The reaction between pentacarbonylbis(trimethylsilyl)ethynetungsten(0), W(CO)5(&amp / #951 / 2-btmse), and triphenylbismuthine, Bi&Oslash / 3, yields pentacarbonyltriphenylbismuthinetungsten(0), W(CO)5(Bi&Oslash / 3), as the sole product. The kinetics of the substitution of btmse by Bi&Oslash / 3 was studied by means of quantitative FT-IR Spectroscopy. The starting complex was prepared photochemically from hexacarbonyltungsten, W(CO)6, in the presence of excess btmse in n-hexane and identified by FT-IR and NMR Spectroscopies. The substitution reactions were performed in cyclohexane solutions at different concentrations of both leaving and entering ligand to observe the dependence of observed rate constant, kobs, on the concentration of entering and leaving ligands and also, at different temperatures to evaluate the activation enthalpy (&amp / #8710 / H&amp / #8800 / ) and the activation entropy (&amp / #8710 / S&amp / #8800 / ). The IR extinction coefficients for CO stretching were determined for both the starting complex W(CO)5(&amp / #951 / 2-btmse), and the product W(CO)5(Bi&Oslash / 3). Quantitative IR Spectroscopy does not show any significant reduction in the total amount of substance (material balance). Formation of W(CO)6 (in small amount) was attributed to the decomposition of the product, W(CO)5Bi&Oslash / 3. From the evaluation of kinetic data, a mechanism was proposed in which the rate determining step is the cleavage of btmse ligand from the starting complex, W(CO)5(&amp / #951 / 2-btmse) and the formation of solvated complex, W(CO)5(solvent). Thus, the reaction is essentially dissociative. The large positive value of activation entropy (&amp / #8710 / S&amp / #8800 / ) and large value of activation enthalpy (&amp / #8710 / H&amp / #8800 / ) are indicative of a dissociative mechanism.

N,N&rsquo / -bis(ferrocenylmethylene)ethylenediamine was prepared from the reaction of ferrocenecarboxaldehyde and ethylenediamine and characterized by IR, Raman, 1H and 13C-NMR spectroscopy. The electrochemical behaviour of this ligand was also studied for the first time by cyclic voltammetry. Diferrocenyl diimine ligand was used in the thermal substitution of 1,5-cyclooctadiene in Cr(CO)4(2:2-1,5-cyclooctadiene) at 38&deg / C in toluene for two hours to form the tetracarbonyl[N,N&rsquo / -bis(ferrocenylmethylene)ethylenediamine]chromium(0), [Cr(CO)4(BFEDA)]. This complex was succesfully isolated and crystallized from its 1:1 toluene/dichloromethane solution and characterized by elemental analysis, MS, IR, 1H, 13C-NMR spectroscopy. Electrochemical behaviour of the complex was also studied by cyclic voltammetry and the mechanism of electrode reaction was investigated by in-situ UV-VIS and IR spectroscopy measurements. This new complex has the iron atom of ferrocene unit in conjugation with the chromium metal center and, therefore, shows an electronic communication between two metal atoms.

In this study a bidentate ligand containing two ferrocenyl moieties, N,N&#039 / -bis(ferrocenylmethylene)ethylenediamine, was prepared by condensation reaction of ferrocenecarboxyaldehyde and ethylenediamine on refluxing in benzene. The molecule was identified by IR, Raman, UV-Vis, 1H-, 13C-NMR spectroscopies. Then, this bidentate molecule was reacted with tetracarbonyl(bicyclo[2.1.1] hepta-2,5-diene)molybdenum(0). The ligand substitution reaction in toluene yielded the new complex, tetracarbonyl[N,N&acute / -bis(ferrocenylmethylene)ethylenediamine] molybdenum(0). This new complex could be isolated from the reaction solution in the form of orange crystals and fully characterized by elemental analysis, IR, UV-Vis, MS, 1H- and 13C-NMR spectroscopies. As a bidentate ligand, N,N&acute / -bis(ferrocenylmethylene)ethylenediamine binds the metal atom in the two cis positions in the pseudooctahedral geometry of the molybdenum-complex. Electrochemistry of the tetracarbonyl[N,N&acute / -bis(ferrocenylmethylene) ethylenediamine]molybdenum(0) was studied by cyclic voltammetry, chronoamperometry and controlled potential electrolysis combined with the UV-Vis or infrared spectroscopy. One irreversible oxidation and three reversible oxidations were observed in the cyclic voltammogram. Irreversible and a reversible oxidations are attributed to molybdenum and the other two reversible oxidation to iron centers. It is found that the two ferrocene groups started communication with each other after formation of molybdenum-complex.

In this study, a bidentate ligand, 6-ferrocenyl-2,2&#039 / -bipyridine, was prepared by the reaction of lithiated ferrocene with bipyridine. The ligand was identified by 1H, 13C- NMR and HMQC and UV-Vis spectroscopies. Then, bidentate molecule was reacted with pentacarbonylbis-(trimethylsilylethyne)tungsten(0). The ligand substitution reaction in CH2Cl2 yielded the new complex, tetracarbonyl(6-ferrocenyl-2,2&#039 / bipyridine)tungsten(0). The isolated and purified complex was fully characterized by elemental analysis, IR, UV-Vis, MS, 1H and 13C- NMR spectroscopies. Tetracarbonyl(6-ferrocenyl-2,2&#039 / bipyridine)chromium(0) was also formed by ligand substitution reaction of 6-ferrocenyl-2,2&#039 / -bipyridine with pentacarbonyl(THF)chromium(0) which was prepared by photolytic substitution of CO from hexacarbonyl chromium(0) in THF. However, tetracarbonyl(6-ferrocenyl-2,2&#039 / bipyridine)chromium(0) could not be isolated by column chromatography. Electrochemistry of 6-ferrocenyl-2,2&#039 / -bipyridine and tetracarbonyl(6-ferrocenyl-2,2&#039 / bipyridine)tungsten(0) was studied by cyclic voltammetry and controlled potential electrolysis combined with UV-Vis. The ligand exhibits a reversible reduction and a reversible oxidation belonging to bipyridine and ferrocene moieties, respectively. One reversible reduction, two irreversible oxidation and a reversible oxidation were observed for tetracarbonyl(6-ferrocenyl-2,2&#039 / bipyridine)tungsten(0). The reversible reduction was attributed to bipyridine whereas two irreversible oxidations were assigned to tungsten centers and reversible oxidation to iron center.

Bibliography: leaves 204-208 / 208 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1985

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-08-31T13:23:27Z No. of bitstreams: 1 TESE VERSÃO FINAL_completaseg.pdf: 1586143 bytes, checksum: a57cce30857cde7aaf0e0e909a4950aa (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-02T16:10:30Z (GMT) No. of bitstreams: 1 TESE VERSÃO FINAL_completaseg.pdf: 1586143 bytes, checksum: a57cce30857cde7aaf0e0e909a4950aa (MD5) / Made available in DSpace on 2016-09-02T16:10:31Z (GMT). No. of bitstreams: 1 TESE VERSÃO FINAL_completaseg.pdf: 1586143 bytes, checksum: a57cce30857cde7aaf0e0e909a4950aa (MD5) / A análise dos compostos carbonílicos (CCs) é um dos procedimentos de rotina em muitos laboratórios de cont role de qualidade de bebidas, no entanto, atualmente são quantificados apenas os CCs totais expressos em teores de acetaldeído, sem que sejam associados outros CCs com a sua qualidade. Esses compostos possuem impacto olfativo no aroma dos vinhos e uma forte afinidade pelo bissulfito, adicio nado na vinificação, podendo formar adutos estáveis que interferirão também no aroma. Os maiores desafios, no entanto, consistem em predizer qu ais CCs têm maior afinidade pelo S(IV), que circunstâncias favorecem es ta interação e como analisá-los em conjunto. Por esse motivo, no presente estudo foi avaliado o perfil de 22 CCs em “solução modelo" e em dez amostras reais de vinhos, empregando uma metodologia desenvolvida e validada para analisá-los de forma simultânea, que utiliza CLAE co m sistema de gradiente binário de eluição. Baseado na Análise de Componentes Principais (ACP) e nas constantes de dissociação (K d ), os resultados revelaram que os aldeídos alifáticos formam adutos com S(IV), enquanto as cetonas, os aldeídos cíclicos e os trans-alcenais interagiram fracamente e são encontrados predominantemente em sua forma livre . Estes resultados revelaram também que a faixa de pH entre 10 e 11 foi definida como a mais apropriada para a dissociação do adu to CC-S(IV), favorecendo a quantificação segura dos CCs na form a total. Nos vinhos e uvas estudados foram identificados o fo rmaldeído, acetaldeído, butanal, hexanal, furfural, benzaldeído, E -penten-2-al, ciclo hexanona e 2-etil hexanal, sendo este último identificado pela primeira vez neste tipo de matriz. Os quatro primeiros aldeídos citados podem ser considerados aromas primários por estarem presentes tanto nos vinhos quanto nas uvas que lhes deram origem. / Carbonyl compounds analysis is one of the routine procedures in several laboratories of control and quality of beverages. However, only total CCs, expressed by the acetald ehyde concentration, are quantified which results in a lack of knowl edge about the beverage’s quality and other CC concentrations. Although present in minute quantity, other CCs have a strong olfactory impact in many fermented beverages. In addition, the CCs found in wines have a strong affinity for bisulfite, added in winemaking process, and can form st able adducts, which will also interfere in the characteristics of ar oma. The greatest challenge, however, is to predict which CCs have the st rongest affinity for S(IV), what conditions favor this interaction and ho w to analyze them jointly. In order to better understand the reaction of CC- bisulfite adduct formation, this study has evaluated the role of 22 CCs in a “model soluction” containing bisulfite and in ten real samples of different wines, using a methodology developed and validated to analyze them simultaneously. This methodology is based on HPLC with binary gradient system of elution. On the basis of Principal Component Analysis (PCA) and dissociation constants (K d ), the results revealed that aliphatic aldehydes form adducts with S(IV), whereas ketones, cyclic aldehydes and trans- alkenes interact weakly and are found predominantly in their free form. These results revealed also that pH 10 and 11 were defined as the most appropriate for CC-S(IV) adduct dissociation and the total CCs were quantified reliably. In the wines and grapes studied were identified formaldehyde, acetaldehyde, butanal, hexanal, furfural, benzaldehyde, cyclo hexanone, E -pent-2-en-1-al, and 2-ethil hexanal, being the last one firstly identified in wines. Formald ehyde, acetaldehyde, butanal, and hexanal can be considered primary aroma since they are present in wines as well in their respective grapes.

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-08-31T14:06:01Z No. of bitstreams: 1 Tese_Fernanda_Revisão Final.pdf: 5433077 bytes, checksum: 30cfa44a7a7312cf3778c6606c92d4ff (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-02T16:14:00Z (GMT) No. of bitstreams: 1 Tese_Fernanda_Revisão Final.pdf: 5433077 bytes, checksum: 30cfa44a7a7312cf3778c6606c92d4ff (MD5) / Made available in DSpace on 2016-09-02T16:14:00Z (GMT). No. of bitstreams: 1 Tese_Fernanda_Revisão Final.pdf: 5433077 bytes, checksum: 30cfa44a7a7312cf3778c6606c92d4ff (MD5) / Braskem / A nafta e o etanol são matérias-primas importantes da indústria petro e alcoolquímica respectivamente, tendo o eteno e o propeno como seus principais derivados da primeira geração. A eficiência desses processos produtivos pode ser comprometida por traços de compostos carbonílicos e carboxílicos voláteis neles contidos. Tal contaminação pode afetar, por exemplo, a qualidade de embalagens de alimentos, uma vez que tais derivados são compostos precursores para produção dos plásticos utilizados nessas embalagens. No presente trabalho foram desenvolvidos métodos simples para a determinação de compostos carbonílicos e carboxílicos em matrizes líquidas e gasosas derivadas do petróleo por cromatografia em fase gasosa com sistema de detecção por ionização em chama (CG/DIC), cromatografia líquida de alta eficiência (CLAE), cromatografia gasosa acoplada à espectrometria de massas (CG/EM) e CG/DIC acoplado a sistema analítico Dean Switch. Para a determinação dos ácidos acético, propanóico, butanóico e pentanóico em matrizes líquidas e gasosas, a cromatografia em fase gasosa com sistema de detecção por ionização em chama por injeção direta utilizando coluna cromatográfica capilar FFAP (for free fatty acids) foi a técnica mais adequada. O desvio padrão relativo (RSD) obtido foi de 5,6% a 6,5% para 2 g.g-1 em n-hexano, 2,1% a 5,8% para 10 g.g-1 em etanol e 4,2 a 7,7% para 10 g.g-1 em propeno. Os limites de detecção encontrados foram de 0,036 - 0,12 g.g-1 em hidrocarbonetos gasosos (eteno e propeno), 0,047 - 0,16 g.g-1 em matrizes puras de hidrocarbonetos líquidos (n-hexano) e 0,08 – 0,18g.g-1 em matriz alcoólica (etanol). Para a determinação do teor de ácidos carboxílicos em matrizes complexas como a nafta, a CLAE foi a técnica utilizada, precedida de extração líquido- Fernanda Seabra Vianna Vieira 11/238 líquido sob condições controladas. O RSD obtido foi de 5,5% a 7,7% para 40 g.g-1 e o limite de detecção médio foi de 4 g.g-1. Para a determinação dos teores dos compostos carbonílicos (aldeídos e cetonas) em matrizes líquidas e gasosas, a cromatografia empregando o sistema analítico comercial Dean Switch mostrou-se como a mais adequada. Valores de RSD da ordem de 2,6% a 3,5% para propeno; 0,9% a 1,4% para n-hexano e 1,6% a 2,6% para a nafta em padrões contendo respectivamente 2 g.g-1, 2 g.g-1 e 10 g.g-1. Os limites de detecção de 0,033 - 0,084 g.g-1 (propeno), 0,021- 0,09 g.g-1 (n-hexano) e 0,049 - 0,26 g.g-1 (nafta) confirmam a eficiência de detecção e quantificação para matrizes de hidrocarbonetos de origem petroquímica tipicamente inferiores a 10 g.g-1. A partir dos resultados obtidos foi feita uma avaliação comparativa entre as técnicas, evidenciando as vantagens e desvantagens de cada método para cada aplicação específica. / Although metals and nitrogen & sulfur compounds have been the main concern in the petroleum industry, issues on the harmful effects on catalysts poisoning and products contamination of other contaminants such as oxygen- containing compounds have been raised. Trace amounts of carbonyl and carboxyl compounds in petroleum products can lead to catalyst poisoning and overall decrease on reactions yield. Furthermore, oxygenates may be present in the polyethylene and polypropylene resins, affecting the quality of the food packagings obtained from these materials. The available literature on C1-C5 aldehydes, ketones and carboxylic acids determination in petroleum products such as naphtha, ethylene and propylene is quite rare. Therefore, in the present work we intend to review the analytical approaches that could be applied to such analytical purpose, present the features of each potential technique and some studies performed on somewhat similar matrices. For acetic, propanoic, butanoic and pentanoic acids determination in liquid and gas matrices, gas chromatography with flame ionization detector and FFAP for free fatty acids capillary column was the most appropriate method. The relative standard deviation (RSD) was 5.6% to 6.5% in the range of 2 g.g-1 in n-hexane, 2.1% to 5.8% in the range of 10 g.g-1 in ethanol and 4.2 to 7.7% in the range of 10 g.g-1 in propylene. The detection limits found were from 0.036 to 0.12 g.g-1 in hydrocarbons gases (ethylene and propylene), 0.047 to 0.16 g.g-1 in pure liquid hydrocarbons (n-hexane) and 0.08 to 0.18 g.g-1 in alcoholic matrices (ethanol). For carboxylic acid determination in complex matrices such as naphtha, the HPLC technique was used, preceded by liquid-liquid extraction under Fernanda Seabra Vianna Vieira 9/238 controlled conditions. The RSD obtained was 5.5% to 7.7% in the range of 40 g.g-1 within the average detection limit was 4 g.g-1. For carbonyl compounds (aldehydes and ketones) determination in gas and liquid matrices, the commercial analytical system Dean Switch proved to be the most appropriate. RSD values of around 2.6% to 3.5% for propylene; 0.9% to 1.4% for n-hexane and 1.6% to 2.6% for naphta in standards containing respectively 2 g.g-1, 2 g.g-1 and 10 g.g-1. The detection limit of 0.033 to 0.084 g.g-1 (propylene), 0.021 to 0.09 g.g-1 (n-hexane) and 0.049 to 0.26 g.g-1 (naphtha) confirm the efficiency of detection and quantification for range of hydrocarbons of petrochemical origin typically less than 10 g.g-1.

Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2013-04-23T12:41:25Z No. of bitstreams: 1 Luciana.pdf: 1586143 bytes, checksum: a57cce30857cde7aaf0e0e909a4950aa (MD5) / Made available in DSpace on 2013-04-23T12:41:25Z (GMT). No. of bitstreams: 1 Luciana.pdf: 1586143 bytes, checksum: a57cce30857cde7aaf0e0e909a4950aa (MD5) Previous issue date: 2007 / A análise dos compostos carbonílicos (CCs) é um dos procedimentos de rotina em muitos laboratórios de controle de qualidade de bebidas, no entanto, atualmente são quantificados apenas os CCs totais expressos em teores de acetaldeído, sem que sejam associados outros CCs com a sua qualidade. Esses compostos possuem impacto olfativo no aroma dos vinhos e uma forte afinidade pelo bissulfito, adicionado na vinificação, podendo formar adutos estáveis que interferirão também no aroma. Os maiores desafios, no entanto, consistem em predizer quais CCs têm maior afinidade pelo S(IV), que circunstâncias favorecem esta interação e como analisá-los em conjunto. Por esse motivo, no presente estudo foi avaliado o perfil de 22 CCs em “solução modelo" e em dez amostras reais de vinhos, empregando uma metodologia desenvolvida e validada para analisá-los de forma simultânea, que utiliza CLAE com sistema de gradiente binário de eluição. Baseado na Análise de Componentes Principais (ACP) e nas constantes de dissociação (Kd), os resultados revelaram que os aldeídos alifáticos formam adutos com S(IV), enquanto as cetonas, os aldeídos cíclicos e os trans-alcenais interagiram fracamente e são encontrados predominantemente em sua forma livre. Estes resultados revelaram também que a faixa de pH entre 10 e 11 foi definida como a mais apropriada para a dissociação do aduto CC-S(IV), favorecendo a quantificação segura dos CCs na forma total. Nos vinhos e uvas estudados foram identificados o formaldeído, acetaldeído, butanal, hexanal, furfural, benzaldeído, E-penten-2-al, ciclo hexanona e 2-etil hexanal, sendo este último identificado pela primeira vez neste tipo de matriz. Os quatro primeiros aldeídos citados podem ser considerados aromas primários por estarem presentes tanto nos vinhos quanto nas uvas que lhes deram origem. / Salvador

Orientadores: Pedro Luiz Onofrio Volpe, Maria Regina Alcantara / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T01:16:47Z (GMT). No. of bitstreams: 1 Bombard_AntonioJoseFaria_D.pdf: 17369274 bytes, checksum: 8d592533d59e6cf4325ee9574b58724c (MD5) Previous issue date: 2005 / Doutorado / Físico-Química / Doutor em Ciências

Na última década, a utilização de misturas de gasolina e etanol em qualquer proporção como combustível em veículos do tipo “flex” aumentou de forma significativa no Brasil. Compostos Carbonílicos (CC) pertencem a uma importante classe de poluentes emitidos pela frota veicular. A cidade de São Paulo, Brasil, tem 9,2 milhões de veículos, os quais afetam diretamente a qualidade do ar. Neste trabalho, foi determinada a concentração de quatorze CC na atmosfera, em três diferentes sítios de amostragem localizados na zona oeste da cidade de São Paulo, dois nos campus da Cidade Universitária: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG) e Instituto de Ciências Biomédicas (ICB) e um em Cerqueira César, Faculdade de Saúde Pública (FSP), no período de 2008/2009. Os CC foram coletados em cartucho de sílicagel, impregnada com 2,4-dinitrofenilhidrazina e analisados por Cromatografia Líquida de Alta Eficiência (CLAE) com detecção UV-visível. O conjunto de dados gerado foi caracterizado aplicando Análise de Componentes Principais (PCA) e Análise de Agrupamentos Hierárquicos (HCA). Foi utilizado o cromatograma completo, uma abordagem quimiométrica ainda não utilizada para avaliação de CC na atmosfera. Os cromatogramas das amostras foram alinhados utilizando os algoritmos Peakmatch e Optim_COW, deslocamentos de linha base e ruído foram removidos empregando, respectivamente, a primeira derivada e o método de ajuste polinomial de Savitzky- Golay. As amostras coletadas nos três sítios apresentaram contrações significativas de formaldeído (F), acetaldeído (A) e acetona e concentrações menores de butiraldeído, benzaldeído, valeraldeído e propionaldeído. A quantidade de acetaldeído foi superior à de formaldeído para a maioria das amostras, levando a uma razão F/A menor do que 1, fato que tem sido atribuído ao uso de etanol em larga escala como combustível veicular. Na análise univariada, foi observado um perfil semelhante nos gráficos de concentração dos CC em qualquer um dos sítios de amostragem. Na análise multivariada por PCA, a PC1 representou a quase totalidade da variação experimental (97,6%). Estes resultados podem sugerir a presença de uma única fonte de emissão. O gráfico de scores da PCA e o dendograma da HCA indicaram a formação de dois agrupamentos: um formado pelas amostras FSP e IAG e outro pelas amostras ICB. O gráfico de loadings da PCA indicou que as diferenças são devidas à concentração de todos os CC. A separação das amostras ICB das demais pode ser explicada pelas diferentes condições meteorológicas observadas no sítio ICB / In the last decade, the use of ethanol-blended-gasoline in any proportion as fuel in light vehicles (flex fuel) has significantly increased in Brazil. Carbonyl compounds (CC) are an important class of vehicular total hydrocarbons emission. São Paulo City, Brazil, has 9,2 million vehicles that directly affect the air quality. In this work, the concentration of fourteen CCs in the air of three different sites of São Paulo city was determined during 2008/2009. Two sites (IAG and ICB) were located inside São Paulo University whereas a third one was located in Cerqueira César (FSP). Compounds were collected in a silica-gel cartridge coated with 2,4-dinitro-phenylhydrazine and analyzed by CLAE with UV-Vis detection (365 nm). The sites were characterized by Principal Component Analysis (PCA) and Hierarquical Cluster Analysis (HCA). The entire chromatogram was used to multivariate calculations, which represents an innovative approach in CC studies. Chromatograms of the samples were aligned using the Optim_COW and Peakmatch algorithms, the baseline was corrected by the first derivative and instrumental noise was removed by Savitzky-Golay polynomial fit. The samples collected at the three sites presented different amounts of formaldehyde (F), acetaldehyde (A) and ketone and minor concentrations of butiraldehyde, benzaldehyde, valeraldehyde and propionaldehyde. The acetaldehyde content was observed to be superior to the formaldehyde, so that the F/A was lower than 1 for all sites. This fact can be related to the increasing use of ethanol as fuel. It was observed a similar profile of CC concentration in all sites studied. In PCA analysis, only one Principal Component could describe a large amount of experimental variability (97.57 %), indicating that a single emission source (vehicular) might have been present. The PCA scores graph and HCA dendogram pointed out that samples from FSP and IAG were similar whereas samples from ICB presented a different behavior. The loadings graph indicated that those differences were due to concentration of all CC. This fact could be due to different climatic conditions during sampling