Synergistic solvent extraction of Thorium(IV) and Uranium(VI) with β-diketones in presence of oxo-donors

The thesis entitled “Synergistic solvent extraction of Thorium(IV) and Uranium(VI) with β-diketones in presence of oxo-donors” embodies the results of the investigations carried out on the extraction of thorium(IV) an uranium(VI) with heterocyclic β-diketones in the presence and absence of various macrocyclic ligands and neutral organophosphorus extractants. The objective of this work is to generate the knowledge base to achieve better selectivity between thorium(IV) and uranium(VI) by understanding the interactions of crown ethers or neutral organophosphorus extractants with metal-heterocyclic β-diketonate complexes. Para-substituted 1-phenyl-3-methyl-4-aroyl-5-pyrazolones, namely,1-phenyl-3-methyl-4-(4-fluorobenzoyl)-5-pyrazolone (HPMFBP) and 1-phenyl-3-methyl-4-(4-toluoyl)-5-pyrazolone (HPMTP) were synthesized and characterized by elemental analysis, IR and H NMR spectral data. The synthesized ligands have been utilized for the extraction of thorium(IV) and uranium(VI) from nitric acid solutions in the presence and absence of various crown ethers. Thorium(IV) and uranium(VI) complexes with HPMPP(1-Phenyl-3-methyl-4-pivaloyl-5-pyrazolone) and neutral organophosphorus extractants were synthesized and characterized by IR and P NMR spectral data to further understand the interactions of neutral organophosphorus extractants with metal-chelates. Solid complexes of thorium(IV) and uranium(VI) with para-substituted 4-aroyl-5-isoxazolones and crown ethers were isolated and characterized by various spectroscopic techniques to further clarify the nature of the extracted complexes.

Synthese und Charakterisierung neuer Stärkederivate für die klinische Anwendung

Ein neuartiges, mehrstufiges Syntheseverfahren wurde zur Darstellung von unterschiedlichen Stärkederivaten (Ether und Ester) entwickelt, die hinsichtlich ihres Eigenschaftsprofils und ihrer Reinheit für die klinische Anwendung als Blutvolumenersatzmittel geeignet sind. Die Synthesen wurden dahingehend gestaltet, dass Produkte mit einer hohen Regioselektivität resultierten. Dabei konnten sämtliche Reaktionsschritte, die zur Modifikation der ursprünglich eingesetzten Wachsmais- und Kartoffelstärken notwendig waren, in einem homogenen, wäss-rigen System ohne zwischenzeitliche Aufarbeitung in einem Eintopfverfahren durchgeführt werden. Die auf diese Weise bevorzugt synthetisierten Carboxymethylstärken wurden mit NMR-spektroskopischen Methoden und GPC-MALLS strukturell eingehend charakterisiert. Mit eigens entwickelten Enzym-Assays konnten essentielle Informationen über die physiolo-gische Wirksamkeit der verschiedenen Stärkederivate in vitro gewonnen werden. Die Ergebnisse konnten mit Untersuchungen an Humanblut verifiziert werden.

Identification of lipophilic flavones and flavonols by comparative HPLC, TLC and UV spectral analysis

The identification of lipophilic flavones and flavonols using a combination of high performance liquid chromatography, thin layer chromatography and UV spectral analysis is discussed. Data are provided for the flavones, apigenin, luteolin and tricetin and twelve of their methyl ethers, 8-hydroxyluteolin, 6-hydroxyluteolin and scutellarein and fourteen of their methyl ethers, and some 6,8-dihydroxyapigenin and 6,8-dihydroxyluteolin derivatives. Data for some forty two flavonols with extra 6- and/or 8-hydroxylation, mostly 6-hydroxykaempferol and quercetagetin derivatives, are also presented. The remaining compounds analysed include fourteen 5-deoxyflavones, four 5-methoxyflavones and five 5-deoxyflavonols plus further 5-hydroxylated flavones and flavonols without B-ring oxidation or with 2-, 5- or 6-hydroxylation. Copyright © 2003 John Wiley & Sons, Ltd.

Microfabrication of high-performance aromatic polymers as nanotubes or fibrils by in situ ring-opening polymerisation of macrocyclic precursors

Melt-phase nucleophilic ring-opening polymerisation of macrocyclic aromatic ethers and thioethers at high temperatures within the cylindrical pores of an anodic-alumina membrane, followed by dissolution of the template, enables replication of the membrane's internal pore structure and so affords high-performance aromatic polymers with well-defined fibrillar or tubular morphologies.

A contribution to the differentiation between nectar honey and honeydew honey

Thirty genuine honey samples were analyzed for pH, acidity, water, ash, net absorbance, total polyphenols (Folin-Ciocalteau method) and glucose, fructose, melezitose and erlose (as their trimethylsilyl oximes and trimethylsilyl ethers) by capillary gas chromatography. The resulting data were used, along with palynological analysis, to characterize the samples in relation to their possible source (nectar, honeydew and mixture honeys). Some minor components (carboxylic acids and cyclitols), eluting before monosaccharides, were also determined. One of these compounds was quercitol (1,3,4/2,5-cyclohexane-pentol), a deoxyinositol which has been previously determined in Quercus sp. samples. Quercitol was present in a broad concentration range (0.01-1.50 g/100 g) in honeys whose major source was honeydew but it was never higher than 0.01 g/100 g in samples characterized as nectar honeys. Quercitol concentrations appear to be related to the presence and amount of Quercus sp. honeydew as honey source, although further research is required to confirm this. (C) 2004 Elsevier Ltd. All rights reserved.

Sugars and related compounds as flavour precursors in meat

Sugars and related substances, namely sugar phosphates and ribonucleotides, are important meat flavour precursors. In particular, ribose and ribose 5-phosphate have been shown to be important in aroma development in heated model systems. There are few quantitative data on the concentrations and the variations of sugars and related substances in meat. This paper will report on the analysis of glucose, fructose, ribose, ribose 5-phosphate, fructose 6-phosphate, glucose 6-phosphate and inosine 5'-monophosphate (IMP) in aged beef. Sugars and related compounds were extracted from lean meat and derivatised to the corresponding TMS ethers. Analysis and quantitation of the sugars and sugar phosphates were performed using GC and GC/MS, while IMP analysis was performed using capillary electrophoresis (CE).

A mesoscopic modelling approach to anaesthetic action on brain electrical activity

Relating the measurable, large scale, effects of anaesthetic agents to their molecular and cellular targets of action is necessary to better understand the principles by which they affect behavior, as well as enabling the design and evaluation of more effective agents and the better clinical monitoring of existing and future drugs. Volatile and intravenous general anaesthetic agents (GAs) are now known to exert their effects on a variety of protein targets, the most important of which seem to be the neuronal ion channels. It is hence unlikely that anaesthetic effect is the result of a unitary mechanism at the single cell level. However, by altering the behavior of ion channels GAs are believed to change the overall dynamics of distributed networks of neurons. This disruption of regular network activity can be hypothesized to cause the hypnotic and analgesic effects of GAs and may well present more stereotypical characteristics than its underlying microscopic causes. Nevertheless, there have been surprisingly few theories that have attempted to integrate, in a quantitative manner, the empirically well documented alterations in neuronal ion channel behavior with the corresponding macroscopic effects. Here we outline one such approach, and show that a range of well documented effects of anaesthetics on the electroencephalogram (EEG) may be putatively accounted for. In particular we parameterize, on the basis of detailed empirical data, the effects of halogenated volatile ethers (a clinically widely used class of general anaesthetic agent). The resulting model is able to provisionally account for a range of anaesthetically induced EEG phenomena that include EEG slowing, biphasic changes in EEG power, and the dose dependent appearance of anomalous ictal activity, as well as providing a basis for novel approaches to monitoring brain function in both health and disease.

Optimization of the ultrasound-assisted synthesis of allyl 1-naphthyl ether using response surface methodology

Allyl 1-naphthyl ethers are useful compounds for different purposes, but reported methods to synthesize them require long reaction times. In this work, we have obtained allyl 1-naphthyl ether in good yield using ultrasonic-assisted methodology in a 1-h reaction. A central composite design was used to obtain a statistical model and a response surface (p < 0.05; R(2) = 0.970; R(adj)(2) = 0.949; R(pred)(2) = 0.818) that can predict the optimal conditions to maximize the yield, validated experimentally. (C) 2010 Elsevier B.V. All rights reserved.

Synthesis of Tetrahydrofurans by Cyclization of Homoallylic Alcohols with Iodine/Iodine(III)

Tetrahydrofuran derivatives can be obtained by cyclo-functionalization of homoallylic alcohols bearing a terminal double bound by using [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser`s reagent) in the presence of a catalytic amount of 12 (20 mol %) in MeOH under mild conditions. This transformation is an overall 5-endo-trig cyclization, which occurs by two different pathways. The first is a 4-exo-trig cyclization followed by ring expansion, whereas the second is an electrophilic addition followed by a 5-endo-tet cyclization.

Fenchyl substituted 1,2-dioxetanes as an alternative to adamantyl derivatives for bioanalytical applications

The synthesis and study of the chemiluminescence parameters and thermal stability of 1,2-dioxetanes containing a spirofenchyl substituent are reported. Three fenchyl-substituted 1,2-dioxetanes were synthesized by photooxygenation of the corresponding alkenes, obtained by Barton-Kellogg olefination of the readily available (-)-fenchone. The fenchyl-substituted 1,2-dioxetanes showed thermal stabilities similar to those of the corresponding spiroadamantyl-substituted derivatives, although being slightly more labile with respect to unimolecular decomposition than the latter derivatives, which are widely utilized as labels in a great variety of chemiluminescent immunoassays. Fluoride induced decomposition of one triggerable fenchyl 1,2-dioxetane derivative showed kinetic parameters similar to those of the corresponding adamantyl-substituted derivative. The chemiluminescence quantum yields in the one percent range are also similar to that of other widely utilized chemiluminescence systems as the luminol reaction. These results indicate that fenchyl-substituted 1,2-dioxetanes can potentially be utilized as a cheaper alternative to substitute the corresponding spiroadamantyl derivatives in bioanalytical applications. (C) 2010 Elsevier B.V. All rights reserved.

Ring Contraction of 1,2-Dihydronaphthalenes Promoted by Thallium(III) in Acetonitrile: A Diastereoselective Approach to Indanes

trans-1,3-Disubstituted indanes are conveniently accessed by a stereoselective ring contraction of 1,2-dihydronaphthalenes upon treatment with thallium(III) nitrate (TTN) in acetonitrile. Under these conditions, the oxidative rearrangement of either di- or trisubstituted double bonds is possible.

Estrutura e dinâmica da interação de éteres de celulose com surfactantes

As técnicas de fluorimetria, condutometria, viscosimetria, turbidimetria, espalhamento de luz e espalhamento de raios-X a baixo ângulo (SAXS) foram empregadas no estudo da agregação de diferentes surfactantes aniônicos em presença de soluções aquosas diluídas de (hidroxipropil)celulose (HPC) 0,25% m/m, (hidroxipropilmetil)celulose (HPMC) 0,20% m/m e HPMC 0,10% m/m / NaCl 0,10 mol L-1. Também foram investigadas através de SAXS soluções concentradas de HPC (30, 40 e 50% m/m). Admitindo-se uma faixa geral de concentração, entre 10-4 e 10-1 mol L-1, foram utilizados neste estudo os surfactantes colato de sódio (CS), deoxicolato de sódio (DC), derivados dos sais biliares, e o alquilsintético dodecilsulafato de sódio (SDS). Observou-se que os polímeros contribuem diferentemente no processo de agregação de cada surfactante, evidenciado pela mudança dos valores da concentração de agregação crítica (CAC) em relação à concentração micelar crítica (CMC). Os resultados condutométricos confirmaram a interação éteres de celulose/sais biliares, embora a mesma tenha se mostrado mais fraca em relação a éteres de celulose/SDS. Os dados termodinâmicos demonstraram que a formação de agregados polímero/surfactante apresenta maior estabilidade do que as próprias micelas livres. Os resultados de viscosimetria e turbidimetria evidenciaram as diferenças estruturais entre HPC e HPMC, assim como entre os surfactantes. Através do espalhamento de luz dinâmico, verificou-se a existência de dois modos de correlação, rápido e lento. O primeiro é atribuído à cadeia polimérica isolada, agregados polímero/surfactante intramoleculares ou mesmo a micelas livres. Por sua vez, o modo lento relaciona-se a clusters poliméricos ou agregados polímero/surfactante intermoleculares. Adicionalmente, as curvas de distribuição dos tempos de relaxação demonstraram a influência de cada surfactante sobre a dinâmica dos polímeros. Tal influência é percebida antes mesmo da CAC, contrariando o modelo da interação polímero/surfactante proposto por Cabane. Os resultados de SAXS acusaram a formação de domínios líquido-cristalinos em xx soluções concentradas de HPC, assim como confirmaram a presença de micelas livres a altas concentrações de surfactantes nos sistemas diluídos. Em linhas gerais, os resultados indicaram a interação dos polímeros com SDS mais efetiva do que os mesmos polímeros e os sais biliares. No que tange à natureza do polímero, a HPC mostrou uma maior estabilidade na sua interação com os surfactantes do que a HPMC.

Síntese, aplicação e avaliação do efeito do teor de fósforo da celulose fosfatada em argamassa de alvenaria com aditivo comercial a base de hidroxi-etil-metil celulose (HEMC)

Generally, cellulose ethers improves mortar properties such as water retention, workability and setting time, along with adherence to the substrate. However, a major disadvantage of the addition of cellulose ethers in mortars is the delay in hydration of the cement. In this paper a cellulose phosphate (Cp) was synthesized water soluble and has been evaluated the effect of their incorporation into mortar based on Portland cement. Cellulose phosphate obtained was characterized by spectrophotometry Fourier transform infrared (FTIR), X-ray diffraction (XRD), elemental analysis and scanning electron microscopy (SEM). Mortar compositions were formulated with varying phosphorus content in cellulose and cellulose phosphate concentrations, when used in partial or total replacement of the commercial additive based hydroxyethyl methyl cellulose (HEMC). The mortars formulated with additives were prepared and characterized by: testing in the fresh state (consistency index, water retention, bulk density and air content incorporated) and in the hardened state (absorption by capillarity, density, flexural and compression strength). In mixtures the proportion of sand:cement of 1:5 (v / v) and factor a / c = 1.31 and water were held constant. Overall, the results showed that the celluloses phosphates employed in mortars added acted significantly when partially substituting the commercial additive. With regard to consistency index, water retention and bulk density in the fresh state and absorption by capillarity and bulk density apparent in the hardened state, showed no appreciable differences as compared to the commercial additive. The incorporated air content in the fresh state reduced markedly, but did not affect other properties. The mortars with cellulose phosphate, partially replacing the commercial additive showed an improvement of the properties of flexural strength and compressive strength

Reduction capability of soil humic substances from the Rio Negro basin, Brazil, towards Hg(II) studied by a multimethod approach and principal component analysis (PCA)

This paper characterizes humic substances (HS) extracted from soil samples collected in the Rio Negro basin in the state of Amazonas, Brazil, particularly investigating their reduction capabilities towards Hg(II) in order to elucidate potential mercury cycling/volatilization in this environment. For this reason, a multimethod approach was used, consisting of both instrumental methods (elemental analysis, EPR, solid-state NMR, FIA combined with cold-vapor AAS of Hg(0)) and statistical methods such as principal component analysis (PCA) and a central composite factorial planning method. The HS under study were divided into groups, complexing and reducing ones, owing to different distribution of their functionalities. The main functionalities (cor)related with reduction of Hg(II) were phenolic, carboxylic and amide groups, while the groups related with complexation of Hg(II) were ethers, hydroxyls, aldehydes and ketones. The HS extracted from floodable regions of the Rio Negro basin presented a greater capacity to retain (to complex, to adsorb physically and/or chemically) Hg(II), while nonfloodable regions showed a greater capacity to reduce Hg(II), indicating that HS extracted from different types of regions contribute in different ways to the biogeochemical mercury cycle in the basin of the mid-Rio Negro, AM, Brazil. (c) 2007 Published by Elsevier B.V.

Fast dynamics in the optical storage with Langmuir-Blodgett films of a diazocrown ether molecule

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)