The vaporization enthalpy and vapor pressure of S (+)-methamphetamine at T=298.15K by correlation gas chromatography

Vapor pressures and vaporization enthalpies of a series of esters used in flavors by correlation gas chromatography

“…The equation of this line can then be used to evaluate the vaporization enthalpy of the targets at temperature T. In these experiments the vaporization enthalpies are generally referenced to T = 298.15 K. Best results are obtained when the enthalpies of transfer of the standards bracket those of the targets, resulting in better adjustments for the heat capacity differences between the liquid and gas phase of the target substances [4,5]. Vapor pressures can also be obtained from correlations between ln(p/p o ) and ln(t o /t a ).…”

The Vaporization Enthalpy and Vapor Pressure of (±) N-Ethyl Amphetamine by Correlation Gas Chromatography

“…Vapor pressure results for N-ethylamphetamine are reported in Tables 6 and 7. A vapor pressure of (19 ± 11) Pa compares to a value of 38 Pa evaluated for S (+)-methamphetamine at T = 298.15 K. Similarly, estimated boiling temperatures at p = 101,325 Pa of T = (490 [8], 489 [21]) K for S (+)-methamphetamine compare to a corresponding estimated temperature of T = (499 ± 3 (this work), 508 [21]) K. Additionally, several experimental boiling temperatures at reduced pressures have been reported for N-ethylamphetamine. Figure 2 provides a qualitative comparison of these values to the values evaluated in this work.…”

“…As indicated in the table, only one set of Antoine constants are applicable at ambient temperatures. We have previously observed however, that the vapor pressures generated by these constants, correlated quite well as a function of temperature [8]. With the exception of 4-benzylpiperidine, all amines are members of a homologous series.…”

“…Our laboratory has been investigating the use of a technique referred to a correlation gas chromatography to evaluate both vaporization enthalpies and vapor pressures of materials that are either difficult to access, or beyond the current capabilities of most conventional techniques used for these purposes. This includes substances that are present in complex mixtures [5,6], are either quite non-volatile [7], or as in this case, available only in very small quantities [8]. This work describes our results for (±) N-ethylamphetamine whose structure is given in Figure 1 along with the materials used as standards.…”

“…All correlation coefficients (r 2 ) exceeded 0.9968 over this temperature range. Table 6 illustrates the correlation performed at T = 298.15 K. The resulting values of ln (p/p o ) as a function of temperature were then fit to a second order polynomial, Equation (8). The resulting constants of Equation ( 8) are provided in Table 7.…”