Gas chromatographic determination of liquid vapour pressure and heat of vaporization of tetrachlorobenzyltoluenes

Haelst, A.G. van; Wielen, F.W.M. van der; Govers, H.A.J.

doi:10.1016/0021-9673(95)01146-3

Cited by 19 publications

(16 citation statements)

References 15 publications

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“…In the present article, all experimental data were treated using eq in its simplified version that is, assuming the ratio of activity coefficients γ s ∞ ( T )/γ x ∞ ( T ) is unity and a single standard reference compound is needed (GLC-RT1S). This approach has been used by a number of authors. ,,− It should be stressed that the only difference between exploitation of eq and using the Hamilton approach (eq ) lies in smoothing retention times with a two-parameter equation, as shown in Figures S1 to S4 in the Supporting Information; only eq will be considered in the remainder of this paper. However, previous approaches have typically required serious approximations and/or extrapolations to be made, necessitating a subsequent calibration with more or less related compounds.…”

Section: Results and Discussionmentioning

confidence: 99%

Extracting Vapor Pressure Data from GLC Retention Times. Part 1: Analysis of Single Reference Approach

Koutek

Mahnel²,

Šimáček³

et al. 2017

J. Chem. Eng. Data

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The vapor pressures of 52 compounds including n-alkanes and their monosubstituted derivatives, as well as chloro- and alkylbenzenes were determined exploring the gas chromatographic relative retention time (GLC-RT) technique in its simplest form, that is, using a single reference standard and neglecting the activity coefficient effect (GLC-RT1S). The selection of compounds was limited to those which are in the liquid state under the measurement conditions and for which high-quality vapor pressures obtained by direct methods are available at temperatures of GLC measurements. This approach should eliminate possible secondary error sources (such as data extrapolation or recalculation from supercooled liquid to solid phase or vice versa). On the basis of a thorough comparison of the GLC-RT1S-based and directly measured vapor pressures for the group of (functionalized) n-alkanes and by exploiting n-alkanes as reference solutes it is clear that deviations from direct data are significant (in many tens of percent) when single reference compounds are used. However, when an n-alkane that has a retention time lower than the test compound but close to it is used as the reference, the relative errors do not exceed 20%. Overall, the method has been found to be rather reliable over a wide range of conditions for nonpolar and slightly polar substances. For polar compounds, such as alcohols or nitriles, the results do confirm the need to carefully select standards with the same functionality as the targets to be evaluated. In contrast to homologous series no regular pattern can be observed for functionalized benzenes even if the reference compounds were selected from the same group of substituted benzenes.

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Section: Results and Discussionmentioning

confidence: 99%

Extracting Vapor Pressure Data from GLC Retention Times. Part 1: Analysis of Single Reference Approach

Koutek

Mahnel²,

Šimáček³

et al. 2017

J. Chem. Eng. Data

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“…Detailed descriptions of the method used can be found elsewhere (1,5,6). In short, the Kováts retention indices of the un-…”

Section: Physical-chemical Modelmentioning

confidence: 99%

“…Because the Kováts retention indices of the n-alkanes are, by definition, independent of the temperature, a (small) correction is necessary if the substance is not an n-alkane. The nature of this correction is not known exactly, but good results are found by using a simple quadratic relationship of the Kováts index and the temperature according to the following equation (5): [5] After determination of the Kováts indices of the unknown compound and the square of the temperature, I 0 and I 1 can be determined by linear regression. The next step is the calculation of log P z of the n-alkanes by fitting T and z to experimental values of the vapor pressure, heat of vaporization, and heat capacity differences according to the following equation: [6] with A z = 4.877735 (± 0.014939) + 0.303157 (± 0.00222)z − 0.007281 (± 0.00007)z 2 ; B z = 485.68961 (± 5.613) − 261.5436 (± 0.47628)z + 5.8678 (± 0.005539)z 2 ; C z = −86487.5 (± 55.09) + 344.999 (± 14.2985)z − 874.879 (± 0.8257)z 2 .…”

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confidence: 99%

Determination of environmentally relevant physical‐chemical properties of some fatty acid esters

Krop

Velzen

Parsons

et al. 1997

J Americ Oil Chem Soc

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Fat models frequently use input parameters that are defined at environmental conditions. In a recently developed gas-liquid chromatography method (GC-VAP), vapor pressures, heats of vaporization, and heat capacity differences (gas-liquid) of fatty acid esters are determined over a large temperature range that includes environmental temperatures. This method also allows an accurate determination of the normal boiling point temperature of a substance. Literature values of vapor pressure, boiling point temperature, and heat of vaporization at 298.15 K for the chosen esters are all in excellent agreement with those determined with the developed method. Correlations between carbon number and heat of vaporization are high. JAOCS 74, 309-315 (1997). KEY WORDS:Fatty acid esters, heat capacity, heat of vaporization, QSAR, solubility parameter, vapor pressure. METHODS Physical-Chemical ModelDetailed descriptions of the method used can be found elsewhere (1,5,6). In short, the Kováts retention indices of the un-

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“…Consequently, I x values should provide relative data on the physical properties of the compounds with improved accuracy. There have been several attempts to correlate retention indices to vapor pressures, − some of which were successful to a degree. − ,, The conceptual basis of the method is presented below.…”

Section: Introductionmentioning

confidence: 99%

Extracting Vapor Pressure Data from Gas–Liquid Chromatography Retention Times. Part 2: Analysis of Double Reference Approach

et al. 2018

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The vapor pressures of 46 compounds including n-alkanes and their monofunctionalized derivatives, some monoterpenes, as well as chloro-and alkylbenzenes were determined by GLC exploring the Kovats retention indices (KI) technique, primarily in its basic form using two alkane references (GLC-RTKI). The fundamental advantage of the GLC-RTKI method is that it guarantees appropriate selection of alkane reference compounds. Typical relative errors in vapor pressures accompanying this method were below 30% for compounds of low polarity, while for polar compounds (nitriles, alcohols) the errors can reach percentages in the hundreds. In contrast, vapor pressures obtained from the modified Kovats method, relying on reference standards whose functional group matches that of the test compound (GLC-RTmKI), were found mostly within 5% of directly measured values. However, the success of this method is dependent on the availability of reliable vapor pressure data for compounds to serve as reference standards. As our methodology eliminates possible secondary error sources (e.g., data extrapolation, or recalculation from supercooled liquid-to-solid phase or vice versa), we propose that the results obtained are as accurate as is feasibly possible with GLC-RTKI and GLC-RTmKI methods. This study also yielded a novel set of directly measured (static method) data on the vapor pressures of C7−C9 alkyl nitriles.

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Gas chromatographic determination of liquid vapour pressure and heat of vaporization of tetrachlorobenzyltoluenes

Cited by 19 publications

References 15 publications

Extracting Vapor Pressure Data from GLC Retention Times. Part 1: Analysis of Single Reference Approach

Extracting Vapor Pressure Data from GLC Retention Times. Part 1: Analysis of Single Reference Approach

Determination of environmentally relevant physical‐chemical properties of some fatty acid esters

Extracting Vapor Pressure Data from Gas–Liquid Chromatography Retention Times. Part 2: Analysis of Double Reference Approach

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