Rozprawy doktorskie na temat „Alcohols”

An applicable method for the racemic synthesis of 1,2-amino alcohols having tertiary alcohol moiety was developed. This method can be used as a general method for the synthesis of various 1,2-amino alcohols with various tertiary alcohol moieties by changing chloroacetone with different monohalo ketones, and with different aryl halides or alkyl halides. The resultant racemic 1,2-aminoe alcohols were tried to resolve by using various hydrolase type enzymes under different conditions by changing the parameters i.e. solvent, temperature and substrate: enzyme ratios. Finally, poorly resolved amino alcohol 20 with 21 % was used as chiral ligand in diethyl zinc reaction to benzaldhyde and afforded (R)-1-phenylpropan-1-ol almost with 21 % e.e..

The selective oxidation of alcohols is one of the most challenging reactions in green chemistry. While the current chemical industry uses organic and inorganic oxidants to produce carbonyl compounds, it is highly desirable to use a heterogeneous catalyst for the efficient oxidation of alcohols. The present research is focused on increasing the activity and selectivity towards the corresponding carbonyl of the heterogeneous oxidation for alcohols. The low activity of 5 wt.%Pt-1 wt. %Bi/Carbon for the oxidation of 2-octanol was investigated in a 500ml stirred tank reactor. The fast reaction rate drops dramatically from 0.23 M/hr to 0.006 M/hr after 15 minutes reaction time when heptane was used as solvent. Different possible causes such as overoxidation, leaching and poisoning were examined. It was found that the loss of high conversion rate was due to product adsorption and hence, different solvents were investigated. A mixture of 16-18% v/v dioxane in heptane was able to effectively regenerate active sites and allow a constant reaction rate of 0.07M/hr. The effects of temperature and pressure were also studied. Gas-liquid, liquid-solid and internal mass transfer effects were determined experimentally and semi-empirically. Six different Langmuir-Hinshelwood rate models were examined where a modified model based on Schuurman et al. (1992) was found to adequately describe the experimental data. The novel 2.5%Au-2.5%Pd/titania catalyst was investigated for the oxidation of benzyl alcohol. Different parameters such as catalyst oxidation state, pressure and stirrer design were studied to increase the activity and selectivity of the catalyst. The selectivity was shown to be highly dependent on the oxygen concentration. Therefore, the pressure, temperature, catalyst treatment were optimised and the reactor configuration was re-designed to enhance oxygen transport to the catalyst. While the conversion rate was unaffected by the oxygen concentration, the catalyst pre-treatment significantly increased the reaction rate. Eventually, the use of a Rushton Turbine at 20 rps with a shower disc sparger and a treated catalyst allowed the selectivity to reach 93%. The reaction could be described with a Power Law model satisfactorily. Transition Metal Oxide catalysts such as \(AgO/ SiO_2, Fe_2O_3/SiO_2, CuO/SiO_2\) and \(CuO/Al_2O_3\) were investigated as an alternative to the expensive noble metal based catalyst. However, it was shown that such catalysts are ineffective for the oxidation of different alcohols by studying the effects of different engineering parameters. The maximum conversion reached was 15% with calcined copper oxide catalyst for 1-octanol oxidation.

Thesis (MScEng)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Pure primary alcohols are very valuable as raw materials and solvents. Close-boiling alcohol mixtures are produced as byproducts from the Fischer Tropsch synthesis. These byproducts include the mixtures 1-butanol+2- penta noI and 1-pentanol+2-hexanol. Due to the small difference in boiling points these alcohols cannot be separated from one another by using conventional distillation. This study has been undertaken to determine whether primary and secondary alcohols may be separated by exploitation of their chemical properties. Esterification of the alcohols followed by distillation of the esters into cuts and hydrolyses of the esters, has been attempted to separate the alcohols. This however, was unsuccessful. In this study the difference in dehydration rate of secondary and primary alcohols in acidic media has also been investigated. Several acidic resins and liquid catalysts have been used. The acidic resins gave no dehydration or extremely low dehydration rates in the liquid phase. The liquid catalysts H2S04, Oxalic Acid, NaHS04 and H3P04 were investigated. H3P04 gave excellent results. Laboratory experiments were conducted at the boiling point of the reaction mixture at atmospheric pressure. The reaction mixture was sampled at varying time intervals and analysed. The secondary alcohol dehydrated rapidly to the corresponding alkene. The primary alcohol formed symmetrical ethers at a very low rate. The primary and secondary alcohol also combined to form small amounts of unsymmetrical ethers. After the dehydration reaction the organic products can be separated from the acid with a'short path distillation unit. The primary alcohol can further be purified by conventional distillation. Conceptual process designs were done for the separation and purification of the reactor product streams of the alcohol mixtures 1-butanol+2-pentanol and 1-pentanol+2-hexanol. n laboratory scale it was found that for the separation of 85% 1-butanol and 15% 2-pentanol (mass %), 90 % H3P04 (mass %) at an acid:alcohol ratio of 1,5: 1 results in suffcient dehydration of 2-pentanol. A reaction time of 70 minutes is required. A conceptual design on the purification of the 1-butanol predicted a product quality of 99,5 % 1-butanol (mass %) and a 1-butanol recovery of 75 %. The 1-butanol recovery is low, because a major part of the 1-butanol is lost in the purification as part of the ternary azeotrope with water and n-butylether. On laboratory scale it was also found that for the separation of 85 % 1- pentanol+15 % 2-hexanol (mass %),90 % H3P04 (mass %) at an acid:alcohol ratio of 1,5:1 gives sufficient dehydration of 2-hexanol. A reaction time of only 35 minutes is required. A conceptual design on the purification of the 1- pentanol predicted a product quality of 99,9 % 1-pentanol and a 1-pentanol recovery of > 98 %. The 1-pentanol recovery is excellent, only the 1- pentanol that is converted to ethers is lost. In this study it has been proven that a dehydration separation process can be applied successfully to remove secondary alcohols from a primary+secondary alcohol mixture. Especially the removal of 2-hexanol from a 1-pentanol+2- hexanol mixture gave promising results. In order to assess the economic viability of this dehydration process an economic evaluation should be done. This could be part of subsequent studies. The dehydration separation process should be investigated further. It is believed that this dehydration separation process can be expanded to higher alcohols, e.g. 1-hexanol+2-heptanol. It would be extremely advantageous if a solid catalyst could be found for the separation. In this case the recovery of the organics from the reaction mixture would be very much easier. If a solid catatyst is not found, a continuous process using H3P04 as liquid catalyst should be developed.
AFRIKAANSE OPSOMMING: Suiwer primêre alkohole is baie waardevolle rou materiale en oplosmiddels. Alkohol mengsels, wat uit naby-kokende alkohole bestaan, word as neweprodukte in die Fischer Tropsch Sintese gevorm. Hierdie newe-produkte sluit alkohol mengsels soos 1-butanol+2-pentanol en 1-pentanol+2-hexanol in. Weens die klein verskil in kookpunte van hierdie alkohole kan die alkohole nie met konvensionele distillasie van mekaar geskei word nie. Hierdie studie is onderneem om te bepaal of die chemiese eienskappe van alkohole benut kan word om primêre en sekondêre alkohole van mekaar te skei. 'n Poging is aangewend om die alkohole met behulp van esterifikasie te skei. Die alkohole is eers ge-esterifiseer, daarna met behulp van distillasie in verskeie snitte verdeel en die alkohol is vrygestel deur hidrolise van die esters. Dit was egter onsuksesvol. Die verskil in dehidrasie tempo van sekondêre en primêre alkohole in suur mediums is ook ondersoek. Verskeie suur harse en vloeibare kataliste is ondersoek. Die suur .harse het of geen dehidrasie of baie lae dehidrasie tempo's in die vloeistoffase gegee. Die vloeistof kataliste H2S04, Oksaalsuur, NaHS04 en H3P04 is ondersoek. H3P04 het uitstekende resultate gelewer. Eksperimente is op laboratoriumskaal en onder atmosferiese druk uitgevoer. Monsters is van die reaksiemengsels by verskillende tydsintervalle geneem en geanaliseer. Die sekondêre alkohol het vinnig na die ooreenstemmende alkeen gedehidreer. Die primêre alkohole het simmetriese eters teen 'n lae tempo gevorm. Die primêre en sekondêre alkohole het ook gekombineer om gemengde eters te vorm. Kort-pad-distillasie kan gebruik word om na die dehidrase reaksie die organiese produkte van die suur te verwyder. Die primêre alkohole kan verder met konvensionele distillasie gesuiwer word. Konseptueie prosesontwerpe is uitgevoer vir die skeiding en suiwering van die alkohol mengsels 1-butanol+2-pentanol en 1-pentanol+2-hexanol nadat dehidrasie van die mengsels uitgevoer is. Op laboratoriumskaal is dit gevind dat vir die skeiding van 85% 1-butanol en 15% 2-pentanol (massa %), 90 % H3P04 (massa %) met 'n suur:alkohol verhouding van 1,5:1 effektiewe dehidrase van 2-pentanol lewer. fn Reaksietyd van 70 minute word benodig. fn Konseptueie ontwerp vir die suiwering van die 1-butanol het fn produkkwaliteit van 99,5 % 1-butanol (massa %) en fn 1-butanol opbrengs van 75 % voorspel. Die 1-butanol opbrengs is laag aangesien fn groot deel van die 1-butanol verlore gaan as deel van die ternêre azeotroop wat 1-butanol met n-butieleter en water vorm. Dit is ook op laboratoriumskaal vasgestel dat vir die skeiding van 85 % 1- pentanol+15 % 2-hexanol (massa %), 90 % H3P04 (massa %) met fn suur:alkohol verhouding van 1,5:1 effektiewe dehidrase van 2-hexanollewer. fn Reaksietyd van slegs 35 minute word benodig. fn Konseptueie ontwerp vir die suiwering van die 1-pentanol het fn produkkwaliteit van 99,9 % 1-pentanol en fn 1-pentanol opbrengs van > 98 % voorspel. Die 1-pentanol opbrengs is uitstekend, en slegs die 1-pentanol wat omgeskakel word na eters gaan verlore. In hierdie studie is dit bewys dat fn dehidrasie skeidingsproses suksevol aangewend kan word om sekondêre alkohole uit fn primêre+sekondêre alkohol mengsel te verwyder. Veral die verwydering van 2-hexanol uit fn 1- pentanol+2-hexanol mengsel het belowende resultate gelewer. Om die ekonomiese lewensvatbaarheid van so fn skeidingsproses te bepaal moet fn ekonomiese evaluasie van die proses gedoen word. Dit behoort deel van verdere studies te vorm. Die dehidrasie skeidingsproses behoort verder ondersoek te word. Dit word verwag dat die proses na hoër alkohol mengsels, bv. 1-hexanol+2-heptanol uitgebrei kan word. Dit sou baie voordelig wees indien fn geskikte soliede katalis vir die skeiding gevind word. In so fn geval sou die herwinning van die organiese produkte van die reaksiemengsel baie makliker wees. Indien fn soliede katalis nie gevind word nie, behoort fn kontinu proses waarin H3P04 as vloeistof katalis gebruik word, ontwikkel te word.

Els enzims presenten una sèrie d’avantatges catalítiques respecte als catalitzadors químics emprats en síntesis química clàssica: especificitat, selectivitat i la possibilitat de treballar en condicions suaus de temperatura i pressió. No obstant, també presenten una sèrie de limitacions com són la baixa estabilitat i les baixes productivitats. En el present treball es combinen dues tècniques per tractar d’optimitzar les reaccions d’interès seleccionades: la immobilització i l’enginyeria de reacció. Les reaccions objectiu d’aquest treball són reaccions d’oxidoreducció centrades en la biosíntesis de molècules, de mitjà i alt valor afegit, d’alt interès industrial. En la primera part de la tesis s’ha utilitzat una alcohol deshidrogenasa (ADH99) per a la oxidació de l’alcohol chlorolactol a chlorolactona i una NAD(P)H oxidasa (NOX) com a sistema de regeneració del cofactor. La chlorolactona és un precursor per a la síntesis d’estatines les quals són fàrmacs utilitzats per a la reducció del LDL-colesterol ja que inhibeixen l’enzim encarregat de la seva biosíntesis. Ambdós enzims van ser immobilitzats eficientment en diferents suports, dels quals es van seleccionar els tres que van mostrar major activitat retinguda. Seguidament es va estudiar l’estabilitat dels derivats immobilitzats en condicions de reacció i es va determinar la càrrega enzimàtica màxim per a cada enzim. Es va descartar l’ús de la NOX immobilitzada ja que no es va millorar l’estabilitat amb cap suport. Posteriorment es van optimitzar les condicions de reacció amb un disseny experimental (DoE) amb l’ADH99 soluble però utilitzant la quantitat màxima d’ADH99 que es pot afegir a la reacció quan es fa servir el l’ADH99 immobilitzada en epoxy-agarosa-UAB M2. Finalment es va estudiar la capacitat de reutilització del derivat immobilitzat, on es va poder millorar 1.5 vegades tant el producte obtingut com el rendiment del biocatalitzador. No obstant, la millor configuració va resultar ser la utilització dels dos enzims en forma soluble. La segona part d’aquesta tesis es va centrar en la reacció d’oxidació de l’alcohol vainillínic a vanil·lina biocatalitzada per l’eugenol oxidasa (EUGO). La vanil·lina és la molècula que dona les propietats organolèptiques a la vainilla, el segon aromatitzant més car del món. La síntesi de vanil·lina via biotecnològica és d’un gran interès industrial ja que pot etiquetar-se com a natural. L’EUGO va ser immobilitzada eficientment en diferents suports dels que es van seleccionar els tres que van retenir més activitat i se’n van estudiar els mateixos paràmetres de l’apartat anterior. En aquest cas els tres derivats immobilitzats van ser utilitzats per a realitzar la reacció de síntesi, amb l’objectiu de seleccionar el més estable operacionalment. Tots els derivats van permetre ser reutilitzats 5 vegades conservant una elevada conversió en l’últim cicle. L’epoxy-agarosa-UAB M2 va ser el suport que millor estabilitat va mostrar. Els bons resultats obtinguts en el segon apartat d’aquest treball van permetre aprofundir en aquesta reacció. Pel que, en el tercer apartat, es va realitzar una optimització de les condicions de reacció des del punt de vista de millorar les mètriques del procés i també amb l’objectiu de fer el procés més sostenible ambientalment. A l’hora d’escollir les noves condicions de reacció es van tenir en compte l’activitat de la EUGO i la seva estabilitat. Ambdues condicions van ser testades en la reacció objectiu amb l’EUGO soluble i immobilitzada. En les noves condicions es va poder millorar la productivitat volumètrica 5.7 i 6.6 vegades respectivament, en comparació a les condicions prèvies. Finalment, en el reciclatge de l’enzim immobilitzat es van poder realitzar 5 cicles de reacció en les primeres condicions i 18 cicles de reacció en les noves condicions on es va poder millorar el rendiment del biocatalitzador 3.9 i 12.4 vegades respectivament.
Las enzimas presentan una serie de ventajas catalíticas respecto a los catalizadores químicos empleados en síntesis química clásica: especificidad, selectividad y la posibilidad de trabajar en condiciones suaves de temperatura y presión. No obstante, también presentan una serie de limitaciones como son la baja estabilidad y las bajas productividades. En el presente trabajo se combinan dos técnicas para tratar de optimizar las reacciones de interés seleccionadas: la inmovilización y la ingeniería de reacción. Las reacciones objetivo de este trabajo son reacciones de oxidoreducción centradas en la biosíntesis de moléculas, de medio y alto valor añadido, de alto interés industrial. En la primera parte de la tesis se ha utilizado una alcohol deshidrogenasa (ADH99) para la oxidación del alcohol chlorolactol a chlorolactona y una NAD(P)H oxidasa (NOX) como sistema de regeneración del cofactor. La chlorolactona es un precursor para la síntesis de estatinas las cuales son fármacos utilizados para la reducción del LDL-colesterol puesto que inhiben la enzima encargada de su biosíntesis. Ambas enzimas fueron inmovilizados eficientemente en diferentes soportes, de los cuales se seleccionaron los tres que mostraron mayor actividad retenida. Seguidamente se estudió la estabilidad de los derivados inmovilizados en condiciones de reacción y se determinó la carga enzimática máximo para cada enzima. Se descartó el uso de la NOX inmovilizada puesto que no se mejoró la estabilidad con ningún apoyo. Posteriormente se optimizaron las condiciones de reacción con un diseño experimental (DoE) con la ADH99 soluble pero utilizando la cantidad máxima de ADH99 que se puede añadir a la reacción cuando se usa la ADH99 inmovilizada en epoxy-agarosa-UAB M2. Finalmente se estudió la capacidad de reutilización del derivado inmovilizado, donde se pudo mejorar 1.5 veces tanto el producto obtenido como el rendimiento del biocatalizador. No obstante, la mejor configuración resultó ser la utilización de las dos enzimas en forma soluble. La segunda parte de esta tesis se centró en la reacción de oxidación del alcohol vanillínico a vanillina biocatalizada por la eugenol oxidasa (EUGO). La vanillina es la molécula que da las propiedades organolépticas a la vainilla, el segundo aromatizante más caro del mundo. La síntesis de vainillina vía biotecnológica es de un gran interés industrial puesto que puede etiquetarse como natural. La EUGO fue inmovilizada eficientemente en diferentes soportes de los que se seleccionaron los tres que retuvieron más actividad y se estudiaron los mismos parámetros que en el apartado anterior. En este caso los tres derivados inmovilizados fueron utilizados para realizar la reacción de síntesis, con el objetivo de seleccionar el más estable operacionalmente. Todos los derivados permitieron ser reutilizados 5 veces conservando una elevada conversión en el último ciclo. La epoxy-agarosa-UAB M2 fue el soporte que mejor estabilidad mostró. Los buenos resultados obtenidos en el segundo apartado de este trabajo permitieron profundizar en esta reacción. Por lo que, en el tercer apartado, se realizó una optimización de las condiciones de reacción desde el punto de vista de mejorar las métricas del proceso y también con el objetivo de hacer el proceso más sostenible ambientalmente. A la hora de escoger las nuevas condiciones de reacción se tuvieron en cuenta la actividad de la EUGO y su estabilidad. Ambas condiciones fueron testadas en la reacción diana con lo EUGO soluble e inmovilizada. En las nuevas condiciones se pudo mejorar la productividad volumétrica 5.7 y 6.6 veces respectivamente, en comparación a las condiciones previas. Finalmente, en el reciclaje de la enzima inmovilizada se pudieron realizar 5 ciclos de reacción en las primeras condiciones y 18 ciclos de reacción en las nuevas condiciones donde se pudo mejorar el rendimiento del biocatalitzador 3.9 y 12.4 veces respectivamente.
Enzymes have some catalytic advantages over chemical catalysts used in classical chemical synthesis: specificity, selectivity and the possibility to work under mild conditions of temperature and pressure. However, they also have some limitations such as low stability and low productivity. This work combines two techniques aiming to optimise the target reactions: immobilisation and reaction engineering. The target reactions of this work are redox reactions focused on the biosynthesis of molecules, of medium-high value, of industrial interest. In the first part of the thesis, an alcohol dehydrogenase (ADH99) was used, with an NAD(P)H oxidase (NOX) as a cofactor regeneration system, to oxidise a chlorolactol to chlorolactone. Chlorolactone is a precursor for the synthesis of statins which are drugs used to lower LDL-cholesterol by inhibiting the enzyme responsible for its biosynthesis. Both enzymes were efficiently immobilised on different supports, selecting the three that showed the highest retained activity. The stability of the immobilised derivatives under reaction conditions was studied and the maximum enzyme load for each enzyme also was determined. The use of immobilised NOX was discarded because no stability improvements were achieved with any support. The reaction conditions were optimised by design of experiments (DoE), using soluble ADH99 added at maximum loading onto an epoxy-agarose support. Finally, the reusability of the immobilised enzyme was studied, where both the total product obtained and the biocatalyst yield could be improved 1.5-fold. However, the best configuration resulted from the use of the two enzymes in soluble form. The second part of this thesis was focused on the oxidation reaction of vanillyl alcohol to vanillin catalysed by eugenol oxidase (EUGO). Vanillin is the molecule that gives vanilla its organoleptic properties. Vanillin biotechnological synthesis is of high interest industrially because it is the second most expensive flavouring in the world and the product can be labelled as natural. Similar to the previous section, EUGO was efficiently immobilised onto different supports, selecting the three that retained most activity. These supports were used to study the stability of the immobilised enzyme and the maximum EUGO load that can be immobilised. In this case, the three immobilised derivatives were used to perform the target reaction, in order to select the most stable operationally. All immobilised derivatives could be reused 5 times maintaining a high conversion in the last cycle. Epoxy-agarose-UAB M2 was the support that showed the best stability, improving the biocatalyst yield 3-fold. The encouraging results obtained in the second section of this work allowed us to deepen the study of this reaction. Therefore, in the third section, an optimisation of the reaction conditions was carried out to improve the process metrics and also aiming to make the process more environmentally sustainable. The EUGO activity and its stability were taken into account to choose the reaction conditions. Both conditions, maximum activity and maximum stability, were tested in the target reaction with soluble and immobilised EUGO. Using the new conditions, it was possible to improve the volumetric productivity 5.7 and 6.6-fold respectively, compared to the previous conditions. Finally, the reusability of the immobilised EUGO allowed us to perform 5 reaction cycles and 18 reaction cycles, with unoptimised and optimised reaction conditions respectively. This resulted in an improvement of the biocatalyst yield of 3.9 and 12.4-fold, respectively, compared to reactions with soluble enzyme under the same conditions.
Universitat Autònoma de Barcelona. Programa de Doctorat en Biotecnologia

Bibliography: leaves 72-76.
The conversion of basic and renewable organic materials into valuable chemical products via simple processes is essential for generation of economic wealth. Value can be added to low value basic chemical materials produced in large quantities by converting them into speciality chemicals. The present study is an example. By-products of sugar industry, namely molasses and bagasses, can be used as a feedstock to produce valuable chemicals. By fermentation, molasses can be converted into a variety of organic compounds including ethanol, and other alcohols, lactic, glutamic and citric acids, glycerol and some antibiotics; Hydroamination of low alcohols (C2-C4) over Co/Si02 catalysts yielding amines, has been selected as an option to add value to these materials. This process involves reaction of alcohol with ammonia at temperatures ranging from 150 to 210°C and pressures of 18 to 200 bar in presence of hydrogen. Amines are of considerable industrial importance and find a huge application in almost every field of modem technology, agriculture and medicine, as intermediates and end products. Their commercial value is higher than that of sugar. A number of general mechanisms for the amination of alcohols over metal catalysts have been proposed, but the mechanism is still under discussion with some steps and/or intermediates not being conclusively proven. Most proposed mechanisms in literature assume the consecutive formation of the higher substituted amines.

The enzyme ADH-A and one of its mutants ADH-A C1B1 from ​ Rhodococcus ruber,​ have in previous studies been proved to act as proper biocatalysts, fully capable of performing redox reactions. Two redox reactions were studied during this project, were those enzymes act as catalysts. For that matter, ADH-A wild type and ADH-A C1B1 genes were expressed in ​ E. coli​ and the encoded enzymes were purified and used for kinetic studies with a final goal on studying the kinetic isotope effect that is generated between them and the molecules that contain deuterium. HPLC analysis on these products showed that the reactions were not thermodynamically favored and conclusions on the best reaction conditions for both enzymes as well as for further improvements are discussed.

Crystallisation, one of the oldest unit operations, is of major economic importance in the hydrometallurgical industry for the separation and/or production of inorganic metal compounds in the form of good quality crystals, both in terms of purity and size. However, industrial crystallisation techniques usually have high energy requirements (e.g. evaporative crystallisation) and the residual solutions are often extremely corrosive, resulting in elevated operating and maintenance costs. Additionally, the majority of industrial crystallisation methods do not render to the appropriate supersaturation control, therefore the produced salts are agglomerates of fine crystallites with heavy solution entrainment and contamination.
In this work, the Solvent Displacement Crystallisation (SDC) technique is investigated as an attractive alternative to the conventional crystallisation methods. SDC involves the addition of low-boiling point, water-miscible organic solvents (MOS) to aqueous solutions to cause salt precipitation based on the salting out effect. The crystals are separated by filtration whereas the solvent is subsequently recovered for reuse by low-temperature distillation. The present work was initiated with the main objective to develop a solid scientific understanding of the SDC process and propose specific applications to hydrometallurgical systems of practical interest.
Criteria for the selection of organic solvents with suitable physical and chemical properties have been established and various compounds screened to determine their amenability to SDC; 2-propanol was selected as an effective salting out agent to cause precipitation of most metallic sulphates of practical interest from acidic solutions and opted for use in further studies. Differences in crystallisation behaviour among the various metal sulphates were attributed to differences in hydration energy (the energy required for a hydrated ion to be separated from its bound water).
None of the tested metal chlorides could be successfully separated from HCl-H2O system with 2-propanol. This was explained in terms of enhanced metal chlorides solubilities in non-aqueous solvents relative to water by formation of chloro-complexes of larger stability constants. The preferential formation of chloro-complexes in mixed aqueous and organic solvents is the result of the almost linear drastic increase in the activity of Cl - with mole fraction organic.
Successful examples of using the SDC method in conjunction with an industrial process involve precipitation of NiSO4·6H2O from copper electrorefining spent electrolytes, residual sulphate removal as gypsum (CaSO4·2H2O) in chloride leaching processes and ZnO separation/NaOH regeneration in the system Na2ZnO2, - NaOH - H2O. By maintaining a low supersaturation (i.e. controlled addition of the solvent to the electrolyte) and heterogeneous crystallisation conditions (use of seed/product recycling), crystal growth is favoured while impurity uptake/contamination is minimised.

Pentaerythritol is an important industrial chemical for use in paints and coatings, primarily, but also in fuels, explosives, medicine and polymers. The current process for this material is over 50 years old and is a multi-step process involving 3 homogeneous aldolizations and a crossed Cannizzaro reaction, generating 1.5 tonnes of waste for every 4 tonnes of product. This is also very energy inefficient. We are currently developing a radically different concept, shown below. This will deliver an integrated heterogeneous catalytic process with no waste and a high energy and materials efficiency. Methanol/ Dehydrogenation Base Hydrog Ethanol Catalyst Catalyst Catalyst Pentaerythritol The initial step, CH3OH HCHO + H2, will involve the use of Ag/SiO2 catalysts. This will be in the absence of O2, which differs from the current oxidative dehydrogenation process used to produce HCHO, i.e. a direct dehydrogenation. This step has been optimised by investigation of different surface properties to determine how surface area and dispersion will affect the overall adsorption and consequently the methanol/ethanol conversion and product yields. Deactivation of these catalysts has also been touched on by use of in-situ temperature programmed oxidation’s. Base catalysis involving an aldol type reaction of 2 aldehydes, HCHO and CH3CHO, will give the methylolated aldehyde intermediate. This will then undergo a final hydrogenation to the desired product. Any unreacted aldehydes will, therefore, be hydrogenated back to starting materials and consequently recycled. It will be attempted to couple all three reactions to explore how the catalysts perform when used in succession.

Propargylic alcohols are easily accessed through the reaction of alkynes with aldehydes and ketones. The 1,3-isomerisation of propargylic alcohols to enones is known as the Meyer-Schuster rearrangement. We have demonstrated efficient room temperature reaction conditions for the Au-catalysed Meyer-Schuster rearrangement (>30 examples) of a wide array of secondary and tertiary propargylic alcohols to the corresponding enones in generally excellent yields and with high E-selectivity. Primary propargylic alcohols rearrange to give highly reactive terminal enones, which can undergo conjugate addition reactions with nucleophiles to access β-substituted products through suitable one-pot procedures. Diethyl acetal substituted propargylic alcohols can be used to access synthetically useful 3-alkoxy furans in the presence of Au in high yield. The use of silver as a catalyst promotes substitution of the propargylic alcohol with various oxygen, carbon and nitrogen nucleophiles. β-Hydroxyketones can be accessed via a Au-catalysed hydration, employing phenols or acidic alcohols as the reaction additive.

I rapporten framgår det en termodynamisk analys för reverse water gas shift med att sammanmata etanol för att undvika det långsammaste steget i reaktionen för att producera högre alkoholer. Ifrån ett termodynamiskt perspektiv, verkar det möjligt att utgå ifrån reverse water gas shift för att producera högre alkoholer vid 100 bar med en temperatur på 300C . Reaktionen är exotermisk, vilket gynnas av det låga temperaturer och det rekommenderas höga tryck p.g.a. en mol kontraktion. Jämviktshalterna var låga, det föreslås att ta bort vatten ifrån jämvikten.  I den matematiska modellen utgick det ifrån en kedja-reaktion för att producera högre alkoholer med reverse water gas shift i processförhållanden på 10–200 bar. I modellen utfördes en senstivty-analysis för jämvikten på tryck och vattenborttagning. Genom att ta bort vatten ifrån jämvikten låg CO2 utbytet kring 95% vid 200 bar även vid låga tryck som 10 bar. Inom CO2 hydrering till högre alkoholer är det begränsat med data och reaktionsmekanismen bakom reaktionen är inte riktigt förstådd. Experimentella försök krävs för att få en mer ökad förståelse. I modellen beskrevs CO2 hydrering och resterande reaktioner som en funktion av en sigmoid. Inom litteraturstudien kom det fram till att det fanns ingen kommersiell tillgänglig membran förtillfället för att ta bort vatten inom krävande process förhållanden. Tekniken ser dock lovande ut.
In this work, a thermodynamic analysis for CO2 hydrogenation by co-feeding ethanol to higher alcohols was performed with the HSC software package. The results suggested a high pressure and a low temperature for the reaction. However, it yielded low equilibrium compositions for the higher alcohols even at a high pressure of 100 bar at 300C . Increasing the equilibrium compositions for the higher alcohols can be done by removing water.  A mathematical model was used to analyse the rate-limiting step in a process for the production of higher alcohols from CO2.  In this process, reverse water gas shift (RWGS) reaction was used to convert CO2 to CO, subsequently, the obtained CO reacts with ethanol and hydrogen to produce higher alcohols directly. The mathematical model was developed in MATLAB to simulate how the reaction could behave by feeding CO2, H2 and ethanol at different pressures ranging from 10-200 bars. The water removal effect on the equilibrium is measured in terms of CO2   conversion by achieving 95% for removing water.  The results indicated that the process can be used to convert CO2 to higher alcohols and at a lower pressure. The limiting factor for CO2 hydrogenation is the reaction mechanism, it’s an urgent problem for the development of the catalysts. In this model it was assumed to be a logistic function. The conversion of CO2 into higher alcohols is an important problem that is required to be addressed by more experimental verifications to understand the mechanism. The literature review shows that there is no available membrane for removal of water for the process currently, due to the harsh process conditions, mainly because of the membrane stability. However, membrane technology is a promising method for separation of water/organic mixtures that can be studied further in the future.

Die vorliegende Arbeit beschäftigt sich mit der Untersuchung von a-Azidoalkoholen, welche über die Reaktion von aliphatischen sowie aromatischen Aldehyden mit HN3 leicht zugänglich sind und die im Gleichgewicht mit den jeweiligen Ausgangsstoffen vorliegen. Bei Raumtemperatur stellt sich dieses Gleichgewicht sehr schnell ein und man erhält spezifische Konzentrationen an Eduktaldehyd, Stickstoffwasserstoffsäure und a-Azidoalkohol. Die Reaktion von Aldehyden mit HN3 generiert dabei ein neues Chriralitätszentrum, wodurch die Umsetzung chiraler Aldehyde, wie z. B. von Zuckerderivaten, zwei anomere Produkte hervorbringt. Die erstmalig erfolgreichen Synthesen zur Erzeugung von 4-Brom-4-methylpentanal sowie 4-Azido-4-methylpentanal werden ebenfalls beschrieben. Letztere Verbindung reagiert dabei ebenso wenig via einer intramolekularen 1,3-dipolaren Cycloaddition zum entsprechenden 4,5-Dihydro-1,2,3,4-oxatriazol-Derivat wie das analoge-Azidobutanal, was im Gegensatz zu Literaturangaben steht. Des Weiteren werden einige interessante Reaktionen der a-Azidoalkohole untersucht. Die Oxidation mit Pyridiniumchlorochromat (PCC) bei –60°C führt zu Carbonylaziden. Die Photolyse bei –50°C generiert unter Stickstofffreisetzung Nitrene, welche mittels Wasserstoffwanderung und anschließender Tautomerisierung des resultierenden Intermediats zu Säureamiden umlagern. Die ebenfalls mögliche 1,2-Wanderung einer Gruppe R in a-Position führt dabei zu einem Intermediat, aus welchem sofort das entsprechende Formamid-Derivat entsteht. a-Azidoalkohole reagieren mit PBr3 in einer sauberen Reaktion durch die Substitution der Hydroxylfunktion unter Bildung der jeweiligen 1-Azido-1-brom-Verbindung
In this work, α-azido alcohols which exist in equilibrium with the starting materials have been studied by the reactions of aliphatic and aromatic aldehydes with HN3. In some cases the title compounds can be isolated from the mixture at low temperature. At room temperature, however, the equilibrium is fast and there are again specific concentrations of the aldehyde, hydrazoic acid, and the α-azido alcohol. The reaction of aldehydes with HN3 creates a new chiral center and a chiral aldehyde, e.g. sugar derivatives, produces two anomeric products. The first procedures to prepare 4-bromo-4-methylpentanal and 4-azido-4-methylpentanal are also reported. The latter compound and also the parent 4-azidobutanal do not lead to 4,5-dihydro-1,2,3,4-oxatriazoles by intramolecular 1,3-dipolar cycloaddition, although it was claimed in the literature. Furthermore, some interesting reactions of the α-azido alcohols have been investigated. The oxidation of α-azido alcohols with pyridinium chlorochromate (PCC) at −60 °C leads to formation of carbonyl azides. The photolysis of α-azido alcohols at −50 °C generates nitrenes with liberation of dinitrogen, which lead to the formation of acid amides after the migration of hydrogen and subsequent tautomerism of the intermediate. 1,2-Migration of a group R in the α-position can produce an intermediate stage which is rapidly converted into formamide derivative. α-Azido alcohols react with PBr3 to give 1-azido-1-bromo derivatives in a clean reaction by substitution of hydroxyl group at the α-position

This thesis is divided into three main parts: Introduction, Results and Discussion and Experimental. The introduction (Chapter 1) reviews transition metal catalysed 'Redox Neutral' Hydrogen Autotransfer Processes where both the hydrogen donor and the hydrogen acceptor are incorporated into the final or target molecule, e.g. utilisation of alcohols as e1ectrophiles III C-N and C-C bond form~tions. The review also gives a brief introduction to the Meerwin-Ponndorf-Verley (MPV)-reduction and the reverse Oppenauer oxidation together with their modern transition metal catalysed versions and their mechanisms. The Results and Discussion section details the author's own work -and is divided into four Chapters: Chapter 2 describes the development of a highly efficient iridium catalysed selective monoalkylation cascade of arylacetonitriles with primary alcohols to afford a-alkylated nitriles in 67-93% yield. It was further demonstrated that such processes can'be achieved by conventional or microwave heating and that bis- and trisprimary alcohols are also processed efficiently. The mechanism was studied using deuterium labelled substrates and mechanism proposed. Chapter 3 describes the investigation of other activated methylene pronucleophiles such as 1.3-dimethylbarbituric acid which successfully undergoes selective mono C5alkylation with a variety ofalcohols under both conventional and microwave heating. Chapter 4 describes investigations into an uimsual C5-autoxidation process of the C5- , , monoalkylated barbiturates and its development into a novel iridium catalysed sequential one-pot C5-alkylation f.hydroxylation cascade of 1,3-dimethylbarbituric acid and alcohols giving the corresponding tertiary alcohols in 49-83% yield. The oxidation process is believed to involve singlet oxygen and shows interesting additive effects. Chapter 5. describes the successful extension 'of the iridium catalysed alkylation cascade into a novel bimetallic sequential one-pot Ir(III) / Pd(O) catalysed process which gives easy access to compounds of high molecular complexity from simple starting materials. This highly atom economic cascade involves the formation of three new C-C bonds, one tetrasubstituted carbon centre, one spirocyclic ring and one di- or trisubstituted exocyclic alkene regio- and stereoselectively. Chapter 6 (Experimental) contains full experimental details of the author's own work, together with appropriate physical, spectroscopic and analytical data for all new, compounds.

Frothers are non ionic surfactants, commonly alcohols and polyglycols, used to provide two functions in flotation, namely to reduce bubble size and stabilize froth. Both functions imply an impact on the properties of the air-water interface (bubble surface) but there is no consensus on the mechanism, particularly with regard to bubble size reduction. Blending frothers is becoming common in flotation practice arguably enhancing performance by permitting independent control of the two frother functions. However, there have been no studies to determine this blend possible action. The blends used here focused on a small addition of polyglycol (F150 and DF250) to alcohols (1-pentanol and MIBC). The effect of blends on gas dispersion properties (bubble size and gas holdup) and froth properties (froth height and water overflow rate) was measured in three units, bubble column, 800 L and 5.5 L mechanical cells. Froth height and water overflow rate showed a strong blend effect, both increasing significantly compared to individual frothers. However, while the bubble size was decreased at blend concentration below the critical coalescence concentration (CCC) of the alcohol frother, bubble size was significantly larger above the alcohol CCC. Gas holdup data supported these effects on bubble size. This bubble size effect compromised testing the hypothesis of independent function control using blends. The thesis focussed on explaining the bubble size observations by designing coalescence and beak-up experiments. Coalescence time of bubbles generated from two horizontal capillaries did not show a blend effect. Break-up tests for one-bubble-at-a-time and from an air stream conducted for F150 – pentanol blends showed that the blend reduced bubble break-up compared to single frothers. The increase in bubble size above the base CCC therefore appears to due to decreased break-up. A mechanism based on the Marangoni effect is introduced to explain this phenomenon.
Les moussants sont des surfactants non ioniques. Ceux-ci sont communément des alcools et des polyglycols, utilisés en flottation pour assumer deux fonctions : réduire la taille de la bulle et stabiliser la mousse. Ces deux fonctions exercent une influence sur les propriétés de l'interface air-eau (surface des bulles). Cependant il n'existe pas de consensus sur le mécanisme, particulièrement en ce qui a trait à la réduction de la taille des bulles. Mélanger des moussants devient une pratique généralement acceptée en flottation, laquelle sans doute renforce la performance en permettant le contrôle indépendant des deux fonctions de moussants. Toutefois, aucune étude n'a été réalisée pour déterminer l'action possible du mélange des moussants. Le mélange utilisé dans ce travail est un ajout d'une petite quantité de polyglycol (F150 et DF250) aux alcools (1-pentanol et MIBC). L'effet des mélanges sur les propriétés de dispersion de gaz (taille des bulles, rétention de gaz) que sur celles de la mousse (hauteur de la mousse, vitesse du flux du trop plein d'eau) a été mesurée en trois unités, colonne à bulles, 800 L et 5.5 L cellules mécaniques. La hauteur de la mousse et la vitesse du flux du trop plein d'eau ont révélé un fort effet de mélange puisque les deux paramètres accusent dans le cas du mélange une augmentation significative en comparaison aux moussants individuels. Alors que la taille des bulles avait diminué lorsque la concentration du mélange avait atteint une valeur inferieure à la concentration critique de coalescence (CCC) de la mousse d'alcool, la taille de la bulle était devenue largement supérieure à celle d'alcool CCC, contre toute attente. Les données sur la rétention de gaz ont aussi corroboré ces effets affectant la taille des bulles. Cet effet de taille de la bulle compromise tester l'hypothèse de la contrôle indépendante de fonction utilisant des mélanges. Le pivot de cette thèse est l'explication des observations de la taille des bulles par le biais des tests de coalescence et de rupture. Le temps de coalescence de bulles générées à partir de deux capillaires horizontaux n'a pas démontré un effet du mélange. Les tests de rupture réalisés avec une seule bulle à la fois et à partir d'un courant d'air pour le mélange F150 – pentanol, démontre que le mélange a réduit la possibilité de rupture par rapport à un seul moussant. L'augmentation de la taille de la bulle au-delà de la base CCC pourrait être due à la diminution de l'effet de rupture. Afin d'expliquer ce phénomène, un mécanisme basé sur l'effet de Marangoni est introduit.

Thesis advisor: James P. Morken
The metal-catalyzed diboration of alkenes has gained fame as a practical methodology for use in the stereoselective construction of complex organic molecules and synthetic building blocks. The created carbon-boron bonds have tremendous versatility and can easily be manipulated into carbon-carbon or carbon-heteroatom bonds. Unfortunately, metal-catalyzed diborations often suffer from limitations such as substrate specificity. To address these issues, we investigated diboration reactions in the absence of transition-metal catalysts. Herein is presented a transition-metal-free, diastereoselective diboration methodology utilizing alkenyl alcohols as substrates. Allylic alcohols can be treated with an organolithium base and bis(pinacolato)diboron to generate 1,2,3-triols upon oxidation. Most studies were done on homoallylic alcohols, which can be performed using a carbonate base and an alcohol additive. This methodology has many strengths, such as a wide substrate scope and high levels of diastereoselectivity. Further investigations into product functionalization and synthetic applications will be pursued in due time
Thesis (MS) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

Thesis advisor: Kian L. Tan
Scaffolding ligand, 14, was designed to direct the hydroformylation of 1,2 disubstituted alkenes, such that the aldehyde forms at the carbon distally from the directing group. The ligand has the ability to form reversible covalent bonds with the substrate and bind to the metal to achieve high conversion, regio- and diastereoselectivity of homoallylic alcohol products
Thesis (MS) — Boston College, 2013
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

The overall aim of this investigation was to identify novel bacterial and fungal biocatalytic routes towards monoterpene alcohols such as enantiopure linalool and menthol, and geraniol, each of which find many applications within the flavour and fragrance industries. The first part of the investigation targeted hydrolytic transformations of racemic monoterpene esters. Enantioselective linalyl acetate esterase activity was detected in Rhodococcus ruber DSM 43338, offering a potential route towards enantiopure (R)- and (S)- linalool. Fractions displaying complementary enantioselectivity for the reaction were isolated from anion-exchange chromatography of cell extracts, giving enantiomeric excess values for linalool ranging from 60% (R)- to 79% (S)-. Attempts to isolate the genes encoding relevant esterases via polymerase chain reactions resulted in a gene fragment representing 75% of a putative tertiary alcohol esterase (TAE). An alternative gene putatively encoding a TAB from a closely related Actinomycete Nocardia farcinica (NITAE) was cloned and expressed in E. coli, and the enzyme purified and characterised. NITAE was inactive towards linalyl acetate, but catalysed the hydrolysis of racemic menthyl acetate to give the commercially-preferred 1(R)-enantiomer of menthol. In the second part of the project, a strain of Rhodococcus erythropolis MLTl was isolated by selective enrichment from soil surrounding hop plants using the hop terpene f3-myrcene as sole carbon source. Resting-cell preparations transformed 13- myrcene to the high-value monoterpene alcohol geraniol. While the relevant enzyme remains to be identified, initial studies suggested an inducible operon for f3-myrcene degradation in MLTl.

Solid acid catalysts were prepared through silicon substitution into aluminophosphate frameworks. Silicon incorporation was confirmed using solid state nuclear magnetic resonance spectroscopy. The nature of the acid sites generated was determined using Fourier Transform infrared spectroscopy. These materials were tested as catalysts for the dehydration of ethanol to ethylene at low operating temperatures. The materials were active for dehydration of ethanol to ethylene with significant differences observed between aluminophosphate frameworks both in terms of selectivity to the desired product but also in terms of the nature of the silicon substitution and the active sites. Links have been made between these properties and the observed catalytic behaviour. The effect of the catalytic framework is further explored though the testing of cobalt substituted aluminophosphates for ethanol dehydration. Silicon substituted aluminophosphates have been tested for the dehydration of 1-phenylethanol to styrene as an example of catalysis in the liquid phase. Here the influence of framework was particularly significant due to the large substrate. The effect of redox metals in the aluminophosphate framework has been investigated through the use of calcined and pre-reduced cobalt substituted aluminophosphates for the dehydration of ethanol to ethylene. Analysis of the catalytic product stream was combined with UV-Visible measurements to investigate potential redox processes occurring during the reaction time on stream and the influence of the oxidation state of the redox metal on the catalytic products of the reaction.

Bibliography: pages 220-231.
A series of crystalline Cholic acid inclusion compounds were studied with a view to understanding the role of guest molecules in inducing and stabilizing a particular Cholic acid (host) lattice structure. Alcohols in the series CH₃(CH₂nOH (n= 0 to 3 and 2-propanol) were employed as guest molecules and enclathrated in the host lattice of Cholic acid during crystallization. Single crystal structure analyses were performed by X-ray diffraction. Two types of molecular packing were identified. Cholic acid inclusion compounds with methanol, ethanol and 1-propanol are characterized by a 3-D host and guest molecule network stabilized by hydrogen bonds with symmetry of P2₁2₁2₁ space group. The guest molecules 2- propanol and 1-butanol, by nature of their size, induce a molecular packing with a larger guest cavity than that in the P2₁2₁2₁ space structures. Symmetrically defined by the P6₅22 space group, the crystal lattice is characterized by a helix of Cholic acid molecules generated by the six-fold screw axis through the origin and parallel to the c axis. The lattice is stabilized by an intricate hydrogen bonding scheme. The conformation of Cholic acid (particularly that of the flexible side-chain) in the two types of molecular packing was studied. The size and shape of the guest cavities created by the host lattices were examined. Thermal analyses (Thermogravimetric analysis and Differential Scanning Calorimetry) were performed on these compounds to examine the guest content and the strength of host-guest interactions. ₁₂₃₅

The aim of this research was to assess the effect of oxygenated hydrocarbons on the knocking characteristics of an engine when blended with low-leaded gasoline. Alcohols, ethers, esters and ketones were tested individually and in various combinations up to an oxygen content of 4% wt/wt in a blend with Series F-7 gasoline of 90, 92, 94 and 96 RON. Tests were carried out at wide open throttle, constant speed and standard timing setting. Engine speed was varied using a dynamometer and knock was detected by two piezoelectric transducers, one on the cylinder head monitoring all four cylinders and one monitoring the cylinder most prone to knock. The engine speeds associated with trace and light knock of a continuous nature were noted. Curves were produced for each oxygenate blend of base RON used against engine speed for the two knock conditions which were compared with those produced using pure Series F-7 fuels. From this a suggested RON of the blend was derived. RON increase was less when using a higher RON base fuel in the blend. Most individual oxygenates showed similar effects in similar concentrations when their oxygen content was comparable. Blends containing more than one oxygenate showed some variation with methanol/MTBE/3 methylbutan-2-one and methanol/MTBE/4 methyl pentan-2-one knocking less than expected and methanol/MTBE/TBA also showing good knock resistance. Further tests to optimise initial findings suggested a blend of methanol and MTBE to be superior although partial replacement of MTBE by 4 methyl pentan-2-one resulted in a fuel of comparable performance. Exhaust emissions were tested for a number of oxygenated blends in 2-star gasoline. 2-star and 4-star fuels were also tested for reference. All oxygenate blends reduced carbon monoxide emissions as expected and hydrocarbon emissions were also reduced. The largest reduction in carbon monoxide occurred using a 14.5 % (1 : 1 : 1) methanol/MTBE/4 methyl pentan-2-one blend. Hydrocarbon emissions were most markedly reduced by a blend containing 25.5 % 4 methyl pentan-2-one. Power output was tested for the blends and indicated a maximum increase of about 5 % at low engine speeds. The most advantageous blends were methanol/4 methyl pentan-2-one (6 : 5) 11% in 2-star and methanol/MTBE/4 methyl pentan-2-one (6 : 3 : 2) 11% in 2-star. In conclusion methanol/MTBE (6 : 5) and (5 : 5), and various combinations of methanol/MTBE/4 methyl pentan-2-one, notably (6 : 3 : 2) gave good results in all tests conducted. CFR testing of these blends showed them to increase both RON and MON substantially.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19754号
農博第2150号
新制||農||1038(附属図書館)
学位論文||H28||N4970(農学部図書室)
32790
京都大学大学院農学研究科食品生物科学専攻
(主査)教授 安達 修二, 教授 入江 一浩, 教授 保川 清
学位規則第4条第1項該当

The current research is focused on the study and evaluation of a new process for the hydrogen generation, named as Chemical-Loop Reforming (CLR) of Ethanol. The main principle of the CLR process is that an oxygen-storage material is first reduced by ethanol stream (T-450oC), and then re-oxidized by water (T-450oC), in order to produce hydrogen and restore the original oxidation state of a looping-material. Different M-modified spinel-type mixed oxides: TYPE I – MFe2O4 and TYPE II – M0.6Fe2.4Oy viz. modified ferrospinels (where M=Cu, Co, Mn, Mg, Ca and Cu/Co, Cu/Mn, Co/Mn), as potentially attractive ionic oxygen and electron carrier looping materials, were prepared via co-precipitation method and tested in terms of both redox properties and catalytic activity to generate hydrogen by oxidation with steam, after the reductive step carried out with ethanol. Particularly, the focus on the reactivity behavior of binary/ternary materials explained by their ability to form thermodynamically stable spinel oxides which allow us to re-obtain the initial spinel phase upon cycling and in turn increase a stability of the looping material itself. In addition, the research includes in-situ DRIFTS and in-situ XPS studies that allowed to extract information at molecular level and to follow surface changes within the reduction/re-oxidation processes during CLR process. Bulk characterizations have been done using XRD, TEM/SEM/EDX, TPR/O, Magnetic measurements and Raman/Mössbauer Spectroscopic techniques. Moreover, a modification of the conventional CLR process with an addition of the 3rd regeneration step (carried out with air) was done in order to increase the stability of the looping material and to overcome the deactivation problems, such as: a coke deposition/accumulation and an incomplete re-oxidation of M0 during the 2nd step.

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on April 6, 2010). Vita. Thesis advisor: Shivendra D. Shukla. "August 2008" Includes bibliographical references

An investigation of the factors influencing the inhibitory and toxic effects of ethanol and higher alcohols, byproducts of alcoholic fermentation, on yeast, is presented. The relative potency of alcohols was found to correlate strongly with the carbon chain-length or molecular size and the lipid solubility of the respective alcohols. Higher alcohols act synergistically with each other and with ethanol in causing cell death of suspensions of non-growing Saccharomyces cerevisiae. The presence of higher alcohols in fermented broth, even at low concentrations, and other by-products of alcoholic fermentation, could explain the higher potency of ethanol produced during fermentation compared to added ethanol. The kinetics of uptake of labelled ethanol supplied at different concentrations gave no evidence of enzymic involvement in the ethanol uptake process. The rate of release of labelled ethanol by cells fed labelled glucose paralled the rate of p14sC-C0b2s release. This does not support the view that ethanol accumulates within the cells to higher concentrations than occur in the medium. Supplementation of a basal synthetic medium with various nutrients did not confer additional survival capacity on yeast against the adverse effects of alcohol. Osmotic pressure did not influence alcohol toxicity below 10% (w/v) sorbitol equivalent of osmotic pressure. Alcohol toxicity is not influenced by hydrogen ion concentration (pH) over a range of pH 5.3 to 3.5.

The present thesis concerns catalytic conversion of syngas (H2+ CO) into a blend of methanol and higher alcohols, an attractive way of producing fuels and chemicals. This route has the potential to reduce the oil dependence in the transport sector and, with the use of biomass for the syngas generation, produce CO2-neutral fuels. Alkali promoted MoS2-based catalysts show a high selectivity to higher alcohols, while at the same time being coke resistant, sulfur tolerant and displaying high water-gas shift activity. This makes this type of catalyst especially suitable for being used with syngas derived from biomass or coal which typically has a low H2/CO-ratio. This thesis discusses various important aspects of higher alcohol synthesis using MoS2-based catalysts and is a summary of four scientific papers. The first part of the thesis gives an introduction to how syngas can be produced and converted into different fuels and chemicals. It is followed by an overview of higher alcohol synthesis and a description of MoS2-based catalysts. The topic alcohol for use in internal combustion engines ends the first part of the thesis. In the second part, the experimental part, the preparation of the MoS2-based catalysts and the characterization of them are handled. After describing the high-pressure alcohol reactor setup, the development of an on-line gas chromatographic system for higher alcohol synthesis with MoS2 catalysts is covered (Paper I). This method makes activity and selectivity studies of higher alcohol synthesis catalysts more accurate and detailed but also faster and easier. Virtually all products are very well separated and the established carbon material balance over the reactor closed well under all tested conditions. The method of trace level sulfur analysis is additionally described. Then the effect of operating conditions, space velocity and temperature on product distribution is highlighted (Paper II). It is shown that product selectivity is closely correlated with the CO conversion level and why it is difficult to combine both a high single pass conversion and high alcohol selectivity over this catalyst type. Correlations between formed products and formation pathways are additionally described and discussed. The CO2 pressure in the reactor increases as the CO conversion increases, however, CO2 influence on formation rates and product distribution is to a great extent unclear. By using a CO2-containing syngas feed the effect of CO2 was studied (Paper III). An often emphasized asset of MoS2-based catalysts is their sulfur tolerance. However, the use of sulfur-containing feed and/or catalyst potentially can lead to incorporation of unwanted organic sulfur compounds in the product. The last topic in this thesis covers the sulfur compounds produced and how their quantity is changed when the feed syngas contains H2S (Paper IV). The effect on catalyst activity and selectivity in the presence of H2S in the feed is also covered.

QC 20150115

This thesis concerns the selective aerobic oxidation of allylic alcohols over practical and model palladium c~alysts. The goal was to elucidate the nature of the active catalyst site and origin of deactivation, which have hindered industrial implementation of such systems. It is hoped that understanding such fundamental aspects of the catalytic process will help optimise future· catalysts exhibiting high turnover frequencies as well as longer lifetimes on-stream. To realise these goals wet-chemical inorganic materials synthesis has been married with Ultra High Vacuum (UHV) single crystal methodologies. A series of amorphous, y-alumina supported palladium catalysts were prepared containing variable Pd concentrations. These allowed the impact of particle size on their resultant catalysis to be studied systematically. Characterising these small metal particles proved challenging, necessitating the combination of powerful bulk and surface sensitive techniques including X-ray Absorption (XAS) and Xray Photoelectron Spectroscopy (XPS) to identify the nature/structure ofthe active phase. These measurements revealed a progressive transformation from large metallic Pd clusters to small oxidised palladium clusters with decreasing precious metal loading. The concentration of surface palladium oxide correlated with the Turnover Frequency (TOF) towards the selective oxidation of both crotyl and cinnamyl alcohols. Surfactant templating routes were subsequently employed to produce high . surface, area mesoporous alumina supports, with a view to boosting the palladium dispersion and proportion of active metal oxide. Bulk and surface spectroscopies revealed similar trends in Pd cluster size and oxidation state with loading as observed for the amorphous supports, albeit with smaller more heavily oxidised palladium at the lowest loadings. High-resolution, high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) revealed that mesoporous alumina was able to stabilize isolated Pd(II) atoms on its surface. Synergy between these atomically-dispersed reduced palladium centers, and improved reactant/product mass transport through the mesoporous structure resulted in extremely active catalysts for alcohol selective oxidation. Decreasing II' II J _ _~ ~ t. ', ...... '... - - - ....:-. .• the Pd concentration increased TOFs as observed for the amorphous alumina catalysts. The single-site catalyst possessed initial TOFs of4400 and 7080 hr-I for cinnamyl and crotyl alcohol oxidation to their respective aldehydes. In order to shed insight into/the un~erlying reactant/surface interaction and deactivation mechanism, UHV studies were subsequently conducted over Pd(lll) single crystal surfaces, to model the most stable (111) facets of larger metal clusters found in practical oxidation catalysts. The adsorption geometry and thermal chemistry of both benzene and bromobenzene were first studied to examine the interaction of the phenyl group in cinnamyl alcohol with Pt(111). Fast XPS and NEXAFS spectra shoW that both benzene and bromobenzene adsorb non-dissociatively, but whilst the former bonds parallel to the surface, bromobenzene shows a significant tilt angle of-60°. Thermal-desorption spectroscopy showed that 20 % of a saturated benzene monolayer desorbs intact in two states, with the remainder undergoing successive dehydrogenations depositing surface-bound hydrocarbon fragments. For bromobenzene, low temperature C-Br bond cleavage results in surface-bound -phenyl groups. A proportion ofthese dehydrogenate at 400 K, liberating hydrogen which subsequently reacts with bromine, or other surface bound phenyls, yielding HBr, benzene and H2. Approximately 30% of a bromobenzene monolayer desorbs either reversibly or as reactively-formed hydrocarbons. The chemistry of crotyl alcohol was subsequently explored on clean and oxygen covered Pd (111) surfaces. Synchrotron X-ray experiments were 'combined with laboratory mass spectrometry to elucidate the associated binding geometry and reaction network. NEXAFS and Fast XPS revealed crotyl alcohol adsorbs molecularly at 95 K, with the allyl moiety parallel to the surface. Surface_ annealing induces oxidative dehydrogenation to crotonaldehyde at sub-ambient temperatures, in competition with a minor dehydration route to butene and water. Crucially, alcohol decarbonylation was also observed at catalytically relevant temperatures, resulting in an accumulation of surface bound CO and hydrocarbon fragments over the bare metal surface. Coadsorbed oxygen suppressed this decarbonylation pathway, promoting crotonaldehyde desorption over a similar temperature regime to that observed over dispersed PdfAh03 clusters.

This report summarises the work done on monohydroxy aliphatic alcohol upgrading using Au/TiO2 catalysis. The catalysts were initially tested using a plug-flow CO oxidation reactor; complete conversion of a stream of CO flowing over the catalyst bed at a GHSV of approximately 79,500 hr-1 was typically achieved without any required external heating. TEM analysis showed that the freshly prepared catalyst does not contain detectable Aunano clusters, while the spent CO oxidation catalyst had clearly visible nanoparticles with an average size of approximately 1.6 nm. XRD analyses showed that the final pH to which the deposition-precipitation procedure was adjusted had a major role in determining the average nanocluster size. Alcohols were oxidised using the 1% Au/TiO2 catalyst in a plug-flow reactor, with the alcohol vapour being produced by sparging a blended stream of helium and oxygen (typically made up to a total flowrate of 100 ml min-1). The temperature of the alcohol could be adjusted, thereby controlling the vapour mole fraction of alcohol. For methanol oxidation, the primary reaction pathway across the entire range of studied feed compositions was combustion. The onset of combustion occurred dramatically, in the range of 140-160°C. For ethanol oxidation, acetaldehyde selectivity increases and overall conversion decreases as the oxygen content of the feed stream decreases. The kinetics of the catalysed ethanol oxidation showed a compensation effect, described by the equation ln(A) = 0.2032EA + 2.6102 (EA in kJ mol-1). Propanol oxidation demonstrated the highest selectivity towards a value added product (propanaldehyde), with propanaldehyde being formed in significant quantities. However, combustion was still favoured at high temperatures when large excesses oxygen were present. The thermokinetic data calculated for n-propanol oxidation did not exhibit the compensation effect observed in ethanol oxidation; the EA for this reaction was stable at approximately 38 kJ mol-1. In the anaerobic catalysed reactions of ethanol and n-propanol, an oily layer was collected above the water meniscus in a cold trap. This oil could potentially be formed via poly-aldol condensation reactions of the aldehydes produced during oxidation. Though other researchers suggest these condensation reactions typically end in a cyclic dehydration into aromatic compounds, electrospray mass spectrometry found no indication of such products. Control reactions performed using unloaded TiO2 and porous Au (obtained by in-situ reduction of Au2O3) produced different product distributions, all requiring substantially higher reaction temperatures. This suggests that there must be a synergistic effect between the Au and TiO2 substrate which facilitates reactions. Furthermore, the product distributions of the 1% Au/TiO2 catalysed reactions were significantly different from results published by other researchers performing similar oxidations on Au(111) single crystals, where substantially higher selectivity towards value-added products (formaldehyde, acetaldehyde, and propanaldehyde) is typically observed.

Vapor-liquid equilibria (VLE) in alkanes and alcohols was measured and a contribution Patel-Teja (GPT) equation proposed in this work. systems of nmodified Group of state was Isothermal vapor-liquid equilibria at temperatures between 298.7K and 333. 7K have been measured for the binary systems n-pentane + n-hexane. n-pentane + noctane. n-pentane + n-decane. and n-pentane + l-propanol. The data were found to be consistent according to a point-to-point consistency test and were correlated using the Wilson. NRTL. and UNIQUAC activity coefficient models. The parameters of the models were estimated using the maximum likelihood principle. A new version of the Group contribution Patel-Teja equation of state was proposed in which a new temperature dependent group interaction expression was introduced. Group interaction parameters for four constituent groups of the alcohols and n-alkanes (viz. CH 2• CH 3 • CH and OH) were determined. These parameters were then used for the prediction of VLE in mixtures of n-alkane + n-alkane. n-alkane + n-alcohol. and n-alcohol + n-alcohol. VLE predictions with the new GPT equation of state were found to be superior to predictions with the original group contributions with molecular equations. The modified equation can be used in systems of nalkanes and alcohols where data for molecular parameters are lacking. The proposed temperature dependence of the group interaction parameters improved predictions over a wide range of temperature and pressure.

This thesis describes the development of a more economical catalytic system for the N-alkylation of amines by “borrowing hydrogen” and its application in the synthesis of a variety of amines including the dopamine agonist Piribedil and the antihistamine agents Antergan and Tripelennamine. Chapter 2 describes the development of the ruthenium-catalysed N-alkylation of primary amines with primary alcohols by “borrowing hydrogen”. Chapter 3 describes the application of the ruthenium-catalysed N-alkylation of secondary amines with primary alcohols by “borrowing hydrogen”. The ruthenium-catalysed synthesis of dimethylamines by “borrowing hydrogen” is also described and a mechanistic proposal for the N-alkylation of alcohols with amines has been proposed. Chapter 4 describes the role of amines in pharmaceuticals and the ruthenium-catalysed synthesis of Piribedil, Antergan and Tripelennamine by “borrowing hydrogen”.

Thesis: S.M., Massachusetts Institute of Technology, Department of Chemistry, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 46-50 (first group)).
Different stereoisomers of bioactive molecules can have distinct activities in biological systems. For this reason, it is routine procedure in the drug discovery and development process to prepare the full matrix of possible stereoisomers of drug candidates for biological evaluation and to determine the stereochemical purity of these molecules. Despite many recent advances in asymmetric synthesis, the development of general and practical strategies that are fully divergent and give rise to all stereoisomers of products bearing multiple contiguous stereocenters remains a significant challenge. Herein we report a stereodivergent copper-based approach for the expeditious construction of amino alcohols with high levels of chemo-, regio-, diastero- and enantioselectivity. Specifically, these amino alcohol products were synthesized using the sequential copper hydride-catalyzed hydrosilylation and hydroamination of readily available enals and enones. This strategy provides a route to all possible stereoisomers of these amino alcohol products, which contain up to three contiguous stereocenters. Catalyst control and stereospecificity were simultaneously leveraged to attain exceptional control of the product stereochemistry. Beyond the utility of this protocol, the strategy demonstrated here should inspire the development of methods providing complete sets of stereoisomers for other valuable synthetic targets.
by Zackary L. Wong.
S.M.