The Vaporization Enthalpies and Vapor Pressures of Some Primary Amines of Pharmaceutical Importance by Correlation Gas Chromatography

Abstract

Vapor pressures, vaporization, and sublimation enthalpies of several pharmaceuticals have been evaluated by a combination of correlation chromatography experiments, differential calorimetry measurements with existing literature values. The compounds investigated and their properties include 1-adamantylamine [Δcr l H m(T fus)/kJ·mol–1 = (7.3 ± 0.2); T fus/K = (477.4 ± 0.9); Δl g H m(298.15 K)/kJ·mol–1 = (59.9 ± 2.5); Δcr g H m(298.15 K)/kJ·mol–1 = (∼59.9 ± 3.5); p (l)/Pa = (21 ± 1); p (cr)/Pa = (11.5 ± 2.1)]; 1-adamantyl-ethanamine, [Δl g H m(298.15 K)/kJ·mol–1 = (68.7 ± 3.7); p (l)/Pa = (3 ± 1)]; α,α-dimethylphenethylamine [Δl g H m(298.15 K)/kJ·mol–1 = (60.2 ± 2.6); p (l)/Pa = (35 ± 4)]; trans 2-phenylcyclopropylamine [Δl g H m(298.15 K)/kJ·mol–1 = (60.3 ± 2.1), p (l)/Pa = (28 ± 5)]; 1-dodecanamine [Δcr g H m(298.15 K)/kJ·mol–1 = (118.3 ± 1.8); p (cr)/Pa = 1.6 ± 0.1]; and 1-tetradecanamine [Δcr g H m(298.15 K)/kJ·mol–1 = (134.5 ± 2.1); p (cr)/Pa = 0.12 ± 0.04]. Vapor pressure equations also derived from vapor pressureretention time correlations as a function of temperature are reported for both standards and targets. The equations appear applicable from T/K = 298.15 to each compound’s respective boiling temperature.

Evaluation of the Vaporization Enthalpies and Liquid Vapor Pressures of (R)-Deprenyl, (S)-Benzphetamine, Alverine, and a Series of Aliphatic Tertiary Amines by Correlation Gas Chromatography at T/K = 298.15

“…19 More recent work with amines has demonstrated that best results for aliphatic primary amines are obtained using aliphatic primary amine standards as opposed to primary aromatic amines. 25 Therefore, the existing vaporization enthalpy of tri-n-butylamine was re-evaluated by correlation gas chromatography in this case using tertiary aliphatic amines as standards. Values for N,N-dimethylbenzylamine (49.7 ± 0.4), 14 N,N-dimethyloctylamine (54.5 ± 0.5), 15 and N,N-dimethyldodecylamine (69.3 ± 0.3) 16 kJ•mol −1 are relatively recent and from reputable sources.…”

“…This correlation repeated as a function of temperature can provide a vapor pressure−temperature profile of the targets. 6,7,19,25,27,28 Vapor pressures near ambient temperatures are available for four of the five compounds used as standards in this study.…”

A Comparison of Results by Correlation Gas Chromatography with Another Gas Chromatographic Retention Time Technique. The Effects of Retention Time Coincidence on Vaporization Enthalpy and Vapor Pressure

“…We have discussed previously some potential reasons for the slight differences observed We have found that on capillary columns, by choosing the reference compounds carefully, specifically with regards to the functional groups present and demonstrating experimentally that the vaporization enthalpies of the reference compounds correlate linearly with their corresponding enthalpies of transfer, the problem associated with differences in activity appears to be adequately addressed and accurate vaporization enthalpies and vapor pressures of the targets included in the mixture can be obtained. − These correlations have proven successful in providing vaporization enthalpies and vapor pressures at temperatures other than at the mean temperature of measurement, T m , provided that all the values of the standards used are available at the same temperature. Best results were obtained when the retention times of the target substances are bracketed by related standards.…”

Thermodynamics of the Antiviral and Antiparkinsonian Drug Amantadine Hydrochloride: Condensed State Properties and Decomposition

“…) tot or HCl HCl HCl amine amine amine (8) where p amine * and p HCl * are the partial pressures of 1aminoadamantane and HCl in the cell; S or is the effusion orifice area; k amine and k HCl are the transmission probabilities for the molecules of 1-aminoadamantane and HCl through the orifice, respectively; T is the average temperature in the effusion experiment; M amine and M HCl are the molar masses of the effusing vapors of 1-aminoadamantane and HCl (M = (0.15125 and 0.03646…”

“…Thermodynamic properties have recently been studied for 1-aminoadamantanethe amine form of the drug. , However, little information on physical and thermodynamic properties of amantadine hydrochloride is available in the literature, despite its long history of medical use. Nonmedical studies are typically focused on molecular/ion mobility in the solid phase, , because many adamantane derivatives form orientationally disordered, or plastic, crystals exhibiting extensive molecular rotations in their lattice sites, and regular changes in their molecular structures can shed light on the interconnection between molecular structure peculiarities and plastic crystal formation.…”