Heats of vaporization of monoalkylcyclohexanes by the gas chromatography – calorimetry method

Abstract

RICHARD FUCHS and L. ALAN PEACOCK. Can J. Chem. 56,2493Chem. 56, (1978. A recently developed empirical method for measuring heats of vaporization (AH,'') by a combination of gas chromatography and calorimetric heats of solution in the stationary phase has been applied to a series of 9 monoalkylcyclohexanes having CI-CIZ side chains. The uncertainties in the measurements (0.07-0.23 kca1;mol) are critically evaluated. Comparison with literature AH, measurements indicates good agreement for low boiling cornpounds, and for high boiling compounds, values substantially more reliable than were previously obtained from vapor pressure measurements.RICHARD FLCHS et L. ALA\ PEACOCK. Can. J. Chem. 56, 2493Chem. 56, (1978.Une~methode empirique dtveloppee recemment pour mesurer les chaleurs de va~orisation (AH,") en combinant la chromatographie en phase gazeuse et des chaleurs calorii~~etriques de solution dans une phase stationnaire a kte appliquee a une serie de 9 monoalkylcyclohexanes portant des chaines laterales de I a 12 carbones. 011 a kvalue d'une faqon critique les incertitudes dans les mesures (0.07 a 0.23 kcal/mol). Une comparaison avec des rnesures de AH, retrouvees dans la litterat~rre suggere une bonne concordance dans le cas des composes de bas points d'ebullition; dans le cas des composks de points d'ebullition plus eleves on obtient des valeurs beaucoup plus sures que celles obtenues anterieurement a partir de mesures de pression de vapeur.[

Thermodynamic, energetic, and topological properties of crystal packing of pyrazolo[1,5-a]pyrimidines governed by weak electrostatic intermolecular interactions

“…In this work, gas chromatography was used to measure the vaporization enthalpy (ΔH vap (298 K)) in accordance with the method that was proposed by Peacock and Fuchs [20][21][22][23][24][25] . and modified by Chickos et al [26][27][28] The pyrazoloij1,5-a]pyrimidines 1, 5, 6, 7, 9, 12, and 13 were chosen for this study and there were at least two compounds in each of the groups formed according to the substituent in R 7 : compounds 1 and 13 with R 7 = CCl 3 ; compounds 5, 6, and 7 with R 7 = CF 3 ; and compounds 9 and 12 with R 7 = aryl/heteroaryl.…”

Comprehensive Thermodynamic Study of Alkyl-Cyclohexanes as Liquid Organic Hydrogen Carriers Motifs

“…Significantly more data on experimental vaporisation enthalpies of alkyl-cyclohexanes (see Tables 6, S3 and S4) are available compared to data on formation enthalpies (see Table 3). The fourteen enthalpies of vaporisation were taken from the comprehensive book by Majer and Svoboda [43]; the seven enthalpies of vaporisation were compiled from the original literature [44,45]; for four alkyl-cyclohexanes enthalpies of vaporisation were derived from experimental vapour pressures found in the literature (see Table S4). Kovats retention indices were taken from the original literature [46][47][48] (see Table S3), and normal boiling points were taken from online databases [16,49,50] (see Table S4).…”

Regression against Temperature of Gas–Liquid Chromatography Retention Factors. Van’t Hoff Analysis

“…Gas–liquid chromatography (GLC) is a valuable analytical technique of proven power for physicochemical measurements and generating thermodynamic data of analytes, with the advantage of its simplicity as compared with direct techniques such as the calorimetric and equilibrium methods. , Basic physicochemical quantities, namely the vapor pressure, − heat of vaporization, − equilibrium distribution constant K , − enthalpy of solvation, and entropy of solvation, , and even the octanol–air partition coefficient − can be determined from the retention data, such as specific or net retention volumes, , Kovats retention indices ( I ), , or retention factors ( k ) − and their temperature dependence. In this study, we use the isothermal retention factor k as the most relevant and reproducible chromatographic measure of the retention.…”