Absorption-stripping with aqueous, concentrated piperazine (PZ) is a viable retrofit technology for post-combustion CO2 capture from coal-fired power plants. The rate of thermal degradation and oxidation of PZ was investigated over a range of temperature, CO2 loading, and PZ concentration. At 135 to 175 °C, degradation is first order in PZ with an activation energy of 183.5 kJ/mole. At 150 °C, the first order rate constant, k1, for thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity is 6.12 × 10-9 s-1. After 20 weeks of degradation at 165 °C, 74% and 63%, respectively, of the nitrogen and carbon lost in the form of PZ and CO2 was recovered in quantifiable degradation products. N-formylpiperazine, ammonium, and N-(2-aminoethyl) piperazine account for 57% and 45% of nitrogen and carbon lost, respectively. Thermal degradation of PZ likely proceeds through SN2 substitution reactions. In the suspected first step of the mechanism, 1-[2-[(2-aminoethyl) amino]ethyl] PZ is formed from a ring opening SN2 reaction of PZ with H+PZ. Formate was found to be generated during thermal degradation from CO2 or CO2-containing molecules. An analysis of k1 values was applied to a variety of amines screened for thermal stability in order to predict a maximum recommended stripper temperature. Morpholine, piperidine, PZ, and PZ derivatives were found to be the most stable with an allowable stripper temperature above 160 °C. Long-chain alkyl amines or alkanolamines such as N-(2-hydroxyethyl)ethylenediamine and diethanolamine were found to be the most unstable with an allowable stripper temperature below 120 °C. Iron (Fe2+) and stainless steel metals (Fe2+, Ni2+, and Cr3+) were found to be only weak catalysts for oxidation of PZ, while oxidation was rapidly catalyzed by copper (Cu2+). In a system with Fe2+ or SSM, 5 kPa O2 in the inlet flue gas, a 55 °C absorber, and one-third residence time with O2, the maximum loss rate of PZ is expected to 0.23 mol PZ/kg solvent in one year of operation. Under the same conditions but with Cu2+ present, the loss rate of PZ is predicted to be 1.23 mole PZ/kg solvent in one year of operation. Inhibitor A was found to be effective at decreasing PZ loss catalyzed by Cu2+. Ethylenediamine, carboxylate ions, and amides were the only identified oxidation products. Total organic carbon analysis and overall mass balances indicate a large concentration of unidentified oxidation products. / text

To screen amine solvents for application in CO2 capture from coal-fired power plants, the equilibrium CO2 partial pressure and liquid film mass transfer coefficient were characterized for CO2-loaded and highly concentrated aqueous amines at 40 – 100 °C over a range of CO2 loading with a Wetted Wall Column (WWC). The acyclic amines tested were ethylenediamine, 1,2-diaminopropane, diglycolamine®, methyldiethanolamine (MDEA)/Piperazine (PZ), 3-(methylamino)propylamine, 2-amino-2-methyl-1-propanol and 2-amino-2-methyl-1-propanol/PZ. The cyclic amines tested were piperazine derivatives including proline, 2-piperidineethanol, N-(2-hydroxyethyl)piperazine, 1-(2-aminoethyl)piperazine, N-methylpiperazine (NMPZ), 2-methylpiperazine (2MPZ), 2,5-trans-dimethylpiperazine, 2MPZ/PZ, and PZ/NMPZ/1,4-dimethylpiperazine (1,4-DMPZ). The cyclic CO2 capacity and heat of CO2 absorption were estimated with a semi-empirical vapor-liquid-equilibrium model. 5 m MDEA/5 m PZ, 8 m 2MPZ, 4 m 2MPZ/4 m PZ and 3.75 m PZ/3.75 m NMPZ/0.5 m 1,4-DMPZ were identified as promising solvent candidates for their large CO2 capacity, fast mass transfer rate and moderately high heat of absorption. The speciation in 8 m 2MPZ and 4 m 2MPZ / 4 m PZ at 40 °C at varied CO2 loading was investigated using quantitative 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. In 8 m 2MPZ at 40 °C over the CO2 loading range of 0 – 0.37 mol CO2/mol alkalinity, more than 75% of the dissolved CO2 exists in the form of unhindered 2MPZ monocarbamate, and the rest is in the form of bicarbonate and dicarbamate; 19% - 56% of 2MPZ is converted to 2MPZ carbamate at 0.1 - 0.37 mol CO2/mol alkalinity. A rigorous thermodynamic model was developed for 8 m 2MPZ in the framework of the Electrolyte Nonrandom Two-Liquid (ENRTL) model. At 40 °C, the reaction stoichiometry for 2MPZ and CO2 is around 2 at lean loading but diminishes to 0 at rich loading. Bicarbonate becomes the major product at CO2 loading greater than 0.35 mol/mol alkalinity. The predicted heat of CO2 absorption is 75 kJ/mol at 140 °C and decreases with temperature when CO2 loading is above 0.25. The mass transfer rate data for 8 m 2MPZ was represented with a rate-based WWC model created in Aspen Plus®. The reaction rate was described with termolecular mechanism on an activity basis. With minor CO2 loading adjustment and regression of pre-exponential kinetic constants and diffusion activation energy, a majority of the measured CO2 fluxes in the WWC experiments were fitted by the model within ±20% over 40 – 100 °C and 0.1 – 0.37 mol CO2/mol alkalinity. The diffusion activation energy for 8 m 2MPZ at the rich loading is about 28 kJ/mol. The activity-based reaction rate constant at 40 °C for 2MPZ carbamate formation catalyzed by 2MPZ is 1.94×1010 kmol/m3•s. The calculated liquid film mass transfer coefficients are in close agreement with the experimental values. The liquid film mass transfer rate is dependent on the diffusion coefficients of amine and CO2 to the same extent at lean loading and 40 °C. The sum of the powers for the two diffusivities is approximately equal to 0.5 over the loading range of 0 – 0.4 mol CO2/mol alkalinity. The sum of the powers for the dependence of the liquid film mass transfer coefficient on the carbamate formation rate constants (k2MPZ-2MPZ and k2MPZCOO--2MPZ) approaches 0.5 at very lean loading at low temperature, but it decreases as CO2 loading and temperature is increased. At 100 °C, the physical liquid film mass transfer coefficient is the most important factor that determines the liquid mass transfer rate. The pseudo-first order region shifts to higher range of physical liquid film transfer coefficient as temperature increases. / text

The solvent 7 molal (m) methyldiethanolamine (MDEA)/2 m piperazine (PZ) presents an attractive option to industry standard solvents including monoethanolamine (MEA) for carbon dioxide (CO₂) capture in coal-fired power plant flue gas scrubbing applications. The solvent was tested under thermal and oxidizing conditions, including temperature cycling in the Integrated Solvent Degradation Apparatus (ISDA), to measure rates of degradation for comparison to other solvents. Unloaded 7 m MDEA/2 m PZ was generally thermally stable up to 150 °C, exhibiting very low loss rates. However, at a loading of 0.25 mol CO2/mol alkalinity, loss rates of 0.17 ± 0.21 and 0.24 ± 0.06 mM/hr, respectively, for MDEA and PZ were measured. No amine loss was observed in the unloaded blend. Thermal degradation was modeled as first-order in [MDEAH⁺], and a universal Ea for amine loss was estimated at 104 kJ/mol. An oxidative degradation model for 7 m MDEA was developed based on the ISDA data. From the model, the rate of amine loss in 7 m MDEA/2 m PZ was estimated at 1.3 X 10⁵ kg/yr, based on a 500 MW power plant and 90% CO₂ capture. In terms of amine loss, the solvent can be ranked with other cycled solvents from greatest to least as follows: 7 m MDEA>7 m MDEA/2 m PZ>8 m PZ. Thermal degradation pathways and mechanisms for 7 m MDEA/2 m PZ include SN2 substitution reactions to form diethanolamine (DEA), methylaminoethanol (MAE), 1-methylpiperazine (1-MPZ), and 1,4-dimethylpiperazine (1,4-DMPZ). The formation of the amino acids bicine and hydroxyethyl sarcosine (HES) has been directly tied to the formation of DEA and MAE, respectively, through oxidation. As a result of the construction and operation of the ISDA for cycling of solvents from an oxidative reactor to a thermal reactor, several practical findings related to solvent degradation were made. The ISDA results demonstrated that increasing dissolved oxygen in solvents leaving the absorber will increase the rate of oxidation. A simple N2 gas stripping method was tested and resulted in a reduction to 1/5th the high temperature oxidation rate associated with dissolved oxygen present in the higher temperature regions of an absorber/stripper system. The ISDA experiments also demonstrated the need to minimize entrained gas bubbles in absorber/stripper systems to control oxidation. When the ISDA was modified to intercept entrained gas bubbles, the oxidation rate was reduced 2 to 3X. / text

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-11-12T18:44:31Z No. of bitstreams: 2 Dissertação - Oscar Romero Lopes Rodrigues - 2015.pdf: 1210572 bytes, checksum: 9080ec829a41c8754d39489573c4cd56 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-11-12T18:46:20Z (GMT) No. of bitstreams: 2 Dissertação - Oscar Romero Lopes Rodrigues - 2015.pdf: 1210572 bytes, checksum: 9080ec829a41c8754d39489573c4cd56 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-11-12T18:46:20Z (GMT). No. of bitstreams: 2 Dissertação - Oscar Romero Lopes Rodrigues - 2015.pdf: 1210572 bytes, checksum: 9080ec829a41c8754d39489573c4cd56 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The Laboratório de Química Farmaceutica Medicinal designed and synthesized a new piperazine derivative tert-butyl 4-((1-phenyl-1H-pyrazol-4-yl)methyl)piperazine-1-carboxylate (LQFM104) based on molecular framework of clozapine. This study aimed the pharmacological evaluation in the central nervous system of the LQFM104. Treatment with LQFM104 at doses of 25 , 50 or 100 μmol/kg (p.o.) in the open-field test did not alter in animals the number of grooming behavior, the number of fecal boluses, the total number of crossings, immobility time, number of rears, the percentage of crossings in the central area and the time spent in the center. None of groups of doses tested with LQFM104 was able to change the time spent in the chimney test. In pentobarbital-induced sleep test, the treatment with LQFM104 25, 50 or 100 μmol/kg (p.o.) did not affect sleep latency, while the sleep duration has increased by 65%, 64.4% and 78.6% respectively compared to the control group treated orally with vehicle 10 ml/kg (28.8 ± 2.9 minutes). In the standardization of apomorphine-induced climbing test, the treatment with haloperidol at dose of 2.6 μmol/kg was able to reduce the climbing behavior in 97.8%, whereas clozapine at dose of 45 μol/kg, has reduced this behavior in 78 % when compared to control (16.87 ± 2.8). The LQFM104 50 or 200 μmol/kg (p.o.) was not able to reduce the climbing behavior. In the forced swimming test just LQFM104 50 μmol/kg (p.o.) was able to reduce the immobility time in 19.8% compared to the control group ( 263.2 ± 6.7 seconds) and increased the latency to immobility in 43%, compared with the control ( 70.6 ± 6.5 seconds). Similarly, in the tail suspension test, only the LQFM104 50 μmol/kg (p.o.) increased immobility time (32.1%) compared to the control (216.1 ± 13.2 seconds). The LQFM104 50 μmol/kg (p.o.) had their antidepressant-like effects completely reversed by blocking treatment with PCPA and NAN-190. And the quantification of brain-derived neurotrophic factor the LQFM104 50 μmol/kg (p.o.) did not change these levels. The results with LQFM104 in the open-field test indicated no changes in spontaneous locomotor activity and showed no anxiogenic activity. The chimney test did not reveal impairment in motor coordination. The pentobarbital-induced sleep test increased sleep duration without reducing the latency, thus suggesting a sedative action. The forced swimming test and the tail suspension test confirmed for LQFM104 50 μmol/kg (p.o.) an antidepressant activity in mice. The blockade with NAN-190 and PCPA suggests the involvement of serotonergic system and 5-HT1A receptor. / O laboratório de Química Farmacêutica Medicinal projetou e sintetizou um novo derivado piperazínico o tert-butil 4-((1-fenil-1H-pirazol-4-il)metil)piperazina-1-carboxilato (LQFM104) baseado no arcabouço molecular da clozapina . O objetivo deste estudo foi a avaliação farmacológica no sistema nervoso central do LQFM104. O tratamento com LQFM104 nas doses de 25, 50 ou 100 μmol/kg (v.o.), no teste de campo aberto não alterou nos animais o número de comportamento de auto-limpeza, o número de bolos fecais, o número total de cruzamentos, o tempo de imobilidade, número de levantadas, a porcentagem de cruzamentos na área central e o tempo despendido no centro. Nenhum dos grupos de doses testadas com LQFM104 tiveram alterações no tempo gasto pelo teste da chaminé. No teste do sono induzido por pentobarbital, o tratamento com LQFM104 25, 50 ou 100 μmol/kg (v.o.) não afetou a latência ao sono, enquanto que a duração do sono aumentou em 65%, 64,4% e 78,6% respectivamente, em comparação com o grupo controle tratado oralmente com veículo 10 ml/kg (28,8 ± 2,9 minutos). Na padronização do teste de escalada induzido por apomorfina, o tratamento com haloperidol na dose de 2,6 μmol/kg foi capaz de reduzir o comportamento de escalada em 97,8%, e a clozapina, na dose de 45 μmol/kg, causou este comportamento reduzido em 78% quando comparado com o controle (16,87 ± 2,8). O LQFM104 nas doses de 50 ou 200 μmol/kg (v.o.) não foi capaze de reduzir o comportamento de escalada. No teste do nado forçado, apenas a dose de 50 μmol/kg (v.o.) foi capaz de reduzir o tempo de imobilidade, em 19,8% em comparação com o grupo controle (263,2 ± 6,7 segundos) e aumentou a latência para a imobilidade em 43%, em comparação com o controle (70,6 ± 6,5 segundos). De modo semelhante, no teste de suspensão pela cauda, apenas o LQFM104 50 μmol/kg (v.o.), aumentou o tempo de imobilidade (32,1%) em comparação com o controle (216,1 ± 13,2 segundos). O LQFM104 50 μmol/kg (v.o.) teve seu efeito tipo antidepressivo completamente revertido pelo bloqueio com o tratamento com PCPA e NAN-190. Na quantificação do fator neurotrófico derivado do cérebro o LQFM104 50 μmol/kg (v.o.) não alterou esses níveis. Os resultados com LQFM104 no teste de campo aberto não indicaram nenhuma alteração na atividade locomotora espontânea e não mostraram nenhuma atividade ansiogênica. O teste da chaminé não mostrou diminuição na coordenação motora. O teste de sono induzido por pentobarbital aumentou a duração do sono, sem reduzir a latência, o que sugere uma ação sedativa. O teste do nado forçado e o teste de suspensão pela cauda confirmou para LQFM104 50 μmol/kg (v.o.) uma atividade tipo antidepressiva em camundongos. O bloqueio com PCPA e NAN-190 sugerem o envolvimento de sistema serotonérgico e do receptor 5-HT1A.

Orientador: Pedro Oliver Dunstan Lozano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T07:28:40Z (GMT). No. of bitstreams: 1 Khan_AbdulMajeed_D.pdf: 3004508 bytes, checksum: 1d8c778094bf0cb1b93fa7bf80e19074 (MD5) Previous issue date: 2013 / Resumo: Os adutos MX2.nL (M = Mn, Fe, Co, Ni, Cu ou Zn, L = 3-cianopiridina, piperidina ou piperazaina, X = Br, n = 0,5, 0,75, 1, 1,5, 2 ou 4), foram sintetizados e caracterizados através de análise elementar, determinação de pontos de fusão, espectroscopia IV e eletrônica e análise termogravimétrica. Todos os adutos são sólidos e sensíveis à umidade atmosférica. Os dados espectroscópicos na região do infravermelho, para os adutos, indicam a presença de um mesmo padrão de bandas em comparação com os respectivos ligantes livres. No entanto, deslocamentos de algumas bandas são evidentes devido à coordenação dos íons metálicos aos ligantes. As entalpias de dissolução em HCl 1,2 molL dos adutos, brometos metálicos e ligantes, foram determinados. Através de ciclos termoquímicos apropriados, foram calculadas as variações de entalpia padrão para as reações: MBr2 (s) + nL (s,l) MBr2.nL (s) DrH MBr2.nL (s) MBr2 (s) + nL (g) DDH MBr2 (g) + nL (g) MBr2.nL (s) DMH Foram também calculadas as variações entálpicas padrão de formação dos adutos e as variações entálpicas padrão da ligação metal-nitrogênio. Os parâmetros termoquímicos permitiram determinar a ordem de acidez dos adutos: para os adutos de ligante 3-cianopiridina: NiBr2>FeBr2> CoBr2>MnBr2 e ZnBr2>CuBr2, para os adutos de ligante piperidina: FeBr2 > MnBr2, CoBr2 > NiBr2, para adutos de ligante piperazina: FeBr2 > MnBr2 > NiBr2 e CuBr2 > ZnBr2 > CoBr2. A ordem de basicidade das ligantes e (Piperidina) >(3-cianopiridina) para os adutos de ZnBr2 e (Piperidina) > (Piperazina) para os adutos de CuBr2. / Abstract: The adducts MX2.nL (M = Mn, Fe, Co, Ni, Cu or Zn, L = 3-cyanopyridine, piperidine or piperazaina, X = Br, n = 0.5, 0.75, 1, 1.5, 2 or 4), were synthesized and characterized by elemental analysis, melting point measurements of the adducts, vibrational and electronic spectroscopy and thermogravimetric analysis. All adducts are solid and sensitive to moisture. The spectroscopic data in the infrared region, indicate the presence of a similar band pattern as compared with the free ligands. However, dislocation of some bands are observed due to coordination of the metal ions to the ligands. The enthalpies of dissolution in HCl 1.2 molL of the adducts, metal bromides and ligands have been determined. Through appropriate thermochemical cycles, we calculated the standard enthalpy changes for the reactions: MBr2 (s) + nL (s,l) MBr2.nL (s) DrH MBr2.nL (s) MBr2 (s) + nL (g) DDH MBr2 (g) + nL (g) MBr2.nL (s) DMH Standard enthalpy of formation and standard mean enthalpy of Metal-Nitrogen bonds were also calculated. The thermochemical parameters allowed to determine the acidity order of metal bromides for the adducts of the same stoichiometry: For the adducts of ligand 3-cyanopyridine: NiBr2> FeBr2> CoBr2> MnBr2 and ZnBr2> CuBr2. for the adducts of ligand piperidine: FeBr2> MnBr2 and CoBr2> NiBr2. for the adducts of ligand piperazine: FeBr2> MnBr2> NiBr2 and CuBr2> ZnBr2> CoBr2. The order of basicity is (Piperidine)> (3-cyanopyridine) for the adducts of ZnBr2 and (Piperidine)> (Piperazine) for the adducts of CuBr2. / Doutorado / Quimica Inorganica / Doutor em Ciências

El objetivo central del presente trabajo de Tesis Doctoral fue restablecer in vitro la susceptibilidad antimicrobiana de cepas comensales de Escherichia coli (con fenotipo multirresistente-MDR-) aisladas de explotaciones pecuarias, mediante la asociación de diferentes antimicrobianos con el inhibidor de bombas de eflujo 1-(1-naphthylmethyl)-piperazine (NMP). De esta manera, se pretende contribuir al desarrollo de planes de dosificación de máxima eficacia antimicrobiana minimizando el riesgo de emergencia y diseminación de resistencia bacteriana; permitiendo así la obtención de productos de origen animal de excelencia sanitaria, en función de la correcta interpretación de los parámetros farmacocinéticos/farmacodinámicos (modelización PK/PD) para una correcta dosificación, del mecanismo de resistencia y del eventual bloqueo de éste último. Se obtuvieron muestras de materia fecal mediante hisopado rectal de vacas en ordeñe, terneros y animales de compañía, pertenecientes a tambos de la provincia de Buenos Aires; así como también de pozos sépticos, agua de consumo y bombas estercoleras. Se determinaron los perfiles de sensibilidad, mediante el método estandarizado de Kirby-Bauer de difusión en agar, frente a ocho antimicrobianos a todas las cepas de E.coli aisladas. Se hallaron diez cepas de E. coli multirresistentes a partir de los animales muestreados en el estudio de tipo transversal. Se emplearon cepas isogénicas de E. coli con diferentes grados de expresión de bombas de eflujo como control de calidad (AG100A con deleción total de bombas de eflujo, AG100 como cepa “normal” y AG112 con sobreexpresión de bombas). Se determinó la concentración inhibitoria mínima (CIM) y la concentración bactericida mínima (CBM) de florfenicol, ciprofloxacina, tetraciclina y ampicilina por el método de microdilución seriada en caldo Luria-Bertani (LB) con y sin NMP. Para la determinación de las interacciones entre los tres antimicrobianos seleccionados (florfenicol, ciprofloxacina y tetracilina) y el inhibidor de bombas se calculó el Índice de Concentración Inhibitoria Fraccionaria (CIF) a fin de evaluar la manifestación o no de efecto sinérgico. Para evaluar la cinética de muerte bacteriana se realizaron curvas de muerte bacteriana de las cepas de referencia y las cepas de campo MDR con y sin NMP. Con los datos obtenidos se realizó el análisis estadístico correspondiente. Por último, a partir de la información farmacodinámica obtenida se realizó una modelización farmacocinética/farmacodinámica (PK/PD), para lo cual se utilizaron datos obtenidos de estudios farmacocinéticos de florfenicol, danofloxacina y oxitetraciclina realizados previamente por el grupo de investigación de la Cátedra de Farmacología. Se aislaron cepas resistentes y multirresistentes con altos niveles de resistencia frente a tetraciclina y ampicilina. Todas las combinaciones de resistencia múltiple siempre incluyeron en su perfil a la tetraciclina. El NMP asociado a ampicilina tuvo un efecto nulo tanto en las cepas isogénicas como en las de campo. Sin embargo, ciprofloxacina, florfenicol y tetraciclina, demostraron ser claros sustratos de las bombas. Se evidenció la ocurrencia de sinergismo de potenciación ya que con una concentración de antimicrobiano varias veces inferior a la de su CIM, se logró un efecto antibacteriano mejorado con la incorporación de NMP. Se comprobó que es posible disminuir la concentración de los antimicrobianos -florfenicol, ciprofloxacina y tetraciclina- con la incorporación de NMP, sin modificar de manera importante la “cinética de muerte bacteriana”, tanto en las curvas de muerte de las cepas de referencia como en las cepas problema. En cuanto a la relación PK/PD, en la cepa AG112 se mejoraron notablemente los parámetros predictores de eficacia con la adición del inhibidor, con la consecuente disminución de la concentración de los antimicrobianos. Resulta prometedor el efecto de la combinación de un fármaco inhibidor de bombas de eflujo como coadyuvante de aquellos antimicrobianos sustratos de las bombas de eflujo sobreexpresadas como mecanismo inespecífico de resistenca bacteriana.

Neste trabalho foram aprofundados nossos estudos para obtenção da (S)-2-terc-butilamida-4-(3-picolil)piperazina, pela abertura da (S)-2-terc-butilcarboxamida-N-p-tosilaziridina seguida de ciclização, em 78% de rendimento, com o triflato de vinildifenilsulfônio. A aziridina foi preparada por um processo de ciclização, em condições de transferência de fase, partindo-se da L-serina, um aminoácido natural de baixo custo. Esta rota sintética rendeu um material que apresenta a mesma estereoquímica S do fragmento piperazínico usado na síntese do Indinavir, podendo vir a constituir uma via alternativa para a obtenção deste fármaco. / In this work we performed a deeper study for obtaining (S)-2-tert-butylamide-4-(3-picolyl)piperazine by opening (S)-2-tert-butylcarboxamide-N-p-tosylaziridine followed by cyclization, in 78% yield, with diphenylvinylsulfonium trifluoromethanesulfonate. The aziridine were prepared by a cyclization process in phase transfer conditions, starting from L-serine, a low cost amino acid. This synthetic route yielded a material which has the same S piperazinic fragment stereochemistry used in the synthesis of Indinavir, and may constitute an alternative route for obtaining this drug.

This thesis describes the development of new synthetic methodologies for preparation of bioactive interesting compounds, e.g. substituted pyridines, piperidines or piparazines. Thesecompounds are synthesized from commercially available, cheap and easily prepared reagents, videlicet the reaction between Grignard reagents and heterocyclic N-oxides.  The first part of this thesis deals with an improvement for synthesis of dienal-oximes and substituted pyridines. This was accomplished by a rapid addition of Grignard reagents to pyridine N-oxides at rt. yielding a diverse set of substituted dienal-oximes. During these studies, it was observed that the obtained dienal-oxmies are prone to ring-close upon heating. By taking advantage of this, a practical synthesis of substituted pyridines was developed. In the second part, an ortho-metalation of pyridine N-oxides using Grignard reagents is discussed. The method can be used for incorporation of a range of different electrophiles, including aldehydes, ketones and halogens. Furthermore, the importance for incorporation of halogens are exemplified through a Suzuki–Miyaura coupling reaction of 2-iodo pyridine N-oxides and different boronic acids. Later it was discovered that if the reaction temperature is kept below -20 °C, the undesired ringopening can be avoided. Thus, the synthesis of 2,3-dihydropyridine N-oxide, by reacting Grignard reagents with pyridine N-oxides at -40 °C followed by sequential addition of aldehyde or ketone, was accomplished. The reaction provides complete regio- and stereoselectivity yielding trans-2,3-dihydropyridine N-oxides in good yields. These intermediate products could then be used for synthesis of either substituted piperidines, by reduction, or reacted in a Diels–Alder cycloaddtion to give the aza-bicyclo compound. In the last part of this thesis, the discovered reactivity for pyridine N-oxides, is applied on pyrazine N-oxides in effort to synthesize substituted piperazines. These substances are obtained by the reaction of Grignard reagents and pyrazine N-oxides at -78 °C followed by reduction and protection, using a one-pot procedure. The product, a protected piperazine, that easily can be orthogonally deprotected, allowing synthetic modifications at either nitrogens in a fast and step efficient manner. Finally, an enantioselective procedure using a combination of PhMgCl and (-)-sparteine is discussed, giving opportunity for a stereoselective synthesis of substituted piperazines.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A eficÃcia e a seguranÃa terapÃutica de um medicamento a base de piperazina hexahidratada associada com o extrato fluido de Rhamnus purshiana (DM IndÃstria FarmacÃutica) usada como tratamento anti-helmÃntico em pacientes no CearÃ, Brasil, foi testado em comparaÃÃo com o produto composto de piperazina sem qualquer associaÃÃo (DM IndÃstria FarmacÃutica). Um estudo prospectivo, randomizado, controlado e duplo cego, comparando taxas de cura para infecÃÃo por Ascaris lunbricoides. Amostras coprolÃgicas de 990 pacientes foram coletadas inicialmente e a prevalÃncia de infecÃÃes parasitÃrias intestinais foi examinada. 130 pacientes com amostras fecais positivas para Ascaris lumbricoides foram incluÃdos nos ensaios clÃnicos, no intuito de ser comprovada a eficÃcia e a seguranÃa terapÃutica. InformaÃÃes sobre dados socioeconÃmicos e de saneamento foram coletas a partir de questionÃrio prÃprio. Mais da metade dos pacientes mostrou taxa de monoparasitismo (60%) e prevalÃncia de Ascaris lumbricoides de 29%. Taxa positiva para helmintÃase intestinal e infecÃÃes por protozoÃrios atingiram Ãndice de 48,38% (tricurÃase 04%, ancilostomÃase 0%, amebÃase 04%, giardÃase 10%). Taxa de cura da piperazina associada com extrato fluido de Rhamnus purshiana foi de 93,33% e para a piperazina sem associaÃÃes foi de 96,36%, portanto nÃo apresentou diferenÃa estatisticamente significante em relaÃÃo Ãs taxas de cura dos medicamentos em estudo (P = 0,6809). NÃusea (13,84%) e vÃmito (11,53%) foram os eventos adversos mais prevalentes. NÃo foi evidenciada diferenÃa estatisticamente significante em relaÃÃo à ocorrÃncia de eventos adversos nas duas formulaÃÃes (P = 0,2348). Dados socioeconÃmicos e de saneamento mostraram Ãntima relaÃÃo com a ocorrÃncia infecÃÃo por Ascaris lumbricoides. Piperazina associada com extrato fluido com Rhamnus purshiana mostrou-se eficaz e segura no tratamento da ascaridÃase, na populaÃÃo estudada / The efficacy and the therapeutic security of a manufactured piperazina associated with the extract fluid of Rhamnus purshiana (DM IndÃstria FarmacÃutica) used for deworming patients in CearÃ, Brazil, were tested against the product composed by piperazina without any association (DM IndÃstria FarmacÃutica). A prospective, randomized, controlled and double blind clinical trial, comparing cure rates for Ascaris lumbricoides infections. Stool samples from 990 volunteers were collected at baseline and the prevalence of intestinal parasitic infections were viewed. 130 patients with faecal sample positive for Ascaris lumbricoides were included on the clinical trial, to assess the efficacy and therapeutic security. Socio-economic and sanitation information was obtained by an oral questionnaire. More than half of the patient showed monoparasitism (60%) and prevalence of Ascaris lumbricoides was (29%) in the study population. Intestinal helminth and protozoon infections egg positive rate was 48.38% (trichuriasis 4%, ancylostomiasis 0%, amebiasis 04%, giardiasis 10%). Cure rate for piperazine associated with the extract fluid of Rhamnus purshiana was 93.33% and piperazine without any association was 96.36%, so there was no significant difference in the cure rates (P = 0.6809). The most prevalent side effects were nausea 13.84% and vomit 11.53%. There was no significant difference in the prevalence of side effects (P = 0.2348). Socio-economic and sanitation dates showed narrow relation with Ascaris lumbricoides. Piperazine associated with the extract fluid of Rhamnus purshiana was efficient and insurance in the treatment of Ascaris lumbricoides in the studied population

Neste trabalho foram aprofundados nossos estudos para obtenção da (S)-2-terc-butilamida-4-(3-picolil)piperazina, pela abertura da (S)-2-terc-butilcarboxamida-N-p-tosilaziridina seguida de ciclização, em 78% de rendimento, com o triflato de vinildifenilsulfônio. A aziridina foi preparada por um processo de ciclização, em condições de transferência de fase, partindo-se da L-serina, um aminoácido natural de baixo custo. Esta rota sintética rendeu um material que apresenta a mesma estereoquímica S do fragmento piperazínico usado na síntese do Indinavir, podendo vir a constituir uma via alternativa para a obtenção deste fármaco. / In this work we performed a deeper study for obtaining (S)-2-tert-butylamide-4-(3-picolyl)piperazine by opening (S)-2-tert-butylcarboxamide-N-p-tosylaziridine followed by cyclization, in 78% yield, with diphenylvinylsulfonium trifluoromethanesulfonate. The aziridine were prepared by a cyclization process in phase transfer conditions, starting from L-serine, a low cost amino acid. This synthetic route yielded a material which has the same S piperazinic fragment stereochemistry used in the synthesis of Indinavir, and may constitute an alternative route for obtaining this drug.