Estudos de absorção de CO2 com soluções aminadas

A absorção química de dióxido de carbono (CO2) através de soluções aquosas de aminas tem sido estudada nos últimos anos devido à preocupação ambiental face ao aquecimento global. Nestes estudos, foram tidos como principais objectivos a realização de ensaios preliminares de absorção e desabsorção de CO2 em soluções aquosas de aminas bem como a construção de uma instalação piloto para a mesma finalidade. Inicialmente, a nível laboratorial, procedeu-se à absorção de CO2 através de soluções aquosas de aminas. As aminas utilizadas nestes estudos foram a monoetanolamina (MEA), etilenodiamina (EDA), 1,6- hexanodiamina (HDA) e piperazina anidra (PZ). A absorção de CO2 através destas aminas foi realizada experimentalmente às condições normais de pressão e temperatura. A concentração das soluções aquosas foi de 20% em massa de cada amina. Foram também realizados estudos de regeneração das soluções aquosas de aminas saturadas de CO2 em banho de glicerina, para determinar as condições de regeneração. Para além disso, observou-se o estado físico das aminas no estado puro até saturação com CO2 para garantir a não ocorrência de danos a nível de entupimento numa posterior utilização na instalação piloto. Por fim, voltaram-se a repetir todos estes ensaios experimentais utilizando-se, em vez da água destilada, um solvente polar aprótico, dimetilsulfóxido (DMSO). Numa segunda fase destes estudos, a absorção de CO2 através de soluções aquosas de aminas foi investigada experimentalmente numa instalação piloto. O objectivo era utilizar nesta fase do estudo as mesmas aminas utilizadas nos ensaios preliminares mas uma vez que não se dispunha das quantidades necessárias de aminas e para a sua aquisição teria que se despender bastante tempo e dinheiro, utilizaram-se duas soluções aquosas de alcanolaminas. As alcanolaminas utilizadas no presente estudo foram a amina secundária dietanolamina (DEA) e a amina terciária N-metildietanolamina (MDEA), duas aminas amplamente utilizadas nas indústrias químicas e petroquímicas para a purificação dos gases de combustão. A absorção de CO2 através destas duas alcanolaminas foi realizada experimentalmente às condições normais de pressão e temperatura. As concentrações das soluções aquosas foram de (10, 20 e 30) % em massa de MDEA e de DEA. O processo de adição de cloreto de bário (BaCl2.2H2O) às alcanolaminas ajuda à formação de carbonato de bário, quando o CO2 passa através da solução de alcanolamina. A quantidade de carbonato de bário formado foi utilizado para determinar a solubilidade do CO2 (mol CO2/mol alcanolamina). O principal desafio na captura de CO2 dos gases de combustão é o de reduzir o consumo de energia necessária para a regeneração do solvente. Deste modo, foram também realizados estudos de regeneração das soluções de alcanolaminas saturadas, para determinar as condições de regeneração. Os resultados obtidos, a nível laboratorial, revelaram que uma amina secundária (PZ) e uma amina primária de cadeia longa (HDA) são mais favoráveis ao processo de absorção e regeneração de CO2. No entanto, e devido a essa mesma estrutura molecular, necessitam de maiores valores de temperaturas para desabsorver o CO2. Garantiu-se poder trabalhar com as quatro aminas no estado puro em estudos futuros, na instalação piloto, garantindo que não ocorrerão danos a nível de entupimento. Relativamente ao solvente utilizado concluiu-se que um solvente polar aprótico não é um solvente favorável para estes estudos. Os resultados obtidos, na instalação piloto, revelaram que a amina terciária, MDEA, consegue absorver maiores quantidades de CO2 do que a amina secundária, EDA, bem como é a mais fácil de regenerar com menor perda de capacidade de absorção do que a EDA.

Detection in urine of 4-methyl-2-hexaneamine, a doping agent.

Stimulants are banned in-competition for all categories of sports by the World Anti-Doping Agency. A simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay employing electrospray ionisation in positive mode was developed in that work for the quantification in urine specimens of 4-methyl-2-hexaneamine, a primary amine exhibiting sympathomimetic properties. Following a simple pretreatment procedure, the analyte was separated using a gradient mobile phase on reverse phase C8 column. Selected reaction monitoring m/z 116.2-->57.3 was specific for detection of 4-methyl-2-hexaneamine and the assay exhibited a linear dynamic range of 50-700 ng/mL. The validated method has been successfully applied to analyze the target compound in food supplements as well as in urine specimens. The administered drug (40 mg) was detected at the level of 350 ng/mL in the urine up to 4 days.

Hiilidioksidin talteenottoon soveltuvan anioninvaihtohartsin valmistus ja karakterisointi

Tämän työn tarkoituksena oli tutkia hiilidioksidin talteenottoon soveltuvan anioninvaihtohartsin valmistusmenetelmiä, kokeilla eri menetelmiä käytännössä ja tutkia sekä itse valmistettujen että valmiina saatujen hartsien adsorptiokykyä ja muita ominaisuuksia. Kemiallinen adsorptio amiiniryhmän omaavien hartsien avulla on yksi tapa sitoa hiilidioksidia ilmasta. Primäärinen amiiniryhmä sitoo hiilidioksidia parhaiten. Primäärisen amiiniryhmän omaava anioninvaihtohartsi voidaan valmistaa pohjapolymeeristä halogeenialkyloimalla ja aminoimalla, aminoalkyloimalla tai suoraan aminoimalla. Aminoalkylointi voidaan suorittaa erilaisilla reagensseilla ja katalyyteillä. Tässä työssä hartseja valmistettiin aminoimalla polymetyyliakrylaattidivinyylibentseenipohjaista polymeeriä etyylidiamiinilla ja propyylidiamiinilla. Lisäksi suoritettiin polystyreeni-divinyylibentseenipohjaisen polymeerin aminoalkylointi bis(ftaali-imidometyyli)eetterin avulla. Reaktio tehtiin kahdella eri katalyytillä; rikkitrioksidilla ja rautakloridilla. Aminoalkylointireaktioissa tarvittava eetteri piti ennen varsinaista reaktiota valmistaa N-hydroksymetyyliftaali-imidistä. Myös tämän reagenssin syntetisointia ftaali-imidistä kokeiltiin. Kaikki synteesit onnistuivat melko hyvin, paitsi aminoalkylointi rautakloridikatalyytillä. Hartsien valmistuksen lisäksi itse valmistettuja primäärisen amiiniryhmän omaavia hartseja sekä erilaisia amiiniryhmiä omaavia valmiita hartseja karakterisoitiin eri tavoin. Erityisesti haluttiin tutkia hiilidioksidin adsorptiokapasiteettia ja hartsien termistä kestävyyttä. Kaikista tutkituista hartseista lähimpänä haluttuja ominaisuuksia olivat kaksi kaupallista primäärisen amiiniryhmän omaavaa PS-DVBpohjaista makrohuokoista hartsia. Rakenteeltaan samanlainen itse valmistettu hartsi (rikkitrioksidikatalyytin läsnä ollessa aminoalkyloitu) oli myös ominaisuuksiltaan lupaava. Valmistusmenetelmää pitää kuitenkin tutkia ja kehittää lisää vielä parempien tulosten aikaansaamiseksi. Myös kaupallinen polyetyleeni-imiinirakenteen omaava silikapohjainen hartsi oli ominaisuuksiltaan hyvä.

A general A³: coupling reaction based on functionalized alkynes

A range of hydroxypropargylpiperidones were efficiently obtained by a one-pot three-component coupling reaction of aldehydes, alkynols, and a primary amine equivalent (4-piperidone hydrochloride hydrate) in ethyl acetate using copper(I) chloride as a catalyst. The developed protocol proved to be equally efficient using a range of aliphatic aldehydes, including paraformaldehyde, and using protected and unprotected alkynols.

Studies on Some New Metal-Hydrazone Complexes and Their Zeolite Encapsulated Analogues

The thesis deals with the synthesis, characterization and catalytic activity studies of some new Fe (III), Co (II), Ni (II) and Cu (II) complexes of hydrazones and their zeolite encapsulated analogues. Hydrazones have diverse applications in biological, non-biological and biochemical front. During the present study three hydrazone types of ligands namely, acetylacetone- 2-hydroxyphenylhydrazone (APAcAc), acetoacetanilide- 2-hydroxyphenylhydrazone (APAcAcA) and acetoacetanilide-3,5-dihydro-2,4-dione pyrimidylhydrazone (AUAcAcA) were synthesized by diazotization of primary amine and coupling with compounds containing active methylene group. First part of the thesis deals with the synthesis of Fe, Co, Ni and Cu complexes using three hydrazone types of ligands are given. Details regarding the characterization of these complexes with a view to establishing the molecular structures are presented in this part. The other part contains the method of encapsulation of these complexes in zeolite cavities and their characterizations of the encapsulated metal species are described. A comparitive account of the catalytic activities of the pure and encapsulated complexes for cyclohexanol oxidation was also carried out.

Physical factors affecting plasmid DNA compaction in stearylamine-containing nanoemulsions intended for gene delivery

Cationic lipids have been used in the development of non-viral gene delivery systems as lipoplexes. Stearylamine, a cationic lipid that presents a primary amine group when in solution, is able to compact genetic material by electrostatic interactions. In dispersed systems such as nanoemulsions this lipid anchors on the oil/water interface confering a positive charge to them. The aim of this work was to evaluate factors that influence DNA compaction in cationic nanoemulsions containing stearylamine. The influence of the stearylamine incorporation phase (water or oil), time of complexation, and different incubation temperatures were studied. The complexation rate was assessed by electrophoresis migration on agarose gel 0.7%, and nanoemulsion and lipoplex characterization was done by Dynamic Light Scattering (DLS). The results demonstrate that the best DNA compaction process occurs after 120 min of complexation, at low temperature (4 ± 1 °C), and after incorporation of the cationic lipid into the aqueous phase. Although the zeta potential of lipoplexes was lower than the results found for basic nanoemulsions, the granulometry did not change. Moreover, it was demonstrated that lipoplexes are suitable vehicles for gene delivery. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

α-alchilazione di aldeidi, via organocatalisi: un approccio sintetico e computazionale

During this internship, the α-alkylation of branched aldehydes was taken into consideration. An enantiopure Betti’s base derivative was used as catalyst, applying a new concept in catalysis: organocatalysis. The Betti’s base may be of particular interest for organic chemists working in the field of “reactions catalysed by enantiopure small organic molecules”, in particular for the ones interested in enantiopure primary amines. The potential of secondary amines as catalysts has certainly been known for years. It is indeed more innovative to conduct reactions using primary amine derivatives as catalyst. In this work, the efficacy of the primary amine was checked first. Then, the focus was set on finding optimal reaction conditions. Finally, to have a more complete picture of the structure of the compounds used in the project, experimental and computational IR spectra were compared, after the method was validated. Durante il periodo di tirocinio è stata presa in esame la reazione di α-alchilazione di aldeidi branched, utilizzando un derivato dell’ammina di Betti come catalizzatore enantiopuro ed applicando un nuovo tipo di catalisi: l’organocatalisi. Questi composti possono essere di particolare interesse per lavori in chimica organica, nel campo delle reazioni catalizzate da “piccole” molecole organiche, in particolare da ammine primarie a chiralità definita; la potenzialità delle ammine secondarie chirali come catalizzatori è certamente nota da anni, ma innovativo è condurre il tutto con l’impiego di un derivato amminico primario. Altri aspetti significativi sono gli apparenti e innumerevoli vantaggi, dal punto di vista economico ed ambientale, oltre che operativo e sintetico, derivanti dal nuovo tipo di catalisi. In un primo momento è stata verificata l’efficacia dell’ammina primaria sintetizzata nella reazione in progetto, quindi sono state individuate le condizioni di reazione ottimali. Infine, per un’analisi più completa di alcune molecole organiche e dopo un’opportuna validazione del metodo utilizzato, sono stati ottenuti a livello computazionale gli spettri IR delle molecole di sintesi prodotto e catalizzatore.

Bacteriorhodopsin protein hybrids for chemical and biological sensing

Bacteriorhodopsin (bR), an optoelectric protein found in Halobacterium salinarum, has the potential for use in protein hybrid sensing systems. Bacteriorhodopsin has no intrinsic sensing properties, however molecular and chemical tools permit production of bR protein hybrids with transducing and sensing properties. As a proof of concept, a maltose binding protein-bacteriorhodopsin ([MBP]-bR) hybrid was developed. It was proposed that the energy associated with target molecule binding, maltose, to the hybrid sensor protein would provide a means to directly modulate the electrical output from the MBP-bR bio-nanosensor platform. The bR protein hybrid is produced by linkage between bR (principal component of purified purple membrane [PM]) and MBP, which was produced by use of a plasmid expression vector system in Escherichia coli and purified utilizing an amylose affinity column. These proteins were chemically linked using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), which facilitates formation of an amide bond between a primary carboxylic acid and a primary amine. The presence of novel protein hybrids after chemical linkage was analyzed by SDSPAGE. Soluble proteins (MBP-only derivatives and unlinked MBP) were separated from insoluble proteins (PM derivatives and unlinked PM) using size exclusion chromatography. The putatively identified MBP-bR protein hybrid, in addition to unlinked bR, was collected. This sample was normalized for bR concentration to native PM and both were deposited onto indium tin oxide (ITO) coated glass slides by electrophoretic sedimentation. The photoresponse of both samples, activated using 100 Watt tungsten lamp at 10 cm distance, were equal at 175 mV. Testing of deposited PM with 1 mM sucrose or 1 mM maltose showed no change in the photoresponse of the xiv material, however addition of 1 mM maltose to the deposited MBP-bR linked hybrid material elicited a 57% decrease in photoresponse indicating a positive response for targeting of maltose. This chemically linked MBP-bR hybrid protein, with bacteriorhodopsin, as a photoresponsive transducing substrate, shows promise for creation of a universal sensing array by attachment of other pertinent sensing materials, in lieu of the maltose binding protein utilized. This strategy would allow significant reduction in sensor size, while increasing responsiveness and sensitivity at nano and picomolar levels.

Isomeric distribution and catalyzed isomerization of cobalt(III) complexes with pentadentate macrocyclic ligands. Importance of hydrogen bonding

We have investigated the isomeric distribution and rearrangement of complexes of the type [CoXLn](2+,3+) (where X = Cl-, OH-, H2O, and L-n represents a pentadentate 13-, 14-, and 15-membered tetraaza or diaza-dithia (N-4 or N2S2) macrocycle bearing a pendant primary amine). The preparative procedures for chloro complexes produced almost exclusively kinetically preferred cis isomers (where the pendant primary amine is cis to the chloro ligand) that can be separated by careful cation-exchange chromatography. For L-13 and L-14 the so-called cis-V isomer is isolated as the kinetic product, and for L-15 the cis-VI form (an N-based diastereomer) is the preferred, while for the L-14(S) complex both cis-V and trans-I forms are obtained. All these complexes rearrange to form stable trans isomers in which the pendent primary amine is trans to the monodentate aqua or hydroxo ligand, depending on pH and the workup procedure. In total 11 different complexes have been studied. From these, two different trans isomers of [CoCIL14S](2+) have been characterized crystallographically for the first time in addition to a new structure of cis-V-[CoCIL14S](2+); all were isolated as their chloride perchlorate salts. Two additional isomers have been identified and characterized by NMR as reaction intermediates. The remaining seven forms correspond to the complexes already known, produced in preparative procedures. The kinetic, thermal, and baric activation parameters for all the isomerization reactions have been determined and involve large activation enthalpies and positive volumes of activation. Activation entropies indicate a very important degree of hydrogen bonding in the reactivity of the complexes, confirmed by density functional theory studies on the stability of the different isomeric forms. The isomerization processes are not simple and even some unstable intermediates have been detected and characterized as part of the above-mentioned 11 forms of the complexes. A common reaction mechanism for the isomerization reactions has been proposed for all the complexes derived from the observed kinetic and solution behavior.

Characterization of tissue transglutaminase in human osteoblast-like cells

Tissue transglutaminase (tTG) is a calcium-dependent and guanosine 5'-triphosphate (GTP) binding enzyme, which catalyzes the post-translational modification of proteins by forming intermolecular ε(ϒ-glutamyl)lysine cross-links. In this study, human osteoblasts (HOBs) isolated from femoral head trabecular bone and two osteosarcoma cell lines (HOS and MG-63) were studied for their expression and localization of tTG. Quantitative evaluation of transglutaminase (TG) activity determined using the [1,414C]-putrescine incorporation assay showed that the enzyme was active in all cell types. However, there was a significantly higher activity in the cell homogenates of MG-63 cells as compared with HOB and HOS cells (p <0.001). There was no significant difference between the activity of the enzyme in HOB and HOS cells. All three cell types also have a small amount of active TG on their surface as determined by the incorporation of biotinylated cadaverine into fibronectin. Cell surface-related tTG was further shown by preincubation of cells with tTG antibody, which led to inhibition of cell attachment. Western blot analysis clearly indicated that the active TG was tTG and immunocytochemistry showed it be situated in the cytosol of the cells. In situ extracellular enzyme activity also was shown by the cell-mediated incorporation of fluorescein cadaverine into extracellular matrix (ECM) proteins. These results clearly showed that MG-63 cells have high extracellular activity, which colocalized with the ECM protein fibronectin and could be inhibited by the competitive primary amine substrate putrescine. The contribution of tTG to cell surface/matrix interactions and to the stabilization of the ECM of osteoblast cells therefore could by an important factor in the cascade of events leading to bone differentiation and mineralization.

Application of transglutaminases in the modification of wool textiles

The use of the protein-crosslinking enzymes transglutaminases (EC 2.3.2.13), as biocatalysts in the processing of wool textiles offers a variety of exciting and realistic possibilities, which include reducing the propensity of wool fabric to shrink and maintaining or increasing fabric strength. Guinea pig liver (GPL) transglutaminase or the microbial transglutaminase isolated from Streptoverticilium mobaraense, when applied to wool either alone or following a protease treatment, resulted in an increase in wool yarn and fabric strength (up to a 25% increase compared to a control). This indicates that transglutaminases can remediate the negative effects of proteolytic treatments in terms of loss in fibre strength. Incubation of samples pretreated with different oxidative and reducing agents with both sources of transglutaminases led to significant increases in tensile strength for all samples tested, suggesting that yarn strength lost following chemical treatments can also be recovered. The two different transglutaminases (TGases) could also impart a significant reduction in fabric shrinkage. The incorporation of primary amine transglutaminase substrates into wool fibres, with a view to altering wool functionality, was demonstrated using the incorporation of the fluorescent primary amine fluorescein cadaverine (FC). Incubation of wool with this fluorescent amine and transglutaminase led to high levels of incorporation into the fibres. The treatment of wool textiles with transglutaminases indicates that a number of novel and radically different finishes for wool textiles can be developed.

Basicities of primary arylamines and calculated amine nitrogen electronic charges

Mülliken charges on nitrogen atoms were calculated for several arylamines, utilizing the AM1 Quantum Chemistry method, relating their values to experimental amine pKa . Direct relation between pKa and nitrogen charges was found. The amines energies of protonation, calculated by the same method, also correlate directly with these charges.

Basicities of primary arylamines and calculated amine nitrogen electronic charges

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

I. Development of the In Situ Reductive Ozonolysis of Alkenes with Tertiary Amine N-Oxides. II. Progress toward the Asymmetric Synthesis of Peroxyplakoric Acid A3.

Ozone, first discovered in the mid 1800’s, is a triatomic allotrope of oxygen that is a powerful oxidant. For over a century, research has been conducted into the synthetic application and mechanism of reactions of ozone with organic compounds. One of the major areas of interest has been the ozonolysis of alkenes. The production of carbonyl compounds is the most common synthetic application of ozonolysis. The generally accepted mechanism developed by Rudolf Criegee for this reaction involves the 1,3-electrocyclic addition of ozone to the π bond of the alkene to form a 1,2,3-trioxolane or primary ozonide. The primary ozonide is unstable at temperatures above -100 °C and undergoes cycloreversion to produce the carbonyl oxide and carbonyl intermediates. These intermediates then recombine in another 1,3-electrocyclic addition step to form the 1,2,4-trioxolane or final ozonide. While the final ozonide is often isolable, most synthetic applications of ozonolysis require a subsequent reductive or oxidative step to form the desired carbonyl compound. During investigations into the nucleophilic trapping of the reactive carbonyl oxide, it was discovered that when amines were used as additives, an increased amount of reaction time was required in order to consume all of the starting material. Surprisingly, significant amounts of aldehydes and a suppression of ozonide formation also occurred which led to the discovery that amine N-oxides formed by the ozonation of the amine additives in the reaction were intercepting the carbonyl oxide. From the observed production of aldehydes, our proposed mechanism for the in situ reductive ozonolysis reaction with amine N-oxides involves the nucleophilic trapping of the carbonyl oxide intermediate to produce a zwitterionic adduct that fragments into 1O2, amine and the carbonyl thereby avoiding the formation of peroxidic intermediates. With the successful total syntheses of peroxyacarnoates A and D by Dr. Chunping Xu, the asymmetric total synthesis of peroxyplakorate A3 was investigated. The peroxyplakoric acids are cyclic peroxide natural products isolated from the Plakortis species of marine sponge that have been found to exhibit activity against malaria, cancer and fungi. Even though the peroxyplakorates differ from the peroxyacarnoates in the polyunsaturated tail and the head group, the lessons learned from the syntheses of the peroxyacarnoates have proven to be valuable in the asymmetric synthesis of peroxyplakorate A3. The challenges for the asymmetric synthesis of peroxyplakorate A3 include the stereospecific formation of the 3-methoxy-1,2-dioxane core with a propionate head group and the introduction of oxidation sensitive dienyl tail in the presence of a reduction sensitive 1,2-dioxane core. It was found that the stereochemistry of two of the chiral centers could be controlled by an anti-aldol reaction of a chiral propionate followed by the stereospecific intramolecular cyclization of a hydroperoxyacetal. The regioselective ozonolysis of a 1,2-disubstituted alkene in the presence of a terminal alkyne forms the required hydroperoxyacetal as a mixture of diastereomers. Finally, the dienyl tail is introduced by a hydrometallation/iodination of the alkyne to produce a vinyl iodide followed by a palladium catalyzed coupling reaction. While the coupling reaction was unsuccessful in these attempts, it is still believed that the intramolecular cyclization to introduce the 1,2-dioxane core could prove to be a general solution to many other cyclic peroxides natural products.

Rapid inline derivatization of primary and secondary amine containing drugs by capillary electrophoresis with laser-induced fluorescence

Despite the ongoing "war on drugs" the seizure rates for phenethylamines and their analogues have been steadily increasing over the years. The illicit manufacture of these compounds has become big business all over the world making it all the more attractive to the inexperienced "cook". However, as a result, the samples produced are more susceptible to contamination with reactionary byproducts and leftover reagents. These impurities are useful in the analysis of seized drugs as their identities can help to determine the synthetic pathway used to make these drugs and thus, the provenance of these analytes. In the present work two fluorescent dyes, 4-fluoro-7-nitrobenzofurazan and 5-(4,6-dichlorotriazinyl)aminofluorescein, were used to label several phenethylamine analogues for electrophoretic separation with laser-induced fluorescence detection. The large scale to which law enforcement is encountering these compounds has the potential to create a tremendous backlog. In order to combat this, a rapid, sensitive method capable of full automation is required. Through the utilization of the inline derivatization method developed whereby analytes are labeled within the capillary efficiently in a minimum span of time, this can be achieved. The derivatization and separation parameters were optimized on the basis of a variety of experimentally determined factors in order to give highly resolved peaks in the fluorescence spectrum with limits of detection in the low µg/mL range.