Licenciatura em Química (UAST)
URI permanente desta comunidadehttps://arandu.ufrpe.br/handle/123456789/2945
Siglas das Coleções:
APP - Artigo Publicado em Periódico
TAE - Trabalho Apresentado em Evento
TCC - Trabalho de Conclusão de Curso
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2 resultados
Resultados da Pesquisa
Item Síntese do pigmento CoCr2O4 pelo método de gelatina comercial(2018) Sousa, Tassia Pereira de; Câmara, Maria Suely Costa da; http://lattes.cnpq.br/9163311260887432; http://lattes.cnpq.br/7879045291487919There is a growing interest of the ceramic industries in developing more stable pigments that are low cost and little environmental damage. The ceramic industries mainly use pigments of predominantly inorganic nature, such pigments are the most used because they havean excellent chemical and thermal stability besides a lower toxicity to the man and few environmental damages. The most commonly used inorganic pigments used in ceramics are mixed oxides with spinel structure and AB2O4. Spinels are one of the most interesting crystalline structures in the development of stable and chemically inert pigments. In this structure, ions of different oxidation states are present in both tetrahedral and octahedral sites. In addition, there are several ways of arranging the cationsat these sites (normal and inverse spinel). These characteristics led to the development of different colors, being these intense and stable, suitable for use as pigments. Among the compounds used as ceramic pigments, we have highlighted CoCr2O4which is a mineral oxide belonging to the group of spinel, such structures cover a group of well-establishedmagnetic materials that may have a green coloration. The objective of the present work was to synthesize the CoCr2O4pigment using commercial gelatin as precursor and to characterize the following techniques: Thermogravimetric analysis (TG), Xray diffraction (XRD), surface area (BET), Scanning electron microscopy (SEM) spectroscopy in the infrared region (FTIR), and colorimetric measurements by the CIEL*a*b*method. The route of synthesis used was confirmed viable from the results. Crystalline, monophasic and high surface area compounds were obtained. The powders presented green coloration with phase obtained from 500 ºC.Item Alilação do tipo Barbier de Aldeídos aromáticos promovida por Zn e catalisada por L-Prolina em meio aquoso(2019) Souza, Fabrícia Aparecida Marques de; Silva, Renato Augusto da; http://lattes.cnpq.br/5111987334920733; http://lattes.cnpq.br/0102375050840904Given the various strategies to form C-C bonding, involving organometallic intermediates, the Barbier reaction has proved to be an important methodology that can be performed efficiently in aqueous media with several advantages.The use of organocatalysts has also been very advantageous in various chemical reactions to a synthesis of safe and environmentally correct products.In this work, synthetic methodologies were studied to obtainhomoallyl alcoholsby means of alilation of the Barbier type. In order to follow the principles of green chemistry, the method relies on allylation reactions from aromatic aldehydes, allyl bromide, zinc and L-proline as catalyst, using water as the solvent. Aromatic aldehydes with allyl bromide, zinc and a 20% L-proline as catalyst were tested, being 4-F-benzaldehyde, 4-OMe-benzaldehyde and 2-naphthaldehyde using water as the solvent. Secund, the increase in the amount of L-proline to 80% was added and 3 aromatic aldehydes were tested, being 4-F-benzaldehyde, 2-OH-benzaldehyde and 2-OMe-benzaldehyde with allyl bromide, zinc and water. All data were previously monitored by CG-FID and CCD and the homoallyl alcoholswere characterized from the respective signals by GC-MS, throughcomputerized comparison of the library masses of the apparatus itself and the specific fragmentation pattern.In the first 3, with 20% L-proline, excellent conversions were detected, but 4-F-benzaldehyde was fully converted to 1-(4-fluorophenyl) but-3-en-1-ol with only 1h of magnetic stirring , 4-OMe-benzaldehyde converted to 1-(4-methoxyphenyl) but-3-en-1-ol with 4h and 2-naphthaldehyde converted to 1-(2-naphthyl) but-3-en-1-ol with 1h, in all cases, without formation of by-products. Subsequently, in the last 3 assays, with 80% proline L, the reaction time of 4-F-benzaldehyde was reduced to 30 minutes with complete conversion of the 1-(4-fluorophenyl) but-3-en-1-ol alcohol; 2-OH-benzaldehyde and 2-OMe-benzaldehyde were converted respectively into 1-(2-hydroxyphenyl) but-3-en-1-ol and 1-(2-methoxyphenyl) but-3-en-1, however, traces of the starting materials were still detected. The 1-(4-fluorophenyl) but-3-en-1-ol and 1-(2-naphthyl) but-3-en-1-ol alcohols were also characterized by 1 H and ¹³C NMR.