Navegando por Autor "Freitas Filho, João Rufino de"

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Experimentação utilizando como contexto alimentos e alimentação: uma abordagem para o ensino de Química
(2023-05-12) Oliveira, Gabriela Alves de; Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850; http://lattes.cnpq.br/2277869864110720
Chemistry classes are seen by many students as boring or difficult to understand, generating disinterest and discouragement in the study of this science. One way of reversing this situation is the insertion of contextualization and experimentation in chemistry teaching, as a way of bringing scientific knowledge closer to students' daily lives, as well as arousing greater interest from experimental activities. Having foods and feeding as this focus, it emerges as the main theme for an experimentation activity, since they are treated at all levels of education and are part of everyone's life. That way, this study was carried out in a municipal school in Recife - PE, with students from the 6th to the 9th grade of elementary school and had the general objective: To develop and carry out an experimentation activity in the teaching of chemistry, seeking to promote the awareness of students of a school in the city of Recife on the quality of food and healthy eating practices, in order to contextualize chemical knowledge with everyday life. The research, classified as qualitative and of the pedagogical intervention type, was carried out with 22 students participating in the Science Club of the Science and Technology Laboratory of the school, in three meetings, each lasting 60 minutes. In the first methodological moment, the students' previous conceptions about the concepts of foods, healthy eating and food quality were collected; In the second stage, a dialogic expository class was held, seeking to introduce students to the chemistry present in this theme; And in the third and last stage, the importance of food quality was discussed and an experimental activity was performed on the physical-chemical analyzes used to attest to the quality of the milk consumed by the students. Data collection was made from questionnaires applied during the pedagogical intervention, as well as observations of the class during classes. It was noticed with the answers to the questionnaires, that at the beginning of the activity, most students did not have knowledge about the composition of foods, but that in general they had a balanced diet due to the number of meals eaten in the full school. During the execution of the activity, especially in the experimentation part, the class showed a lot of interest in studying the subject and because it was something that was part of their daily life, there was great participation and acceptance of the class, thus concluding that contextualization and experimentation are essential and in fact great allies for the teaching of chemistry. In the end, it was found that there were advances in the answers given by the students and it is hoped that with this activity, the participating students have awakened to issues related to healthy eating, food quality and how chemistry is present in the most diverse situations around us,not just limited to what is studied in the classroom.
Memorial descritivo: memória da caminhada acadêmico-profissional na constituição da identidade profissional como professor-pesquisador
(Universidade Federal Rural de Pernambuco, 2021-10-15) Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850
Montagem de uma aparelhagem com materiais alternativos para a extração do limoneno das cascas de laranja
(2022-06-01) Silva Filho, Josué Berto da; Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850
Essential oils are volatile substances and can be obtained through several methods: hydrodistillation, extraction by organic solvents, steam distillation, extraction by supercritical fluid, flowering, cold pressing, among others. This work aimed to investigate the extraction of essential oils from the orange peel using a distillation apparatus assembled with alternative materials and to compare its efficiency with the conventional apparatus used in the laboratory. For the extraction of limonene, the methodology used was the hydrodistillation technique, which is an old and versatile method in which the plant material remains in contact with boiling water, the steam forces the cell walls to open and the oil that is between them evaporates. the plant cells. The proposal to build the material and extract the oil was due to the need to facilitate the teaching and learning of chemistry concepts in high school. The idea of extracting the essential oil from the orange peel was an artifice used to encourage experimental activities at school. Because, when observing an experiment, the student has the opportunity to make an internal reconstruction of everything experienced at that moment. In conclusion, in this work, the construction of a low cost homemade condenser was elaborated, using alternative materials and later the oil extraction where some concepts can be studied, such as boiling point, condensation, evaporation, intermolecular forces, solubility, polarity etc.
Síntese e caracterização de 2-(3-aril-1,2,4-oxadiazol-5-il)-(1E,3E)-penta-1,3-dien-1-ila
(2024-03-07) Silva, Juliana Carolina do Nascimento; Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850; http://lattes.cnpq.br/6231482289837230
1,2,4-oxadiazoles are heterocyclic compounds containing two nitrogen atoms, one oxygen atom and two double bonds in their structure and due to their low aromaticity they are called a conjugated system. Due to its notable importance of its biological properties such as: anti-inflammatory, anti-asthmatic, anti-cancer, anti-tumor, among others. In this work, the synthesis and characterization of 1,2,4-oxadiazoles from amidoximes and ethyl sorbate are described. The approach adopted was qualitative and experimental. Characterization was carried out by infrared spectroscopy and ¹H and ¹³C nuclear magnetic resonance. The results revealed that the arylamidoximes obtained by the stirring method for 24 hours showed good yields, ranging from 75% to 90%. Ethyl sorbate prepared by Fischer esterification showed a yield of 82%. However, the 1,2,4-oxadiazoles obtained by the superbase method showed yields between 45% and 50%, due to the formation of byproducts with similar polarity to the compound of interest.
Síntese e docking molecular de 1,2,4-oxadiazol como potencial agente antioxidante
(2024-07-30) Silva, Ryan Henrique Gomes da; Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850; http://lattes.cnpq.br/6976073462477884
The present work aimed to synthesize and characterize 1,2,4-oxadiazoles 29a-c, and to evaluate their antioxidant capacity using in vitro and computational methods. For this purpose, the synthesis of an important precursor, the arylamide oximes 27a-c, was carried out using the magnetic stirring method, obtaining excellent yields (84.9% - 95.7%). Then, the synthesis of 1,2,4-oxadiazoles 29a-c was described using the solvent-free method, which does not use solvents, bases or salts, obtaining low to moderate yields (30.6% - 56.2%). Furthermore, these heterocyclics were characterized by IR, 1H NMR and melting point. Thus, with the application of the DPPH• and ABTS•+ free radical scavenging test, it was found that the 1,2,4-oxadiazoles presented better results in reducing these radicals in the ABTS•+ method than in DPPH•, with emphasis on compound 29b (EC50 = 4.055 μg.mL-1), which presented promising free radical scavenging capabilities very similar to the standard antioxidant TROLOX (EC50 = 4.1 μg.mol-1), used as a positive control. Regarding the computational procedures, the molecular docking method was used to verify the energetic stability and the types of interaction of the complexes formed with compounds 29a-c and a pro-oxidant enzyme, Xanthine Oxidoreductase (ID PDB: 1N5X), which is involved in the superoxide release process. Therefore, based on the LGA calculations of the AutoDock 4.2.6 program, it was observed that the 1,2,4-oxadiazoles used as ligands formed stable complexes with the target enzyme, highlighting compound 29c (ΔH = –7.69 kcal.mol-1), which generated a complex with more stable energy close to the original inhibitor ligand, Tei-6720 (ΔH = –8.63 kcal.mol-1), indicating these compounds as potential antioxidants.
Síntese verde e assinalamento completo de novos oxadiazóis 2,3-enopiranosídeos
(2021-12-22) Acioli, Bianca Micaela Macario Gonçalves; Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850; http://lattes.cnpq.br/7172195105463623
In carbohydrate chemistry, the 2,3-unsaturated O-glycoside is a vital organic molecule with varied biological applications that can be enhanced by utilizing other functional groups that are linked through the glycosidic bond. In this work, the use of the 1,2,4-Oxadiazole functional group as an aglycone connected to the saccharide group was developed, considering that it has multiple applications, whether in medicinal chemistry, in the chemistry of new materials or also in agricultural chemistry. The synthesis and characterization of different arylamidoximes, precursors of the oxadiazole ring, are also described; of 1,2,4-oxadiazole and of the 2,3-enopyranoside ring, as sequenced reactions. Deriving from the synthesis of arylamidoximes, the results were obtained in good yields (80-90%) when compared with results already described in the literature. The six specimens of 3,5-Disubstituted-1,2,4-oxadiazole were synthesized through the methodology of heating without solvent and without base, which constitutes an innovative method to obtain 1,2,4-oxadiazoles, with yield ranging from 40-70%. After synthesizing the 1,2,4-oxadiazoles, they were reacted with tri-o-Acetyl-D-Glical in the presence of Montimorillonite K-10, as a catalyst, using a focused microwave under different reaction conditions, with yield of 25-50%. The structures of the compounds obtained were clarified using conventional spectroscopic techniques: Infrared and 1H and 13C Nuclear Magnetic Resonance. Despite the divergence between the yields obtained, this project demonstrates the importance of adopting green and eco-conscious synthesis, aiming at the preservation of the environment and the safety of employees for the construction of an inclusive and plural chemistry.
Síntese, caracterização e atividades biológicas de 1,2,4-oxadiazóis
(2020-10-22) Silva, André Ricardo França da; Freitas Filho, João Rufino de; http://lattes.cnpq.br/9252404584350850; http://lattes.cnpq.br/6873023837824366