Experimental Study on the Thermochemistry of Some Derivatives of Piperidinol

Abstract

Standard (p° = 0.1 MPa) massic energies of combustion for 1-methyl-3-piperidinol, 1-ethyl-3-piperidinol, and 1-methyl-4-piperidinol were measured at T = 298.15 K by static bomb calorimetry. The standard molar enthalpies of formation of the condensed phase were derived. The standard molar enthalpies of vaporization at T = 298.15 K of the three piperidinol derivatives studied were determined by high-temperature Calvet microcalorimetry. The respective standard molar enthalpies of formation in the gaseous phase at T = 298.15 K were derived.

Temperature Dependence of the Dissociative Electron Attachment to 2-Thiothymine

“…As shown in Figure 1, ΔP meas plotted as a function of 1/T follows the Clausius− Clapeyron equation ln(ΔP meas ) = C − B meas /T, 17 indicating that the investigated material directly sublimates from the solid. From this present experimental data, B meas is measured to be 14727.5 K, which is found to be lower by about 8% than that obtained by thermochemistry measurements (B therm = 15754.5 K 18 ). This difference is likely to be attributed to the accuracy of our pressure gauge in the chamber, and therefore, we will use the thermochemistry data to recalibrate the measured pressure: ΔP = A•ΔP meas •exp(−(B them − B meas )/T), "A" being a scaling factor.…”

A thermodynamic study of ketoreductase-catalyzed reactions 5. Reduction of substituted ketones in n-hexane

“…These results are consistent with the hydrogen bond suggested spectroscopically for the 3-isomer [36] and the resultant stabilization and the seeming absence of such stabilization for the 4-isomer [37]. However, it is not consistent with the calorimetrically determined standard molar enthalpies of formation [32]. Conversely, the standard molar enthalpy of formation and the standard molar Gibbs free energy of formation of 4-piperidinone is calculated to be 7.3 kJ AE mol À1 more stable than the 3-isomer.…”

“…The standard molar enthalpies of formation of a variety of substituted piperidines have recently been reported by Ribeiro da Silva and Cabral [32][33][34]. These authors report [32] D f H m ¼ Àð289:2 AE 1:7Þ kJ Á mol À1 and D f H m ¼ Àð298:3 AE 1:7Þ kJ Á mol À1 , respectively, for 1-methyl-3-hydroxypiperidine(l) and 1-methyl-4-hydroxypiperidine(l). The corresponding values for the gas phase species are D f H m ¼ Àð225:5 AE 2:0Þ kJ Á mol À1 and D f H m ¼ Àð226:8 AE 1:8Þ kJ Á mol À1 .…”

Thermochemical study of some chloro and bromo alkyl substituted phthalimides: Structural–energetic correlations

“…The systematic experimental and theoretical study on the energetics of nitrogen aromatic heterocycles has been, for some years, one of the main interests of our research group, as being partially presented in two review papers [1,2] and lately extended to other aromatic nitrogen heterocycles like azols [3][4][5][6][7][8][9], phenylpyridine isomers [10], chloropyridines [11], pyrimidines [12], quinoxalines [13] and quinolines [14,15]. More recently our research interested have focused on non-aromatic nitrogen heterocycles with the piperidine ring [16][17][18][19][20][21][22] and with the phthalimide structure [23,24].…”