Introduction: The macroporous Amberlite XAD resins were coated with LIX-64N and examined for the rate of uptake of copper . XAD-7 was by far the best support and gave a satisfactory rate of uptake up to loadings of 60% (w/w). The specific surface area of XAD-7 was measured by the adsorption of methylene blue from aqueous solution. The area of the wetted resin was five times less than that of the dry resin. LIX-65N was purified and the anti isomer characterised using spectroscopic techniques . The rate of uptake of copper was not improved by use of purified LIX-65N or by addition of LIX-63. XAD-7 coated with LIX-65N was used in columns. Elution curves for copper showed negligible tailing, and rapid separations of copper from iron (111), nickel, cobalt and magnesium by selective absorption were achieved. Copper was concentrated from very dilute solution at a flow rate of 50 ml min -1 ,and a 99% recovery was obtained. The method was applied to the rapid determination of copper in brass and bronze. A series of long-chain hydroxamic acids were synthesised and tested for suitability as stationary phase on XAD-7. Oleohydroxamic acid and naphthenohydroxamic acid were the most promising. The r ate of uptake of copper was reduced by the use of nonylphenol or amyl alcohol as a diluent. The capacities for copper of the hydroxamic acids were less when supported on XAD-7 than when used as liquid ionexchangers. The distribution coefficients of cobalt, nickel, zinc, lead, vanadium, uranium, iron (111) and copper were measured as a function of pH. XAD-7 coated with oleohydroxamic acid was used in columns for the rapid separation of iron (111) from copper and of copper from nickel, cobalt, lead and zinc. Copper was concentrated from very dilute solution at a flow rate of 45 ml min -1 and a 100,8% recovery was obtained. Copper was successfully separated from nickel by selective elution. The elution curves obtained show negligible tailing. The resin loaded with oleohydroxamic acid lost capacity due to chemical instability. Naphthenohydroxamic acid supported on XAD-7 was not suitable for use in columns, because it was physically unstable.

No description available.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-07-14T19:24:36Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação lucas pereira 20.01.16 14h.pdf: 3030489 bytes, checksum: d08690f65be6ab72afc4f01820c878d4 (MD5) / Made available in DSpace on 2017-07-14T19:24:36Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação lucas pereira 20.01.16 14h.pdf: 3030489 bytes, checksum: d08690f65be6ab72afc4f01820c878d4 (MD5) Previous issue date: 2014-08-03 / Capes / Em estudos prévios, realizados por Almeida, foram obtidas substâncias 2-isoxazolinas aza-biciclicas, que deram origem a núcleos como o 2-isoxazolina[5,4-b]piperidina e 2- isoxazolina[5,4-b]pirrolidina. Amidas N benzoiladas derivadas dessas substâncias apresentaram-se farmacologicamente ativas, principalmente em testes anti-inflamatório e antimicrobianos realizados com esses compostos. Além disso, várias substâncias contendo a função oxima, em sua forma livre e como éteres de oxima, são descritas na literatura, apresentando atividades biológicas antimicrobianas. Diante disso, foi obtido através da hibridização molecular, derivados 2-isoxazolínicos aza-biciclico contendo a função oxima em sua estrutura. Os ésteres isoxazolínicos 34 e 36 foram obtidos através de reações de cicloadição 1,3-dipolar por duas diferentes rotas sintéticas, pela reação do óxido de nitrila 41 (CEFNO) tanto com o enecarbamato cbz, quanto com as enamidas endocíclicas para-substituídas. Os cicloadutos oriundos do enecarbamato endocíclico, sofreram reações de hidrogenólise e posterior N-benzoilação. A porção éster, presente nos compostos N-benzoilados para-substituídos, foi reduzida a álcool e em seguida submetida a uma oxidação de Swern, resultando nos aldeídos isoxazolínicos. A partir desses aldeídos 38, através de uma reação com hidroxilamina, chegou-se nas oximas isoxazolínicas 39. Os novos derivados foram submetidos a testes biológicos com o intuito de avaliar sua atividade antimicrobiana. O teste foi realizado pelo método de difusão em disco, contendo bactérias Gram negativas e Gram positivas, onde os derivados isoxzolínicos apresentaram halos variados frente aos microrganismos em estudo. O composto 39b caracterizou-se como uma substância promissora no desenvolvimento de novos agentes antimicrobianos, com halos de 10 mm para o Staphylococcus aureus, 11 mm para o Micrococcus luteus, 13 mm Bacillus subtilis e 13 mm para o microrganismo Micobacterium smegmatis. / In previous studies conducted by Almeida substances were obtained isoxazolines 2-azabicyclic, giving rise to nuclei as 2-isoxazoline [5,4-b] piperidine and 2-isoxazoline [5,4-b] pyrrolidine. N benzoiladas amides derived from these substances had become pharmacologically active, especially in anti-inflammatory and antimicrobial tests conducted with these compounds. Furthermore, substances containing various oxime function, in free form and as oxime ethers are described in literature, showing microbial biological activities. Thus, was obtained by molecular hybridization, derivatives aza-bicyclic 2-isoxazolínicos containing the oxime function in its structure. Esters isoxazolínicos 34 and 36 were obtained by cycloaddition 1,3-dipolar cycloaddition reactions of two different synthetic routes, by reaction of the nitrile oxide 41 (CEFNO) with both the cbz enecarbamate, as with the endocyclic enamides para-substituted. Cicloadutos coming from the endocyclic enecarbamate suffered reactions of hydrogenolysis and subsequent N-benzoylation. The ester moiety present in the N-substituted compounds for benzoilados was reduced to alcohol, and then subjected to a Swern oxidation, resulting in isoxazolínicos aldehydes. From these aldehydes 38 by means of a reaction with hydroxylamine, was reached in isoxazolínicas oximes 39. The novel derivatives were subjected to biological tests in order to evaluate its antimicrobial activity. The test was performed using the disk diffusion method, comprising Gram negative and Gram positive where isoxzolínicos halo derivatives showed varied across the microorganisms under study. Compound 39b was characterized as a promising substance in the development of new antimicrobial agents with halos of 10 mm for Staphylococcus aureus, 11 to Micrococcus luteus mm, 13 mm and 13 mm Bacillus subtilis microorganism Mycobacterium smegmatis for.

Pyrethroids are the only class of insecticides approved by the World Health Organization (WHO) for use in insecticide treated nets (ITNs), the first line of malaria vector control. Widespread resistance development to pyrethroids undermines current control efforts, and hence an urgent need for alternative chemistries. I report the evaluation of pharmacological differences between insect and vertebrate acetylcholinesterase (AChE) as well as selectivity and toxicity testing of new carbamate insecticides on Anopheles gambiae, the African malaria mosquito. AChE gorge pharmacology data revealed differences between insect and vertebrate AChE that can be exploited in the design of a bivalent insecticide. Toxicokinetic analysis showed that metabolic detoxication and cuticular penetration affect toxicity of carbamates in a manner dependent on the chemical structure. Structure activity relationships of side-chain branched N-methylcarbamates emphasized the importance of structural complementarity of ligands to the AChE catalytic active site and the substrate, acetylcholine. Monovalent pyrazoles and acetophenone oxime carbamates were toxic to both susceptible and carbamate-resistant mosquitoes carrying a G119S mutation within the catalytic site. A bivalent phthalimide-pyrazole carbamate and sulfenylated phenyl N-methyl carbamates were highly toxic when topically applied onto insect but less toxic by treated filter paper assays. In vitro evaluation of a molecular mosquito-selectivity model using AChE peripheral site ligands confirmed that selectivity of PRC 472 was due to presence of I70 in mosquito, which is Y70 in human AChE. The findings presented here are important steps in the on-going search of a mosquito-selective and resistance mitigating carbamate insecticide for control of malaria mosquitoes. / Ph. D.

Les molécules-aimants, ou Single-Molecule Magnets en anglais, sont des complexes polymétalliques qui possèdent la propriété remarquable de se comporter individuellement comme des aimants. Synthétisées selon les méthodes de la chimie de coordination elles sont devenues l’objet d’une intense activité de recherche multidisciplinaire à l’interface de la chimie et de la physique. C’est dans ce contexte que se situe notre travail de thèse qui nous a conduit à synthétiser plusieurs séries de complexes polynucléaires nouveaux puis a les caractériser cristallographiquement et étudier leurs propriétés magnétiques dont les résultats sont présentés dans ce mémoire. Le premier chapitre présente l’approche théorique, expérimentale et les avancées scientifiques principales dans le domaine des molécules-aimants. Le deuxième chapitre concerne quatre séries de composés obtenus avec des ligands de type oxime. Deux de ces composés [Mn3]n et [Mn6] sont des complexes homonucléaires à base de manganèse et les deux autres [Ln2Cu2] et [Ln3Cu8] (LnIII = Dy, Gd, Tb, Y) des complexes hétéronucléaires CuII - LnIII. D’après les études magnétiques nous avons constaté que [Mn3]n, [Dy2Cu2] et [Dy3Cu8] se comportent comme des molécules-aimants mais que [Mn6] ne manifeste pas les propriétés d’une molécule-aimant. Le troisième chapitre concerne un composé tetranucléaire [Mn4] et une série de complexes dodecanucléaires [Ln4Cu8] (LnIII = Dy, Gd, Tb, Y) obtenus avec des ligands de type benzoxazoles. Les études des propriétés magnétiques ont mis en évidence le couplage antiferromagnétique des ions Mn dans le cubane [Mn4]. Pour la série [Ln4Cu8] (LnIII = Dy, Gd, Tb, Y) sur la base du complexe d’yttrium le couplage Cu-Cu a été négligé et pour le complexe [Gd4Cu8] nous avons mis en évidence des interactions Cu-Gd ferromagnétiques et Gd-Gd antiferromagnétiques. Les mesures faites sur le composé [Dy4Cu8] ont mis en évidence le comportement caractéristique d’une molécule-aimant. Le dernier chapitre présente les résultats obtenues pour un complexe tetradécanucléaire à valence mixte MnII – MnIII [Mn14] que nous avons obtenu a partir d’un ligand de type base de Schiff et dans lequel coexistent des interactions antiferromagnétiques et ferromagnétiques entre les ions manganèse avec un zero-field splitting important. La conclusion générale fait le bilan de nos résultats et donne quelques perspectives ouvertes par notre travail. / The Single-Molecule Magnets (SMMs) are polymetallic complexes containing unpaired electrons that have the remarkable property to behave individually as magnets. Synthesized according to the methods of coordination chemistry they have become the subject of intense multidisciplinary research at the interface of chemistry and physics. In this context our thesis was focused on the synthesis of several series of new polynuclear complexes and their characterization by X-ray diffraction and magnetic measurements. The obtained results are discussed in this manuscript. The first chapter presents the theoretical approach and scientific advances in the field of molecular magnets. The second chapter describes the coordination compounds obtained using the oxime-based ligands: two homonuclear complexes, [Mn3]n and [Mn6], and two heteronuclear series, [Ln2Cu2] and [Ln3Cu8] (LnIII = Dy, Gd, Tb, Y). According to the magnetic studies [Mn3]n, [Dy2Cu2] and [Dy3Cu8] behave as SMM. The third chapter is related to a tetranuclear [Mn4] cluster and a series of dodecanuclear benzoxazoles-based complexes [Ln4Cu8] (LnIII = Dy, Gd, Y). The magnetic measurements made on [Dy4Cu8] showed the characteristic behavior of a SMM. The final chapter presents a valence-mixed MnII - MnIII [Mn14] complex with ferromagnetic and antiferromagnetic interactions between manganese ions obtained using a Schiff base ligand. To conclude the main obtained results will be discussed and some perspectives opened by our work will be proposed.

As populações axial/equatorial em oximas e O-metiI oximas de 2-X-cicloexanonas (X= F, CI, Br, OCH3, SCH3 e N(CH3)2) foram efetivamente determinadas pela análise dos deslocamentos químicos dos prótons 6, utilizando-se os derivados da 4-tércio-butil-cicloexanona como modelos das conformações equatorial e axial. As populações dos confôrmeros axiais também foram determinadas pela análise dos deslocamentos químicos do carbono 4. Este carbono está em uma posição gama gauche em relação ao heteroátomo e sofre assim uma blindagem quando a conformação é axial. Usando-se os deslocamentos químicos observados do carbono 4 do isômero Z, foi possível calcular estas populações no isômero E. Os isômeros Z não apresentam este equilíbrio axial I equatorial porque existe uma compressão estérica grande entre o heteroátomo e o oxigênio na hipotética conformação equatorial. As populações axiais nestes compostos variam de 86% a 96% e apresentam uma dispersão muito pequena com os diferentes métodos utilizados. Ao se comparar oximas com éteres nota-se que para os substituintes mais polarizáveis, como metiltio, cloro e bromo há um aumento da população axial nos éteres comparado às oximas. As frequências de estiramento vCN se correlacionaram com os parâmetros indutivos de Taft (σl) e com a polarizabilidade média da ligação carbono-heteroátomo, o que apoia a idéia de uma interação πCN/σ*cx. Além disso, as frequências de estiramento vOH também se correlacionaram com estes parâmetros e neste caso o efeito indutivo e a polarizabilidade levam a um aumento de acidez destas oximas. / The axial/equatorial populations of oximes and O-methyl oximes of 2-X-cyclohexanones ((X= F, CI, Sr, OCH3, SCH3 e N(CH3)2) were determined by the chemical shifts of the protons bonded to carbon 6, making use of the 4-tert-butyl- cyclohexanone derivatives as models for the equatorial and axial conformations. The axial conformer populations were also determined by the C-4 chemical shift analysis. This carbon lies in a gamma gauche position to the heteroatom and suffers shielding when the conformation is axial. It has been possible to calculate those populations in the E isomer, using the C-4 chemical shift of the Z isomer. The latter do not present an axial/equatorial equilibrium because there is a too high steric compression between the nitrogen and the heteroatom in the hypothethical equatorial conformation. The axial populations of these compounds vary from 86 to 96% and present a small deviation along the different methods used. All substituents are preferentially in the axial conformation, even fluorine and methoxyl, which are predominantly equatorial in the corresponding ketones. It is noted that there is a increase in the axial population for more polarizable substituents like methylthio, chloro and bromo, on going from the oximes to the oximes O-methyl ethers. The vCN stretching frequencies are correlated with Taft\'s inductive parameters (σl) and the mean polarizability of the carbon-heteroatom bond, which supports the view of a πCN/σ*cx interaction. Sesides, the vOH stretching frequencies are also correlated with those parameters and in this case, both the inductive effect and polarizability lead to a increase of the oximes acidity.

Nos últimos anos a química é apontada como solução para diversos problemas globais originados por um modo de vida não sustentável, em virtude disso o desenvolvimento econômico e social ficam vinculados aos conhecimentos em ações sustentáveis embasadas na química verde. Neste contexto emerge a indústria química baseada em matérias-primas renováveis, dentre as biomassas renováveis destacam-se os carboidratos com cerca de 75% da biomassa da terra. Os glicosídeos são moléculas orgânicas nas quais o açúcar está ligado à uma porção não-carboidrato (aglicona), dentre eles os C-glicosídeos se destacam por apresentarem tanto resistência à hidrólise ácida quanto à enzimática, característica que confere interesse a indústria de fármacos e às ciências dos materiais apresentando-se como excelentes blocos de construção. A condensação de Knoevenagel é a reação entre um grupo metileno ativado e um aldeído ou cetona levando à formação de um composto β, β-insaturado e é muito relevante na derivatização de C-glicosídeos. O objetivo principal deste trabalho é empregar a D-glicose, como fonte de matéria-prima renovável, na obtenção de Cglicosídeos e potenciais derivados de interesse industrial, visando oferecer ao ambiente uma opção através de processos mais sustentáveis, para isso dividiu-se o trabalho em três etapas: a primeira de preparação da cetona β-C-glicosídeos e reações de proteções, a segunda, de derivações diretas dessas moléculas, por meio das preparações das oximas, das aril cetonas C-glicosídeos, da cicloexenona C-glicosídeo e do metil pentenol C-glicosídeo e a terceira consistiu de derivação de moléculas, obtidas na segunda etapa, em gem halo-nitro, oxima aril e isoxazol aril. Na primeira etapa, síntese da cetona β-C-glicosídeo, fez-se alterações metodológicas e obteve-se um rendimento médio de 92%, o composto foi confirmado por TGA, FT-IR e RMN 13C, nas reações de proteção à cetona β-C-glicosídeo, acetilação e benzoilação, obteve-se rendimentos de 60% e 31,4% respectivamente, os compostos foram confirmados por FT-IR e RMN 13C. Na segunda etapa sintetizou a aril cetona C-glicosídeo, desprotegida e protegida, com 91% e 78% de rendimentos respectivamente, a cicloexenona C-glicosídeo acetilada com 60% de rendimento e o metil pentenil C-glicosídeo acetilado com até 71% de rendimento, oximas a partir da cetona β-C-glicosídeo desprotegida e posterior proteção (economizando uma etapa) e oximas a partir da cetona β-C-glicosídeo acetilada obtendo rendimentos de 73,6 % e 83%, também foi sintetizada a oxima da glicose e sua acetilação gerou o nitrilo da glicose em 60% de rendimento, os compostos foram confirmados por FT-IR e RMN 13C. Na terceira etapa foram obtidos os derivados, gem bromo-nitro C-glicosídeo acetilado 30% (rota desprotegida) e 73% (rota protegida), gemcloro C-glicosídeo acetilados 30% (rota desprotegida) e 72% (rota protegida). A aril cetona C-glicosídeo acetilada, a oxima aril C-glicosídeo acetilada e isoxazol C-glicosídeo acetilado apresentaram rendimentos 45%, 78% e 31% respectivamente, todos confirmados por FT-IR e RMN 13C. A síntese da cetona β-C-glicosídeo desprotegida em meio aquoso alcalino apresenta um alto rendimento e demonstrou uma enorme versatilidade podendo ser empregada na obtenção de muitos derivados, no entanto as reações de proteção são necessárias para derivação dessas moléculas e facilitação da análise. / In recent years, chemistry has been identified as a solution to several global problems caused by an unsustainable way of life, as economic and social development are linked to the knowledge of sustainable actions based on green chemistry. In this context emerges the chemical industry based on renewable raw materials, among the renewable biomasses stand out the carbohydrates with about 75% of the earth\'s biomass. Glycosides are organic molecules in which sugar is bound to a non-carbohydrate (aglycone) moiety, among them the C-glycosides stand out because they have both resistance to acid and enzymatic hydrolysis, which is of interest to the pharmaceutical industry and sciences of materials presenting themselves as excellent building blocks. The Knoevenagel condensation is the reaction between an activated methylene group and an aldehyde or ketone leading to the formation of an β, β-unsaturated compound and is very relevant in the derivatization of Cglycosides. The main objective of this work is to use D-glucose, as a source of renewable raw material, to obtain C-glycosides and potential derivatives of industrial interest, aiming to offer the environment an option employing more sustainable processes, for this the work was divided in three stages: the first one of preparation of the ketone β-C-glycosides and reactions of protections, the second, of direct derivations of these molecules, through the preparations of oximes, aryl ketones C-glycosides, cyclohexenone C-glycoside and methyl pentenol C-glycoside and the third step consisted of derivation of molecules obtained in the second step in gem halo-nitro, aryl oxime and isoxazole aryl. In the first step, synthesis of the β-C-glycoside ketone made methodological changes and obtained an average yield of 92%, the compound was confirmed by TGA, FT-IR and 13C NMR, in the protection reactions to β-C-glycoside ketone, acetylation and benzoylation, yields of 60% and 31.4% respectively were obtained, the compounds were confirmed by FT-IR and 13C NMR. In the second step, the unprotected and protected C-glycoside aryl ketone was synthesized in 91% and 78% yields respectively, the acetylated C-glycoside cyclohexenone in 60% yield and the acetylated methyl pentenyl C-glycoside in up to 71% yield, oximes from the deprotected β-C-glycoside ketone and subsequent protection (saving one step) and oximes from acetylated β-C-glucoside ketone yielding 73.6% and 83% yields, the glucose oxime was also synthesized and its acetylation generated the glucose nitrile in 60% yield, the compounds were confirmed by FT-IR and 13 C NMR. In the third stage the derivatives were obtained, gem bromo-nitro C-glycoside acetylated 30% (unprotected route) and 73% (protected route), gem-chloro C-glycoside acetylated 30% (route deprotected) and 72% (protected route). The acetylated C-glycoside aryl ketone, the acetylated C-glycoside aryl oxime and the acetylated C-glycoside isoxazole presented yields of 45%, 78% and 31% respectively, all confirmed by FT-IR and 13C NMR. The synthesis of β-C-glycoside ketone deprotected in alkaline aqueous medium presents a high yield and demonstrated an enormous versatility that can be used to obtain many derivatives, however the protection reactions are necessary for derivation of this molecules and facilitation of the analysis.

Les molécules-aimants, ou Single-Molecule Magnets en anglais, sont des complexes polymétalliques qui possèdent la propriété remarquable de se comporter individuellement comme des aimants. Synthétisées selon les méthodes de la chimie de coordination elles sont devenues l'objet d'une intense activité de recherche multidisciplinaire à l'interface de la chimie et de la physique. C'est dans ce contexte que se situe notre travail de thèse qui nous a conduit à synthétiser plusieurs séries de complexes polynucléaires nouveaux puis a les caractériser cristallographiquement et étudier leurs propriétés magnétiques dont les résultats sont présentés dans ce mémoire. Le premier chapitre présente l'approche théorique, expérimentale et les avancées scientifiques principales dans le domaine des molécules-aimants. Le deuxième chapitre concerne quatre séries de composés obtenus avec des ligands de type oxime. Deux de ces composés [Mn3]n et [Mn6] sont des complexes homonucléaires à base de manganèse et les deux autres [Ln2Cu2] et [Ln3Cu8] (LnIII = Dy, Gd, Tb, Y) des complexes hétéronucléaires CuII - LnIII. D'après les études magnétiques nous avons constaté que [Mn3]n, [Dy2Cu2] et [Dy3Cu8] se comportent comme des molécules-aimants mais que [Mn6] ne manifeste pas les propriétés d'une molécule-aimant. Le troisième chapitre concerne un composé tetranucléaire [Mn4] et une série de complexes dodecanucléaires [Ln4Cu8] (LnIII = Dy, Gd, Tb, Y) obtenus avec des ligands de type benzoxazoles. Les études des propriétés magnétiques ont mis en évidence le couplage antiferromagnétique des ions Mn dans le cubane [Mn4]. Pour la série [Ln4Cu8] (LnIII = Dy, Gd, Tb, Y) sur la base du complexe d'yttrium le couplage Cu-Cu a été négligé et pour le complexe [Gd4Cu8] nous avons mis en évidence des interactions Cu-Gd ferromagnétiques et Gd-Gd antiferromagnétiques. Les mesures faites sur le composé [Dy4Cu8] ont mis en évidence le comportement caractéristique d'une molécule-aimant. Le dernier chapitre présente les résultats obtenues pour un complexe tetradécanucléaire à valence mixte MnII - MnIII [Mn14] que nous avons obtenu a partir d'un ligand de type base de Schiff et dans lequel coexistent des interactions antiferromagnétiques et ferromagnétiques entre les ions manganèse avec un zero-field splitting important. La conclusion générale fait le bilan de nos résultats et donne quelques perspectives ouvertes par notre travail.

Reactivators of acetylcholinesterase inhibited by organophosphate inhibitors play an important role in organophosphate poisoning therapy. There are a large number of reactivators being tested for their ability of penetration through blood-brain barrier (BBB) nowadays. The main aim of this thesis is to test this ability in four well know reactivators {--} HI-6, K-027, K-074 and TO-032. The 5% lethal dose (LD50) {--} therapeutic dose - of each reactivator was i.m. (intramuscularly) applied to experimental animals (Wistar rats) into right posterior thighs. Then the animals were sacrificed and the blood (plasma) and brain were collected for HPLC analysis. Subsequently, brain and plasma were frozen at -80 °C and stored until the assay. The reactivator concentrations were measured in plasma and four parts of the brain {--} frontal cortex (FC), basal ganglia (BG), ponto-medullar part (PM) and cerebellum (Ce). There were five animals for each group used for the purpose of the experiment. The concentrations of reactivators in plasma and blood samples were measured using HPLC-UV/VIS methodology. HI-6 concentrations CFC were on the average 4.29% of Caverage in plasma, CBG were on the average 1.9% of Caverage in plasma, CPM were on the average 2.3% of Caverage in plasma, and CCe were on the average 1.85% of Caverage in plasma. These rates were counted from all concentrations within the scope of particular observed parts of the brain. All the other tested reactivators were not quantified in brain at all.

As populações axial/equatorial em oximas e O-metiI oximas de 2-X-cicloexanonas (X= F, CI, Br, OCH3, SCH3 e N(CH3)2) foram efetivamente determinadas pela análise dos deslocamentos químicos dos prótons 6, utilizando-se os derivados da 4-tércio-butil-cicloexanona como modelos das conformações equatorial e axial. As populações dos confôrmeros axiais também foram determinadas pela análise dos deslocamentos químicos do carbono 4. Este carbono está em uma posição gama gauche em relação ao heteroátomo e sofre assim uma blindagem quando a conformação é axial. Usando-se os deslocamentos químicos observados do carbono 4 do isômero Z, foi possível calcular estas populações no isômero E. Os isômeros Z não apresentam este equilíbrio axial I equatorial porque existe uma compressão estérica grande entre o heteroátomo e o oxigênio na hipotética conformação equatorial. As populações axiais nestes compostos variam de 86% a 96% e apresentam uma dispersão muito pequena com os diferentes métodos utilizados. Ao se comparar oximas com éteres nota-se que para os substituintes mais polarizáveis, como metiltio, cloro e bromo há um aumento da população axial nos éteres comparado às oximas. As frequências de estiramento vCN se correlacionaram com os parâmetros indutivos de Taft (σl) e com a polarizabilidade média da ligação carbono-heteroátomo, o que apoia a idéia de uma interação πCN/σ*cx. Além disso, as frequências de estiramento vOH também se correlacionaram com estes parâmetros e neste caso o efeito indutivo e a polarizabilidade levam a um aumento de acidez destas oximas. / The axial/equatorial populations of oximes and O-methyl oximes of 2-X-cyclohexanones ((X= F, CI, Sr, OCH3, SCH3 e N(CH3)2) were determined by the chemical shifts of the protons bonded to carbon 6, making use of the 4-tert-butyl- cyclohexanone derivatives as models for the equatorial and axial conformations. The axial conformer populations were also determined by the C-4 chemical shift analysis. This carbon lies in a gamma gauche position to the heteroatom and suffers shielding when the conformation is axial. It has been possible to calculate those populations in the E isomer, using the C-4 chemical shift of the Z isomer. The latter do not present an axial/equatorial equilibrium because there is a too high steric compression between the nitrogen and the heteroatom in the hypothethical equatorial conformation. The axial populations of these compounds vary from 86 to 96% and present a small deviation along the different methods used. All substituents are preferentially in the axial conformation, even fluorine and methoxyl, which are predominantly equatorial in the corresponding ketones. It is noted that there is a increase in the axial population for more polarizable substituents like methylthio, chloro and bromo, on going from the oximes to the oximes O-methyl ethers. The vCN stretching frequencies are correlated with Taft\'s inductive parameters (σl) and the mean polarizability of the carbon-heteroatom bond, which supports the view of a πCN/σ*cx interaction. Sesides, the vOH stretching frequencies are also correlated with those parameters and in this case, both the inductive effect and polarizability lead to a increase of the oximes acidity.