Academic literature on the topic 'Chemical tests and reagents'

This thesis describes the preparation of 4-chloro-2-trimethyl-stannyl-1-butene (8̲4̲) and its conversion into a number of structurally interesting and synthetically useful donor-acceptor reagents. Thus, transmetalation of (8̲4̲) with methyllithium produced 4-chloro-2-lithio-1-butene (9̲5̲), which reacted smoothly at -78°C in tetrahydrofuran with aldehydes, ketones and α,β-unsaturated N,N',N'-trimethylcarboxhydrazides to provide the addition products (1̲0̲8̲)-(̲1̲1̲3̲) and (̲1̲2̲8̲)-(̲1̲3̲0̲). When the reaction mixtures were treated with hexamethylphosphoramide and were then allowed to warm to room temperature, the 3-methylenetetrahydro-furan derivatives (̲1̲1̲4̲)-(̲1̲1̲9̲) and the 3-methylenecyclopentanecarboxylic acid derivatives (̲1̲3̲1̲)-(̲1̲3̲3̲) were produced in good yields. Treatment of reagent (̲9̲5̲) with 1 equiv of phenylthiocopper or cuprous cyanide provided solutions of the corresponding cuprate reagents (̲1̲7̲9̲) and (̲1̲8̲0̲). Conjugate addition of the latter species to the cyclic enones (̲1̲8̲1̲)-(̲1̲8̲6̲) afforded very good yields of the ketones (̲1̲8̲7̲)-(̲1̲9̲2̲), which, when treated with potassium hydride in tetrahydrofuran, provided the methylenecyclopentane annulation products (̲1̲̲9̲3̲)-(̲1̲9̲8̲), respectively. This methylenecyclopentane annulation method served as a key process in the total synthesis of two structurally interesting triquinane sesquiterpenoids, (±)-Δ⁹⁽¹²⁾ -capnellene (̲2̲0̲5̲) and (±)-pentalenene (̲2̲5̲1̲). Thus, copper bromide - dimethylsulfide catalyzed addition of the Grignard reagent (̲2̲3̲3̲) to 2-methyl-2-cyclopenten-1-one (̲1̲8̲4̲), followed by intramolecular alkylation of the resultant chloro ketone (̲1̲9̲0̲), gave the annulation product (̲1̲9̲6̲). This material was converted into the enone (̲2̲3̲1̲) , which was subjected to an annulation sequence identical with that used in the conversion of (̲1̲8̲4̲) into (̲1̲9̲6̲). Removal of the carbonyl group from the resultant product (̲2̲3̲2̲) provided (±)-Δ⁹⁽¹²⁾ capnellene (̲2̲0̲5̲). Transformation of the readily available keto acetal (̲2̲8̲̲7̲) into the enone (̲2̲8̲4̲), followed by subjection of the latter substance to the methylenecyclopentane annulation sequence, gave the tetracyclic keto olefin (̲2̲8̲5̲). Treatment of an acetic acid solution of this material with hydrogen in the presence of platinum metal produced a mixture of the epimeric ketones (2̲9̲8̲) and (2̲9̲9̲), which was converted into a mixture of (±)-pentalenene (2̲5̲1̲) and (±)-9-e̲p̲i̲-pentalenene (2̲6̲9̲), respectively. [Formula Omitted]<br>Science, Faculty of<br>Chemistry, Department of<br>Graduate

Immunochemical reagents were characterized under carefully controlled laboratory conditions using conventional high performance liquid chromatography instrumentation. The stationary phase was prepared by attaching antigen molecules to an insoluble support through a covalent linkage. Experiments were carried out by introducing antibody molecules into the mobile phase and monitoring their interaction with the stationary phase. Monoclonal antibodies were employed because of their more homogeneous properties compared to polyclonal antisera. Radioisotopes were employed to study low level adsorption on the stationary phase. Recovery experiments were carried out in which it was possible to account for all of the material introduced into the mobile phase. Antibodies were purified over a preparative scale antigen affinity column following labeling to insure high immunoreactivity. Studied under normally dissociating conditions, irreversible adsorption of picomole amounts of protein on the antigen stationary phase was greater than on other ligand modified stationary phases. This accumulation decreased with repeated use of the affinity column. The present study provides a framework for evaluation of other immunoaffinity systems and demonstrates that reproducible recovery of immunologically active material in high yield is possible. Monoclonal antibodies labeled with fluorescein were different from unlabeled molecules in binding and physical characteristics. Computer simulations were used to describe binding behavior. Although fluorescein labels improve detection sensitivity over native protein absorbance, their use in this case decreased binding affinity significantly. Heterogeneity of affinity purified fluorescein labeled and unlabeled monoclonal antibodies was examined with two dimensional gel electrophoresis. In addition to increased charge heterogeneity in the labeled antibody fragments, both light and heavy chains possessed more negative character. These results agree with each other. Fluorescein contains a carboxylic acid group, and modification of antibody light chains may interfere with binding affinity. The number and location of labels covalently attached to antibodies must be carefully controlled to obtain maximum detection sensitivity and preserve immunoreactivity.

Made available in DSpace on 2014-06-11T19:35:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-28Bitstream added on 2014-06-13T20:26:01Z : No. of bitstreams: 1 silva_as_dr_araiq.pdf: 2860868 bytes, checksum: 0a5366c12c615d912dea72ff05ef8e46 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O produto comercial Roundup®, contendo o glifosato como principal ingrediente ativo, é vendido mundialmente por ser um herbicida sistêmico, pós-emergente e não seletivo. Além disso, a alta eficiência no processo de remoção de plantas indesejadas e o aumento de culturas transgênicas favorecem seu uso extensivo. Embora não seja considerado um sério contaminante para o homem, o controle e monitoramento destes herbicidas são muito importantes. Desta forma, o presente projeto propõe o desenvolvimento de sistemas de screening e métodos analíticos limpos que possam ser aplicados à determinação de glifosato, uma vez que a literatura dispõe de poucos métodos de análise que visam à aplicação dos princípios da Química Verde. Os métodos propostos neste estudo foram espectroscopia de reflectância difusa, espectrofotometria e sistemas em fluxo, empregando análise por injeção em fluxo (FIA) e multi-bombas (MPFS), com detecção na região do UV-Vis. Os métodos de análise propostos são baseados na reação entre glifosato e p-dimetilaminocinamaldeído (p- DAC), em meio acidificado, com um máximo de reflecção ou absorção em 495 nm. Após a otimização das condições experimentais e validação dos métodos propostos, através de parâmetros como linearidade da curva analítica, exatidão, precisão, limite de detecção, limite de quantificação, recuperação e estudos de possíveis íons interferentes, estes foram aplicados em amostras de herbicidas comerciais e águas (naturais e de consumo humano). Os resultados obtidos na determinação de glifosato nas amostras de herbicidas comerciais empregando reflectância difusa concordaram com os resultados obtidos empregando análise por injeção em fluxo, os quais apresentaram teores de 378,8 g L-1 para a amostra A, 392,4 g L-1 para a amostra...<br>The commercial product Roundup®, containing the glyphosate as its main active ingredient, is marketed worldwide because it is a nonsystemic, post-emergent and nonselective herbicide. Moreover, the high efficiency in the process of the removal of unwanted plants and the increase in the introduction transgenic plants favor their extensive use. Although it has not been considered a serious contaminant to humans the control and monitoring of this herbicide are very importants. The present project proposes the development of screening systems and clear analytical methods that can be applied to determine the presence of glyphosate, since in the literature there are few methods of analysis that apply Green Chemistry’s principles. The proposed methods in this study were diffuse reflectance spectroscopy, spectrophotometry and flow systems, employing flow injection analysis (FIA) and multi-pumping (MPFS), with detection in the Uv-vis region. The proposed analysis methods are based in the reaction between glyphosate and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, it presents a reflection or absorption maximum in 495 nm. After the optimization of the experimental conditions and validation of the proposed methods, through parameters such as: linearity of the analytical curve, accuracy, precision, limit of detection, limit of quantification, recovery and study of possible interference ions, these were applied to commercial herbicides and water samples (naturals and for human consumption). The results obtained in the determination of glyphosate in the commercial herbicides employing diffuse reflectance were agree with the results obtained by employing flow injection analysis, which presented levels of 378.8 g L-1 to the A sample, 392.4 g L-1 to the B sample and 330.6 g L-1 to the C sample... (Complete abstract click electronic access below)

The strategy required for the development of the immunochemical reagents needed for a non-competitive assay for the detection of haptens was investigated. For this work, these reagents were termed "anti-complex" antibodies. To preserve the integrity of such an assay, these "anti-complex" antibodies should not react with either the free anti-hapten antibody or the free hapten and they should not compete with the hapten for binding to the anti-hapten antibody. Anti-hapten hybridomas were developed using standard hybridoma technology. The development of anti-complex hybridomas was investigated using standard hybridoma technology and the novel approach of intrasplenic immunization. Both immunization protocols addressed the three questions concerning the strategy for developing such hybridomas, namely the type of immunization (snygeneic or allogeneic), the physico-chemical nature of the hapten in the complex (free or conjugated) and the physico-chemical nature of the anti-hapten antibody in the complex (intact or fragmented). (Abstract shortened with permission of author.)