Estudo de N-metilformamida em meio aquoso e não aquoso (THF)
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Data
2012-02-17
Autores
Borges, Alexandre [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Utilizando a simulação molecular com método Monte Carlo estudou-se neste trabalho as características estruturais e termodinâmicas dos líquidos puros N–Metilformamida (NMF) e Tetrahidrofurano (THF), bem como de suas misturas em diferentes concentrações. Realizou- se também um estudo das características estruturais e termodinâmicas de misturas N– Metilformamida–Água, em diferentes concentrações, para fins de comparação. Os resultados estruturais obtidos para os líquidos puros foram comparados com resultados experimentais de difratometria de nêutrons com posterior refinamento estrutural por potencial empírico (EPSR). Na simulação computacional foi utilizado o programa DIADORIM. As simulações foram realizadas no ensemble estatístico NpT, ou seja, com número de moléculas, pressão e temperatura constantes. O número total de moléculas na caixa de simulação foi de 400, à pressão de 1 atm e à temperatura de 298,15K. A concordância entre os resultados experimentais e teóricos dos líquidos puros foi boa, o que permitiu prosseguir sabendo que os resultados obtidos para as misturas seriam confiáveis. Em relação aos líquidos puros foi mostrada a presença de ligações de hidrogênio na estrutura da NMF e da água, sendo que estes líquidos apresentam-se bem estruturados. Conclui-se que o THF apresenta estrutura ―desorganizada‖.Os resultados obtidos para a mistura NMF–THF sugerem a existência de ligações de hidrogênio entre estas moléculas de NMF e THF no líquido, e os valores de suas energias de ligação de hidrogênio, segundo os resultados obtidos, apresentam valores semelhantes à interação NMF–NMF, o que juntamente com a observação das propriedades termodinâmicas estudadas neste trabalho indicam um comportamento ideal da solução. Também pode ser observado...
The structural and thermodynamic properties of pure liquids N-methylformamide (NMF) and Tetrahydrofuran (THF), as well as their mixture in different concentrations were studied through Monte Carlo simulation. The structural and thermodynamic properties of N– Methylformamide–water in different concentrations was also investigated, aiming comparisons. The structural results obtained to pure liquids were compared to experimental results of neutron diffratometry with empirical potential structure refinement (EPSR). For the computational simulation, was used the DIADORIM program. The simulations were carried out on the NpT statistical ensemble. The total number of molecules in the simulation box was 400, over a 1 atm pressure and 298,15K temperature. The accordance between the experimental and theoretical structure of pure liquids was good, what permits to infer on the reliability of the results obtained for the mixtures. Regarding to pure liquids it was shown the presence of hydrogen bonds in NMF and water structures, being that those liquids are well structured. It was not observed the presence of hyrogen bonds among the molecules of THF presenting this liquid a disorganized structure. The obtained results of the NMF–THF mixture, suggest the presence of hydrogen bonds between those molecules in the liquid. It was also observed by the obtained results that this liquid is well structured. The mixture NMF–water, as well as the mixture NMF-THF, are well structured, but either NMF and water are proton acceptors and donors and leads to the presence of two hydrogen connections between NMF and water molecules. The study of structural and thermodynamic properties of the mixture NMF–water, show a proper behavior for the solution, as in the case THF-NMF, but when comparing NMF-NMF in both cases, the water appeared to interfere more on the interaction between NMF molecules than THF ones
The structural and thermodynamic properties of pure liquids N-methylformamide (NMF) and Tetrahydrofuran (THF), as well as their mixture in different concentrations were studied through Monte Carlo simulation. The structural and thermodynamic properties of N– Methylformamide–water in different concentrations was also investigated, aiming comparisons. The structural results obtained to pure liquids were compared to experimental results of neutron diffratometry with empirical potential structure refinement (EPSR). For the computational simulation, was used the DIADORIM program. The simulations were carried out on the NpT statistical ensemble. The total number of molecules in the simulation box was 400, over a 1 atm pressure and 298,15K temperature. The accordance between the experimental and theoretical structure of pure liquids was good, what permits to infer on the reliability of the results obtained for the mixtures. Regarding to pure liquids it was shown the presence of hydrogen bonds in NMF and water structures, being that those liquids are well structured. It was not observed the presence of hyrogen bonds among the molecules of THF presenting this liquid a disorganized structure. The obtained results of the NMF–THF mixture, suggest the presence of hydrogen bonds between those molecules in the liquid. It was also observed by the obtained results that this liquid is well structured. The mixture NMF–water, as well as the mixture NMF-THF, are well structured, but either NMF and water are proton acceptors and donors and leads to the presence of two hydrogen connections between NMF and water molecules. The study of structural and thermodynamic properties of the mixture NMF–water, show a proper behavior for the solution, as in the case THF-NMF, but when comparing NMF-NMF in both cases, the water appeared to interfere more on the interaction between NMF molecules than THF ones
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Palavras-chave
Simulação (Computadores), Metodo de Monte Carlo, Monte Carlo method
Como citar
BORGES, Alexandre. Estudo de N-metilformamida em meio aquoso e não aquoso (THF). 2012.. 85 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Engenharia de Ilha Solteira, 2012..