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Conformational Space and Photochemistry of α-Terpinene
Marzec, K. M.; Reva, I.; Fausto, R.; Malek, K.; Proniewicz, L. M.α-Terpinene is a natural product that is isolated from a variety of plant sources and is used in the pharmaceutical and perfume industries. In the atmosphere, under the influence of sunlight, α-terpinene undergoes a series of photochemical transformations and contributes to the formation of the secondary organic aerosols. In the present work, α-terpinene has been isolated in low-temperature xenon and argon matr...
The Chapman-type rearrangement in pseudosaccharins: The case of 3-(methoxy)-1,2...
Kaczor, A.; Proniewicz, L.M.; Almeida, R.; Gómez-Zavaglia, A.; Cristiano, M.L.S.; Beja, A.M. Matos; Silva, M. Ramos; Fausto, R.The thermal Chapman-type rearrangement of the pseudosaccharin 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID) into 2-methyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide (MBIOD) was investigated on the basis of computational models and knowledge of the structure of the reactant and product in the isolated and solid phases. X-ray diffraction was used to obtain the structure of the substrate in the crystalline phas...
Matrix-Isolated Monomeric Tryptophan: Electrostatic Interactions as Nontrivial...
Kaczor, A.; Reva, I. D.; Proniewicz, L. M.; Fausto, R.An extensive analysis of the conformational space of tryptophan (Trp) was performed at the B3LYP/6-311++G(d,p) level and verified by comparison with the infrared spectra of the compound isolated in low-temperature argon and xenon matrixes. Different types of conformers have been unequivocally identified in the matrixes. Type I exhibits the trans arrangement of the carboxylic group and is stabilized by an O−H···...
Importance of Entropy in the Conformational Equilibrium of Phenylalanine: A Ma...
Kaczor, A.; Reva, I. D.; Proniewicz, L. M.; Fausto, R.The conformational behavior and infrared spectrum of l-phenylalanine were studied by matrix-isolation infrared spectroscopy and DFT [B3LYP/6-311++G(d,p)] calculations. The fourteen most stable structures were predicted to differ in energy by less than 10 kJ mol-1, eight of them with abundances higher than 5% at the temperature of evaporation of the compound (423 K). Experimental results suggest that six conform...
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