Dissertations / Theses on the topic 'Ether solvent'

Semicrystalline thermoplastic polyimides based upon bis(4-aminophenoxy)benzene and related "triphenyl ether" diamines were synthesized via the classical two step amic acid route. More specifically, polyimides were derived from para linked 1,4-bis(4-aminophenoxy)benzene, or TPEQ (triphenyl ether diamine- hydroquinone) and its meta isomer 1,3-bis(4-aminophenoxy)benzene, or TPER (triphenyl ether diamine-resorcinol). The reaction of these diamines with rigid or semi-rigid dianhydrides such as pyromellitic dianhydride (PMDA), biphenyl dianhydride (BPDA), and oxydiphthalic anhydride (ODPA) yields very thermally stable semi-crystalline polymers which have excellent resistance to organic liquids. Amorphous polyimides could be derived from hexafluoroisopropylidene-linked diphthalic anhydride (6FDA), but these systems were not extensively investigated. Importantly, molecular weight characterization of the semicrystalline systems at the soluble amic acid stage was successful by employing hydrodynamic volume calibrated, viscosity detector size exclusion chromatography (SEC). The experimental values were found to be within the targeted <M_n> range of 20-30,000 g/mole. Polyimide powders derived from these ether diamines were prepared by solution imidization at 180°C, to afford about 70% imidized structures as judged by dynamic thermal gravimetric analysis (TGA), before crystallization/precipitation occurred. Relatively small particle sizes ranging from 2 to 25 μm in size were generated, which would be appropriate for thermoplastic polymer matrix composites prepared by powder processing. All specimens showed excellent thermooxidative stability, consistent with the aromatic imide structure. The molecular design of the aromatic polyetherimide repeat unit was critical for the successful utilization of these semicrystalline high performance materials. The metba-linked TPER system when combined with the thermally stable s-biphenyl dianhydride (BPDA) produced a melting endotherm, T_m, at about 395°C, which was well within the thermal stability limitations of organic materials, i.e., less than or approximately 450°C. It was also demonstrated to be important to quantitatively endcap both ends of the chains at about 20-30,000 <M_n> with non-reactive phthalimide groups to achieve appropriate melt viscosities and good melt stability. This was done by off-setting the stoichiometry in favor of the diamine, reacting with a calculated amount of phthalic anhydride and imidizing in bulk above the Tg (≈210°C) at 300°C. These considerations allowed for remarkable melt stability in nitrogen at 430°C for at least 45 minutes, and importantly, repeated recrystallizations from the melt to afford tough, ductile semicrystalline films with excellent solvent resistance. If the macromolecular chains were not properly endcapped, it was demonstrated that viscosity increased rapidly at 430°C, suggesting reactions such as transimidization involving terminal amine end groups with in-chain imide segments and/or other side reactions, which quickly inhibited recrystallization, probably by reducing molecular transport processes. In contrast, polyimides based upon the more rigid para-linked TPEQ did not demonstrate melt or flow characteristics below 400°C, and degraded around the T_m at about 470°C! The less thermally stable TPEQ-ODPA based polyimide did melt around 409°C, and lower molecular weight samples, e.g., 10,000 M_n, recrystallized from the melt after short melt times, but cast films were brittle. It was hypothesized that the weak link may be the relatively electron rich arylene ether bond derived from the ODPA dianhydride. Several alkylated derivatives of TPER were synthesized in good yield by the reactions of alkylated resorcinol precursors with p-fluoronitrobenzene to produce dinitro compounds, which were subsequently reduced. These model diamines were then used to synthesize polyimides by the classical two step route. As expected, few of the polyimides derived from BPDA and these diamines displayed melting transitions (T_m), probably because of poor chain packing. However, they could have potential as new thermally stable membrane materials. Several amorphous polyimides prepared from 1,3-bis(p-aminophenoxy)-4-hexylbenzene were soluble in selected common organic solvents and could be cast into flexible films.<br>Ph. D.

Experimental data were obtained for the computation of mole fraction solubilities of three dichloronitrobenzenes in organic solvents at 25oC, and solubility ratios were obtained from this data. Abraham model equations were developed for solutes in tributyl phosphate that describe experimental values to within 0.15 log units, and correlations were made to describe solute partitioning in systems that contain either "wet" or "dry" tributyl phosphate. Abraham model correlations have also been developed for solute transfer into anhydrous diisopropyl ether, and these correlations fit in well with those for other ethers. Abraham correlations for the solvation of enthalpy have been derived from experimental and literature data for mesitylene, p-xylene, chlorobenzene, and 1,2-dichlorobenzene at 298.15 K. In addition, the enthalpy contribution of hydrogen bonding between these solutes and acidic solvents were predicted by these correlations and were in agreement with an established method. Residual plots corresponding to Abraham models developed in all of these studies were analyzed for trends in error between experimental and calculated values.

L’objectif général de ce travail était d’étudier la relation entre exposition professionnelle maternelle aux solvants organiques et malformations congénitales.Ce projet s’est appuyé sur les données de la cohorte PELAGIE. Il s’agit d’une cohorte mère enfant avec inclusion de 3 421 femmes en début de grossesse en population générale en Bretagne. L’exposition aux solvants était définie par différentes méthodes (expositions déclarées, matrices emplois-expositions, dosages urinaires de métabolites de solvants chlorés et d’éthers de glycol).Nous avons mis en évidence une relation entre l’exposition aux solvants mesurée par des méthodes indirectes et les malformations congénitales. Puis, pour un échantillon aléatoire de451 femmes, nous avons étudié les déterminants de la détection urinaire des métabolites de solvants. Enfin, dans le cadre d’une étude cas-témoins dans la cohorte, la relation entre métabolites urinaires de solvants et malformations congénitales a été étudiée<br>The aim of this project was to study the relation between maternal occupational exposure to solvents and congenital malformations.This project used data from the PELAGIE study. This is a mother child cohort which had included 3 421 women from the general population at the beginning of their pregnancy in Britany. Occupational exposure to solvents was assessed by different methods (self-report, job exposure matrix, and urinary determination of glycol ethers and chlorinated solvents metabolites).We have shown an association between solvent exposure using indirect method of assessment and congenital malformations. Using a randomized sample of 451 women, we have studied the occupational and non occupational determinants of urinary detection of glycol ethers and chlorinated solvents metabolites. Finally, we have studied in a nested case-control study, the relation between urinary solvent metabolites and congenital malformations

Cette thèse se situe dans un contexte de programme de recherche de Chimie Verte. Elle traite des substitutions nucléophiles aromatiques (S(N)Ar) en utilisant le couplage de deux techniques: catalyse par transfert de phase sans solvant et irradiation micro-ondes. Deux objectifs sont mis en avant: d'une part, la méthodologie pour l'amélioration de procédé (obtention des rendements les plus élevés possibles dans des conditions douces), d'autre part, la mise en évidence d'effets spécifiques des micro-ondes et la compréhension des phénomènes mis en jeu dans l'interaction rayonnement-matière. En ce qui concerne l'optimisation des rendements des S(N)Ar, l'étude se compose essentiellement de deux parties: - des éthérifications d'halogénures aromatiques ou azaaromatiques, - la fluoration de chlorodiazines. Dans le premier cas, des éthers ont pu être synthétisés avec des rendements excellents sur des substrats aromatiques activés ou non, grâce à une activation micro-ondes raisonnable et des temps de réaction d'au plus une heure. Dans le deuxième cas, l'échange fluor - chlore a été optimisé jusqu'à l'obtention de très bons rendements, de meilleures sélectivités, dans des conditions bien plus douces que la littérature. Ce mémoire propose également une discussion sur les différences non thermiques entre micro-ondes et chauffage classique (effets spécifiques). La discussion s'articule autour de la sensibilité du milieu avec le champ électrique, et de l'évolution de la polarité des espèces au cours du mécanisme réactionnel, à l'appui de mesures de caractéristiques diélectriques (e' et e") et de calculs de chimie quantique. Ces effets dépendent de la polarité et de la position relative des réactifs et de l'état de transition sur les coordonnées réactionnelles<br>This thesis takes place in a research program of Green Chemistry. It deals with nucleophilic aromatic substitutions (S(N)Ar) using the mixing of two techniques: solvent-free phase transfer catalysis and microwave irradiation. It consists in two objectives: - a methodology approach aiming to improvements in procedure (highest yields under mild reaction conditions), - a study of interactions between the electric field and the medium concerning specific microwave effects. Concerning the first point, the study is dealing with, on one band etherification of aromatic or azaaromatic halides and, on an other hand tluorination of chlorodiazines. In the first case, ethers have been synthesised with excellent yields on activated or non-activated aromatic halides thanks to microwave irradiation within one hour or legs as reaction time. In the second case, tluorine-chlorine exchange has been improved up to very good yields, better selectivity and under milder conditions than in the literature. This memory also focuses on non-purely thermal differences between microwave and conventional heating (specific effects). The experimental results concern the medium sensibility to the electric field and the evolution of species polarity according to the mechanism. They are based on dielectric characterics measurements (e' and e") and theoretical calculations. The specific effects depend on the relative polarities of ground and transition states and its position along the reaction coordinates

Les techniques de la chromatographie en phase liquide ont permis de mettre au point une separation optimisee des impuretes de la cyclododecanone oxime. La methode la plus performante est la chromatographie de partage a polarite de phases inversee sur un gel de silice greffee octadecyle avec une phase mobile ayant la composition suivante : methanol-acetonitrile-tetrahydrofurane-eau 33:24:3,5:39,5 (v/v). Une trentaine d'impuretes sont ainsi mises en evidence grace a l'emploi d'une colonne de petit calibre de 1 metre de long et de 1 millimetre de diametre interieur. Cette colonne contient 30000 plateaux theoriques. La duree de la separation est de 3,5 heures. L'identification d'un certain nombre de ces impuretes a ete effectuee par la conjonction de differentes methodes : couplage en ligne avec la spectrometrie de masse et chromatographie semi-preparative permettant d'isoler des quantites notables de certaines impuretes identifiees par la spectrometrie de masse differee de meme on a pu appliquer a ces impuretes la spectrometrie infrarouge par transformee de fourier

L'objectif général de ce travail était d'étudier la relation entre exposition professionnelle maternelle aux solvants organiques et malformations congénitales.Ce projet s'est appuyé sur les données de la cohorte PELAGIE. Il s'agit d'une cohorte mère enfant avec inclusion de 3 421 femmes en début de grossesse en population générale en Bretagne. L'exposition aux solvants était définie par différentes méthodes (expositions déclarées, matrices emplois-expositions, dosages urinaires de métabolites de solvants chlorés et d'éthers de glycol).Nous avons mis en évidence une relation entre l'exposition aux solvants mesurée par des méthodes indirectes et les malformations congénitales. Puis, pour un échantillon aléatoire de451 femmes, nous avons étudié les déterminants de la détection urinaire des métabolites de solvants. Enfin, dans le cadre d'une étude cas-témoins dans la cohorte, la relation entre métabolites urinaires de solvants et malformations congénitales a été étudiée.

A study has been made on the irradiation induced grafting of MMA to PPE and cellulose subtrates in the presence of various solvents and Irgacure 819 photoinitiator, a new photoinitiator on the market at the commencement of this project. UV is the main irradiation source used. The grafting yields have been found to vary with parameters such as the subtrate types and thickness, MMA concentration, solvents used, Irgacure 819 concentration and UV doses. For the cellulose subtrate, good grafting yields were obtained only when solvents such as methanol and DMF were used. On the contrary, MMA could graft to PPE with or without solvents, although high grafting yields were achieved in the presence of methanol, DMF and other chlorinated solvents. The solvent effects on the grafting process of MMA to PPE and cellulose subtrates were attributed to the wetting and swelling effects by the solvents as well as the Trommsdorff effect. During the course of this study, a comparison in the performance between Irgacure 819 and other photoinitiators (PIs) was also carried out. A study was made of the UV radiation induced grafting of styrene to PPE subtrate with EP vinyl monomers and vinyl ethers as comonomers. The possibility of spontaneous polymerization of styrene/EP vinyl monomer mixtures under the influence of UV radiation was also investigated. Grafting yields were found to vary with the comonomer types and their concentrations, the presence or absence of solvents and additives such as Irgacure 819 photoinitiator, K185 cationic photoinitiator, mineral acids and CT complexes. In addition, the composition of grafted subtrates was studied by using the FT-IR spectroscopy technique

Le dioxyde de carbone supercritique (SF-CO2) a été choisi afin d'étudier l'extraction en milieu supercritique d'ions métalliques tels que le césium et l'uranium. Un intérêt particulier a été porté au rôle de l'eau lors de ces extractions ainsi qu'à son interaction avec des agents chélateurs (AC). En première partie, les éthers couronne ont été choisis comme AC du césium et leur interaction avec l'eau a été étudiée dans le SF-CO2 en utilisant la spectroscopie InfraRouge à Transformée de Fourier (IR-TF). La configuration sandwich entre deux éthers couronne et une molécule d'eau a été observée dans le SF-CO2. Pour les configurations simple et pontée, l'équilibre a été défini et l'enthalpie de formation de la liaison hydrogène a été calculée. Ces résultats ont ensuite été comparés à ceux obtenus dans des mélanges de CHCl3 et de CCl4 en utilisant la spectroscopie à Résonance Magnétique Nucléaire (RMN). Pour conclure cette première partie, le rôle de l'eau a été étudié lors de l'extraction du picrate de césium par le DCH18C6 et les constantes d'équilibre ont été calculées. Dans une deuxième partie, l'extraction de l'uranium a été étudiée dans le SF-CO2. Des complexes de Phosphate de TriButyle (TBP), d'eau et d'acide nitrique ont été utilisés comme AC et oxydants. L'IR-TF a été utilisée pour étudier l'interaction entre le TBP et l'eau dans le SF-CO2. Ces résultats ont été comparés à ceux trouvés dans le CHCl3 en utilisant la RMN. Cette même spectroscopie a été utilisée pour comprendre les interactions entre l'acide nitrique, le TBP et l'eau, seuls puis dissous dans du CHCl3. La formation de microgouttelettes d'acide et d'eau dues à l'effet anti-solvant a été observée et quantifiée. Pour conclure ce travail de thèse j'ai réussi à optimiser l'extraction et la récupération d'uranium enrichi provenant de cendres d'incinération de déchets de fabrication de combustible nucléaire. Un complexe de TBP, d'eau et d'acide nitrique dissous dans du SF-CO2 a été utilisé à cette fin.

Etude spectrophotometrique de la stabilite des complexes de l'ion uo::(2)**(2+) et de l'ion cu**(2+), dans l'eau et eau-acetonitrile. Structures possibles des complexes 1:1, 1:2 et 2:1. Mecanismes de formation des complexes

L'etude de deux systemes destines a l'application batterie lithium-ion a ete menee. Le premier systeme est constitue d'une membrane a base de polymethacrylonitrile (pman), un polymere capable de jouer un role actif dans les phenomenes de solvatation et de conduction du cation li +. Le second est constitue d'un separateur microporeux de polyfluorure de vinylidene impregne d'electrolyte liquide. Des copolymeres triblocs pman/polyether/pman et pman/polydioxolane/pman ont ete synthetises par voie anionique et caracterises. Les complexes sel/polymeres ont ensuite ete etudies. En particulier, la comparaison des phenomenes de solvatation avec ceux rencontres dans l'homopolymere de pman permet d'estimer le pouvoir solvatant du pman par rapport a celui de divers blocs centraux (poe, pop, pdxl). Des caracterisations physico-chimiques et electrochimiques de pvdf microporeux ont ete menees. Ainsi, l'influence des interactions au sein du systeme polymere/solvants/sel sur les performances et les proprietes de la membrane a ete determinee. L'importance de l'affinite solvant/polymere sur les phenomenes de degradation, de modification irreversible, et de mobilite des especes ioniques a notamment ete mise en evidence. Les effets de sel, de temperature et des synergies sur l'equilibre et la cinetique de gonflement de la membrane pvdf ont par ailleurs ete caracterises.

碩士<br>國立成功大學<br>化學工程研究所<br>83<br>Cold crystallization kinetics of virgin and solvent-treated poly (ether ether ketone) (PEEK) were investigated by differential scanning calorimetry (DSC) at isothermal conditions. The morphology of these samples was examined using scanning electron microscopy (SEM) and wide-angle x-ray scattering (WAXS) analysis. The kinetic analysis has shown that the cold crystallization of virgin untreated PEEK proceeds with an Avrami exponent of n1=2.5-2.6, demonstrating a circular lamellar growth with homogeneous nucleation. In addition, direct SEM observation has provided evidence of an interesting crystalline morphology in cold-crystallized virgin PEEK. The crystalline morphology of cold-crystallized PEEK is populated with sporadically scattering snow flake-like dendrites with branches running with large angles to the main parent fibrils. On the opposite side, cold crystallization of solvent-desorbed PEEK samples proceeds with n=1.0-1.2, reflecting probably an irregular line growth with heterogeneous nucleation. SEM examination revealed a highly porous texture in solvent- desorbed and cold-crystallized PEEK samples. The micro-porous texture in these samples prevented planars or spherulites growth to take place. The results was a random, line growth and neither spherulites nor planar lamellar dendrites were present. However, the final crystalline morphology in solvent-desorbed/ cold-crystallized PEEK could not be easily resolved due to the porous nature in the sample. Futhermore, all the X-ray crystallographs of the cold-crystallized PEEK sample that has been previously solvent-crystallized were different from those of the cold-crystallized virgin PEEK.

碩士<br>國立成功大學<br>化學工程學系碩博士班<br>90<br>Two phase transfer catalysis techniques were employed in this study, one is tri-liquid-liquid-phase catalysis technique in which soluble tetra-ammonium salt (tetra-n-propylammonium bromide Pr4NBr and tetra-n-butylammonium bromide Bu4NBr) were used as the phase transter catalysts, the other is liquid-liquid-solid (i.e. triphase) catalysis technique in which insoluble polymer-supported catalyst was utilized. In the preparation of the polymer-supported catalyst (triphase catalyst) tributylamine was immobilized on chloromethylated polystyrene polymer. With organic product allyl phenyl ether (ROPh) as solvent, we made use of allyl bromide (the organic reactant, RBr) and sodium phenolate (the aqueous reactant, NaOPh) to synthesize allyl phenyl ether. By this way, we can get the pure allyl phenyl ether without separation and purification if all the allyl bromide is converted. Thus, we can save the operation cost, and need not to dispose the waste solvent. It will correspond with the ‘green chemistry’. At the end of this study, the feasibilities and two catalysis techniques were evaluated and compared by operating in continuous-flow stirred vessel reactor (CFSVR). 　　This thesis is composed of three parts. In the first part, the feasibilities of using Pr4NBr and Bu4NBr as the phase transfer catalysts for the tri-liquid-phase reaction in a continuous-flow reactor were evaluated basing on whether a third liquid phase will be formed or not. Then, using Pr4NBr as the catalyst, the tri-liquid-phase catalytic reaction was carried out under different operating conditions by means of a continuous-flow stirred vessel reactor. The performance of prepared polymer-supported catalyst was evaluated by using it as a triphase catalyst repeatedly in a batch reactor under different operating conditions in the second part. The tri-liquid-phase and liquid-liquid-solid catalytic systems were compared in the last part. 　　In the first part, the etherification reaction was carried out with the tri-liquid-phase method, the effects of operating variables, including the most suitable volume of allyl phenyl ether for helping the tri-liquid-phase and mole fraction of Pr4NBr on the conversion of RBr, and the repeated batch operations on the distribution of Pr4NBr or Bu4NBr in various phase were investigated first. After that we investigate the effects of agitation speed, inlet flow rate, reaction temperature, inlet molar ratio of reactant, the number of stages in the extractor and the kinds of catalysts on the performance of CFSVR. Experiment results show that the tri-liquid-phase catalytic system that was formed by the using Pr4NBr as a catalyst and equal amount of allyl phenyl ether and pure water was suitable for being operated in a continuous-flow reactor. When the mole fraction of Pr4NBr was 0.5, most of the catalysts concentrate on the third-liquid phase. Although the catalytic activity of Pr4NBr is lower than Bu4NBr, however, its loss rate is lower when both were used as the catalysts in repeated batch operations. When total volume of inlet fluid is larger than the volume of reactor, the system can reach a steady state. The interfacial mass transfer resistance can be neglected when the agitation speed is beyond 600 rpm. A higher conversion of RBr can be obtained when the inlet flow rate is 1 ml/min. The higher the temperature is, the higher the conversion gets and the more stable more stable the third-liquid phase is. In order to prevent the loss of that the third-liquid phase resulting from agitation, we installed a packed bed or baffles under the continuous-flow reactor, and observed individual. The result shows that the reactor with a packed bed can keep the catalyst loss rate of aqueous being lower. However, the droplet of the third-liquid phase easily stayed under the packed bed rather than go back to the reaction area. Therefore, the reaction is more appropriately carried out in the continuous-flow reactor that has baffles. The more stages the extractor has, the better the effect of extraction is. The effect of extraction will be similar if there is little amount of Pr4N+ among organic phase outlet. Feeding with equal organic-to-aqueous reactant molar ratio can keep the catalyst loss rate lower than unequal reactant molar ratio inlet. Because of lower lipophilicity, Pr4NBr was more suitable to be used as the phase transfer catalyst to run this tri-liquid-phase catalytic reaction than Bu4NBr. 　　In the second part, the etherification reaction was carried out with the liquid-liquid-solid method. Several factors which influence the conversion of RBr is discussed. The factors include agitation speed, volumetric ratio of organic solvent and water, reaction temperature, amount of catalysts, amount of aqueous and organic reactants, amount of salts, amount of tri-n-butylamines and stability of catalyst. Experimental results show that the interfacial mass transfer resistance can be neglected when the agitation speed is beyond 200 rpm. High conversion of RBr will be obtained when the volume of organic solvent and water are equal. Raising the temperature can promote the conversion. But RBr will vaporize and the catalyst will be worsened when the temperature is too high. As a result, the appropriate temperature is 50℃. An amount of 5.4 meq catalyst is economic and cost-effective. When using more NaoPh than RBr, the reaction is pseudo-first-order irreversible reaction. As this time, a higher conversion of RBr comes into effect. Existence of salts restrains the activity of catalyst. The extent of inhibition depends on the amount of salts. Two reasons will cause the decrease of catalyst activity. One is that the activity site on the polymeric support will fall down because of Hofmann elimination reaction. The other is that the force of agitation will destroy the structure of catalyst. The tri-n-butylamine which falls from support can react with organic reactant and form the tetra-alkylamine salt. The tri-n-butylamine salt has catalytic activity but is lower than the form that the tri-n-butylamine fixes on the support. 　　The performances of the tri-phase system and liquid-liquid-solid system are compared in the last part. The comparison is based on four items, namely, catalytic effect, stability of catalysts, the operation of continuous-flow reactor and the procedure of preparing catalysts. Because of the high dispersion and bigger interfacial area, the tri-liquid phase catalyst has better catalytic effect. On the other hand, the tri-liquid phase catalyst is cheaper than the triphase catalyst hence it is more cost-effective. Although the tri-liquid phase catalyst will dissolve in organic and aqueous phase and flow away with outlet, the stability of catalyst is still better than triphase catalyst. The operation of continuous-flow reactor with liquid-liquid-solid catalyst is simpler due to the fact that we don’t have to extract the catalyst from the organic phase. The procedure of preparing polymer-supported catalysts is complicated and the reproducibility is not as well as the formation of a third liquid phase in the tri-liquid phase system.

碩士<br>國立中興大學<br>化學工程學系所<br>101<br>This study investigated ultrasonic solvent extraction, normal phase column elution fractionation and supercritical anti-solvent (SAS) precipitation of fucoxanthin from brown algae of Hincksia mitchellae P.C. Silva. The 5.5 mg/g content of fucoxanthin in algae was evidenced by soxhlet ethyl acetate extraction at 353 K and 16 hours. The 5.4 mg/g content of fucoxanthin of extract was obtained by ultrasonic ethyl acetate extraction at temperature (298 K), solvent to solid ratio (60:1), time (10 min) and continuous 3 times of extraction. Ultrasonic extract eluted by normal phase column fractionations with a mixed solvent of n-hexane and acetone (7:3), then we can get 719.8 mg/g content of fucoxanthin in fraction with an average recovery of 85.4%. preliminary SAS diethyl ether solution precipitation of the column fractions were carried out by investigating the effect of temperature, pressure, retention time, feed flow rate and feed concentration on purity and recovery of fucoxanthin. Two-factor (pressure and time) schemed response surface methodology designed SAS experiments produced micro-sized irregularly flower-type agglomerated precipitates containing 886.2 mg/g of fucoxanthin with a recovery of 98.7% and showed that pressure is a major factor on enhancing purity of fucoxanthin. The result also showed SAS is prior to liquid-liquid anti-solvent precipitation of the fucoxanthin content of 790.5 mg/g. Dissolution rate tests showed the SAS product was faster dissolved in aqueous solution than that of the liquid-liquid anti-solvent precipitates and brown algae powders.

碩士<br>國立成功大學<br>化學工程研究所<br>81<br>In a preliminary study in our laboratory on the reaction between n-butyl bromide and sodium phenolate catalyzed by tetrabutyl ammonium bromide to prepare n-butyl phenyl ether, we found that a third liquid phase appeared apparently when we used polar chemicals, such as n-hexane and cyclohexane, as the solvent for organic reactant.In order to observe the formation condition of the third liquid phase and to elucidate the role it plays on the reaction, we carried out a series of experimental studies on the same reaction with n-hexane as the solvent. The experiment results reveal that the third liquid phase appears in all cases of our experiments. The reaction rate increases with increasing the amount of catalyst and increases at first then decreases with increasing the amount of sodium phenolate. The catalyst is in equilibrium among aqueous phase, oil phase and the third liquid phase. When a small amount of sodium phenolate is used, the reaction rate will first decrease sharply due to the disappearance of the third liquid phase and then increase sharply due to the appearance of the third liquid phase and a vast amount of increase of its catalyst with the amount of sodium hydroxide added.If the amount of sodium hydroxide added is too much, the reaction rate will gradually decrease due to high viscosity and low solubility of n-butyl bromide in the third liquid phase.On the other hand, when a large amount of sodium phenolate is added, the third liquid phase appears only when a large amount of sodium hydroxide has been added. Under such a circumstance, the reaction rate decreases sharply then increases slightly with increasing the amount of sodium hydroxide. When the amount of sodium phenolate added is small and that of sodium hydroxide is high,the reaction changes from pesudo-zero order to pesudo- first order.

碩士<br>國立交通大學<br>應用化學系碩博士班<br>99<br>Part Ι. A modest a-selectivity in DMF-mediated glycosylation with thioglucopyranoside donor was obtained, which was accompanied by some drawbacks such as low reaction yield and longed reaction time. To seek for a better substitution for DMF additive, we used the computational calculation to analyze the electron density of heteroatom of selected derivatives. The results revealed that 1-methyl-2-pyrrolidinone was a possible substitution for DMF owing to the good yield and acceptable reaction time. Part ΙΙ. The C-2 ether protecting function of thioarabinosyl donor in nitrile co-solvent mixture was found to play a participation role and led to a 1,2-trans selectivity . We reveal a Ritter-like association of the oxygen atom in the C-2 ether function with the entrapped nitrile molecule, when they are configured in cis orientation. Application of this concept enables us to develop efficient strategy for the preparation of linear a(1-5) arabinan oligomers.

This thesis involves a study of the thermodynamics of liquid mixtures containing N-methyl-2pyrrolidone (NMP) and hydrocarbons or ethers. NMP is a polar liquid which is used in liquid extraction procedures for the separation of polar and nonpolar hydrocarbons. It was considered important enough to devote an entire thesis to the properties of NMP related to its interactions with simple hydrocarbons and ethers. The thesis consists of four parts: Part one is devoted to liquid-liquid equilibria. Experimental results at 298.2 K, are presented for the mixtures: NMP + an aromatic hydrocarbon + an n-alkane. Firstly, the effect increasing the chain length of the alkane has on the liquid-liquid equilibria was investigated, by studying mixtures of the type: an n-alkane + toluene + NMP; where the n-alkane refers to n-hexane or n-nonane or n-tetradecane or n-hexadecane. Secondly, the effect of substitution on the benzene ring on the equilibria was studied by measuring the liquid-liquid equilibria for the mixtures: n-hexadecane + an aromatic hydrocarbon + NMP; where the aromatic hydrocarbon refers to toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. The chain length of the n-alkane had a significant effect on the liquid-liquid equilibria. Methyl substitution on the benzene ring had a small effect on the liquid-liquid equilibria. Part two is devoted to activity coefficients at infinite dilution. Experimental results at 298,15 K, determined using gas-liquid chromatography, are presented for the mixtures: NMP (solvent) + n-pentane or n-hexane or n-heptane or n-octane or cyclopentane or cyclohexane or cycloheptane or I-hexene or 1-heptene or l-octene or diethyl ether or diisopropyl ether. The magnitudes of the infinite dilution activity coefficients had the following order: n-alkanes > cycloalkanes > l-alkenes > ethers. Part three is devoted to excess molar enthalpies. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Isothermal flow microcalorimetry was used to determine the excess molar enthalpies. Increased methyl substitution on the' benzene ring manifests itself as a reduction in the association between NMP and the aromatic hydrocarbon. Part four is devoted to excess molar volumes. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Densitometry was used to determine the excess molar volumes. The excess molar volumes were negative for all the mixtures.<br>Thesis (M.Sc.)-University of Natal, 1997.

Membrane technology plays a crucial role in different separation processes such as biotechnology, pharmaceutical, and food industries, drinking water supply, and wastewater treatment. However, there is a growing concern that solvents commonly used for membrane fabrication, such as dimethylformamide (DMF), dimethylacetamide (DMAc), and 1-methyl-2-pyrrolidone (NMP), are toxic to the environment and human health. To explore the possibility of substituting these toxic solvents by less toxic or safer solvents, polymers commonly used for membrane fabrication, such as polyacrylonitrile (PAN), cellulose acetate (CA), polyethersulfone (PES), and poly(ether imide sulfone) (EXTEMTM), were dissolved in ionic liquids. Flat sheet and hollow fiber membranes were then fabricated. The thermodynamics of the polymer solutions, the kinetics of phase inversion and other factors, which resulted in significant differences in the membrane structure, compared to those of membranes fabricated from more toxic solvents, were investigated. Higher water permeance with smaller pores, unique and uniform morphologies, and narrower pore size distribution, were observed in the ionic liquid-based membranes. Furthermore, comparable performance on separation of peptides and proteins with various molecular weights was achieved with the membranes fabricated from ionic liquid solutions. In summary, we propose less hazardous polymer solutions to the environment, which can be used for the membrane fabrication with better performance and more regular morphology.

碩士<br>中原大學<br>化學研究所<br>106<br>In this study, a new type of low-temperature catalyst was synthesized. Palladium metal was embedded onto the surface of graphene to prepare a Palladium/Graphene (Pd/G) catalyst. Degradation of dibenzo-p-dioxin (DD), 2-chlorodibenzo-p-dioxin (2CDD), Dibenzofuran (DBF) and 4-Bromodiphenyl ether (4-BDPE) in organic solvents was achieved by using this Pd/G catalyst with the presence of hydrogen gas. The optimal rate of degradation was studied by UV/VIS spectrometry. The experimental results show that by 20 mg of Pd/G catalyst is optimal for the degradation of DD, 2CDD, and 4-BDPE at 115 °C and 20 bar of hydrogen pressure for 1 hour. Whereas for DBF, 20 mg of Pd/G catalyst at 95 °C and 20 bar of hydrogen pressure for 30 minutes is the optimal conditions. The degradation efficiencies are higher than 99 % in all cases. The effect of different solvents was also studied and analyzed by GC-MS. DD has great degradation efficiency by using hexane as the reaction solvent. However, 2CDD and DBF have the same degradation products by using hexane or methanol. 4-BDPE will degrade into small molecules by using mixed solvent or methanol. Various templates for embedding the palladium metal was also studied by replacing graphene with carbon nanofiber to prepare a palladium/carbon nanofiber composite catalyst (Pd/CNF). The experimental results show that Pd/CNF has similar degradation capability to DD, 2CDD, DBF, and 4-BDPE as compared to Pd/G. Simulated real sample study was done by spiking 2CDD into lard and performing degradation of the 2CDD in situ. The results show that 2CDD can be fully degraded by the Pd/G catalyst.