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Conventional methods for forming 2, 4-dinitrophenylhydrazones usually leave traces of acids complexed with derivatives and cause variable melting points. NMR studies showed that traces of acids catalyse the syn-anti isomerization or dehydration of the products and thus cause the melting point anomalies. In recent years anention has been directed to the use of other solvents in which the reagent as the free base is more soluble and which therefore do not require the high acid concentration used in earlier procedures.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2013. / Submitted by Larissa Stefane Vieira Rodrigues (larissarodrigues@bce.unb.br) on 2014-11-03T16:28:05Z No. of bitstreams: 1 2013_LorranaNaraNavesNóbrega.pdf: 3512692 bytes, checksum: 6d3a4a9f33fd9e06e8dc8f8c3cc466a8 (MD5) / Approved for entry into archive by Tania Milca Carvalho Malheiros(tania@bce.unb.br) on 2014-11-03T16:46:16Z (GMT) No. of bitstreams: 1 2013_LorranaNaraNavesNóbrega.pdf: 3512692 bytes, checksum: 6d3a4a9f33fd9e06e8dc8f8c3cc466a8 (MD5) / Made available in DSpace on 2014-11-03T16:46:16Z (GMT). No. of bitstreams: 1 2013_LorranaNaraNavesNóbrega.pdf: 3512692 bytes, checksum: 6d3a4a9f33fd9e06e8dc8f8c3cc466a8 (MD5) / Este trabalho descreve o desenvolvimento e a avaliação de microssistemas de análise por injeção em fluxo (µFIA) para as determinações de nitrito (NO2-), nitrato (NO3-), e fosfato (PO4-3) em águas doces. Para todos os µFIA, a fotolitografia profunda no ultravioleta foi empregada para fabricação dos dispositivos a partir de um fotorresiste a base de uretana-acrilato (UA). Todos os dispositivos apresentaram dimensões tão pequenas quanto à de um cartão de crédito (7,0 cm x 4,0 cm x 0,5 cm) e canais de formato em “U” com até 390 μm de profundidade. Um procedimento simples e de baixo custo foi utilizado para a integração de uma coluna redutora de cádmio ao FIA de NO3-, por meio da inserção manual de grânulos de cádmio selecionados (0,5 a 1,0 mm) à um reservatório dedicado (1,00 mm x 0,65 mm x 20 mm). A coluna demonstrou bom desempenho com 97,5% de eficiência de redução (NO3- para NO2-) e ausência de vazamentos para vazões superiores a 2,0 mL min-1. Os sinais analíticos transientes obtidos com os microssistemas propostos apresentaram razões sinal/ruído satisfatórias e permitiram ajustes lineares (R > 0,99) para as faixas de concentração estudadas (0,06 a 0,37 mg N L-1 (NO2-); 0,23 a 2,26 mg N L-1 (NO3-) e 1,0 a 8,0 mg P L-1 (PO4-3)) sendo estimados os limites de detecção de 0,15 mg N L-1 (NO3-), 0,03 mg N L-1 (NO2-) e 0,54 mg P L-1 (PO4-3). Para as determinações de NO3- e NO2- as figuras de mérito estimadas demonstraram adequação a regulamentação brasileira para águas doces. Empregando-se amostras de águas doces superficiais e/ou amostras de águas comerciais, recuperações de 90,4 % a 114,7 % foram obtidas e não foram observadas diferenças significativas (95% de confiança) entre os valores determinados com os microssistemas e aqueles determinados a partir de métodos de referência, demonstrando uma boa exatidão dos procedimentos. Para todas as determinações, reduções significativas no consumo de reagentes e na geração de resíduos foram observadas em relação aos sistemas de análise por injeção em fluxo usuais, demonstrando que os dispositivos propostos atendem aos preceitos da química verde. ______________________________________________________________________________ ABSTRACT / This work describes the development and evaluation of flow injection analysis (µFIA) microsystems for nitrite (NO2-), nitrate (NO3-), and phosphate (PO4-3) determinations in fresh waters. For all µFIA, deep ultraviolet photolithography was used for fabrication of the devices using a photoresist based on urethane acrylate (UA) photoresist. All devices present dimensions as small as a credit card (7.0 cm x 4.0 cm x 0.5 cm) and "U" shape channels with up to 390 μm deep. A simple and inexpensive procedure was used for the integration of a cadmium reduction column to the µFIA applied for NO3- determination by using manual insertion of selected cadmium particles (0.5 to 1.0 mm) into a dedicated reservoir (1.00 mm x 0.65 mm x 20 mm). The column presented a good performance with an efficiency of reduction of 97,5% (NO3- to NO2-) and no leaks for flow rates higher than 2.0 mL min-1. The proposed microsystem showed adequate signal to noise ratios and provided linear relationships (R> 0,99) for the concentration range studied (0.06 to 0.37 mg L-1 N (NO2-), 0.23 to 2.26 mg L-1 N (NO3-) and 1.0 to 8.0 mg L-1 P (PO4-3)) with estimated detection limits of 0.15 mg L-1 N (NO3 -), 0.03 mg L-1 N (NO2-) and 0.54 mg L-1 P PO4-3). For the determination of NO3- and NO2-, the estimated figures of merit were adequate to Brazilian regulations for freshwater. By employing the proposed devices to fresh superficial water samples and/or commercial water samples, recoveries of 90.4% to 114.7% were obtained and no significant differences were observed (95% confidence) between the values determined with microsystems and those determined from reference methods, demonstrating good accuracy of the procedures. For all determinations, significant reductions in reagent consumption and waste generation were observed when compared to usual flow injection analysis systems demonstrating that the proposed devices are appropriate to the principles of green chemistry.

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La tesis describe el diseño y la síntesis de geles moleculares funcionalizados con fragmentos catalíticos de feniltriazol (PhTzValn), benciltriazol (BzTzAValn) y azidocoumarinatriazol (RAzTzValn) y su aplicación como catalizadores heterogéneos de la reacción de cicloadición azida-alquino catalizada con cobre (CuAAC). Los gelantes sintetizados demostraron capacidad para complejar el cobre (I), resultando en un aumento de sus propiedades mecánicas. Aparte de la actividad catalítica verificada en la reacción `click' entre la bencilazida y el fenilacetileno, la familia de gelantes PhTzValn demuestra también capacidad para catalizar su propia síntesis. El metalogel Cu(I)-PhTzVal3 ha sido utilizado en la catálisis de un sistema multicomponente de las reacciones tándem aldol-`click', promoviendo la formación de un compuesto aldol-triazol. El metalogel anfifílico Cu(I)-Et2NAzTzValn exhibió una mejor actividad catalítica en la reacción `click' modelo entre la bencilazida y el fenilacetileno, derivada de su auto-ensamblaje dinámico. / This thesis describes the design and synthesis of amino acid derived molecular gels functionalized with phenyltriazole (PhTzValn), benzyltriazole (BzTzAValn) and azidocoumarinetriazole (RAzTzValn) catalytic fragments and their application as heterogeneous catalysts on the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The synthesized gelators were able to coordinate copper(I), resulting in the formation of metallogels with improved mechanical properties. Apart from catalytic activity demonstrated towards the model `click' reaction between benzylazide and phenylacetylene, the family of gelators PhTzValn also exhibited autocatalytic activity, being capable of a catalyzing their own synthesis in a self-sustainable way. The metallogel Cu(I)-PhTzVal3 was successfully applied as a tandem heterogeneous catalyst of a three-component reaction system composed by an aldol and a `click' reaction, resulting in the formation of an aldol-triazole compound. The amphiphilic metallogel Cu(I)-Et2NAzTzValn demonstrated the best catalytic activity towards the model `click' reaction between benzylazide and phenylacetylene, arising from the transient self-assembly behavior of the metallogel.

La investigación de esta tesis se centra en la producción de nanoestructuras metálicas dentro de aceites orgánicos y nano-ensambles por ablación láser en líquidos para resolver los mayores problemas en su producción por métodos convencionales: poca estabilidad, producción de residuos químicos y reacciones químicas sin control debido a problemas de pureza. En particular, las mayores contribuciones son, la síntesis de nanofluidos basados en nanopartículas de oro que pueden ser utilizados como absorbentes volumétricos de luz e intercambiadores de calor. La fabricación de un nanofluido con una mejora de conductividad térmica de 4,06% sobre un fluido de transferencia de calor comercial, una mezcla eutéctica de óxido de bifenilo y difenilo, y la mejor estabilidad coloidal reportada en la literatura usando estos materiales. Y, por último, la demostración de la reducción parcial de láminas de óxido de grafeno y su decoración con nanopartículas de oro con ligandos libres, en un solo paso. / The research conducted during this thesis work is focused on producing metal nanostructures inside organic oils and nano-essambles by Pulsed Laser Ablation in Liquids (PLAL) to solve the biggest issues on their production by conventional approaches: Poor stability, production of chemical waste and uncontrolled chemical reactions due to purity problems. In particular, the biggest contributions achieved on the present work, lies on the experimental demonstration of the synthesis of gold nanoparticles-based aqueous nanofluids that can be used as both volumetric light absorbers and heat exchangers. The fabrication of a nanofluid with a thermal conductivity enhancement of 4.06% over a commercial heat transfer fluid, an eutectic mixture of biphenyl and diphenyl oxide, and the best colloidal stability reported in the literature using these materials. And finally, demonstration of partial reduction of graphene-oxide sheets and its decoration with ligand-free gold nanoparticles, in a single reaction stage avoiding the production of chemical waste.