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1
Vu, Duc Nam. "Catalytic cleavage of vegetable oil derivatives to aldehydes and other bio-based building blocks." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1259.
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Les aldéhydes sont des produits chimiques importants dans la synthèse organique, en raison de leurs vastes applications dans les cosmétiques, les produits pharmaceutiques et les herbicides. De plus, ils peuvent être convertis en composés à valeur ajoutée tels que des tensioactifs, des polymères, etc. Classiquement, les aldéhydes sont produits par hydroformylation ou ozonolyse réductrice des alcènes. Cependant, les deux méthodes souffrent de l'utilisation de catalyseurs coûteux et de ligands sophistiqués (hydroformylation) ou de la nécessité d'un procédé à forte intensité énergétique (ozonolyse). En conséquence, le développement d'approches plus durables pour la production d'aldéhydes est hautement souhaitable.Dans ce contexte, nous avons développé deux méthodes pour produire des aldéhydes à partir de dérivés d’acides gras insaturés. La première voie consiste à préparer des a-hydroxycétones grasses à partir de 1,2-diols et les couper pour obtenir des aldéhydes avec de bons rendements. Dans cette voie, deux systèmes catalytiques (homogènes et hétérogènes à base de métaux) ont été développés pour oxyder les diols vicinaux en a-hydroxycétones correspondantes. La coupure de ces espèces a été effectuée par un procédé de rétro-benzoin utilisant des sels de thiazolium thermiquement stables et les aldéhydes ont été récupérés par distillation réactive. La seconde voie repose sur la décomposition des ß-hydroxy hydroperoxydes gras facilement préparés à partir d'oléate de méthyle époxydé. De plus, la décomposition de l'espèce peroxyde a été étudiée dans des conditions thermiques pour donner des aldéhydes. Enfin, la coupure des 1,2-dicétones gras et la valorisation des aldéhydes ont également été étudiés pour conduire aux esters correspondants pouvant être utilisés comme monomèresAldehydes are important chemicals in organic synthesis, due to their vast applications in cosmetics, pharmaceuticals and herbicides. Moreover, they can be converted to value-added compounds such as surfactants, polymers, etc. Conventionally, aldehydes are produced through hydroformylation or reductive ozonolysis of alkenes. However, both methods suffer from the use of expensive catalyst and sophisticated ligands (hydroformylation) or the requirement of high energy intensive process (ozonolysis). As a result, the development of more sustainable approaches for the production of aldehydes is highly desirable.In this context, we have developed two methods to produce aldehydes from unsaturated fatty acid derivatives. The first route involves the preparation of fatty a-hydroxyketones from 1,2-diols and their cleavage to give aldehydes with good yields. In this route, two catalytic systems (metal-based homogeneous and heterogeneous) have been developed to oxidize vicinal diols to corresponding a-hydroxyketones. The cleavage of these species has been carried out through a retro-benzoin process using thermally stable thiazolium salts and the aldehydes were recovered by reactive distillation. The second route relies on the decomposition of fatty ß-hydroxy hydroperoxides that are easily prepared from epoxidized methyl oleate. Moreover, the decomposition of the peroxide species was studied under thermal conditions to give aldehydes. Finally, the cleavage of fatty 1,2-diketones and the valorization of aldehydes were also studied to give the corresponding esters that could be used as monomers
2
Estager, Julien. "Méthodes d'activation non conventionnelles et solvants propres pour une chimie durable : synthèse et valorisation organique des liquides ioniques." Chambéry, 2007. http://www.theses.fr/2007CHAMS048.
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L'étude des liquides ioniques a connu un essor considérable au cours de ces dernières années. En effet, en plus de leur faible volatilité, de leur non inflammabilité et de leur caractère non explosif, ils présentent une grande stabilité thermique et une forte aptitude à solvater, à la fois des composés organiques et inorganiques. Ces propriétés physico-chimiques originales en font des solvants de choix pour une chimie organique respectueuse de l'environnement dans l'optique du développement durable. Les objectifs de ce travail de Doctorat sont la synthèse et la valorisation de ces composés en profitant notamment de certaines de leurs qualités intrinsèques autorisant l'utilisation de méthodes d'activation dites non-conventionnelles comme les ultrasons ou l'irradiation par micro-ondes généralement rattachées à la chimie du développement durable. Après avoir détaillé les différentes propriétés des liquides ioniques, le premier chapitre de ce manuscrit de thèse décrit comment des phénomènes physiques comme des ondes ultrasonores ou micro-ondes peuvent influencer la réactivité chimique de manière différente par rapport à un chauffage thermique classique. Dans ces travaux de doctorat, l'utilisation des ultrasons pour la synthèse des liquides ioniques de seconde génération en une étape est ainsi étudiée; une forte diminution du temps de réaction est observée pour la plupart des liquides ioniques choisis. L'emploi combiné de la sonochimie et de l'irradiation par micro-ondes permet d'accélérer encore plus la cinétique de ces synthèses en mettant en commun les différents effets physiques et chimiques des ultrasons avec le chauffage homogène et rapide généré par les micro-ondes. A la fin de cette étude, des liquides ioniques de seconde génération sont ainsi obtenus avec de bons rendements et une cinétique de l'ordre de quelques minutes, comparées aux quelques 48-72h Emma nécessaires sous chauffage thermique classique. Bien que leur utilisation se limite souvent à un simple rôle de solvant, les liquides ioniques possèdent des propriétés en terme de réactivité qui peuvent aussi être mises à profit notamment en catalyse. Au cours de cette étude, ils ont été utilisés comme catalyseurs pour la réaction de condensation benzoïne, que ce soit sous irradiation ultrasonore ou sous irradiation micro-ondes. Les résultats obtenus ont montré de bonnes conversions et le liquide ionique a été recyclé sous certaines conditions. La réaction de cyclisation de Pictet-Spengler, souvent utilisée pour la synthèse d'hétérocycles bio-actifs, a été catalysée par différents liquides ioniques notamment de seconde génération. Ces sels incorporant des anions halogénures de métaux sont connus pour posséder une forte acidité. Sur cette observation, des liquides ioniques à tâche spécifique acide ont été utilisés pour la synthèse de 1-phényl-tetrahydro-β-carbolines via la réaction de Pictet-SpenglerThese last years, RTILs have become a very attractive alternative to conventional solvents. Because of their negligible vapor pressure, they are used as green solvents. In addition, their wide liquid range, tunable polarity or good solvating ability make them very interesting in organic synthesis. Finally, their non flammability and non explosive character make them good candidates to replace traditional molecular solvents in term of green chemistry. The objectives of this PhD thesis are the synthesis and the valuable use of these compounds by taking advantage of some of their remarkable properties with the use of non conventional activation methods such as microwave and / or ultrasound irradiation. The nature and properties of ionic liquids are described along the first chapter of this work and then the physical effects that lead to sonochemistry and chemistry effects under microwave irradiation are also discussed. The second chapter of this thesis described the advantage of non traditional activation methods for improving the synthesis of second generation ionic liquids. By using, ultrasonic irradiation, different families of nitrogen-bearing ionic liquids are obtained in a solvent-free or in aqueous medium, which gives a greener touch to the overall process. Aiming to overcome some limitations of this method, a new activation method using simultaneous ultrasound/microwave irradiation has been shown to lead to good yields in second generation ionic liquid in a kinetic of only few minutes. Then, the synthesis of benzion via benzoin condensation reaction has been studied with various ionic liquids as catalysts. Microwave activation and ultrasonic irradiation have been tested and good yields in benzoin have been observed whereas the recycling of the ionic catalyst was shown to be possible in specific conditions. Finally, different ionic liquids have been chosen to catalyse the electrophilic cyclisation of Pictet-Spengler, a classical synthetic method to reach bioactive molecules. Various acidic ionic compounds, including task specific ionic liquids have been tested and good conversion in tetrahydro-β-carbolines have been obtained with the most suited ionic catalyst
3
Moutounet, Odile. "La chimie computationnelle appliquée à l'étude de la réactivité et de la sélectivité de mécanismes réactionnels en chimie organique." Thèse, Université de Sherbrooke, 2018. http://hdl.handle.net/11143/11770.
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Grâce à la chimie computationnelle, nous avons pu étudier la réactivité et la sélectivité de trois familles de réactions en chimie organique. Nous avons utilisé la méthode DFT avec la fonctionnelle M06-2X pour l’ensemble de nos projets. Les réactions promues par l’iode hypervalent étudiées dans cette thèse sont en rapport direct avec les travaux réalisés au sein de notre laboratoire de recherche. La collaboration réalisée sur les BACs et les NHCs est un travail pionnier dans l’étude mécanistique détaillée de ces catalyseurs.
Dans le premier chapitre nous nous sommes intéressés à des réactions de cyclisation et de SN2 promue par l’iode hypervalent. Cette étude avait pour but de prédire l’influence de différents groupements sur la préférence entre ces deux réactions, dans le but de favoriser la création d’une liaison carbone-carbone. Nous avons pu démontrer que la présence de certains groupements permet d’envisager la formation de cycles à cinq membres.
Le second chapitre porte sur la réaction d’αhydrolyse oxydante de chloroalcènes, impliquant le réactif de Koser. Nos calculs ont permis de rationaliser les résultats expérimentaux de l’observation de la migration interne du phényle. Nous avons également confirmé que l’intermédiaire provenant de l’addition d’une molécule d’’eau permet de favoriser la migration interne du chlore. Enfin, nous avons appuyé la possibilité d’un mécanisme « release-and-catch » proposé à la suite d’une expérience de mélange réalisée au sein du laboratoire.
Finalement, nous avons pu réaliser une collaboration avec le Professeur Michel Gravel sur la réactivité et la sélectivité de la réaction de Stetter catalysée par un BAC ou un NHC. Nous avons été en mesure de déterminer que la différence de réactivité observée dépend essentiellement de la nature de l’étape déterminante. La sélectivité observée expérimentalement a également pu être rationnalisée grâce aux calculs. Pour finir, les premières conclusions concernant la condensation de benzoïne ont été établies.
4
Lieubray, Jean Pierre. "Toxicologie du péroxyde de benzoyle." Paris 5, 1988. http://www.theses.fr/1988PA05P013.
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McDonald, Frank Carl. "Specific heat measurements of copper benzoate." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002844.
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McDermott, J. Mario. "Benzoate metabolism in Ralstonia eutropha H850 /." Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1075686881&sid=9&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Winkler, Michael. "Beiträge zur Chemie benzoider Reaktionsintermediate." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971638462.
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Smith, Bartina Ciara. "Adsorption of Denatonium Benzoate Using Activated Carbon." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1304684769.
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Torok, Daniel Seth 1963. "Diastereoselective cyclopropanations of alpha,beta-unsaturated ketals derived from chiral hydrobenzoin." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276784.
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2-Cycloalken-1-one-(-)-erythro-hydrobenzoin ketals undergo efficient and diastereoselective cyclopropanation when treated with an excess of Simmons-Smith reagent. The resulting crystalline products yield enantiomerically pure cyclopropyl compounds upon recrystallization. For example, 2-cyclohexen-1-one-(-)-erythro-hydrobenzoin ketal gave, in 90% yield, a 19:1 mixture of diastereomeric cyclopropanes as established by 62.9 MHz ¹³C NMR spectroscopy. Upon one recrystallization, diastereomerically pure cyclopropane was obtained in 78% recovery. Hydrolysis gave (+)-norcaranone of greater than 99% ee. Three other examples are presented which demonstrate the advantages of hydrobenzoin ketals over previously used homochiral ketals, as well as several techniques for the synthesis of chiral hydrobenzoin.
10
Demirtas, Umut. "Fungi Mediated Enantioselective Biohydrogenation Of Benzils To Benzoins." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609232/index.pdf.
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Benzoin is an important a-hydroxy ketone which can be used as chiral intermediate
for the synthesis of several drugs. In this study, it was aimed to synthesize this
compound by high stereoslectivity and yield by the use of fungal bioconversions. For
this purpose, whole cells of four different Fusarium spp. (F. anguoides, F. roseum, F.
solanii, F.bulbigenum) were used for reduction of readily available achiral compound
benzil. The reaction conditions were optimized as glucose peptone broth consisting
of 30g/L glucose and 10 g/L peptone, inoculum size as 20 mg/L and substrate
concentration as 200 mg/L. A complete set of derivatives substituted with electron
donating and electron withdrawing groups of the benzils were also reduced to the
corresponding benzoin derivatives with the same optimized condition with up to 98%
ee.
11
Chen, Tong, and 陳彤. "Anaerobic treatment of benzoate- and phenol- containing wastewaters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212918.
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Chen, Tong. "Anaerobic treatment of benzoate- and phenol- containing wastewaters /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17590607.
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Alaydamee, Hussein Hantoosh. "Coagulation Treatment to Remove Denatonium Benzoate from Water." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1492814062682689.
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Faven, Catherine. "Mise en évidence et dosage du peroxyde de benzoyle par chimiluminescence." Lille 1, 1992. http://www.theses.fr/1992LIL10053.
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Le travail présenté porte sur les réactions chimiluminescentes du peroxyde de benzoyle, en vue d'un dosage de ce dernier. Dans un premier temps, nous avons montré que la réaction de ce peroxyde avec la triéthylamine est chimiluminescente et que la luminescence est proportionnelle à la concentration des réactifs. Le spectre de chimiluminescence a été enregistré et les produits de la réaction identifiés par R. M. N. Par la suite, la réaction a été étendue à d'autres dérivés azotés. La comparaison des résultats obtenus a permis une optimisation des réactifs mis en jeu lors du dosage. Finalement, il a été montré que l'ajout d'une molécule fortement conjuguée au milieu réactionnel augmente considérablement la chimiluminescence de la réaction. Dans ce cas, il y a un transfert d'énergie entre les produits de la réaction initiale et le dérivé aromatique. La luminescence correspond alors à la fluorescence de ce dernier
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Molski, Matthias J. [Verfasser]. "Radikalkationen von halogenierten Benzolen und verwandten Aromaten / Matthias J. Molski." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1030383375/34.
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林淑儀 and Shirley Lam. "Effect of sulphate on the anaerobic degradation of organicpollutants (benzoate)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31252886.
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Molski, Matthias Johann [Verfasser]. "Radikalkationen von halogenierten Benzolen und verwandten Aromaten / Matthias J. Molski." Berlin : Freie Universität Berlin, 2012. http://nbn-resolving.de/urn:nbn:de:kobv:188-fudissthesis000000040171-0.
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Brauman, Alain. "Etude du metabolisme bacterien de termites superieurs a regimes alimentaires differencies : mise en evidence d'une nouvelle voie de fermentation du benzoate et du 3-hydroxybenzoate." Aix-Marseille 2, 1989. http://www.theses.fr/1989AIX22974.
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Whitley, Andrew. "Vibrational spectroscopic studies on the model lubricant 2-ethylhexyl benzoate (EHB)." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6252/.
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In an attempt to investigate the relationship between microscopic and macroscopic fluid properties, like viscosity and density, a vibrational spectroscopic study of the model lubricant 2-ethylhexyl benzoate (EHB) was initiated. The variation in frequencies and band shapes of the vibrational modes of the molecule have been studied as a function of concentration, temperature and pressure. Estimates of correlation times for the reorientational motion of the phenyl ring of EHB, as a function of temperature, have been made from measurements of the Raman bands of the ring v(C-C) deformation mode and (^13)C N.M.R. spin lattice relaxation times. It has been shown using this data that the viscosity/temperature behaviour of EHB is dependent on the reorientational as opposed to the translational motion of the molecule. A noncoincidence of the Raman isotropic and anisotropic bands of the v(C=0) stretching mode of EHB has been seen and explained in terms of a resonance energy transfer (RET) process via transition dipole-transition dipole interactions, most probably as a consequence of preferential alignment via dipole-dipole interactions. It appears from dilution experiments that the EHB molecules do not become completely separated until below 2% mole-fraction. The infrared band of the v(C=0) stretching mode of EHB shows an unusual red shift with increased pressure to 6.5kbar, followed by a blue shift as the pressure is further increased. This has been explained as due to the competing effects of increased alignment of carbonyl dipoles (red shift) and the increase in the repulsive interactions (blue shift). All the other bands exhibit blue shifts, of varying degree, with increased pressure, showing that the repulsive forces dominate the shifts. The spectral changes are consistent with chain extension and increased interchain interactions with increased pressure. The band widths of all the vibrational modes increase with pressure consistent with an increase in vibrational relaxation rate. The fluid appears to exhibit a phase change close to 6.5kbar.
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Lam, Shirley. "Effect of sulphate on the anaerobic degradation of organic pollutants (benzoate) /." Hong Kong : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13813523.
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Korin, Tetyana Olegivna. "Microbial ecology of anaerobic biodegradation of benzoate : microbial communities and processes." Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4138.
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Microbial conversion of hydrocarbons and other aromatic compounds has been studied extensively under various electron accepting conditions, by investigating cultured microorganisms and by using samples collected directly from diverse environments. However, the functions of the principal microbial organisms taking part in the biodegradation process are not fully understood, especially when the organisms comprise complex microbial communities. The focus of the research reported here is the identification of a microbial community enriched during methanogenic benzoate degradation using inocula from two contrasting environments, river sediment and oil sands. Benzoate is a monoaromatic compound used extensively as a model compound in studies of hydrocarbons and other aromatics. The microorganisms which were most abundant and which had been shown by earlier work to take part in syntrophic benzoate degradation were investigated. Their functional potential was also investigated using metagenomic approaches. It was found that enrichments from different environments contained different microbial communities, different members of which were thought to take part in the syntrophic degradation of benzoate. In benzoate enrichments with Tyne sediment, two types of methanogen were enriched: hydrogenotrophic Methanofollis and acetoclastic Methanosaeta. In contrast, in oil sands enrichments with benzoate, the most abundant methanogens were metabolically versatile Methanosarcina spp. The primary benzoate degrader in enrichments with Tyne sediment was Syntrophus, most likely Syntrophus aciditrophicus as was suggested by 99% sequence identity. In oil sands enrichments the supposed primary benzoate degrader was an unknown species of Desulfotomaculum. Syntrophic acetate oxidisers (e.g. Syntrophomonas) were not found in abundance in Tyne sediment cocultures with benzoate. Instead, the conversion of acetate into hydrogen and carbon dioxide appeared to be mediated by acetoclastic methanogenesis, which utilised acetate directly as has been evidenced by the enrichment of acetoclastic methanogens Methanosaeta and Methanosarcina. In the oil sands, syntrophic acetate oxidation was likely to have been carried out by the known acetoclastic methanogen Methanosarcina. However, it was conjectured that unclassified Sphingobacteriales clone WCHB1.69 could have taken part in the acetate utilisation. Regardless of the observed differences between the microbial communities, investigation of the metabolic potential showed the presence of the same pathways, key genes and enzymes that are known to take part in the degradation of benzoate iv and the production of methane. The same four pathways were found in both sets of methanogenic enrichments, namely the benzoate degradation pathway and hydrogenotrophic, acetoclastic and methylotrophic methanogenesis pathways. The same key genes that take part in benzoate degradation, namely dienoyl-CoA hydratase (dch), β-hydroxyacyl-CoA dehydrogenase (had) and β-oxoacyl-CoA hydrolase (oah) were found in high abundance in both enrichment cultures. The same key genes coding for essential proteins involved in methanogenesis were also found in high abundance in all the methanogenic archaea tested in both Tyne sediment and oil sands methanogenic enrichment cultures with benzoate, namely tetrahydromethanopterin S-methyltransferase (mtrA), methyl-coenzyme M reductase A (mcrA) and heterodisulfide reductase subunit A (hdrA). Other genes found in high abundance were methanogenic pathway specific genes, namely formylmethanofuran dehydrogenase, subunit A (fmdA) involved in hydrogenotrophic methanogenesis, phosphate acetyltransferase (pta), acetate kinase (ackA) and acetyl-CoA synthetase (ACSS) involved in acetoclastic methanogenesis and coenzyme M methyltransferase (mtaA) involved in methylotrophic methanogenesis. These results suggest that the functional capabilities of the microorganisms in different environments remain constant but the communities might vary from one environment to another. In addition, a comparison was made between two sequencing platforms, Illumina MiSeq and Ion Torrent PGM. The result suggested that, overall, the two sequencers concurred. The sequencers found the same most abundant taxa, but there were instances where both sequencers detected some microorganisms which were not detected by the other sequencer. Syntrophic degradation of many different types of compound such as alcohols, saturated and unsaturated fatty acids, hydrocarbons and aromatic compounds has been identified in methanogenic environments, suggesting the global importance of this process and of the microorganisms involved. Further work on the syntrophic processes, including methanogenesis, would clarify which microorganisms take part in syntrophy, in which environments syntrophy occurs, what substrates can be utilised, which members of the microbial community participate and how. Such knowledge would be useful in understanding the processes that attenuate the contamination of industrial land and the development of strategies for bioremediation. A quantitative model of syntrophic biodegradation could also assist in understanding the processes that release greenhouse gases. There is also a likelihood that microbial degradation could find a use in the development of sustainable and environmentally innocuous sources of energy.
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Olceroglu, Ayse Hande. "Chiral Separations By Enzyme Enhanced Ultrafiltration: Fractionation Of Racemic Benzoin." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607460/index.pdf.
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In this study, a methodology for separation of chiral molecules, by using enhanced ultrafiltration system was developed. Benzoin was the model chiral molecule studied.
In the scope of developing this methodology, some parameters were investigated in the preliminary ultrafiltration experiments in order to set the operation conditions for enhanced ultrafiltration experiments. Due to the slight solubility of benzoin in pure water, 15% (v/v) Polyethylene glycol (PEG 400) and 30 % (v/v) Dimethyl sulfoxide (DMSO) were selected as cosolvents. Because of the high retention capacity of RC-10000 Da membranes for benzoin, a membrane saturation strategy was developed.
In polymer enhanced ultrafiltration (PEUF) experiments bovine serum albumin (BSA) was used as ligand. Effects of ligand concentration and pH on total benzoin retention and on enantiomeric excess (ee %) were investigated. Benzoin concentration was almost kept constant at ~10 ppm and ~50 ppm for 15% (v/v) PEG 400 and 30 % (v/v) DMSO cosolvents, respectively. It was observed that the increase either in pH or in BSA concentration yielded an increase in total benzoin retention. In 15% (v/v) PEG 400-water, with BSA concentration of 10000 ppm, at pH 10, total benzoin retention reached to 48.7%. For this cosolvent, at different pH values and at different BSA concentrations, all ee % values were about or less than 10%. When 50000 ppm BSA was dissolved in 30 % (v/v) DMSO-water, total benzoin retention increased to 41.3% at pH 10 and ee % reached 16.7 % at pH 11.
In enzyme enhanced ultrafiltration (EEUF) experiments, specific to benzoin, apo form of Benzaldehyde Lyase (BAL, E.C. 4.1.2.38) was used as ligand. These experiments were performed with constant ~ 10 ppm benzoin concentration in only 15% (v/v) PEG 400 &ndashwater solvent. Effect of BAL concentration on total benzoin retention and ee% was investigated. It was found that
for all the studied BAL concentrations in the range of 650- 1936 ppm total benzoin retention and ee % were kept almost constant at ~75% and ~60%, respectively.
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Mitambo, Munyao Musilli. "Probing solute-solvent interactions in ethyl 4-(dimethylamino)benzoate with Raman spectroscopy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0007/MQ59851.pdf.
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Leszczak, Jean-Pierre. "Synthèse d'esters de l'acide benzoïque par catalyse enzymatique en milieu hétérogène microaqueux." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1998. http://tel.archives-ouvertes.fr/tel-00841819.
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La synthèse d'esters de l'acide benzoïque par voie enzymatique en milieu hétérogène microaqueux est envisagée. Cette estérification est possible et est catalysée par la lipase de Candida rugosa en suspension dans un mélange hexane/toluène. Le toluène permet la solubilisation de l'acide benzoïque. De nombreux paramètres influencent la synthèse des benzoates de méthyle et de butyle. La teneur en eau initiale agit uniquement sur la cinétique de réaction sans modifier de manière notable la position de l'équilibre de réaction. Il est préférable, dans la mesure du possible, de travailler à une activité en eau fixée au départ pour s'affranchir d'artefacts liés à la désorption de la pellicule aqueuse entourant les grains d'enzyme. Une approche par les plans d'expériences montre l'influence de plusieurs paramètres et de certaines interactions entre facteurs sur la cinétique et sur l'évolution de la réaction. La vitesse initiale spécifique décroit linéairement avec la fraction de toluène dans des milieux organiques contenant plus de 40% de toluène. Par contre, la variation de la Vi(sp) avec la teneur en enzyme est dépendante de la nature de l'alcool et de sa concentration. les effets de la proportion de toluène dans le mélange et de la teneur en enzyme sont expliqués par la variation de la concentration en substrats dans la pellicule aqueuse entourant l'enzyme. La vitesse initiale de production du benzoate de 1-butyle est modélisée et réalisée dans un mélange équivolumique hexane/toluène à une activité en eau initiale de 0,65. La cinétique suit un schéma réactionnel de type bi bi ping-pong avec inhibition par l'alcool si les concentrations en substrats dans la pellicule aqueuse sont prises en compte. En particulier, la concentration en acide benzoïque dans cette phase est dépendante de la concentration en 1-butanol. Ce travail démontre que la technique d'ajout d'eau dans le système, la variation des coefficients de partage des substrats entre milieu organique et pellicule aqueuse, la nature de l'alcool et les phénomènes d'inhibition par les alcools permettent d'expliquer les variations de vitesses initiales spécifiques. Enfin, ce système catalytique permet d'obtenir ces benzoates avec des taux de conversion supérieurs à 95% et peut- être employé à la synthèse d'autres benzoates.
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Schäfer, Martina. "Untersuchungen zum Abbau chlorierter Benzole durch Mischkulturen in kontinuierlich betriebenen Reaktoren /." Berlin : TU, FG Siedlungswasserwirtschaft, Sekr. KF 7, 1994. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=007288332&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Dal, Magro Jacir. "Efeito do acido borico sobre a reação de formação da oxima da benzoina." reponame:Repositório Institucional da UFSC, 1993. http://repositorio.ufsc.br/xmlui/handle/123456789/75863.
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A reação entre a hidroxilamina e benzoína ocorre em duas etapas: formação de um intermediário de adição e a desidratação deste à oxima. A reação na presença de ácido bórico (0,01M) a pH 8,5 apresenta um aumento no valor de kobs em até l5 vezes. Este valor é maior na presença de ácido fenil bórico, onde a diferença atinge 28 vezes. Tampões que possuem pKas semelhantes não apresentam nenhum efeito em concentrações 0,01M. A reação apresenta catálises ácida e básica geral, com valores de a = 0,75 e b = 0,29. Os gráficos de Brönsted mostram que o ácido bórico apresenta valor de aproximadamente 70.000 vezes superior ao que se pode prever pela linha de Brönsted. O ponto para o borato fica apenas 17 vezes acima da linha de correlação. A provável explicação para o aumento excepcional da velocidade da reação na presença de ácido bórico, é a formação de um complexo cíclico de 5 membros do mesmo com intermediário tetraédrico, facilitando a saída da molécula de água e dando lugar ao complexo oxima-ácido bórico como produto.
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Nicholls, Gareth Antony. "Modelling and kinetics of tetrabutylammonium benzoate-catalysed group transfer polymerisation of methyl methacrylate." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27119.
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Group Transfer Polymerisation (GTP) is a silicon-mediated living polymerisation which can be performed over a wide range of temperatures, allows good control of molecular weight and is a good mechanism for production of block and graft copolymers. A silyl ketene acetal initiator is used to start polymerisation of acrylic or methacrylic monomers which are catalysed by nucleophilic or Lewis acid catalysts in a dry, impurity-free atmosphere. Since its discovery in 1983 by Du Pont, GTP has been ardently researched, although it has not yet been used in an industrial process due to the complicated processing involved and the high cost of initiators.
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Kuhn, Elmar Paul. "Mikrobieller Abbau von Nitrilotriacetat und von substituierten Benzolen bei der Flusswasser/Grundwasser-Infiltration : Laborstudien /." [S.l.] : [s.n.], 1986. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8176.
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Letowski, Jaroslaw. "Isolement et étude d'une souche bactérienne transformant le phénol en benzoate en conditions anaérobies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0025/NQ52112.pdf.
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Chen, Qiao. "The chemistry of benzoate, 3-thiophene carboxylate, nitrobenzene and its derivatives on Cu(110) surface." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366270.
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Ampe, Frédéric. "Métabolisme du benzoate chez Alcaligenes eutrophus : quels mécanismes physiologiques régulent la biodégradation des composés aromatiques ?" Toulouse, INSA, 1995. http://www.theses.fr/1995ISAT0031.
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Le travail presente dans cette these evalue l'influence de la concentration en substrat, de l'oxygene et de la presence d'acides organiques sur le catabolisme du benzoate par alcaligenes eutrophus. Des etudes en bioreacteur montrent que, si le benzoate a faibles concentrations permet une croissance rapide d'a. Eutrophus, au dela de 5 mm, le metabolisme du micro-organisme est profondement modifie: (1) le benzoate inhibe fortement la croissance sans affecter sa vitesse de consommation ; (2) la conversion du catechol en muconate constitue le principal goulot d'etranglement de la voie ortho, et des intermediaires metaboliques (catechol et dhb) s'accumulent ; (3) la voie meta est induite par le dhb et accelere la degradation du catechol ; (4) au-dela de 50 mm, l'activite benzoate-1,2-dioxygenase est fortement alteree. En limitation d'oxygene, la cellule utilise en priorite l'o#2 disponible pour le catabolisme du benzoate, au detriment de la chaine respiratoire: la croissance s'arrete. La presence de nitrates permet la reprise de la croissance, et la totalite de l'oxygene disponible sert alors au catabolisme du benzoate. L'etude des melanges benzoate:acides organiques montre que l'utilisation des substrats se fait de telle sorte que la cellule maximise sa croissance. Dans de nombreux cas, le micro-organisme metabolise simultanement l'aromatique et le second substrat. La consommation rapide de benzoate bloque la consommation d'acetate par la repression de la transcription d'acoe (acetyl-coa synthetase). L'ensemble des resultats laisse supposer l'existence d'une hierarchie dans l'utilisation des substrats fondee sur la vitesse de la croissance qu'ils permettent
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Zietsman, Sharon Lynne. "An investigation into development of a stable aqeous suspension of Metronidazole Benzoate for oral use." Thesis, Nelson Mandela Metropolitan University, 2005. http://hdl.handle.net/10948/456.
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Metronidazole is a synthetic, nitroimidazole-derivative antibacterial and antiprotozoal agent (ed. McEvoy, 2001). It has been reported that crystallization occurs in aqueous suspensions of metronidazole benzoate, a bland-tasting prodrug of metronidazole, as a result of conversion from the anhydrous to the monohydrate form, thereby compromising the stability and clinical efficacy of the substance due to the particle size growth (Hoelgaard & Moller, 1983). A generic South African based pharmaceutical company commenced formulation of an aqueous metronidazole benzoate suspension and experienced problems with crystallization that occurred in products stored at 2 to 8 °C. This study aimed to continue development of the product in order to identify a formulation that prevents formation of the hydrate form of metronidazole benzoate and the accompanying crystal growth. A variety of metronidazole benzoate suspensions were manufactured on a laboratory scale using a number of natural and synthetic suspending agents, including magnesium aluminium silicate, povidone K90, xanthan gum and Avicel® RC-591 (microcrystalline cellulose and carboxymethylcellulose sodium), over a range of concentrations. Analytical quantification methods were developed and validated, and the physicochemical properties of the raw material and finished products were fully characterized. Rheological tests were performed in order to characterize the suspension flow properties. Real-time and accelerated stability studies and a temperature cycle study were conducted in accordance with the International Conference on Harmonization (ICH) guidelines. Conversion of metronidazole benzoate to the monohydrate form took place in suspensions containing xanthan gum 0.65 percent m/v under real-time and accelerated storage conditions. The suspensions containing Avicel® RC-591 were found to be physically and chemically stable after the temperature cycle and over the 12-week period whilst stored at 25 ºC / 60 percent RH and 5 ºC. The suspensions were chemically stable whilst stored at 40 ºC / 75 percent RH but showed sedimentation at this accelerated condition. The metronidazole benzoate contained in these products remained in the anhydrous state under all storage conditions and were consequently concluded to be the most stable formulations out of all the products analyzed in the current study. The suspending agent system consisting of microcrystalline cellulose and carboxymethylcellulose sodium thus shows promise in preventing the conversion of metronidazole benzoate from the anhydrate to the monohydrate form, thereby inhibited the subsequent increase in particle size due to crystal growth.
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Bausch, Cory Charles Johnson Jeffrey Scott. "Benzoin-type reactions and tandem C-C bond forming reactions using acyl anion equivalents." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1478.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Apr. 25, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.
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Cormier, Ryan. "N-Acyl Ciprofloxacins: Synthesis, Antibacterial Activity and Effects on Molecular Loading of Poly(vinyl benzoate) Nanoparticles." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4018.
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Bacterial infections are becoming progressively more difficult to treat due to antibiotic resistance and the decreasing rate at which new antibiotics are brought to market. The Turos laboratory has attempted to tackle this problem for the last 15 years with the discovery of N-thiolated β-lactams leading to the design of polyacrylate nanoparticles to deliver these and other drugs. Chapter 1 discusses many reported instances of utilizing different types of polymeric nanoparticles to deliver antibiotics. Poly(lactic-co-glycolic acid) (PLGA), poly(alkyl cyanoacrylate) (PACA), poly(styrene-co-butylacrylate), and chitosan are the main polymers used to make nanoparticles. Chapter 2 describes the synthesis, antibacterial activity, and mechanism of action of N-acyl ciprofloxacins, which have demonstrated in vitro bioactivity against Staphyloccocus aureus, methicillin-resistant Staphylococcus aureus, Bacillus anthracis, Enterococcus faecalis, Bartonella, and E. coli. Antimicrobial activity was found to diminish with increasingly lipophilic acyl groups of the derivatives. The N-acyl ciprofloxacins were found to utilize the same mechanism of action as the parent drug, ciprofloxacin, however, several exhibited lower mutation frequencies. Chapter 3 discusses the use of the N-acyl ciprofloxacins as probes for experimentation on the poly(vinyl benzoate) nanoparticles. These compounds were incorporated into poly(vinyl benzoate) nanoparticles, also designed in the Turos laboratory, to determine the effects of the lipophilic acyl groups on drug loading and drug release. N-acyl ciprofloxacins with higher lipophilicities (predicted logP values) experienced higher drug loading than the less lipophilic counterparts. However, the nanoparticles were unable to release large amounts of entrapped drug. N-acyl ciprofloxacins with increased hydrophilicity were found to either not be incorporated at all, or in incredibly small amounts. Drug release studies of these drugs indicate that possible the hydrophobic compounds that were associated with the nanoparticles were done so via adsorption onto the surface resulting in a burst release of drug. The work is concluded in Chapter 4, followed by experimental procedures and spectral data in Chapters 5 and 6.
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Kim, Marie [Verfasser], and Wolfgang [Akademischer Betreuer] Buckel. "Exploring the biosynthetic pathways of glutamate and benzoate in Syntrophus aciditrophicus / Marie Kim. Betreuer: Wolfgang Buckel." Marburg : Philipps-Universität Marburg, 2011. http://d-nb.info/1014851858/34.
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Richards, Anthony O'Leary. "The dynamics of enzyme synthesis and benzoate utilisation in batch and chemostat cultures of 'Alcaligenes eutrophus'." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281773.
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Timmers, Jennifer. "Effects of Growth Implants on the Average Daily Gain of Suckling Calves Rotationally Grazing ‘Ky-31’ Endophyteinfected Tall Fescue (Festuca Arundinacea) and Non-Endophyteinfected Tall Fescue." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1740.
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Demands are placed on cattle producers to provide a steady supply of beef at a competitive price. Producers must maximize beef output while minimizing input expenses without compromising product quality. The use of growth implants has become a common practice among cattle producers. The objective of this study was to evaluate the effects of two implant strategies on the average daily gain of suckling calves rotationally grazed on Kentucky – 31 endophyte-infected tall fescue and Kentucky – 31 non-endophyte-infected tall fescue. Eighteen cows with spring calves (N = 18) were used in this study. Calves were grouped by birth date into four blocks. Within each block, calves were stratified by sex and 45d of age body weight into three implant treatment groups for a total of six calves per treatment (n = 6, control 90.3 ± 9.7 kg, zeranol 102.9 ± 10.9 kg, and progesterone (100 mg) and estradiol benzoate (10 mg) 92.4 ± 10.3 kg). Calves were weighed and re-implanted at 129 d of age (84 d after initial implant). Zeranol treated calves were re-implanted using the same implant as the initial implant. Progesterone and estradiol benzoate treated calves were re-implanted after reaching a minimum body weight of 181 kg with either 200 mg progesterone and 20 mg estradiol benzoate or 200 mg testosterone propionate and 20 mg estradiol benzoate depending on sex. Data were analyzed using the REPEATED function in the MIXED procedure of SAS. No interactions were found among sex and treatments for 84d weight gains and 140d weights. There were also no main effects found for 84d weight gains and 140d weight gains. Forage analysis suggested that low crude protein and energy content may have contributed to the low ADG. Low endophyte concentrations may also have played a role.
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Derussi, Ana Augusta Pagnano [UNESP]. "Efeitos da aplicação do benzoato de estadiol na prevvenção de gestação em cadelas." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/98239.
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derussi_aap_me_botfmvz.pdf: 919371 bytes, checksum: 2a418e27dc57dd6def1de0d243e28651 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O objetivo deste estudo foi avaliar os efeitos do benzoato de estradiol na prevenção de gestação em cadelas recém-acasaladas. Utilizou-se 24 fêmeas: GRUPO I (Experimental) – 12 cadelas que receberam uma única aplicação de benzoato de estradiol, dose de 0,2 mg/Kg, via intramuscular, entre o 2º e 7º dia da data da última cobertura. GRUPO II (Controle)- 12 cadelas que receberam solução oleosa diluente, dose de 0,2 ml/Kg, via intramuscular, entre os dias 2 e 7 da última data de cobertura. A ovariohisterectomia (OSH) foi realizada entre os dias 6 a 16 após a última cobertura e foram avaliadas: taxa de recuperação e degeneração ovocitária/ embrionária; viabilidade embrionária e a influência do fármaco sobre à migração, clivagem e implantação embrionária. Foi examinado, também, os efeitos do benzoato de estradiol no sistema hematológico após a utilização da droga. Para avaliação dos hemogramas foi realizado análise de variância –ANOVA (p< 0,05) para medidas repetidas e o teste de Tukey para os parâmetros hematológicos. Para as variáveis recuperação ovocitária e embrionária foi utilizado o coeficiente de correlação de Pearson; para migração embrionária e clivagem embrionária foi realizado o teste de qui-quadrado, na análise de viabilidade embrionária foi utilizado teste exato de Fisher e na análise da implantação foi utilizada análise descritiva dos dados. Todos os testes foram realizados a 5% de nível de significância. Obteve-se 03 embriões no grupo experimental e 52 no grupo controle; o benzoato de estradiol exerceu influencia sobre o número de estruturas recuperadas, porém não influenciou a migração, clivagem e a viabilidade embrionária quando utilizado até o 7°dia após a cobertura. Não foi detectada a presença de vesículas embrionárias implantadas em ambos os grupos, porém...
The purpose of this experiment was to evaluate the effects of the estradiol benzoate on the prevention of pregnancy in mismantig dogs. For that, 24 bitches were divided, in: Experimental Group - 12 bitches that has received a single application of the estradiol benzoate (dose of 0,2 mg/Kg, intramuscular application), in a 2 to 7º days after the last mating. Control Group - 12 bitches received an oily solution (dose of 0,2 mL/Kg, intramuscular application) on the same period (between 2 to 7 days after the last mating). Ovariohysterectomy (OSH) has performed, between days 6 and 16 after the last mating and the parameters evaluated were the recovery rate and the embryonic/ oocytary degeneration rate and the influence of the drug on the migration, the viability, clivage and embryonic implantation. The effect of the estradiol benzoate on the hematologic system after the use of the drug was also investigate. For the oocytary and embryonic recovery variables the coefficient of Pearson correlation was used, in the analysis of the embryonic migration and embryonic clivage a qui-square test was carried qui-square test, in the analysis of embryonic viability were used the Fisher’s exact test were used and in the analysis of the implantation descriptive analysis o was used. All the tests used 5% of significance level.Three embryos in the experimental group and 52 embryos in the control group were acquired; estradiol benzoate did practise influences on the number of structures recouvered, but, nor on the migration, clivage and embryonic viability, when used until the 7° day after the mating. There was no detection the presence of embryonic vesicles in both the groups, Apparently, OSHs were performed to soon for the detection of embryonic vesicle... (Complete abstract click electronic access below)
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Samperio, Cristian. "Formation, Characterization and Stability of Natural Antimicrobial-Cyclodextrin Complexes." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/44251.
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As a response of the need for a natural antimicrobial to replace sodium benzoateâ s use as a preservative in beverages, twenty eight compounds known to have antimicrobial activity were evaluated to quantify their solubility. Twenty three of the compounds evaluated are components of plant essential oils and the remaining five compounds are alkyl esters of para-hydroxybenzoic acid. The test compounds were evaluated for aqueous solubility as well as their solubility in an acid-based beverage mixture. The compounds were found to be practically insoluble (< 100 mg/L), very slightly soluble (100 mg/L â 1,000 mg/L) or slightly soluble (1,000 mg/L to 10,000 mg/L).
o-Methoxycinnamaldehyde, trans,trans-2,4-decadienal, cinnamic acid, and citronellol were complexed with α- and β- cyclodextrin and evaluated through phase solubility analyses. The complexes formed showed improved aqueous solubility for all compounds. Complexation with α-CD resulted in an increase of aqueous solubility of o-methoxycinnamaldehyde by 10-fold, trans,trans-2,4-decadienal by 3.2-fold, cinnamic acid by 6.3-fold, and citronellol by 8-fold. In addition, complexation with β-CD resulted in an increase of aqueous solubility of o-methoxycinnamaldehyde by 1.6-fold, trans,trans-2,4-decadienal by 3.1-fold, cinnamic acid by 1.7-fold, and citronellol by 1.6- fold.
The storage stability of the α-CD complexes of o-methoxycinnamaldehyde trans,trans-2,4-decadienal and citronellol were evaluated for 7 days in an acid-based beverage solution by SPME GC-MS. The complexes exhibited varying levels of degradation throughout the duration of the study all. The concentration of o-methoxycinnamaldehyde detected by SPME GC-MS decreased by 61.7%. Similarly, the concentration of trans,trans-2,4-decadienal and that of citronellol decreased by 62.7% and 43% respectively. Additionally, a comparison by UV/Vis of the storage stability of the complexes stored in glass and PET containers was performed. The storage stability comparison proved that absorption into the PET polymer membrane did not occur.Master of Science
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Niemeier, Oliver [Verfasser]. "Neue chirale Triazoliumsalze in der Carben-katalysierten intramolekularen gekreuzten Benzoin-Reaktion / vorgelegt von Oliver Niemeier." Aachen : Mainz, 2006. http://d-nb.info/999974599/34.
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Du, Yong. "Time-resolved spectroscopic studies of the photophysics and photochemistry of selected benzoin and benzophenone compounds." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B39707350.
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Du, Yong, and 杜勇. "Time-resolved spectroscopic studies of the photophysics and photochemistry of selected benzoin and benzophenone compounds." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39707350.
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Duygu, Arife Nese. "Synthesis Of Camptothecin Derivatives." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606302/index.pdf.
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This study presents synthetic studies on camptothecin, a potent antitumor agent in order to improve its stability and solubility without reducing its activity. The study consists of the modification of camptothecin at 20-OH position a new strategy for the targeted and controlled release of the drug and modification at C-7 position to overcome the stability and solubility problems of the free drug.
In the first part of the study, the 20-OH functional group of camptothecin was replaced with an unsymmetrical benzoin derivative that is able to release the drug under photolysis at 350 nm. The new prodrugs synthesized possessed higher stability than the camptothecin itself. The in vitro irradiation of the prodrugs at 350 nm was satisfactory without any decomposition of the active substance.
The second part of the study comprises the studies on the modification of the 7th position of camptothecin, which is the most suitable position for the modification. In this part of the study, 7-amino and silyl substituted camptothecins were synthesized.Combination of camptothecin with some other drugs such as cisplatin was also investigated in this study. The synthetic efforts showed that the reactions are very promising and the combination studies can be studied as a major subject in the future.
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Birck, Cécile. "Conception et caractérisation de films antimicrobiens à base de poly(alcool vinylique) pour l’emballage à contact alimentaire." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10074/document.
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L’objectif de ce travail était de développer des films antimicrobiens à base de poly(alcool vinylique)(PVOH) réticulés par de l’acide citrique (CTR). La démarche choisie a consisté à incorporer dans le polymère du benzoate de sodium (NaBz), seul ou sous forme de complexe avec l’hydroxypropyl-β-cyclodextrine (HPβCD). La combinaison des fonctions résiduelles du CTR greffé sur le polymère et du NaBz libre permet d’envisager des effets antimicrobiens par contact et par diffusion. Les films ont été réalisés par casting à partir de solutions aqueuses et réticulés par un traitement thermique. La réaction de réticulation a été mise en évidence et suivie à travers l’étude des composés résiduels, l’évolution de la Tg et des fonctions COOH résiduelles en fonction du temps de réticulation. L’étude de différentes compositions a permis de sélectionner les concentrations de 20 et 30 wt% en CTR pour un compromis entre réticulation suffisante et ductilité du film préservée. Le temps nécessaire pour lier l’ensemble des réactifs diminue avec l’augmentation de la température ou de la quantité de CTR. La réaction de réticulation n’est pas modifiée par la présence d’HPβCD. Avec l’ajout de CTR ou d’HPβCD et la réticulation, les films restent faiblement perméables à O2 et fortement perméables à la vapeur d’eau. Concernant la libération du NaBz dans l’eau, la cinétique est ralentie à partir de 360 min de réticulation et de 20 wt% de CTR. L’HPβCD n’a pas d’influence sur la cinétique de libération mais a permis de doubler la quantité libérée. L’activité antimicrobienne par contact et par diffusion a été mise en évidence pour la majorité des films contre l’ensemble des microorganismes étudiésThe aim of this work was to develop antimicrobial films based on polyvinyl alcohol (PVOH) crosslinked by citric acid (CTR). In our approach, sodium benzoate (NaBz) was introduced in polymer, alone or in complex form with hydroxypropyl-β-cyclodextrin (HPβCD). Both CTR residual functions grafted on polymer and free NaBz are expected to provide antimicrobial effects by contact and diffusion. Films were elaborated by casting from aqueous solutions and crosslinked by heat treatment. Crosslinking reaction has been highlighted and followed through the study of residual reagents, the evolution of Tg and residual COOH functions according to crosslinking time. From this investigation, a compromise between sufficient crosslinking and preserved film ductility has been found for a CTR concentration between 20 and 30 wt%. The time required to bind all of the reagents decreases with the increase of temperature or amount of CTR. The crosslinking reaction was not modified by the presence of HPβCD. With the addition of CTR or HPβCD and the crosslinking step, the films remain slightly permeable to O2 and highly permeable to water vapor. Considering the NaBz release in water, kinetics is slowed from 360 min of crosslinking and 20 wt% CTR. HPβCD has no major influence on the kinetics of release but allow to double released amount. Antimicrobial activity by contact and diffusion has been demonstrated for the majority of films against all studied microorganisms
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Reddy, Dondleti Srinivasa. "Mechanism Of The Benzoin Condensation And Related Studies." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/2391.
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Chapter 1: An assessment of the mechanism of the benzoin condensation. The reaction under non-hydroxylic conditions. The generally accepted mechanism for the well known benzion condensation is unviable for the following reasons: 1) No experimental evidence for formation of carbanion from oxyanion. 2) No experimental reports on pKa of ‘C-H” in intermediate oxyanion. 3) From previous reports, these types of carbanion are stable only at -78° C. 4) Carbanions possessing nucleofuges generally form carbenes.
It was observed that the O- protected benzaldehyde cyanohydrin (1) and O-MOM protected ethyl mandelate (2) are possibly less acidic than benzyl cyanide (3). Attempts to affect hydrogen-deuterium exchange in the O-methyl ether of benzaldehyde cyanohydrin (1) did not yield clear-cut results; neither could the analogous carbanion from O-MOM protected ethyl mandelate be formed, under analogous conditions. O-Protected benzaldehyde cyanohydrin and O-MOM protected ethyl mandelate (2) did not condense with electrophiles like benzaldehyde (4); however benzyl cyanide (3) was condensed with benzaldehyde to form the stilbene cyanide (5) under similar conditions to the benzoin condensation.
Scheme 1: Reactions under benzoin conditions.
All these evidences indicate that carbanions derived from 1 and 2 are not formed under the conditions of the benzoin reaction. An alternative mechanism via intramolecular participation in the cyanohydrin oxyanion leads initially to an imino-oxirane intermediate; electrophilic capture of this in the key step finally leads to benzoin (Scheme 2). This is an attractive possibility that avoids many of the problems of the earlier mechanism, and is also not incompatible with most of the available experimental evidence. Further experimental and theoretical work is indicated before an acceptable mechanism for the benzoin condensation finally emerges.
Scheme 2: A possible alternative mechanism of benzoin condensation
Scheme 2: A possible alternative mechanism of benzoin condensation
From the studies on mechanism of benzoin condensation, it seems possible to form imino-oxirane from oxyanion of benzaldehyde cyanohydrin instead of carbanion by participation of cyanide ion. To prove the cyanide ion participation in mechanism of benzoin condensation and to avoid ambiguities from O-H peak, the reaction was performed in 1,4 dioxane solvent with benzaldehyde (4) and cyanide with the phase transfer catalyst 18-crown-6, instead of EtOH and H2O as solvent. After mixing the IR spectra for the crude product, indicated the formation of benzoin (8), which was confirmed upon work up. This led to the developing of a novel method for the benzion under anhydrous conditions.
Scheme 3: Formation of benzoin under anhydrous conditions
Chapter 2: Stereochemical stability of benzion. Generally α-hydroxy ketones undergo tautomerism to the enediol form, which are stabilized by intramolecular hydrogen bonding. Because of this, they undergo racemisation. Benzoin is also a α-hydroxy ketone, but it can be resolved into its enantiomeric forms. It indicates enediol form of benzion is unstable possibly due to steric interference.
It was observed from the crystal structure of the carbonate analog of ene-diol form of benzoin that there is steric interference between the two phenyl rings. These were twisted out of the plane of the carbonate moiety by 19.92° and -47.32°. (The crystal structure of 4,5-diphenyl-1,3-dioxol-2-one (9) was reported first time.) This structure also indicated the existence of atropisomerism in the crystalline lattice.
Chapter 3: Polymerisation of benzaldehyde. α-Hydroxy esters can be viewed as surrogates of cyanohydrins. To prove the cyanohydrin anion intermediate in classical benzoin condensation mechanism is very difficult. An interesting alternative is to employ α-hydroxy esters instead.
It was observed that methyl 2-phenylglyoxylate and methyl 2-(methoxymethyl)-2-phenylglyoxylate (2) failed to react with benzaldehyde in aqueous methanol with sodium carbonate as base. IR spectra indicated that the carbonyl peak of benzaldehyde has disappeared, but NMR spectra showed a mixture of methyl 2-(methoxymethyl)-2-phenylglyoxylate (2) and benzaldehyde (4). This seems to indicate the polymerization of benzaldehyde (10) (Scheme 4). However, the product was not stable enough to be isolated and purified.
Scheme 4: Reaction between benzaldehyde and MOM-protected methyl mandalate
(For structural formula pl see the abstract file.)
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LINI, FRESHSYA ZATA, and 菲斯雅. "Effects of Templating Molecules of Sodium Benzoate, 1:1 Co-crystal of Benzoic Acid - Sodium Benzoate, and 2:1 Co-crystal of Benzoic Acid - Sodium Benzoate on the Crystallization Kinetics of 2:1 Co-crystal of Benzoic Acid – Sodium Benzoate." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/4xca5e.
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碩士國立中央大學
化學工程與材料工程學系
105
More than 65% of new drug candidates in pharmaceutical industry are poorly aqueous soluble drug. Co-crystallization technique can be used to overcome this problem through enhancing the high-end product purification and bioavailability of the drug by combining the API (Active Pharmaceutical Ingredient) with the co-former agent. In this work, co-crystallization of benzoic acid as the API with sodium benzoate as the co-former in co-solvent of 4:1 v/v of ethanol-water was generated by reaction crystallization method. A clear saturated solution was prepared by diluting Solution A containing 17.22 g (0.141 mol) of benzoic acid (HBz) in 50 mL of 4:1 v/v ethanol – water co-solvent and Solution B containing 1.89 g (0.047 mol) of sodium hydroxide (NaOH) in 6 mL of 2:1 v/v ethanol – water co-solvent. The solution then was cooled from room temperature to 16oC until the crystals were generated and the solution became turbid, indicating that the system had reached the end of the induction time, τ, of crystallization which can be used to determine some fundamental kinetic and thermodynamic parameters of nucleation and crystal growth, such as: the interfacial energy, γ, the Gibbs energetic barrier, ΔGcr, the nucleation rate, J, the critical size of stable nuclei, rc, and the relative growth rate, RG. All of these parameters were evaluated with different initial supersaturation ratio of the system, S0, which were: 1.66, 1.54, 1.48, and 1.43. To study the effect of templating in co-crystal system, about 1.5 wt % template of: sodium benzoate, 2:1 co-crystal of benzoic acid-sodium benzoate, and 1:1 co-crystal of benzoic acid-sodium benzoate were iii introduced for each system with different S0. In general, the induction times for all systems ranged from 3 to 40 minutes, where the higher S0 value gave the faster τ value. Moreover, introducing a template in the system gave a faster induction time, τ. ΔGcr and rc decreased, while J and RG increased on a faster induction time, indicating that co-crystallization thermodynamic and kinetic were directly related to the initial concentration of the drug. The final product of the solid crystals for each system was verified as 2:1 co-crystal of benzoic acid – sodium benzoate by PXRD, FTIR, DSC, and TGA. Finally, these results showed that co-crystallization of API, benzoic acid, with its co-former, sodium benzoate, was feasible, both kinetically and thermodynamically.
47
劉奕賢. "Sodium benzoate ameliorates ketamine-induced behavioral disturbances." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dme542.
Full textAbstract:
碩士國立政治大學
神經科學研究所
106
Ketamine is a synthetic dissociative anesthetic and has rapid onset antidepressant effect. It has become a common abused substance, recently. Heavy ketamine use often results in synaptic dysfunction and behavioral disturbances including depression, social deficits, cognitive impairments and decrease synapse-associated protein expression. Growing evidence shows that enhancement of NMDA receptor function can ameliorate the effects of ketamine-induced behavioral and neurochemical responses. Sodium benzoate, an inhibitor of D-amino acid oxidase, can indirectly increase the NMDA receptor function through increasing the levels of D-serine and is also beneficial to the patients with depression or schizophrenia in the clinical study. The present study examined whether sodium benzoate could protect or reverse the behavioral dysfunction and synaptic dysfunction in mice exposed to ketamine acutely or repeatedly. Our results showed that sodium benzoate has antidepressant-like responses in the forced swimming test, whereas it did not produce additive effect with ketamine. Sodium benzoate enhanced the anesthetic responses of ketamine in the loss of righting reflex test, but attenuated the ketamine-induced psychotomimetic behaviors in the social interaction test and novel object recognition test. Repeated cotreatment of sodium benzoate and ketamine for 14 days significantly attenuated ketamine-induced persistent behavioral abnormalities including social withdrawal, recognition impairment, depression-like behaviors and hypersensitiveness of 5-HT2A receptor-mediated head twitch response. Moreover, the behavioral manifestation and lower level of synaptic protein PSD-95 after repeated ketamine exposure could be ameliorated by post-treatment of sodium benzoate. These findings suggest that sodium benzoate might have potential to reduce negative behavioral consequences of heavy ketamine use.
48
Jer-Horng, Wu, and 吳哲宏. "Anaerobic syntrophic consortia degrading terephthalate, methylbenzoate and benzoate." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/14544554109053602968.
Full textAbstract:
博士國立成功大學
環境工程學系
89
Chemical production of Purified Terephthalic Acid (PTA) as the raw material was one of the important petrochemical and related industry in Taiwan. In addition to acetate, wastewater generated from the PTA manufacturing process mainly contained aromatic compounds including terephthalate (isomers), 4-methylbenzoate and benzoate. In the preliminary studies of biodegradability assays, the results revealed that the aromatic compounds were relatively slowly mineralized by the methanogenic consortia with the acclimation periods of more than 3 to 16 months. The thesis was thus aimed for providing the ecological insight into the microbial diversity associated with the degradation of terephthalate, 4-methylbenzoate and benzoate by the methanogenic consortia. Energetics analysis suggested that the carboxylated aromatic compounds had to be degraded syntrophically by fermenting bacteria at the conditions with the low levels of acetate and hydrogen which were manipulated by the methanogens in the methanogenic consortia. The syntrophic degradation was evidently supported by the observation that the primary intermediates such as acetate and hydrogen were identified in the degradation of aromatic compounds. With built-up of the acetate and/or hydrogen by adding the selective inhibitors (2-bromoethanesulfonic acid or sodium molybdate), the anaerobic degradation of terephthalate and 4-methylbenzoate reached the thresholds with the actual Gibbs free energy change in the range from —72 to —82 kJ/mol, equivalent to the energy quantum needed for the synthesis of one ATP unit, approximately. The energy conserved in the bacteria responsible for degrading terephthalate and 4-methylbenzoate was substantially higher than that for degrading benzoate and fatty acids. It was likely that the higher energy was conserved from the decarboxylation and demethylation processes. In addition, anaerobic degradation of terephthalate and 4-methylbenzoate was shown to be rate-limited in the fermentation step. Morphological characterization of the mature biofilm and the granulated sludge individually obtained from the anaerobic fluidized bed (AnFB) reactor and the upflow anaerobic sludge bed (UASB) reactors treating PTA wastewater was conducted by using the scanning and the transmission electron microcopies. The micrographs clearly demonstrated the architectures of the biofilm and the granule with the distribution of microbial clusters that were composed of the unidentified bacteria in syntrophic association with the hydrogenotrophic methanogen-like (Methanobrevibacter-like) and/or the acetoclastic methanogen-like (Methanosaeta-like and Methanosarcina-like) bacteria. The comparative results further revealed the morphotypic similarity of the overall microbial composition but the distribution discrepancy of the Methanosaeta-like and Methanosarcina-like populations between the biofilm and the granule degrading the mixed substrates of PTA wastewater. In the methanogenic consortia individually enriched with terephthalate, 4-methylbenaoate and benzoate, the methanogen-like populations were quite similar but the predominant bacteria with the rod morphotypes were obviously different. The rod bacteria with the distinctive traits were also frequently observed in the biofilm and granule from the AnFB and UASB reactors treating PTA wastewater, suggesting the role in the anaerobic degradation of aromatic compounds. Using 16S rDNA-based molecular techniques, the phylogenetic diversity of the members within the methanogenic consortia degrading terephthalate, 4-methylbenzoate and benzoate was investigated. 16S rDNA sequence fragments were amplified by polymerase chain reaction (PCR) with genomic DNA directly extracted from the methanogenic consortia and retrieved by the cloning and sequencing approach. Most of the retrieved 16S rDNA sequences were related to the populations without the known isolates, suggesting the unique community structures. Comparative analysis of the identified clonal sequences and closely related references from the public database indicated that the bacterial members, which might be involved in the aromatic degradation were phylogenetically affiliated with the prevalent divisions including Proteobacteria (delta subdivision), green non-sulfur bacteria (subdivision I), candidate novel MBA1 and many others, specific to the individual community. It was suggested that the members represented by the delta-proteobacterial sequences were the predominant populations in the three communities. More importantly, that the identified delta-proteobacterial sequences were individually classified into three clusters in the phylogenetic tree seemed to depend on the aromatic substrates, suggesting that the populations degrading terephthalate, 4-methylbenzoate and benzoate were probably different. Furthermore, the Archaea members within the terephthalate-enriched methanogenic consortium were found to closely affiliate with the Methanosaeta- and the Methanospirillum-related populations. Fluorescence in situ hybridization (FISH) with the group-specific, 16S rRNA-targeted oligonucleotide probes was used to localize the members in the granules. The fluorescent signals correctly hybridized with the targets revealed that the random or mixed distribution of the microbial populations was elucidated for the non-layered topology of the granule. The FISH technique with the 16S rRNA-targeted probe detected the presence of the Methanobacteriaceae, which the corresponding sequences were not retrieved in the clone library, further suggesting that the microbial diversity of the community could not completely unveiled by only one method. Based on the phenotypic and phylotypic database established in this thesis, it can provide the microbial indicators or information for the further application in the anaerobic processes treating PTA wastewater and in the isolation of the novel anaerobic microorganisms.
49
Ge, Yong. "Enzymes involved in the bacterial degradation of benzoate." Thesis, 2003. http://hdl.handle.net/2429/14797.
Full textAbstract:
The objective of this doctoral research project is to investigate the specificity, and
the structural determinants thereof in two important classes of enzymes that catalyze
successive transformations in the aerobic catabolism of aromatic compounds. The first
class is ring-hydroxylating dioxygenases represented by toluate 1,2-dioxygenase of
Pseudomonas putida mt-2 (TADOmt2, E.C. 1.14.12.-) and benzoate dioxygenase of
Acinetobacter calcoaceticus ADP1 (BADOADPI, E.C. 1.14.12.10). The second class is
aryl cis-diol dehydrogenases represented by l,2-cw-dihydroxy-3-methyl-cyclohexa-3,5-
diene-carboxylate (m-toluate 1,2-diol) dehydrogenase from P. putida mt-2 (XylLmt2, E.C.
1.3.1.59) and l,2-cis-dihydroxy-3-phenyl-cyclohexa-3,5-diene (biphenyl 2,3-dihydrodiol)
dehydrogenase from Burkholderia sp. strain LB400 (BphBLB4oo, E.C. 1.3.1.56).
TADOmt2 and BADOADPI are two-component enzymes that share 63% sequence
identity, but that catalyze the 1,2-dihydroxylation of different ranges of substituted
benzoates. The active site of these enzymes is contained in an oxygenase of α3β3
configuration. The two components of TADOmt2 and BADOADPI were hyperexpressed,
anaerobically purified and their substrate specificities were compared. Reconstituted
TADOmt2 had a specific activity of 3.8 U/mg using m-toluate, and that of BADOADPI
using benzoate was 5.0 U/mg. Each component had a full complement of their respective
[2Fe-2S] centres. Steady-state kinetics data obtained using an oxygraph assay and by
varying substrate and dioxygen concentrations were analyzed using a compulsory order
ternary complex mechanism. TADOmt2 had greatest specificity for m-toluate, displaying
apparent parameters of KmA = 9 ± 1 μM, kcat = 3.9 ± 0.2 s-1, and Kmo2 = 16 ± 2 μM (100
mM sodium phosphate, pH 7.0, 25 °C). The enzyme utilized benzoates in the following
order of specificity: m-toluate > benzoate ~ 3-chlorobenzoate > p-toluate ~ 4-
chlorobenzoate » o-toluate ~ 2-chlorobenzoate. The transformation of each of the first
five compounds was well coupled to O2-utilization and yielded the corresponding 1,2-cis dihydrodiol. In contrast, the transformation of ortho-substituted benzoates was poorly
coupled to O2 utilization, with > 10 times more O2 being consumed than benzoate.
However, the apparent Km of TADOmt2 for these benzoates was > 100 μM, indicating that
they do not effectively inhibit the turnover of good substrates. Reconstituted BADOADPI
had greatest specificity for benzoate, displaying apparent parameters of KmA = 26±1
μM, kcat = 8.6 ±0.1 s-1, and Kmo2 = 53 ± 2 μM. The enzyme had a significantly narrower
apparent specificity than TADOmt2, utilizing only four of the seven tested benzoates in
the following order of apparent specificity: benzoate > m-toluate > 3-chlorobenzoate > otoluate.
To investigate the structural determinants of substrate specificity in these
dioxygenases, hybrid oxygenases consisting of the α subunit of one enzyme and the β
subunit of the other were constructed and anaerobically purified. The apparent substrate
specificity of the αBβT hybrid oxygenase for these benzoates corresponded to that of
BADOADPI , the parent from which the α subunit originated. In contrast, the apparent
substrate specificity of the αBβT hybrid oxygenase differed slightly to that of TADOmt2
(3-chlorobenzoate > m-toluate > benzoate ~ p-toluate > 4-chlorobenzoate » o-toluate >
2-chlorobenzoate). Moreover, the αBβT hybrid catalyzed the 1,6-dihydroxylation of otoluate,
not the 1,2-dihydroxylation catalyzed by the TADOmt2 parent. Finally, the
turnover of this ortho substituted benzoate was much better coupled to (Vutilization in
the hybrid than in the parent. Overall, these results support the notion that the a subunit
harbors the principal determinants of specificity in ring-hydroxylating dioxygenase.
However, they also demonstrate that the β subunit contributes significantly to the
enzyme's function.
XylLmt2 and BphBLB4oo catalyze the NAD+-dependent dehydrogenation of cisdiols
in the aerobic catabolism of toluates and biphenyl, respectively. Each enzyme was
heterologously expressed and purified, and their respective specificities for each of 4 aryl cis-diols were determined. Of the tested compounds, the best substrate of XylLmt2 was
m-toluate 1,2-diol (apparent Km = 23.5 ± 1.6 μM and kcat = 0.31 ± 0.01 s-1) and that of
BphBLB4oo was biphenyl 2,3-dihydrodiol (apparent Km = 11.2 ± 1.2 μM and kcat = 26.7 ±
0.02 s-1), consistent with the pathways in which these enzymes occur. Although the
apparent specificity of BphBLB4oo for its preferred substrate was approximately 180 times
higher than that of XylLmt2 for its preferred substrate, the former had a markedly
narrower substrate specificity. Thus, the apparent specificity constant of XylLmt2 for 1,2-
cis-dihydroxy-3-methyl-cyclohexa-3,5-diene (toluene 2,3-dihydrodiol), a noncarboxylated
aryl cis-diol, was half that for m-toluate 1,2-diol. In contrast, BphBLB400 did
not transform either of the tested carboxylated aryl cis-diols. Phylogenetic studies of aryl
cis-diol dehydrogenases reveal that there are at least three evolutionarily distinct types of
these enzymes. BphBLB400 and XylLmt2 represent separate classes of the type II (SDR-type)
enzymes.
50
chou, Pei Lin, and 周珮琳. "Kinetics for Synthesis and Hydrolysis of Ethyl Benzoate." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/34503079619041470427.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
91
The kinetic behavior of synthesis and hydrolysis of ethyl benzoate over an acidic cation-exchange resin, Amberlyst 39, was investigated with a fixed-bed reactor. The esterification was peformed at temperatures between 323.15 K and 353.15 K and molar ratios of feed ΘB0 (ethanol to benzoic acid) from 5 to 9. The hydrolysis was conducted also at temperatures between 323.15 K and 353.15 K, and the molar ratios of feed ΘC0´ (ethyl benzoate to water) from 0.5 to 8 and ΘB0 ´ (ethanol to water) from 1 to 7.42. The equilibrium conversion of benzoic acid was found to increase with increasing both temperature and the composition of feed ΘB0. The results of hydrolysis experiments showed that the reaction rate of hydrolysis was quite slow. Even the molar ratio of feedΘC0´ was as high as about 4, the conversion of water was only about 0.2, while the contact time was as long as 700 (g min/ml ). The relative adsorption strengths for the reacting species were determined from adsorption experiments. The results indicated that the magnitude of adsorption strengths followed the order of water >ethanol >ethyl benzoate > benzoic acid. The kinetic data were correlated with the quasi-homogeneous, the Langmuir-Hinshelwood, and the Eley-Rideal models. The frequency factor, the activation energy of the forward reactions, the heat of reaction, and the adsorption equilibrium constant of water were determined by correlating the kinetic data with those models. The Langmuir-Hinshelwood model yielded the best representation for the kinetic behavior of liquid-solid catalytic synthesis and hydrolysis of ethyl benzoate.