Dispersed niobia catalysts were prepared via a non-aqueous synthesis route. The effects of the type of oxide support, the support thermal pre-treatment, the calcination temperature and the niobia loading on the activity and selectivity for mesityl oxide (MO) synthesis at 160C were investigated in an autoclave reactor. The morphological and chemical properties of the catalysts were characterized via EDXRF, XRD, BET and Raman spectroscopy. The strength and nature of the acid sites were elucidated via in situ DRIFT spectra of the adsorption of pyridine as well as the temperature programmed desorption of NH3 interacting with the surface oxide phase. All four catalyst parameters had significant effects on the catalytic properties. Significantly, the nature of the acidity was clearly linked to the catalyst activity and particularly the catalyst stability. Catalysts exhibiting predominantly Lewis acidity invariably deactivated despite good initial activity, with the final acetone conversion dependent on the catalyst formulation. In contrast, catalysts exhibiting Bronsted acidity showed no evidence of catalyst deactivation after 8 hours of reaction. A plausible mechanism which explains these observations is proposed. Catalysts exhibiting Lewis acidity were more active when the supports were first activated at elevated temperature, likely due to a stronger support-surface oxide interaction as a consequence of increased surface coordinative unsaturation of the support. SiO¬2 supported catalysts exhibiting Bronsted acidity were more active if the supports were initially activated at 100C. Evidently, the hydroxyl groups on the oxide support contribute to the generation of Bronsted acidity. Different oxide supports gave rise to distinct acidic and catalytic properties in the niobia overlayer. The most striking example of this was the direct comparison of niobia dispersed onto two kinds of silica supports following the same preparative method. Unique and very strong acid sites were observed in niobia dispersed onto a commercial SiO¬2 catalyst carrier that were not observed in niobia dispersed onto fumed SiO¬2. For SiO2 catalysts, the activity increased linearly with niobia loading regardless of calcination temperature. In contrast, Al2O3 catalysts exhibited an initial increase in activity for MO synthesis with niobia loading followed by a decrease in activity after reaching a maximum activity below 1/3 monolayer coverage. The effect was more pronounced for catalysts exhibiting Bronsted acidity. It is proposed that adlineation sites are primarily responsible for catalytic activity in Nb2O5/-Al2O3 catalysts exhibiting Bronsted acidity. Niobia catalysts were developed using commercially available catalyst carriers as supports. The macrokinetics of MO and MIBK syntheses were investigated in a benchtop fixed bed flow reactor. The catalysts showed excellent activity for MO and MIBK syntheses at 160°C, typically 0.9 to 1.3 [g/hr*gcat]. However, the MIBK selectivity was constrained from 82 to 85% due to the coproduction of 2-propanol and diisobutyl ketone. The productivity for MO synthesis was found to be strongly dependent on the space velocity suggesting product inhibition. The intrinsic kinetics of the one-step synthesis of MIBK over a 15.2 wt% Pd/Nb2O5/SiO2 catalyst was investigated in an autoclave reactor. A kinetic model was developed and is reported. The one step synthesis of MIBK was investigated at the pilot plant scale via catalytic distillation (CD). An important finding was that while operating at 100% reflux, the accumulation of water in the reactive section resulted in the suppression of the DAA dehydration reaction. The in situ removal of water from the reactive section via an overhead distillate stream operating at 83 to 97% reflux directly resulted in an increase in MIBK productivity and hydrogen uptake efficiency by factors of about 20 yielding a moisture free reboiler product stream with as high as 53 wt% MIBK. The process was found to be controlled by the external mass transfer of hydrogen. Interestingly, the results suggest that the catalyst wetting efficiency affects the transport of hydrogen to the active sites as evidenced by the dependence of MO conversion on the reflux flow rate. The condition of minimum reflux flow rate and maximum hydrogen flow rate resulted in 97% MO conversion and 90 wt% MIBK selectivity.

Dispersed niobia catalysts were prepared via a non-aqueous synthesis route. The effects of the type of oxide support, the support thermal pre-treatment, the calcination temperature and the niobia loading on the activity and selectivity for mesityl oxide (MO) synthesis at 160C were investigated in an autoclave reactor. The morphological and chemical properties of the catalysts were characterized via EDXRF, XRD, BET and Raman spectroscopy. The strength and nature of the acid sites were elucidated via in situ DRIFT spectra of the adsorption of pyridine as well as the temperature programmed desorption of NH3 interacting with the surface oxide phase. All four catalyst parameters had significant effects on the catalytic properties. Significantly, the nature of the acidity was clearly linked to the catalyst activity and particularly the catalyst stability. Catalysts exhibiting predominantly Lewis acidity invariably deactivated despite good initial activity, with the final acetone conversion dependent on the catalyst formulation. In contrast, catalysts exhibiting Bronsted acidity showed no evidence of catalyst deactivation after 8 hours of reaction. A plausible mechanism which explains these observations is proposed. Catalysts exhibiting Lewis acidity were more active when the supports were first activated at elevated temperature, likely due to a stronger support-surface oxide interaction as a consequence of increased surface coordinative unsaturation of the support. SiO¬2 supported catalysts exhibiting Bronsted acidity were more active if the supports were initially activated at 100C. Evidently, the hydroxyl groups on the oxide support contribute to the generation of Bronsted acidity. Different oxide supports gave rise to distinct acidic and catalytic properties in the niobia overlayer. The most striking example of this was the direct comparison of niobia dispersed onto two kinds of silica supports following the same preparative method. Unique and very strong acid sites were observed in niobia dispersed onto a commercial SiO¬2 catalyst carrier that were not observed in niobia dispersed onto fumed SiO¬2. For SiO2 catalysts, the activity increased linearly with niobia loading regardless of calcination temperature. In contrast, Al2O3 catalysts exhibited an initial increase in activity for MO synthesis with niobia loading followed by a decrease in activity after reaching a maximum activity below 1/3 monolayer coverage. The effect was more pronounced for catalysts exhibiting Bronsted acidity. It is proposed that adlineation sites are primarily responsible for catalytic activity in Nb2O5/-Al2O3 catalysts exhibiting Bronsted acidity. Niobia catalysts were developed using commercially available catalyst carriers as supports. The macrokinetics of MO and MIBK syntheses were investigated in a benchtop fixed bed flow reactor. The catalysts showed excellent activity for MO and MIBK syntheses at 160°C, typically 0.9 to 1.3 [g/hr*gcat]. However, the MIBK selectivity was constrained from 82 to 85% due to the coproduction of 2-propanol and diisobutyl ketone. The productivity for MO synthesis was found to be strongly dependent on the space velocity suggesting product inhibition. The intrinsic kinetics of the one-step synthesis of MIBK over a 15.2 wt% Pd/Nb2O5/SiO2 catalyst was investigated in an autoclave reactor. A kinetic model was developed and is reported. The one step synthesis of MIBK was investigated at the pilot plant scale via catalytic distillation (CD). An important finding was that while operating at 100% reflux, the accumulation of water in the reactive section resulted in the suppression of the DAA dehydration reaction. The in situ removal of water from the reactive section via an overhead distillate stream operating at 83 to 97% reflux directly resulted in an increase in MIBK productivity and hydrogen uptake efficiency by factors of about 20 yielding a moisture free reboiler product stream with as high as 53 wt% MIBK. The process was found to be controlled by the external mass transfer of hydrogen. Interestingly, the results suggest that the catalyst wetting efficiency affects the transport of hydrogen to the active sites as evidenced by the dependence of MO conversion on the reflux flow rate. The condition of minimum reflux flow rate and maximum hydrogen flow rate resulted in 97% MO conversion and 90 wt% MIBK selectivity.

No description available.

Made available in DSpace on 2014-12-17T15:41:42Z (GMT). No. of bitstreams: 1 EdjaneFBS.pdf: 3994026 bytes, checksum: e61df5b55740f230b29442d65ddbda8d (MD5) Previous issue date: 2008-02-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Due to environmental restrictions around the world, clean catalytic technology are of fundamental importance in the petrochemical industry and refineries. Creating the face of this a great interest in replacing the liquid acids for solid acids, so as molecular sieves have been extensively studied in reactions involving the acid catalysis to produce chemical substances with a high potential of quality. Being the activity of the catalysts involved in the reaction attributed to the acid character of them involved for the Lewis and Br?nsted acid sites. Based on this context, this study aimed to prepare catalysts acids using a molecular sieve silicoalumino-phosphate (SAPO-11) synthesized in hidrotermical conditions and sulphated with sulphuric acid at different concentrations, using to it the method of controlled impregnating. The samples resulting from this process were characterized by x-ray difratometry (DRX), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermal analysis (TG-DTG) and determination of total acidity (by n-butilamin adsorption). The results show that the synthesis method used was efficient in the formation of AEL structure of SAPO-11 and when being incorporated the sulfate groups in this structure the acidity of the material was increased, pointing out that to very high concentrations of acid there is a trend of decrease the main peaks that form the structure. Finally they were tested catalytictly by the reaction model of conversion of m-xylene which showed favorable results of conversion for this catalyst, showing to be more selective of cracking products than isomerization, as expected, in order that for the o-xylene selectivity there was no positive change when to sulfate a sample of SAPO-11, while for light gases of C1-C4 this selectivity was remarkably observed / Devido ?s restri??es ambientais em todo o mundo, tecnologias catal?ticas n?o poluentes s?o de fundamental import?ncia na ind?stria petroqu?mica e nas refinarias. Diante disto, surge o grande interesse em substituir os ?cidos l?quidos por s?lidos ?cidos. Para isso, as peneiras moleculares t?m sido extensivamente estudadas nas rea??es que envolvem cat?lise ?cida a fim de produzir subst?ncias qu?micas com alto potencial de qualidade. Sendo a atividade dos catalisadores envolvidos na rea??o atribu?da ao car?ter ?cido deles distribu?dos em s?tios ?cidos de Lewis e Br?nsted. Com base neste contexto, este trabalho teve como objetivo preparar catalisadores ?cidos utilizando uma peneira molecular silicoaluminofosf?tica (SAPO-11) sintetizada hidrotermicamente e sulfatada com ?cido sulf?rico a diferentes concentra??es, empregando-se para isso o m?todo da impregna??o controlada. As amostras resultantes deste processo foram caracterizadas por difratometria de raios-x (DRX), microscopia eletr?nica de varredura (MEV), espectroscopia na regi?o do infravermelho por transformada de Fourier (FT-IR), an?lise t?rmica (TG-DTG) e determina??o de acidez total (via adsor??o de n-butilamina). Os resultados mostram que o m?todo de s?ntese utilizado foi eficiente na forma??o da estrutura AEL do SAPO-11 e ao serem incorporados os grupos sulfatos a esta estrutura, a acidez do material foi aumentada. Ressaltando-se que, para concentra??es muito elevadas do ?cido, h? uma tend?ncia dos principais picos que formam a estrutura diminu?rem. Por fim, as amostras foram testadas cataliticamente pela rea??o modelo de convers?o do mxileno a qual apresentou resultados favor?veis de convers?o para este catalisador, se mostrando ser mais seletivo a produtos de craqueamento do que de isomeriza??o, como se esperava, tendo em vista que para a seletividade a o-xileno n?o houve altera??o positiva ao se sulfatar a amostra de SAPO-11, enquanto que para os gases leves de C1-C4 esta seletividade foi notavelmente observada

Orientador: Daniel Barrera Arellano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T11:52:53Z (GMT). No. of bitstreams: 1 Oliveira_RaquelSilveiraPorto_M.pdf: 986495 bytes, checksum: d352a370cc01760bd026619e000bddd8 (MD5) Previous issue date: 2011 / Resumo: O óleo de cera de cana-de-açúcar constitui 25% da cera bruta. O aproveitamento da fração óleo representa uma necessidade urgente que garanta o destino deste material e sua valorização, pois se trata da fração menos nobre e de menor valor agregado em relação às frações contidas na cera. O programa de biocombustíveis brasileiro requer grandes quantidades de óleos para a produção de biodiesel. A proposta deste trabalho foi estudar a viabilidade em transformar o óleo de cera de cana-de-açúcar em ésteres etílicos (Biodiesel) através de uma catálise ácida. Este estudo envolveu as etapas de caracterização do óleo de cera de cana-de-açúcar, reação de esterificação, otimização da reação de esterificação pelo monitoramento da redução da acidez, tentativa de determinação dos ésteres etílicos e a investigação de outros componentes lipídicos presentes no óleo de cera de cana-de-açúcar que poderiam ter efeito na eficiência da reação de esterificação. O óleo apresentou como principais ácidos graxos, os ácidos palmítico (31,8%), linolênico (28,7%), linoléico e oléico (21,2%) e triacontanóico (7,8%). Os monoacilgliceróis e os ácidos graxos livres são predominantes neste material, representando juntos 66,6% das classes lipídicas. Após a reação de esterificação, utilizaram-se as técnicas de RMN-1H, ésteres etílicos totais e famílias de lipídios por CG além de espectroscopia por infravermelho para determinação dos ésteres etílicos totais, porém sem resultados positivos. A técnica de espectrometria de massa (ESI-MS e ESI-FT-MS) revelou a existência de componentes lipídicos oxidados, além de outros não identificados no óleo de cera de cana-de-açúcar. Os resultados indicam que o óleo de cera de cana-de-açúcar é uma amostra complexa, altamente hidrolisada, de insaturação média, mas com baixa estabilidade oxidativa, indicativo, portanto, de uma matéria-prima inadequada para a produção de biodiesel. A determinação de ésteres etílicos totais em óleo de cera de cana-de-açúcar após esterificação pelas três metodologias testadas mostrou-se ineficiente, sendo necessária a revisão das técnicas para contar com um método confiável para esta determinação neste tipo de amostra / Abstract: Sugar cane wax oil makes up 25% of crude wax. The exploitation of the oil fraction represents an urgent need to ensure a destination for this material and its valorization, for it is the less noble and less valuable fraction contained in the wax. The Brazilian biofuels program requires large amounts of oils for biodiesel production. The purpose of this study was to investigate viability of the transformation of sugar cane wax oil into ethyl esters (Biodiesel) through acid catalysis. This study comprised the stages of characterization of sugar cane wax oil, esterification reaction, esterification reaction optimization by means of reducing the acidity, attempt at ethyl esters characterization and investigation of other lipidic components present in the sugar cane wax oil that could possibly have an effect on the efficiency of the esterification reaction. The oil presented its major fatty acids as palmitic (31.8%), linolenic (28.7%), oleic and linoleic (21.2%) and triacontanoic (7.8%). The monoglycerides and free fatty acids are predominant in this fraction, together representing 66.6% of lipid classes. After the esterification reaction, the following techniques were used: 1H-NMR; ethyl esters and total lipids by GC families; infrared spectroscopy for determination of total ethyl esters in oil after esterification. However, none yielded positive results. Mass spectometry (ESI-MS and ESI-FT-MS) revealed the existence of presence of oxidated lipid components as well as unknown lipid components. The results indicated that sugar cane wax oil is a complex sample, highly hydrolyzed, of medium unsaturatation and with low oxidative stability, indicating not to be a suitable source material for biodiesel production. The determination of total ethyl esters in sugar cane wax oil after esterification by three tested methods proved itself inefficient, requiring a review of the techniques in order to achieve a reliable method for such determination in this type of sample / Mestrado / Engenharia de Alimentos / Mestre em Tecnologia de Alimentos

Kationische Zinkkomplexe werden als katalytisch aktive Spezies zahlreicher Lewis-Säure-katalysierter Reaktionen vermutet. Die diesen Katalysereaktionen zugrunde liegenden Mechanismen sind jedoch unzureichend verstanden. Das Ziel der vorliegenden Dissertation ist die Synthese strukturell definierter kationischer Zinkorganyle als Modellverbindungen für katalytisch aktive Spezies zinkkatalysierter Reaktionen. Der Fokus liegt auf Zinkverbindungen mit Cyclopentadienylliganden (Cp-Liganden), da Cp-Liganden ungewöhnliche Bindungssituationen stabilisieren können. In dieser Arbeit wird die erfolgreiche Synthese und Charakterisierung mehrerer kationischer Zinkkomplexe des Pentamethylcyclopentadienylliganden (Cp*-Liganden) beschrieben. Ein gemeinsames Strukturmerkmal dieser Komplexe besteht in der Koordination des Zinkatoms durch einen Cp*-Liganden sowie durch Neutralliganden. Die hohe Elektrophilie dieser Verbindungen ließ sich durch Reaktivitätsuntersuchungen belegen. Ein weiterer Ansatz zur Stabilisierung kationischer Zinkverbindungen besteht in der Verwendung funktionalisierter Cp-Liganden, die über eine neutrale Donorgruppe in einer Seitenkette verfügen. Es wurden neutrale und kationische Zinkkomplexe amino- sowie thiofunktionalisierter Cp-Liganden synthetisiert und charakterisiert. Für die kationischen Komplexe konnte eine intramolekulare Stabilisierung des Zinkatoms durch die Donorgruppe nachgewiesen werden. Einige der in dieser Arbeit beschriebenen Zinkkomplexe wurden als Präkatalysatoren intermolekularer Hydroaminierungsreaktionen eingesetzt, wobei teilweise hohe katalytische Aktivitäten erreicht wurden. Untersuchungen zum Mechanismus der Katalysereaktionen zeigten, dass eine hohe Elektrophilie des Zinkzentralatoms für eine effektive Katalyse entscheidend ist. / Cationic zinc complexes are assumed to act as catalytically active species in various Lewis acid catalyzed reactions. However, the mechanisms of these reactions are poorly understood. The aim of this dissertation is to synthesize structurally well-defined cationic zinc organyls as model compounds for catalytically active species in zinc catalyzed reactions. The thesis focuses on zinc complexes bearing cyclopentadienyl (Cp) ligands, as Cp ligands can stabilize unusual bonding situations. The successful synthesis and characterization of several cationic zinc complexes with pentamethylcyclopentadienyl (Cp*) ligands is described. As a common structural feature of these complexes, the zinc center is coordinated by a Cp* ligand and additional neutral ligands. The highly electrophilic character of these compounds was proven in reactivity studies. A further approach to stabilize cationic zinc compounds is to apply functionalized Cp ligands featuring a donor group in a side chain. Neutral and cationic zinc complexes bearing amino- and thio-functionalized Cp ligands were synthesized and characterized. The cationic donor-functionalized complexes were shown to exhibit an intramolecular stabilization of the zinc atoms by the donor groups. Several zinc complexes which are described in this thesis were examined as precatalysts in intermolecular hydroamination reactions. In some cases high catalytic activities were achieved. Studies on the mechanism of the catalysis reactions revealed that the presence of a highly electrophilic zinc center is crucial for good catalytic performance.

Les alcools sont des partenaires électrophiles attractifs pour des réactions de substitution nucléophile puisque l'eau est le seul sous-produit de la réaction en présence de nucléophiles protiques. Malgré le fait que la réaction soit fortement intéressante, la portée des transformations catalytique reste limitée à une combinaison spécifique alcool/nucléophile, ce qui rend l’emploi d’un ensemble général de conditions catalytiques fortement élusif. Cette thèse décrit le développement d'un système général de catalyse doux pour l'activation d'une large gamme d’alcools π-activés ainsi que d’alcools aliphatiques abordant ainsi les limitations clés dans le domaine. B(C6F6)3•H2O, un acide de Brønsted fort quand il est combiné avec le nitrométhane, a été découvert comme étant un système catalytique idéal pour la substitution chimiosélective d'alcools en présence de fonctionnalités et de groupements protecteurs sensibles aux conditions acides sans le compromis typique entre vitesse de réaction, réactivité substrat/nucléophile et quantité de catalyseur. Plus particulièrement, un effet co-catalytique de composés nitro est décrit pour la réaction d’azidation des alcools aliphatiques tertiaires en employant B(C6F6)3•H2O, permettant, pour la première fois, un turnover catalytique. Sur la base des investigations cinétiques, électroniques et spectroscopiques qui ont été menées, des agrégats de composés nitro et d’acides liés par des intéractions hydrogènes sont proposé comme étant l’espèce catalytiques responsables de la cinétique de la catalyse observée. L'utilité des nouvelles conditions catalytiques a été étendue au-delà de l'activation d'alcool et appliquée au clivage des liaisons fortes C-F dans les réactions de Friedel-Crafts défluorinatives de fluorures aliphatiques tertiaires. / Alcohols are attractive electrophilic partners for nucleophilic substitution reactions as water is the only by-product in a reaction with protic nucleophiles. Despite being a highly desirable reaction, the scope of useful catalytic transformations remains limited to specific alcohol-nucleophile pairs and a general set of catalytic conditions remains elusive. This thesis describes the development of a general and mild catalyst system for the activation of a broad range of π-activated and aliphatic alcohols to address key limitations in the field. B(C6F6)3•H2O, a strong Brønsted acid, when combined with nitromethane has been found as a widely useful catalyst system for chemoselective alcohol substitution in the presence of acid sensitive functionalities and protecting groups without the typical compromises in reaction rates, substrate/nucleophile scope and catalyst loading. In particular, a co-catalytic effect of nitro compounds is described for the B(C6F6)3•H2O catalyzed azidation of tertiary aliphatic alcohols, enabling catalyst turnover for the first time. On the basis of kinetic, electronic, and spectroscopic investigations, higher order hydrogen-bonded aggregates of nitro compounds and acids are proposed as kinetically competent Brønsted acid catalysts at the origin of the enhanced reactivity. The utility of the new catalytic conditions has been extended beyond alcohol activation and applied to the cleavage of strong C–F bonds in defluorinative Friedel-Crafts reactions of tertiary aliphatic fluorides.

Abstract New methods are being sought for the production of chemicals, fuels and energy from renewable biomass. Lignocellulosic biomass consists mainly of cellulose, hemicellulose and lignin. Cellulose and hemicellulose can be converted to their building blocks, i.e. sugars, via hydrolysis. This thesis is focused on glucose production from cellulose by dilute acid hydrolysis. Acid hydrolysis has the drawback of limited glucose yields, but it has the potential to become a short-term solution for biochemical production. During acid hydrolysis, the cellulose chain is split into glucose, which undergoes further decomposition reactions to hydroxymethylfurfural, levulinic acid, formic acid and by-products like insoluble humins. The present thesis aims to increase our knowledge on complicated acid-catalysed hydrolysis of cellulose. Glucose decomposition and cellulose hydrolysis were studied independently in laboratory experiments. Kinetic modelling was used as a tool to evaluate the results. The effect of the hydrogen ion on the reactions was evaluated using formic or sulphuric acid as a catalyst. This thesis provides new knowledge of cellulose hydrolysis and glucose decomposition in formic acid, a novel catalyst for high-temperature dilute acid hydrolysis. Glucose yields from cellulose hydrolysed in formic or in sulphuric acid were comparable, indicating that a weak organic acid could function as a cellulose hydrolysis catalyst. Biomass fibres in the form of wheat straw pulp were hydrolysed more selectively to glucose than a model component, microcrystalline cellulose, using formic acid. Glucose decomposition took place similarly in formic and sulphuric acid when the temperature dependence of the hydrogen ion concentration was taken into account, but a significant difference was found between the reaction rates of cellulose hydrolysis in formic acid and in sulphuric acid. The observations can be explained by changes in the cellulose hydrolysis mechanism. Thus, it is proposed in this thesis that side-reactions from cellulose to non-glucose compounds have a more significant role in the system than has earlier been understood. / Tiivistelmä Uusia menetelmiä etsitään kemikaalien, polttoaineiden ja energian valmistamiseen uusiutuvasta biomassasta. Eräs biomassa, ns. lignoselluloosa, koostuu pääasiassa selluloosasta, hemiselluloosasta ja ligniinistä. Selluloosa ja hemiselluloosa voidaan muuttaa hydrolyysin avulla niiden rakennuspalikoikseen eli sokereiksi. Tämä väitöskirja keskittyy glukoosin tuottamiseen selluloosasta laimean happohydrolyysin menetelmällä. Happohydrolyysi kärsii rajoittuneesta glukoosin saannosta, mutta sillä on potentiaalia tulla lyhyen aikavälin ratkaisuksi biokemikaalien tuotannossa. Happohydrolyysin aikana selluloosaketju pilkkoutuu glukoosiksi, joka reagoi edelleen hajoamisreaktioiden kautta hydroksimetyylifurfuraaliksi, levuliini- ja muurahaishapoiksi ja kiinteäksi sivutuotteeksi. Tämän tutkimuksen tavoitteena on kasvattaa ymmärrystämme monimutkaisesta happokatalysoidusta selluloosan hydrolyysistä. Glukoosin hajoamista ja selluloosan hydrolyysiä tutkittiin erikseen laboratoriokokein. Kineettistä mallinnusta käytettiin työkaluna arvioimaan tuloksia. Vety-ionien vaikutus reaktioihin arvioitiin käyttämällä muurahais- ja rikkihappoja katalyytteinä. Tämä väitöskirja antaa uutta tietoa selluloosan hydrolyysistä ja glukoosin hajoamisreaktioista muurahaishapossa, joka on uusi katalyytti korkean lämpötilan laimean hapon hydrolyysissä. Glukoosisaannot muurahaishappo-hydrolysoidusta selluloosasta olivat vertailukelpoisia vastaaviin rikkihappo-hydrolyysi saantoihin. Tämä viittaa siihen, että heikko orgaaninen happo voisi toimia selluloosahydrolyysin katalyyttinä. Kun katalyyttinä käytettiin muurahaishappoa, vehnän oljesta tehdyt kuidut hydrolysoituivat selektiivisemmin glukoosiksi kuin mallikomponenttina toimineen mikrokiteisen selluloosan. Kun vetyionikonsentraation lämpötilariippuvuus otettiin huomioon, glukoosi hajosi samalla tavalla sekä muurahais- että rikkihappokatalyytissä, mutta merkittävä ero havaittiin selluloosahydrolyysin reaktionopeudessa. Havainnot voidaan selittää selluloosahydrolyysin mekanismissa tapahtuvilla muutoksilla. Väitöskirjassa esitetään, että sivureaktioilla selluloosasta ei-glukoosi-tuotteiksi on merkittävä vaikutus systeemiin.

This study analyzes the reactivity and selectivity of Friedel-Crafts alkylations using benzylic alcohols and phenols in the presence of a Lewis acid, to synthesize methoxylated bisphenols as a benign alternative to BPA. The degree of methoxylation on the electrophile appears to affect the yield of the reaction while the degree of methoxylation on the nucleophile appears to affect the selectivity. A more methoxylated electrophile results in a lower yield whereas a more methoxylated nucleophile results in a change in ratio between the bisphenol isomers and/or causes other isomers to form. Neither the yield nor the selectivity appears to be affected significantly by the temperature.

L'activation catalytique d'alcools vers la formation déshydrative de liaisons chimiques sans pré-activation est devenue un intérêt de recherche majeur au cours des deux dernières décennies. Dans cette thèse, l’effet synergique particulier des acides forts en tant que catalyseurs dans l’hexafluoroisopropanol (HFIP) comme solvant de diverses classes de carbocations instables dans la chimie de Friedel-Crafts a été étudié. Il a été constaté que pour la première fois, les réactions de Friedel-Crafts d'alcools benzyliques primaires fortement désactivés, catalysées par un acide, se déroulaient facilement, en raison des phénomènes d'agrégation induits par l'acide dans HFIP. Une stratégie similaire a été utilisée pour l'activation d'alcools propargyliques, comme nouvelle voie d'accès sélectif aux allènes et indènes portant la fonction CF3, à partir des mêmes composés de départ. De plus, ce système catalytique a été appliqué avec succès pour les réactions de Friedel-Crafts de cyclopropanes de type non activés et donneur-accepteur. Enfin, il a été découvert que le HFIP pouvait atténuer le réarrangement de carbocation classique dans les alkylations de Friedel-Crafts, permettant l’accès aux produits avec chaînes alkyle linéaires en une seule étape à partir d’alcools aliphatiques linéaires. / The catalytic activation of alcohols towards dehydrative bond formation in the absence of pre-activation has become a major research interest over the past two decades. In this thesis, the peculiar synergistic effect of strong acids as catalysts in hexafluoroisopropanol (HFIP) as solvent on various classes of unstable carbocations in Friedel-Crafts chemistry was investigated. It was found that for the first time, Brønsted acid catalyzed Friedel-Crafts reactions of highly electronically deactivated primary benzylic alcohols proceeded smoothly due to the acid-induced aggregation phenomena in HFIP. A similar strategy was used for the activation of propargylic alcohols as a new route to selectively access CF3-substituted allenes and indenes from the same starting compounds. Furthermore, this catalytic system was succesfully applied for Friedel-Crafts reactions of unactivated and donor-acceptor cyclopropanes. Finally, it was discovered that HFIP can mitigate against classical carbocation rearrangement in Friedel-Crafts alkylations, allowing access to linear alkyl chain products in a single step from linear alkyl alcohols.