile butadiene rubber (NBR) in organic solvent by homogeneous catalysis in order to extend its application. This process has been industrialized for many years to provide high performance elastomers (HNBR) for the automotive industry, especially those used to produce components in engine compartments. In the current commercial process, a batch reactor is employed for the hydrogenation step, which is labor intensive and not suitable for large volume of production. Thus, novel hydrogenation devices such as a continuous process are being developed in our research group to overcome these drawbacks. In order to make the process more practical for industrial application, high concentration polymer solutions should be targeted for the continuous hydrogenation. However, many problems are encountered due to the viscosity of the high concentration polymer solution, which increases tremendously as the reaction goes on, resulting in severe mass transfer and heat transfer problems. So, hydrogenation kinetics in high concentration NBR solution, as well as the rheological properties of this viscous solution are very essential and fundamental for the design of novel hydrogenation processes and reactor scale up. In the present work, hydrogenation of NBR in high concentration solution was carried out in a batch reactor. A commercial rhodium catalyst, Wilkinson’s catalyst, was used with triphenylphosphine as the co-catalyst and chlorobenzene as the solvent. The reactor was modified and a PID controller was tuned to fit this strong exothermic reaction. It was observed that when NBR solution is in a high concentration the kinetic behavior was greatly affected by mass transfer processes, especially the gas-liquid mass transfer. Reactor internals were designed and various agitators were investigated to improve the mechanical mixing. Experimental results show that the turbine-anchor combined agitator could provide superior mixing for this viscous reaction system. The kinetic behavior of NBR hydrogenation under low catalyst concentration was also studied. It was observed that the hydrogenation degree of the polymer could not reach 95% if less than 0.1%wt catalyst (based on polymer mass) was used, deviating from the behavior under a normal catalyst concentration. The viscosity of the NBR-MCB solutions was measured in a rotational rheometer that has a cylinder sensor under both room conditions and reaction conditions. Parameters that might affect the viscosity of the solutions were studied, especially the hydrogenation degree of polymer. Rheological properties of NBR-MEK solutions, as well as NBR melts were also studied for relevant information. It is concluded that the hydrogenation kinetics deviates from that reported by Parent et al. [6] when polymer is in high concentration and/or catalyst is in low concentration; and that the reaction solution (HNBR/NBR-MCB solution) deviates from Newtonian behavior when polymer concentration and hydrogenation degree are high.

Dans ce travail de thèse nous décrirons tout d'abord la synthèse de nouveaux composés terpénoïdes par télomérisation de l'éthanolamine avec l'isoprène. Ensuite nous présentons l'utilisation de cette méthode pour la fonctionnalisation des poly-carbohydrates non alimentaires comme le chitosane et une hémicellulose (la gomme de guar) dans l'eau. Avec les substrats bifonctionnels (éthanolamine, chitosane), la réaction de télomérisation des diènes peut avoir lieu avec l'amine ou l'alcool pour conduire à la formation d'éthers ou d'alkylamines fonctionnalisés à longue chaine carbonée. Cette réaction est catalysée par des complexes de palladium-phosphine formés in-situ et est réalisée en présence ou en absence d'une base dans différents solvants (Eau, MeOH, i-PrOH, Eau/iPrOH), y compris en milieu biphasique.L'influence des paramètres réactionnels tels que l'effet du solvant, du précurseur de palladium, de la charge en catalyseur, du rapport Ligand/Palladium, de la nature des ligands phosphines, de la température et du temps réactionnel, de la quantité de diène et de la quantité de la base, a été étudiée. L'activité et la sélectivité de la réaction ont été déterminées en réalisant des analyses de chromatographie gazeuse GC (pour les terpénoïdes), des analyses RMN 1D et 2D (pour les terpénoïdes et les polysaccharides modifiées). Ceci a permis la détermination des conversions, ainsi que des degrés de substitution (DS) des polysaccharides modifiés. Des analyses élémentaires {C, H, N} ont été réalisées pour valider les structures et la pureté des produits obtenus. La stabilité thermique des télomères des carbohydrates (chitosane et gomme de guar) a été étudiée par analyse thermogravimétrique (ATG).Avec l'éthanolamine, le rendement total en terpénoïdes varie de 31% à 81 %, distribués entre des monotélomères (50-80%) et des ditélomères (20-50%). Pour les polysaccharides, des degrés de substitution compris entre 0.03 et 0.61 (DS =0.61 dans l'eau) pour les alkyl-chitosane et 0.01 et 0.31 (dans l'eau) pour la gomme de guar modifiée sont obtenus / In this thesis, we will first describe the synthesis of new terpenoid compounds by telomerization of isoprene with ethanolamine. Then we will present the usage of this method for the functionalization of non-food related poly-carbohydrates such as the hemicellulose (guar gum) and the chitosan in water.With the bifunctional substrates (ethanolamine, chitosan), the reaction of telomerization of the dienes can take place between the amine or the alcohol in order to lead either to the formation of the ethers or to the formation of the functionalized alkylamines with a long carbon chain. This reaction is catalyzed by palladium-phosphine complexes formed in situ, and realized in the presence or in the absence of a base in different solvents (water, MeOH, i-PrOH, water/iPrOH), and in biphasic medium.The influence of reactional parameters such as the effect of the solvent, that of the precursor of palladium, that of the catalyst charge, that of the Ligand/Palladium ratio, that of the nature of the phosphines ligands, that of the temperature and the reaction time, as well as the effect of the quantity of diene and of the base were studied.The activity and the selectivity of the reaction were determined using the gas chromatography analysis (for the terpenoids), and 1D & 2D RMN analyses (for the terpenoids and modified polysaccharides). This allowed us to determine the conversions and the degree of substitution of the modified polysaccharides. Elementary analysis (C, H, N) were also performed to validate the structures and the purity of the products obtained. The thermal stability of the carbohydrates telomeres (chitosan and guar gum) was studied by thermogravimetric analysis.With the ethanolamine, the total yield in terpenoids varied between 31% and 81% and was distributed between monotelomers (50-80%) and ditelomers (20-50%).For the polysaccharides, the degree of substitution obtained varied between 0.03 and 0.61 (DS=0.61 in water) for the alkyl-chitosan and between 0.01 and 0.31 (in water) for the modified guar gum

This thesis describes the synthesis and characterisation of novel mono and dinuclear homogenous [Zn(II)] and [In(III)] metal complexes. Their applications as catalysts for CO₂/epoxide or epoxide/anhydride ring opening copolymerisation and lactide ring opening polymerisation to generate polycarbonates and polyesters, respectively, are also reported. Chapter 3 reports the first indium phosphasalen catalysts for CO₂/cyclohexene oxide ring opening copolymerization. The catalysts are active at 1 bar pressure of CO₂ and are most effective without any co-catalyst. It is also possible to use the complexes to isolate and characterise the key intermediates in the catalytic cycle. Kinetic and spectroscopic analyses show that polymerisation proceeds via a rare cis-mononuclear coordination- insertion mechanism. Chapter 4 describes a series of mono and dinuclear zinc macrocycle catalysts with very high activities for the racemic lactide ring opening polymerisation. In most cases, the dinuclear zinc catalysts significantly out-perform the mono-zinc homologue. In addition, kinetic and spectroscopic investigations suggest a role for the ligand conformation in mediating rate. The catalysts perform very well under immortal conditions and operate at low catalyst loading, whilst conserving high activities. Chapter 5 presents four dinuclear zinc acetate salen catalysts for the ring opening copolymerisation of CO₂/cyclohexene oxide and phthalic anhydride/cyclohexene oxide. The catalysts show moderate activities for CO₂/epoxide copolymerisation but are highly active for epoxide/anhydride copolymerisation. Structure/activity relationship studies reveal that the more flexible and electron donating ligand displays the highest activity. Poly(ester-b-carbonate)s are also afforded using the most active catalyst in terpolymerisations of anhydride/epoxide/CO₂.