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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Mise au point d’un procédé de réduction du pouvoir de combinaison des vins à base de biopolymères issus de la biomasse

Saidane, Dorra 12 December 2011 (has links)
L'objectif de cette étude est la diminution du pouvoir de combinaison du dioxyde de soufre des vins blancs liquoreux. La méthode retenue passe par l'élimination du vin de dérivés carbonylés naturellement présents et responsables de la formation de combinaisons bisulfitiques.Les dérivés carbonylés responsables de la plus grande partie du piégeage du dioxyde de soufre sont l'éthanal, l'acide pyruvique et l'acide 2-oxoglutarique. L'extraction de ces composés doit s'effectuer sans dénaturer les qualités organoleptiques du vin et sans générer l'apparition de nouvelles molécules dans le vin. Pour cela, la méthode retenue a été l'extraction liquide-solide : il s’agit de mettre en présence deux réactifs dont l’un l’agent d’extraction est fixé sur un support insoluble. Notre objectif est d’étudier la possibilité de substituer les polymères d’origine industrielle utilisés jusqu’à présent par des supports d’origine naturelle préparés à partir d’un constituant du bois : la lignine. Le recours à des supports d’origine naturelle, dérivé du bois, présente le double intérêt de permettre un meilleur contrôle des matériaux introduits dans le vin à traiter et de rendre les contaminations éventuelles provenant du traitement à priori, plus admissibles, étant constituées de composés déjà présents dans le bois de tonnellerie. / The objective of this study is the reduction of the power of sweet white wines sulfur dioxide combination. The method used relies on the extraction of carbonyl compounds from wine; these are naturally present and responsible for the formation of bisulfite combinations.The carbonyl compounds responsible for most of the trapping of sulfur dioxide are acetaldehyde, pyruvic acid and the 2-oxoglutaric. The extraction of these compounds should be done without altering the organoleptic qualities of wine and without creating the appearance of new molecules in wine. Therefore, the method we used was the liquid-solid extraction: bringing together two reactants, one of which -the extracting agent- is attached to an insoluble support.Our goal is to study the possibility of substituting the industrial polymers, used so far, by natural origin supports, prepared from a wood constituent: the lignin.The use of natural origin materials, deriving from wood, has the double advantage of allowing a better control of materials, introduced in the wine process, and making more acceptable the possible contaminations broad about by the a priori treatment, as they are compounds already present in the wood cooperage.
212

Poluição do ar por compostos orgânicos voláteis (COV) em ambiente interno hospitalar / Air pollution by volatile organic compounds (VOCs) inside hospital

Ivan Alexandre Petroni 07 August 2009 (has links)
A quantificação de 11 compostos carbonílicos (formaldeído, acetaldeído, acetona, acroleína, propionaldeído, crotonaldeído, butiraldeído, benzaldeído, isovaleraldeído, valeraldeído e 2,5-dimetilbenzaldeído) e a identificação de outros 43 compostos orgânicos voláteis (alcanos, alcenos, aromáticos, halogenados e nitrogenados) foram feitas em 9 ambientes diferentes de trabalho localizados em áreas internas do Hospital Universitário, USP, São Paulo. Dentre os compostos carbonílicos, os mais abundantes em ordem decrescente foram formaldeído, acetona, acetaldeído e acroleína. As maiores razões de mistura de formaldeído foram observadas nas salas de Macroscopia (169,9 e 90,2 ppbv) e Técnicas Histológicas (11,7 e 58,7 ppbv), em decorrência da atividade desenvolvida nos locais. Na sala de Macroscopia, os níveis de formaldeído encontrados foram acima do limite (100 ppbv) estabelecido por órgãos internacionais que controlam a qualidade do ar em ambientes internos não industriais. As razões de mistura entre o ambiente interno e o ambiente externo, razões I/E, permitiram indicar a predominância dos compostos carbonílicos nos ambientes internos. A acroleína foi encontrada na faixa de 6,4 a 9,3 ppbv nos ambientes internos estudados. Na área externa, entretanto, foram encontrados valores similares (6,4 e 6,8 ppbv) aos dos ambientes internos obtendo razões I/E próximas de 1. Os compostos podem ter sido emitidos por materiais de construção e acabamento, fumaça do tabaco, adesivos, via metabolismo microbiano e bacteriano ou podem ter sido transportados por correntes de ar do ambiente externo para o ambiente interno / The quantification of 11 carbonyl compounds (formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, crotonaldehyde, butiraldehyde, benzaldehyde, isovaleraldehyde, valeraldehyde and 2,5-dimethylbenzaldehyde) and the identification of another 43 volatile organic compounds (alkanes, alkenes, aromatic, halogenated and nitrogenated compounds) have been done with samples of 9 different indoor places inside the University Hospital at USP in São Paulo. Among the carbonyl compounds, there where found higher quantities of formaldehyde, acetone, acetaldehyde and acrolein in this order. The highest ratios of formaldehyde mixture have been observed at the Macroscopic room (169.88 and 90.2 ppbv) and Histological Techniques (11.7 and 58.7 ppbv), due to the routine activities of these places. At the Macroscopy room, the level of formaldehyde identified (100 ppbv) was above the international limits established to non-industrial internal places. The ratios of the mixture of indoor and outdoor places, I/O, indicate the biggest presence of carbonyl compounds in internal places. Acrolein has been identified (6.4 to 9.3 ppbv) at indoor places. At the external area, there where found similar values (6,4 to 6,8 ppbv), and the ratio I/O obtained is near to 1. The origin of these compounds is possibly construction materials, smoke of cigarettes, adhesives, metabolism of microorganisms or they may have come from the outdoor to the indoor
213

Avaliação da qualidade do ar de cabines de veículos automotores recém-manufaturados / Evaluation of new vehicles cabin indoor air quality

Auzebio Valvassori Filho 23 September 2008 (has links)
Cabines de veículos automotores recém-manufaturados podem ser consideradas críticas quando se avalia a qualidade do ar interno, pois concentrações de compostos orgânicos voláteis encontram-se em níveis mais altos que os ambientes externos. Determinadas substâncias presentes no ar da cabine podem ser prejudiciais ao ser humano em função da sua toxicidade, pricipalmente nos grandes centros urbanos. A avaliação do ar da cabine automotiva se faz necessária. Nesse estudo, foi feita uma avaliação da qualidade do ar interno da cabine de 7 veículos populares recém-manufaturados contendo materiais de acabamento interno iguais. Um total de 46 compostos orgânicos voláteis foi identificado, sendo que 14 deles são compostos carbonílicos e 32 são hidrocarbonetos alifáticos e aromáticos, compostos halogenados e um nitrogenado. Os compostos carbonílicos foram identificados e quantificados por cromatografia a líquido e os outros VOCs apenas identificados por GC-MS. No ar interno da cabine dos veículos estudados, as concentrações médias encontradas para os compostos carbonílicos (µg/m3) em ordem decrescente foram: formaldeído (165,3); acetona (67,5); acetaldeído (56,8); isovaleraldeído (40,8); propionaldeído (21,1); butiraldeído (17,9); crotonaldeído (14,9); hexaldeído (14,9) valeraldeído (9,8); 2.5- dimetilbenzaldeído (9,3); otolualdeído (8,4); p/m tolualdeído (6,8); acroleína (4,2) e benzaldeído (3,8). Com relação aos outros VOCS foram identificados o metilbutano, que apresentou a maior porcentagem de abundância relativa, 8,5%, seguido de outros hidrocarbonetos com abundância relativa entre 5 e 2% , como, 2,7,10-trimetildodecano, 2,2,6-trimetildecano, ciclopentano, 2,3,4-trimetildecano, n-pentano, 3,6-dimetilundecano, 4-metildodecano, 4,6- dimetildodecano, 3,6-dimetildecano e 1,2-dimetilbenzeno. Dois derivados de hidrocarbonetos halogenados também foram encontrados, sendo que o triclorofluormetano foi o majoritário com 5,7%, e um composto nitrogenado, a acetonitrila com 5,4%. Os compostos derivados do benzeno identificados foram: 1,2-dimetilbenzeno, etilbenzeno, metilbenzeno, 1-etil-3- metilbenzeno, 1-etil-3-metilbenzeno e 1,3,5-trimetilbenzeno que perfazem 6,6 % de abundância relativa. O mais abundante entre os aromáticos foi o 1,2-dimetilbenzeno (2,5%). Os resultados experimentais revelaram também a liberação de VOCs pelos materiais de acabamento interno dos veículos automotores recém-manufaturados. / New motor vehicles cabins may be critical when considering the internal air quality, because concentrations of volatile organic compounds are at levels higher than the outdoors. Certain substances present in the cabin air can be harmful to humans according to their toxicity, mainly in the big cities. Assessment of the cabin air becomes necessary. In this study, cabin air quality was assessed and 7 popular new vehicles containing same interior trim materials were evaluated. A total of 46 volatile organic compounds were identified, with 14 of them were carbonylic compounds and 32 are aliphatic and aromatic hydrocarbons, halogenated compounds and a nitrogenated compound. The carbonylic compounds were identified and quantified by the liquid chromatography and other VOCs only identified by GC-MS. Cabin air vehicles studied showed the following average concentrations found for carbonylic compounds ( µg/m3) in a descending order: formaldehyde (165.3), acetone (67.5); acetaldehyde (56.8); Isovaleraldehyde ( 40.8); propionaldehyde (21.1); butyraldehyde (17.9); crotonaldeído (14.9); hexaldeído (14.9) Valeraldehyde (9.8); dimetilbenzaldeído-2.5 (9.3); the - tolualdeído (8.4), p / m - tolualdeído (6.8); acrolein (4.2) and benzaldehyde (3.8). Concerning the other VOCs the following compounds were identified: methylbutane, which had the highest percentage of relative abundance, 8.5%, followed by other hydrocarbons with relative abundance between 5 and 2%, 2,7,10-trimetildodecano, 2.2 ,6- Trimetildecano, ciclopentano, 2,3,4-trimetildecano, n-pentane, 3.6-dimetilundecano, 4- metildodecano, dimetildodecano-4.6, 3.6 and 1.2-dimetildecano-dimetilbenzeno. Two halogenated hydrocarbons were also found, and triclorofluormetano had the biggest relative abundance percentage 5.7%, and a nitrogen compound, the acetonitrile with 5.4%. The benzene compounds identified were: 1.2-dimetilbenzeno, ethylbenzene, methylbenzene, 1- ethyl-3-methyl, ethyl-1-and 3-methyl 1,3,5-trimethylbenzene which comprise 6.6% of relative abundance. 1.2-dimetilbenzeno was the most abundant aromatic compound with relative abundance 2.5%. Results also showed that VOCs were released by studied vehicles interior trim materials.
214

Synthesis, characterization, and kinetics of isomerization, C-H and P-C bond activation for unsaturated diphosphine-coordinated triosmium carbonyl clusters.

Wu, Guanmin 05 1900 (has links)
Substitution of MeCN ligands in the activated cluster Os3(CO)10(MeCN)2 by the unsaturated diphosphine ligands (Z)-Ph2PCH=CHPPh2 (cDPPEn) or 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) proceeds rapidly at room temperature to furnish the ligand-bridged cluster 1,2-Os3(CO)10(P-P) (P-P represents cDPPEn or bpcd). Heating 1,2-Os3(CO)10(P-P) leads to the formation of the thermodynamically more stable chelating isomer 1,1-Os3(CO)10(P-P). Each compound of Os3(CO)10(P-P) has been characterized by x-ray diffraction, IR, 31P NMR and 1H NMR. Ligand isomerization kinetics have been investigated by UV-VIS and 31P NMR (for cDPPEn) or 1H NMR (for bpcd) spectroscopies. The isomerization mechanism is discussed based on the activation parameters and CO inhibition (for cDPPEn) or ligand trapping experiments (for bpcd). Thermolysis of 1,1-Os3(CO)10(bpcd) in refluxing toluene gives the hydrido cluster HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)CH2C(O)] and the benzyne cluster HOs3(CO)8(μ3-C6H4)[μ2,η1-PPhC=C(PPh2)C(O)CH2C(O)]. Photolysis of 1,1-Os3(CO)10(bpcd) using near UV light affords HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)CH2C(O)] as the sole product. HOs3(CO)8(μ3-C6H4)[μ2,η1-PPhC=C(PPh2)C(O)CH2C(O)] has been characterized in solution by IR and NMR spectroscopies. Furthermore its molecular structure has been determined by X-ray crystallography. Reversible C-H bond formation in HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)CH2C(O)] is demonstrated by ligand trapping studies to give 1,1-Os3(CO)9L(bpcd) (where L = CO, phosphine) via the unsaturated intermediate 1,1-Os3(CO)9(bpcd). The kinetics for reductive coupling in HOs3(CO)9[γ-(PPh2)C=C{PPh(C6H4)}C(O)CH2C(O)] and DOs3(CO)9[μ-(PPh2-d10)C=C{P(Ph-d5)(C6D4)}C(O)CH2C(O)] in the presence of PPh3 give rise to a kH/kD value of 0.88, whose magnitude supports the existence of a preequilibrium involving the hydride(deuteride) cluster and a transient arene-bound Os3 species that precedes the rate-limiting formation of 1,1-Os3(CO)9(bpcd). Strong proof for the proposed hydride(deuteride)/arene preequilibrium has been obtained from photochemical studies employing the isotopically labeled cluster 1,1-Os3(CO)10(bpcd-d4ortho), whose bpcd phenyl groups each contain one ortho hydrogen and deuterium atom. Equilibrium and kinetic isotope effects in the orthometallation step has been determined by 1H NMR in photochemical studies. Kinetics for the transformation from HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)CH2C(O)] to HOs3(CO)8(μ3-C6H4)[μ2,η1-PPhC=C(PPh2)C(O)CH2C(O)] has been studied by UV-VIS spectroscopy for which the mechanism is discussed.
215

Chemical vapor deposition of ruthenium-based layers by a single-source approach

Jeschke, Janine, Möckel, Stefan, Korb, Marcus, Rüffer, Tobias, Assim, Khaybar, Melzer, Marcel, Herwig, Gordon, Georgi, Colin, Schulz, Stefan E., Lang, Heinrich 06 March 2017 (has links)
A series of ruthenium complexes of the general type Ru(CO)2(P(n-Bu)3)2(O2CR)2 (4a, R = Me; 4b, R = Et; 4c, R = i-Pr; 4d, R = t-Bu; 4e, R = CH2OCH3; 4f, R = CF3; 4g, R = CF2CF3) was synthesized by a single-step reaction of Ru3(CO)12 with P(n-Bu)3 and the respective carboxylic acid. The molecular structures of 4b, 4c and 4e–g in the solid state are discussed. All ruthenium complexes are stable against air and moisture and possess low melting points. The physical properties including the vapor pressure can be adjusted by modification of the carboxylate ligands. The chemical vapor deposition of ruthenium precursors 4a–f was carried out in a vertical cold-wall CVD reactor at substrate temperatures between 350 and 400 °C in a nitrogen atmosphere. These experiments show that all precursors are well suited for the deposition of phosphorus-doped ruthenium layers without addition of any reactive gas or an additional phosphorus source. In the films, phosphorus contents between 11 and 16 mol% were determined by XPS analysis. The obtained layers possess thicknesses between 25 and 65 nm and are highly conformal and dense as proven by SEM and AFM studies. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
216

Análise conformacional das α-etilsulfinil- e α-etilsulfonil-acetofenonas-para-substituídas; α-metiltio, α-dietoxifosforilacetofenonas-para-substituídas e suas formas mono- e di-oxigenadas / Conformational analysis of α-etyhlsulfinyl- and α-ethylsulphonyl-acetophenones-para-substituted; α-methylthio, α -dietoxyphosphoryl acetophenones-para-substituted and its mono and di-oxygenated forms

Reis, Adriana Karla Cardoso Amorim 20 August 2003 (has links)
A presente tese relata o estudo conformacional e das interações eletrônicas de algumas: a) α-etilsulfinil- (Ia), α-etilsulfonil- (Ib) acetofenonas-para-substituídas Y-Φ-C(O)CH2SOnEt [I, n=1 (a) e n=2 (b)]; b) α-metiltio-α-dietoxifosforilacetofenonas-para-substituídas (IIa) e suas formas mono- (IIb) e di- (IIc) oxigenadas Y-Φ-C(O)CH[SOnMe][P(O)(OEt)2] [II, n=0 (a), n=1 (b)] e n=2 (c)]; c) α-bromo-α-etilsulfonilacetofenonas-para-substituídas Y-Φ-C(O)CH[Br][SO2Et] (III). Este estudo foi realizado através das espectroscopias no Infravermelho, Ressonância Magnética Nuclear, Ultravioleta e cálculos ab initio HF/6-31G**. Nas α-etilsulfinilacetofenonas-para-substituídas (Ia) a conformação cis é a preferencial para toda série, enquanto nas α-etilsulfonilacetofenonas-para-substituídas (Ib) a conformação gauche é a predominante. Nas α-metiltio-α-dietoxifosforilacetofenonas-para-substituídas (IIa) existe uma única conformação estável que apresenta o grupo (SMe) na geometria gauche e o grupo [P(O)(OEt)2] na geometria quasi-cis em relação à carbonila. As α-metilsulfinil-α-dietoxifosforilacetofenonas-para-substituídas (IIb) apresentam duas conformações estáveis, sendo cada uma delas referente a um diastereômero, tanto em solução de solventes de polaridade crescente quanto no estado gasoso. A conformação mais estável (CSSS) apresenta o grupo (MeSO) numa geometria quasi-periplanar (quasi-cis) e o grupo [(P(O)(OEt)2] numa geometria anti-clinal (gauche). A segunda conformação CRSS apresenta os dois substituintes, (MeSO) e [(P(O)(OEt)2], numa geometria sin-clinal (gauche). Nas α-metilsulfonil-α-dietoxifosforilacetofenonas-para-substituídas (IIc) a conformação preferencial apresenta os grupos (MeSO2) e [(P(O)(OEt)2] na geometria sin-clinal em relação à carbonila. As α-bromo-α-etilsulfonilacetofenonas-para-substituídas (III) apresentam-se numa única conformação estável, contendo o grupo (SO)2Et) na geometria sin-periplanar (quasi-cis) e o átomo de (Br) na geometria sin-clinal (gauche). / This thesis reports the conformational and electronic interaction studies of some: a) α-ethylsulfinyl- (Ia) and α-ethylsulfonyl- (Ib) para-substituted acetophenones Y-PhC(O)CH2SOnEt [I, n=1 (a) and n=2 (b)]; b) α-methylthio-α-diethoxyphosphoryl-para-substituted acetophenones (IIa) and their corresponding mono- (IIb) and di- (IIc) oxygenated derivatives Y-PhC(O)CH[SOnMe][P(O)(OEt2)] [II, n=0 (a), n=1 (b)] and n=2 (c)]; c) α-bromo, α- ethylsulfonyl-para-substituted acetophenones Y-PhC(O)[Br][SO2Et] (III). This study was performed by means of Infrared, Nuclear Magnetic Resonance, Ultraviolet spectroscopies, ab initio computations and X-ray diffraction analysis. For the α-ethylsulfinylacetophenones (Ia) the cis conformer predominates over the gauche one while in the case of the α-ethylsulfonylacetophenones (Ib) the gauche conformer is the more stable relative to the quasi-cis one. The α-methylthio-α-diethoxyphosphoryl acetophenones (IIa) present only a single stable conformer which bears the (SMe) group in a syn-clinal (gauche) geometry and the [P(O)(OEt2)] group in the quasi-periplanar (quasi-cis) geometry with respect to the carbonyl group. The α-methylsulfinyl-α-diethoxyphosphoryl acetophenones (IIb) display two stable conformations corresponding each one to a different diastereomer. The most stable conformer CSSS presents the methylsulfinyl group [MeS(O)] in a quasi-periplanar (quasi-cis) geometry and the diethoxyphosphoryl group [P(O)(OEt2)] in a anti-clinal (gauche) geometry relative to the carbonyl group. The second less stable conformer corresponds to the CRSS diastereomer and displays both the [MeS(O)] and the [P(O)(OEt2)] groups in a syn-clinal (gauche) geometry. The α-methylsulfonyl-α-diethoxyphosphoryl acetophenones (IIc) presents only a single stable conformer bearing both the [MeSO2] and [P(O)(OEt)2] groups in a sin-clinal geometry with respect to the carbonyl group. The α-bromo-α-ethylsulfonylacetophenones III present a single stable conformation bearing the the [SO2Et] group in a syn-periplanar (quasi-cis) geometry and the [Br] atom in a syn-clinal (gauche) geometry relative to the carbonyl group.
217

Chromium-Catalyzed Homoaldol Equivalent Reaction, Indium-Mediated Cycloisomerization, and Palladium-Catalyzed Cross-Coupling Reaction

Kang, Jun 2011 August 1900 (has links)
The homoaldol reaction is one of the most powerful methods for the construction of C–C bonds as well as 1,4-oxygenated compounds yet this reaction remains in challenging tasks due to the instability of homoenolates which spontaneously cyclize to the cyclopropanolate. A regioselective catalytic homoaldol equivalent reaction of 3-bromo vinyl acetate with aldehydes under Cr(III)-Mn(0) redox condition was developed. This homoaldol equivalent reaction allows access to the 1,4-oxygenated compounds that are not possible by a conventional aldol process. Mild hydrolysis of the vinyl acetate and reduction of the homoaldol adducts generated diols and lactols in high yield (99%). Further manipulation including stereoselective epoxidation and cyclopropanation was achieved in an efficient manner. Furans, found in many natural products and utilized in drug discovery, have been well studied but current synthetic methods toward furans have some limitations in functional group tolerance, substrate scope, and low product yield in many cases. A highly efficient and catalytic cycloisomerization reaction that transforms acetylenic α,β-epoxides to 2,3,5-tri-substituted furans under InCl3 catalysis was developed. This reaction sequence allows access to rapid construction of highly valuable, tri-substituted furan derivatives. Cross-coupling reactions utilizing transition metals and Lewis acids are important synthetic tools for the formation of C–C and C–N bonds and a number of cross-coupling reactions between α-bromo carbonyl compounds and metal reagents such as aryl metals, alkenyl metals, and alkyl metals have been reported. Transition metal-catalyzed cross-coupling reaction for the construction of α-alkynyl carbonyl compounds has reported in a limited case. The first approach to secondary α-alkynyl carbonyl compounds from secondary α-bromo esters and amides with tributyl(phenylethynyl)stannane under palladium-catalyzed cross-coupling reaction conditions was developed. This synthetic method allows access to secondary α-alkynyl carbonyl compounds which are valuable precursors in pharmaceuticals and agricultural applications.
218

Compostos carbonílicos no ar em ambientes de trabalho de carvoarias na Bahia

Carvalho, Albertinho Barreto de 16 September 2016 (has links)
Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-09-16T13:51:29Z No. of bitstreams: 1 Tese Albertinho.pdf: 2368551 bytes, checksum: 417090fff955b8696ce1e600d35af5e0 (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-16T14:11:51Z (GMT) No. of bitstreams: 1 Tese Albertinho.pdf: 2368551 bytes, checksum: 417090fff955b8696ce1e600d35af5e0 (MD5) / Made available in DSpace on 2016-09-16T14:11:51Z (GMT). No. of bitstreams: 1 Tese Albertinho.pdf: 2368551 bytes, checksum: 417090fff955b8696ce1e600d35af5e0 (MD5) / CNPq, à CAPES e à FINE / Este trabalho foi realizado com os seguintes objetivos: apresentar uma metodologia analítica aplicável à determinação de compostos carbonílicos (CC) em fase vapor, em amostras estacionárias e pessoais coletadas em ambientes de trabalho de carvoarias; determinar o perfil dos CC presentes no ar inalado pelos trabalhadores e; quantificar os CC no ar, na fase vapor, em locais de trabalho e na zona respiratória de trabalhadores carvoeiros. Os trabalhos de campo foram realizados em quatro carvoarias que produziam o carvão a partir da queima de pinho e de eucalipto, todas localizadas a cerca de 150 km, a nordeste de Salvador. Cartuchos Sep-Pak® C18 impregnados com solução ácida a 0,2% de 2,4 dinitrofenilhidrazina coletaram eficientemente os CC atmosféricos, em vazões em torno de 0,1 L/min e quando a duração da coleta foi de, no máximo, 240 minutos, para as amostras pessoais e 120 minutos, para as estacionárias. Foram desenvolvidos dois protocolos analíticos (Método “1” e Método “2”), ambos por cromatografia líquida de alta eficiência utilizando bomba com gradiente de eluição de solventes e sistema de detecção por UV/Visível (365 nm), para a separação e quantificação das 2,4-dinitrofenilhidrazonas de vários CC. O Método “1” permitiu separar e quantificar, em menos de 16 minutos, acetaldeído, acroleína, benzaldeído, ciclohexanona, ciclopentanona, 2- etil hexanal, formaldeído, furfural, hexanal, 2-hexenal, octanal, 2-pentenal, propanal, e propanona, com destaque para a separação dos pares acroleína-furfural e propanona-propanal. Além disso, permitiu estimar a soma das concentrações dos isômeros C4, butanal-isobutanal- butanona. O Método “2” permitiu separar e quantificar, em menos de 30 minutos, 13 dos 17 CC citados para o Método “1”. Por este método foi possível separar a butanona da mistura de butanal e isobutanal. O mesmo não ocorreu com a acroleína e o furfural, que co-eluíram. Os limites de detecção e de quantificação para o formaldeído, o acetaldeído e a propanona foram bastante afetados pelos níveis desses compostos encontrados nos brancos de amostra. Acetaldeído, formaldeído, furfural, isômeros C4 e propanona foram os CC confirmados em todas as amostras coletadas, nas quatro carvoarias. Vários outros CC desconhecidos foram detectados nas amostras. Ciclopentanona, 2-pentenal e CC acima de C8 não foram detectados nas amostras pelos dois métodos cromatográficos. Em amostras válidas foram determinadas concentrações de formaldeído entre 15,0 e 139,1 µg m-3, de acetaldeído entre 37,9 e 164,8 µg m-3, de propanona entre 9,6 e 483,0 µg m-3, de furfural entre 38,9 e 113,7 µg m-3 e de isômeros C4 (butanal+isobutanal+butanona) entre 9,8 e 132,4 µg m-3, em amostras pessoais. Em amostras estacionárias, as faixas de concentrações desses mesmos compostos foram respectivamente, 20,4 a 160,2 µg m-3, 118,6 a 283,6 µg m-3, 327,5 a 643,6 µg m-3, 69,9 a 162,9 µg m-3 e 100,0 a 176,1 µg m-3. Os resultados indicam que os trabalhadores das carvoarias se expõem a concentrações de formaldeído, acetaldeído e furfural acima dos limites estabelecidos por alguns organismos internacionais, como o National Institute for Occupational Safety and Health - NIOSH e o Health Based Exposure Levels Committee - HBELC, ambos dos Estados Unidos. Estes são os primeiros resultados de concentrações de CC no ar obtidos em ambientes de trabalho e na zona respiratória de trabalhadores de carvoarias, que se tem conhecimento até o momento. / The goals of the present work were to present an analytical methodology applicable to the determination of carbonyl compounds (CC) in vapor phase, in area and personal samples collected in charcoal company workplaces; to determine the CC profile in air inhaled by charcoal workers; and to quantify the CC in vapor phase in air of workplaces and breathing zone of workers in charcoal companies. The measurements were obtained in air samples collected in four companies located about 150 km north of Salvador, Bahia, Brazil, which burn eucalyptus and pinus to produce charcoal. The results showed that CC were efficiently collected on Sep-Pak® C18 cartridges coated with 0.2% acidic solution of 2,4- dinitrophenylhydrazine when the sampling flow rates were around 100 mL/min and the sampling time was 240 minutes for the personal samples and 120 minutes for area samples. Two chromatographic methods (Method 1 and Method 2) for separation and quantification of several 2,4-dinitrophenylhydrazones (2,4-DNPHO) were developed using a high performance liquid chromatography system with a gradient pump for the solvent elution and a UV detector (365 nm). Method 1 was able to separate and quantify, in less than 16 minutes, the 2,4- DNPHO of acetaldehyde, acrolein, benzaldehyde, cyclohexanone, cyclopentanone, 2-ethyl hexanal, formaldehyde, furfural, hexanal, 2-hexenal, octanal, 2-pentenal, propanal, and propanone, and estimated the sum of C4 isomers, butanal-isobutanal-butanone. This method separated well acrolein from furfural and propanal from propanone hydrazones. Method “2” allowed separation and quantification, in less than 30 minutes, of 13 of the 17 CC listed for Method 1. This method separated butanone from other components of the C4 mixture and enables the separation of acrolein from furfural. In both methods, the detection and the quantification limits of acetaldehyde, formaldehyde, and propanone were affected by the amount of these compounds found in the blank samples. Acetaldehyde, formaldehyde, furfural, C4 isomers, and propanone were the CC confirmed in all samples collected in all charcoal companies. Several unknown CC were also found. Cyclopentanone, 2-pentenal, and carbonyl compounds with more than 8 carbon atoms were not detected in any of the samples by these methods. Concentrations of formaldehyde, acetaldehyde, propanone, furfural, and C4 isomers (butanal+isobutanal+butanone) found in personal samples ranged between 15.0 and 139.1 µg m-3, 37.9 and 164.8 µg m-3, 9.6 and 483.0 µg m-3, 38.9 and 113.7 µg m-3, and 9.8 and 132.4 µg m-3, respectively. In area samples, the concentrations of the same CC were between 20.4 and 160.2 µg m-3, 118.6 and 283.6 µg m-3, 327.5 and 643.6 µg m-3, 69.9 and 162.9 µg m-3, and 100.0 and 176.1 µg m-3. These results indicated that charcoal workers were exposed to formaldehyde, acetaldehyde, and furfural concentrations that exceed the limit values suggested by the National Institute for Occupational Safety and Health - NIOSH and the Health Based Exposure Levels Committee - HBELC. These were the first results of CC concentrations in workplace air and in breathing zone of charcoal workers reported in the scientific literature up to this mome
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Análise conformacional das α-etilsulfinil- e α-etilsulfonil-acetofenonas-para-substituídas; α-metiltio, α-dietoxifosforilacetofenonas-para-substituídas e suas formas mono- e di-oxigenadas / Conformational analysis of α-etyhlsulfinyl- and α-ethylsulphonyl-acetophenones-para-substituted; α-methylthio, α -dietoxyphosphoryl acetophenones-para-substituted and its mono and di-oxygenated forms

Adriana Karla Cardoso Amorim Reis 20 August 2003 (has links)
A presente tese relata o estudo conformacional e das interações eletrônicas de algumas: a) α-etilsulfinil- (Ia), α-etilsulfonil- (Ib) acetofenonas-para-substituídas Y-Φ-C(O)CH2SOnEt [I, n=1 (a) e n=2 (b)]; b) α-metiltio-α-dietoxifosforilacetofenonas-para-substituídas (IIa) e suas formas mono- (IIb) e di- (IIc) oxigenadas Y-Φ-C(O)CH[SOnMe][P(O)(OEt)2] [II, n=0 (a), n=1 (b)] e n=2 (c)]; c) α-bromo-α-etilsulfonilacetofenonas-para-substituídas Y-Φ-C(O)CH[Br][SO2Et] (III). Este estudo foi realizado através das espectroscopias no Infravermelho, Ressonância Magnética Nuclear, Ultravioleta e cálculos ab initio HF/6-31G**. Nas α-etilsulfinilacetofenonas-para-substituídas (Ia) a conformação cis é a preferencial para toda série, enquanto nas α-etilsulfonilacetofenonas-para-substituídas (Ib) a conformação gauche é a predominante. Nas α-metiltio-α-dietoxifosforilacetofenonas-para-substituídas (IIa) existe uma única conformação estável que apresenta o grupo (SMe) na geometria gauche e o grupo [P(O)(OEt)2] na geometria quasi-cis em relação à carbonila. As α-metilsulfinil-α-dietoxifosforilacetofenonas-para-substituídas (IIb) apresentam duas conformações estáveis, sendo cada uma delas referente a um diastereômero, tanto em solução de solventes de polaridade crescente quanto no estado gasoso. A conformação mais estável (CSSS) apresenta o grupo (MeSO) numa geometria quasi-periplanar (quasi-cis) e o grupo [(P(O)(OEt)2] numa geometria anti-clinal (gauche). A segunda conformação CRSS apresenta os dois substituintes, (MeSO) e [(P(O)(OEt)2], numa geometria sin-clinal (gauche). Nas α-metilsulfonil-α-dietoxifosforilacetofenonas-para-substituídas (IIc) a conformação preferencial apresenta os grupos (MeSO2) e [(P(O)(OEt)2] na geometria sin-clinal em relação à carbonila. As α-bromo-α-etilsulfonilacetofenonas-para-substituídas (III) apresentam-se numa única conformação estável, contendo o grupo (SO)2Et) na geometria sin-periplanar (quasi-cis) e o átomo de (Br) na geometria sin-clinal (gauche). / This thesis reports the conformational and electronic interaction studies of some: a) α-ethylsulfinyl- (Ia) and α-ethylsulfonyl- (Ib) para-substituted acetophenones Y-PhC(O)CH2SOnEt [I, n=1 (a) and n=2 (b)]; b) α-methylthio-α-diethoxyphosphoryl-para-substituted acetophenones (IIa) and their corresponding mono- (IIb) and di- (IIc) oxygenated derivatives Y-PhC(O)CH[SOnMe][P(O)(OEt2)] [II, n=0 (a), n=1 (b)] and n=2 (c)]; c) α-bromo, α- ethylsulfonyl-para-substituted acetophenones Y-PhC(O)[Br][SO2Et] (III). This study was performed by means of Infrared, Nuclear Magnetic Resonance, Ultraviolet spectroscopies, ab initio computations and X-ray diffraction analysis. For the α-ethylsulfinylacetophenones (Ia) the cis conformer predominates over the gauche one while in the case of the α-ethylsulfonylacetophenones (Ib) the gauche conformer is the more stable relative to the quasi-cis one. The α-methylthio-α-diethoxyphosphoryl acetophenones (IIa) present only a single stable conformer which bears the (SMe) group in a syn-clinal (gauche) geometry and the [P(O)(OEt2)] group in the quasi-periplanar (quasi-cis) geometry with respect to the carbonyl group. The α-methylsulfinyl-α-diethoxyphosphoryl acetophenones (IIb) display two stable conformations corresponding each one to a different diastereomer. The most stable conformer CSSS presents the methylsulfinyl group [MeS(O)] in a quasi-periplanar (quasi-cis) geometry and the diethoxyphosphoryl group [P(O)(OEt2)] in a anti-clinal (gauche) geometry relative to the carbonyl group. The second less stable conformer corresponds to the CRSS diastereomer and displays both the [MeS(O)] and the [P(O)(OEt2)] groups in a syn-clinal (gauche) geometry. The α-methylsulfonyl-α-diethoxyphosphoryl acetophenones (IIc) presents only a single stable conformer bearing both the [MeSO2] and [P(O)(OEt)2] groups in a sin-clinal geometry with respect to the carbonyl group. The α-bromo-α-ethylsulfonylacetophenones III present a single stable conformation bearing the the [SO2Et] group in a syn-periplanar (quasi-cis) geometry and the [Br] atom in a syn-clinal (gauche) geometry relative to the carbonyl group.
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Medidas da emissão de compostos carbonílicos por plantas / Measures of emission of carbonyl compounds by plants

Silvana Odete Pisani 04 July 2003 (has links)
A técnica de confinamento de folhas de plantas em câmara de Teflon rígido (cuvette), com visor em vidro, submetida a um fluxo contínuo de ar foi adotada na avaliação da emissão de compostos carbonílicos voláteis por plantas. Os carbonílicos foram coletados sobre sílica impregnada com o reagente derivatizante 2,4-dinitrofenilhidrazina e analisados por cromatografia a líquido de alto desempenho e detecção por ultravioleta. Foram identificados e quantificados aldeídos alifáticos saturados (C1 a C6) e insaturados (acroleína, metacroleína, crotonaldeído), benzaldeído, acetona e 2-butanona. A temperatura ambiente e na superfície das folhas, a umidade relativa do ar, a intensidade da luz solar e os níveis de ozônio e de óxidos de nitrogênio no ar foram monitorados durante as coletas de amostras. Com o objetivo de avaliar os níveis de fundo de carbonílicos no sistema coletor empregado, 29 amostras de ar foram coletadas sem a introdução de folhas de planta no cuvette, em condições ambientais de laboratório e campo. Uma avaliação estatística dos resultados indicou que os níveis de fundo do cuvette vazio foram próximos a zero nas coletas feitas no laboratório e aumentaram de acordo com o aumento da intensidade da luz solar nas coletas em campo. Esses resultados mostraram que a exposição do cuvette à radiação solar conduz à formação de artefato positivo de amostragem. Foram feitas medidas da emissão de carbonílicos pela espécie Ficus benjamina, para a qual foram observadas taxas de emissão de acetaldeído altas em condições de temperatura na superfície das folhas superior a 40°C. Na ausência de luz solar incidente, não foi observada emissão de carbonílicos pelo exemplar avaliado dessa espécie. Foram feitas também medidas da emissão de carbonílicos pelas seguintes espécies de plantas ocorrentes na vegetação nativa da Região Metropolitana de São Paulo: Cecropia pachystachya, Casearia sylvestris, Croton floribundus, Solanum erianthum, Alchornea sidifolia, Syagrus rommanzoffiana e Ficus insipida, para as quais foram observadas taxas de emissão de carbonílicos que variaram entre 1,5 10-2 e 2,3 µgC g-1 h-1. / The leaf enclosure technique in air flow-through rigid Teflon chamber (cuvette) was employed to evaluate volatile carbonyl compound emission from plants. The gaseous carbonyl compounds were collected on silica gel coated with 2,4-dinitrophenylhydrazine and analyzed by high performance liquid chromatography with ultra-violet detection. The identified and quantified carbonyls were saturated (C1 - C6) and unsaturated (acrolein, methacrolein, crotonaldehyde) aliphatic aldehydes, benzaldehyde, acetone and 2-butanone. Ambient and leaf surface temperatures, relative humidity, light intensity, ozone and nitrogen oxides air levels were monitored during carbonyl emission sampling. With the aim of evaluate the collection system carbonyl background leveIs, 29 air samples were collected from the empty cuvette under laboratory and field conditions. Statistical analysis of the data indicated that the cuvette background leveIs were close to zero under laboratory conditions and increased with the increasing of the sunlight intensity under field conditions. These results showed that the cuvette exposition to the sunlight leaded to positive sampling artifact. Carbonyl compound emission from Ficus benjamina species was measured and high acetaldehyde emission rates were observed under leaf surface temperature higher than 40°C. In the absence of direct sunlight no carbonyl emission was measured from the evaluated individual of Ficus benjamina. Also carbonyI emissions from the following native species in the metropolitan region of São Paulo City were measured: Cecropia pachystachya, Casearia sylvestris, Croton floribundus, Solanum erianthum, Alchornea sidifolia, Syagrus rommanzoffzana e Ficus insípida. The observed rate emissions from these plants ranged between 1,5 10 -2 and 2,3 µgC g-1 h-1.

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