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Argilas como catalisadores verdes na esterificação do colesterol: caracterizaçã...
Maria,Teresa M. R.; Nunes,Rui M. D.; Pereira,Mariette M.; Eusébio,M. Ermelinda S.A laboratory experiment that enables the professor to introduce the problematic of sustainable development in pharmaceutical chemistry to undergraduate students is proposed, using a simple synthetic procedure. Cholesteryl acetate is prepared by the esterification of cholesterol using Montmorillonite K10 as heterogeneous catalyst. Cholesterol and cholesteryl acetate are characterized by spectroscopic (¹H RMN, 13...
Molar Heat Capacity of 1,2-Cyclohexanediol Isomers From (173 to 428) K
Maria, Teresa M. R.; Eusébio, M. Ermelinda S.Heat capacities of cis-1,2-cyclohexanediol and trans-1,2-cyclohexanediol enantiomers have been determined in the solid state in the temperature range T = (173 to 368) K for the cis-isomer and T = (173 to 373) K in the case of the trans-isomer and in the liquid state at temperatures up to 428 K. Measurements were carried out by differential scanning calorimetry using the enthalpic method. For the cis-isomer, the...
Enthalpy of sublimation/vaporization of trans-cyclohexyl-1,4-diamine and cis-cy...
Tomé, Luciana I. N.; Rosado, Mário T. S.; Nunes, Sandra C. C.; Maria, Teresa M. R.; Canotilho, João; Eusébio, M. Ermelinda S.The molar enthalpy of sublimation, , of trans-cyclohexyl-1,4-diamine and the molar enthalpy of vaporization, , of cis-cyclohexyl-1,2-diamine, at the temperature 298.15 K, were determined by calorimetry. was obtained for the trans-isomer and for the cis form. The molar enthalpy of fusion of the first compound, at T = 342.1 K, was determined by differential scanning calorimetry. The molar enthalpy of vaporization...
The low temperature crystalline and glassy states of methyl -hydroxy-isobutyrate
Jarmelo, Susana; Maria, Teresa M. R.; Leitão, Maria Luísa P.; Fausto, RuiThe low temperature crystalline and glassy phases of methyl -hydroxy-isobutyrate (MHib) were identified and characterized structurally by differential scanning calorimetry, IR and Raman spectroscopy and molecular modeling. Within the temperature range 13–171 K, MHib exists as a glassy state, where individual molecules may assume the two conformational states previously observed for this compound isolated in an ...
Structural and vibrational characterization of methyl glycolate in the low temp...
Jarmelo, Susana; Maria, Teresa M. R.; Leitão, Maria Luísa P.; Fausto, RuiThe low temperature phases of methyl glycolate (MGly) were identified and characterized structurally by differential scanning calorimetry, infrared and Raman spectroscopies and molecular modeling. Within the temperature range 13–273 K, MGly may exist in three solid phases. A crystalline phase (I) can be formed from the liquid upon slow cooling [Tonset=222–227 K] or from the low temperature glassy state resultin...
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