The effectiveness of chemical process designs and the reliability of mixture models are no better... more The effectiveness of chemical process designs and the reliability of mixture models are no better than the accuracy of the pure-chemical thermophysical properties used. A systems-analysis approach can be used in evaluating data from all available sources to triangulate on the best values which can be of higher accuracy than the individual values. This approach includes applied constraints on property values from interproperty relationships, expected smooth trends of properties between related chemicals, and the impact of chemical similarities and differences. These constraints are simultaneously included in the evaluation of the raw experimental data to provide recommended values of constant properties and correlations for temperature-dependent properties. This paper will illustrate how this systems approach has been used to provide recommended property values in the DIPPR 801 evaluated database. In particular, a recent re-evaluation of the properties of the 1,n-alkanediol compounds in the DIPPR database,...
Journal of Chemical & Engineering Data, Oct 12, 2006
Critical temperature, critical pressure, and vapor pressure measurements have been performed on 1... more Critical temperature, critical pressure, and vapor pressure measurements have been performed on 15 compounds by a flow method with ultralow residence times. These compounds are γ-butyrolactone, di(propylene glycol), 1,3-butanediol, N-methyldiethanolamine, 4-formylmorpholine, 1,2-epoxy-2-methylpropane, diethyl oxalate, n-butyl acrylate, 2-(2-aminoethoxy)ethanol, tert-butyl acetate, 1,1-ethanediol diacetate, p-diisopropylbenzene, dimethyl disulfide, oxazole, and phenyl isocyanate. Accurate vapor pressure data are also included for di-n-butyl disulfide and sulfolane, but these compounds proved too unstable to directly determine the critical constants using this apparatus.
Journal of Chemical & Engineering Data, Jun 21, 2006
Critical temperature, critical pressure, and vapor pressure measurements have been performed on 1... more Critical temperature, critical pressure, and vapor pressure measurements have been performed on 15 compounds by a flow method with ultralow residence times. These compounds are γ-butyrolactone, di(propylene glycol), 1,3-butanediol, N-methyldiethanolamine, 4-formylmorpholine, 1,2-epoxy-2-methylpropane, diethyl oxalate, n-butyl acrylate, 2-(2-aminoethoxy)ethanol, tert-butyl acetate, 1,1-ethanediol diacetate, p-diisopropylbenzene, dimethyl disulfide, oxazole, and phenyl isocyanate. Accurate vapor pressure data are also included for di-n-butyl disulfide and sulfolane, but these compounds proved too unstable to directly determine the critical constants using this apparatus.
Journal of Chemical & Engineering Data, Oct 2, 2001
Critical point measurements consisting of critical temperatures and critical pressures have been ... more Critical point measurements consisting of critical temperatures and critical pressures have been performed on nine compounds by a flow method with ultralow residence times. These compounds along with their Chemical Abstract Service Registry Numbers (provided by the author) are bis(2-aminoethyl)amine (111-40-0), 2-(2-aminoethylamino)ethanol (111-41-1), 1,4-butanediol (110-63-4), 2-(2-butoxyethoxy)ethyl acetate (124-17-4), 2-(2-ethoxyethoxy)ethyl acetate (112-15-2), 2-methyl-1,3-propanediol (2163-42-0), phenyl acetate (122-79-2), 1,3-propanediol (504-63-2), and propylene carbonate (108-32-7). Vapor pressure measurements are also included for these nine compounds.
Henry's law constants and infinite dilution activity coefficients were measured for toluene, 1-bu... more Henry's law constants and infinite dilution activity coefficients were measured for toluene, 1-butanol, anisole, 1,2-difluorobenzene, 4-bromotoluene, 1,2,3-trichlorobenzene, and 2,4-dichlorotoluene in water using the inert gas stripping method at ambient pressure (approximately 86.2 kPa) and at temperatures between 281.15 K and 323.15 K. Fugacity ratios, required to determine infinite dilution activity coefficients for the solid solutes, were calculated from literature values for the heat of fusion and the liquid and solid heat capacities. Chemicals were chosen based on missing or conflicting data from the literature.
Quantitative Structure-Property Relationships (QSPRs) have found applications in many areas of ch... more Quantitative Structure-Property Relationships (QSPRs) have found applications in many areas of chemistry and engineering as effective prediction methods. QSPRs use molecular descriptors to simplify complex molecular properties to a single value and have been used extensively for constant value properties. Liquid heat capacity (c_p^l) is another property where QSPRs can be helpful prediction tools. Researchers have shown strong correlation between the c_p^l and various molecular descriptors, but these predictions are limited to a single temperature, usually 298.15 K. Additionally, other QSPRs have had problems with oxygen-containing functional groups. In this work, QSPRs for c_p^l at various temperatures were developed using data selected from the DIPPR database using a novel search method. This method improves on existing QSPRs for c_p^l by using unique descriptors but does not overcome the issue of oxygen-containing species.
The effectiveness of chemical process designs and the reliability of mixture models are no better... more The effectiveness of chemical process designs and the reliability of mixture models are no better than the accuracy of the pure-chemical thermophysical properties used. A systems-analysis approach can be used in evaluating data from all available sources to triangulate on the best values which can be of higher accuracy than the individual values. This approach includes applied constraints on property values from interproperty relationships, expected smooth trends of properties between related chemicals, and the impact of chemical similarities and differences. These constraints are simultaneously included in the evaluation of the raw experimental data to provide recommended values of constant properties and correlations for temperature-dependent properties. This paper will illustrate how this systems approach has been used to provide recommended property values in the DIPPR 801 evaluated database. In particular, a recent re-evaluation of the properties of the 1,n-alkanediol compounds in the DIPPR database,...
Maintaining currency of thermophysical property values in a chemical database with the rapid pace... more Maintaining currency of thermophysical property values in a chemical database with the rapid pace of published new experimental data is particularly difficult for evaluated databases. Evaluated databases that provide recommended values for each of the properties require labor intensive evaluation of not only the newly published property values, but also all related property values stored in the database. One possible solution to this problem is the establishment of a triage system to evaluate the potential influence of new data on recommended property values. Such a priority assignment system for the DIPPR 801 Pure Chemical Database has been developed. Evaluation of the potential impact of new data on the recommended values is done through a correlation for the Influence Factor (IF) that includes weighting factors for the type of property, the experimental methodology, the quality of the data, the quantity of data upon which the current recommendation is based, and the significance of the potential change. Database IFs help prioritize review work on the DIPPR 801 database and thereby contribute to its quality and currency.
The dielectric constant (e) or relative static permittivity of a material represents the capacita... more The dielectric constant (e) or relative static permittivity of a material represents the capacitance of the material relative to a vacuum and is important in many industrial applications. Nevertheless, accurate experimental values are often unavailable, and current prediction methods lack accuracy and are often unreliable. Reported here is the development and testing of a new QSPR (quantitative structure property relation) correlation of e for organic chemicals. On the basis of the regression analysis and tests of the correlation in prediction mode, the average absolute percent error is expected to be less than 3 % when applied to hydrocarbons and nonpolar compounds and less than 18 % when applied to polar compounds with e values ranging from 1.0 to 50.0. The correlation requires values for the dipole moment, solubility parameter, van der Waals area, and refractive index. We show also that density functional calculations of the dipole moment using B3LYP/6-311+G(3df,2p) can be used in the e correlation, wh...
The mutual-diffusion coefficients, Dl2 , of n-hexane, n-heptane, and n-octane in chloroform were ... more The mutual-diffusion coefficients, Dl2 , of n-hexane, n-heptane, and n-octane in chloroform were modeled using equilibrium molecular-dynamics (MD) simulations of simple Lennard-Jones (LJ) fluids. Pure-component LJ parameters were obtained by comparison of simulations to experimental self-diffusion coefficients. While values of "effective" LJ parameters are not expected to simulate accurately diverse thermophysical properties over a wide range of conditions, it was recently shown that effective parameters obtained from pure self-diffusion coefficients can accurately model mutual diffusion in ideal, liquid mixtures. In this work, similar simulations are used to model diffusion in nonideal mixtures. The same combining rules used in the previous study for the cross-interaction parameters were found to be adequate to represent the composition dependence of D~2. The effect of alkane chain length on D12 is also correctly predicted by the simulations. A commonly used assumption in empirical correlations of Oa2, that its kinetic portion is a simple, compositional average of the intradiffusion coefficients, is inconsistent with the simulation results. In fact, the value of the kinetic portion of D12 was often outside the range of values bracketed by the two intradiffusion coefficients for the nonideal system modeled here.
The effectiveness of chemical process designs and the reliability of mixture models are no better... more The effectiveness of chemical process designs and the reliability of mixture models are no better than the accuracy of the pure-chemical thermophysical properties used. A systems-analysis approach can be used in evaluating data from all available sources to triangulate on the best values which can be of higher accuracy than the individual values. This approach includes applied constraints on property values from interproperty relationships, expected smooth trends of properties between related chemicals, and the impact of chemical similarities and differences. These constraints are simultaneously included in the evaluation of the raw experimental data to provide recommended values of constant properties and correlations for temperature-dependent properties. This paper will illustrate how this systems approach has been used to provide recommended property values in the DIPPR 801 evaluated database. In particular, a recent re-evaluation of the properties of the 1,n-alkanediol compounds in the DIPPR database,...
Journal of Chemical & Engineering Data, Oct 12, 2006
Critical temperature, critical pressure, and vapor pressure measurements have been performed on 1... more Critical temperature, critical pressure, and vapor pressure measurements have been performed on 15 compounds by a flow method with ultralow residence times. These compounds are γ-butyrolactone, di(propylene glycol), 1,3-butanediol, N-methyldiethanolamine, 4-formylmorpholine, 1,2-epoxy-2-methylpropane, diethyl oxalate, n-butyl acrylate, 2-(2-aminoethoxy)ethanol, tert-butyl acetate, 1,1-ethanediol diacetate, p-diisopropylbenzene, dimethyl disulfide, oxazole, and phenyl isocyanate. Accurate vapor pressure data are also included for di-n-butyl disulfide and sulfolane, but these compounds proved too unstable to directly determine the critical constants using this apparatus.
Journal of Chemical & Engineering Data, Jun 21, 2006
Critical temperature, critical pressure, and vapor pressure measurements have been performed on 1... more Critical temperature, critical pressure, and vapor pressure measurements have been performed on 15 compounds by a flow method with ultralow residence times. These compounds are γ-butyrolactone, di(propylene glycol), 1,3-butanediol, N-methyldiethanolamine, 4-formylmorpholine, 1,2-epoxy-2-methylpropane, diethyl oxalate, n-butyl acrylate, 2-(2-aminoethoxy)ethanol, tert-butyl acetate, 1,1-ethanediol diacetate, p-diisopropylbenzene, dimethyl disulfide, oxazole, and phenyl isocyanate. Accurate vapor pressure data are also included for di-n-butyl disulfide and sulfolane, but these compounds proved too unstable to directly determine the critical constants using this apparatus.
Journal of Chemical & Engineering Data, Oct 2, 2001
Critical point measurements consisting of critical temperatures and critical pressures have been ... more Critical point measurements consisting of critical temperatures and critical pressures have been performed on nine compounds by a flow method with ultralow residence times. These compounds along with their Chemical Abstract Service Registry Numbers (provided by the author) are bis(2-aminoethyl)amine (111-40-0), 2-(2-aminoethylamino)ethanol (111-41-1), 1,4-butanediol (110-63-4), 2-(2-butoxyethoxy)ethyl acetate (124-17-4), 2-(2-ethoxyethoxy)ethyl acetate (112-15-2), 2-methyl-1,3-propanediol (2163-42-0), phenyl acetate (122-79-2), 1,3-propanediol (504-63-2), and propylene carbonate (108-32-7). Vapor pressure measurements are also included for these nine compounds.
Henry's law constants and infinite dilution activity coefficients were measured for toluene, 1-bu... more Henry's law constants and infinite dilution activity coefficients were measured for toluene, 1-butanol, anisole, 1,2-difluorobenzene, 4-bromotoluene, 1,2,3-trichlorobenzene, and 2,4-dichlorotoluene in water using the inert gas stripping method at ambient pressure (approximately 86.2 kPa) and at temperatures between 281.15 K and 323.15 K. Fugacity ratios, required to determine infinite dilution activity coefficients for the solid solutes, were calculated from literature values for the heat of fusion and the liquid and solid heat capacities. Chemicals were chosen based on missing or conflicting data from the literature.
Quantitative Structure-Property Relationships (QSPRs) have found applications in many areas of ch... more Quantitative Structure-Property Relationships (QSPRs) have found applications in many areas of chemistry and engineering as effective prediction methods. QSPRs use molecular descriptors to simplify complex molecular properties to a single value and have been used extensively for constant value properties. Liquid heat capacity (c_p^l) is another property where QSPRs can be helpful prediction tools. Researchers have shown strong correlation between the c_p^l and various molecular descriptors, but these predictions are limited to a single temperature, usually 298.15 K. Additionally, other QSPRs have had problems with oxygen-containing functional groups. In this work, QSPRs for c_p^l at various temperatures were developed using data selected from the DIPPR database using a novel search method. This method improves on existing QSPRs for c_p^l by using unique descriptors but does not overcome the issue of oxygen-containing species.
The effectiveness of chemical process designs and the reliability of mixture models are no better... more The effectiveness of chemical process designs and the reliability of mixture models are no better than the accuracy of the pure-chemical thermophysical properties used. A systems-analysis approach can be used in evaluating data from all available sources to triangulate on the best values which can be of higher accuracy than the individual values. This approach includes applied constraints on property values from interproperty relationships, expected smooth trends of properties between related chemicals, and the impact of chemical similarities and differences. These constraints are simultaneously included in the evaluation of the raw experimental data to provide recommended values of constant properties and correlations for temperature-dependent properties. This paper will illustrate how this systems approach has been used to provide recommended property values in the DIPPR 801 evaluated database. In particular, a recent re-evaluation of the properties of the 1,n-alkanediol compounds in the DIPPR database,...
Maintaining currency of thermophysical property values in a chemical database with the rapid pace... more Maintaining currency of thermophysical property values in a chemical database with the rapid pace of published new experimental data is particularly difficult for evaluated databases. Evaluated databases that provide recommended values for each of the properties require labor intensive evaluation of not only the newly published property values, but also all related property values stored in the database. One possible solution to this problem is the establishment of a triage system to evaluate the potential influence of new data on recommended property values. Such a priority assignment system for the DIPPR 801 Pure Chemical Database has been developed. Evaluation of the potential impact of new data on the recommended values is done through a correlation for the Influence Factor (IF) that includes weighting factors for the type of property, the experimental methodology, the quality of the data, the quantity of data upon which the current recommendation is based, and the significance of the potential change. Database IFs help prioritize review work on the DIPPR 801 database and thereby contribute to its quality and currency.
The dielectric constant (e) or relative static permittivity of a material represents the capacita... more The dielectric constant (e) or relative static permittivity of a material represents the capacitance of the material relative to a vacuum and is important in many industrial applications. Nevertheless, accurate experimental values are often unavailable, and current prediction methods lack accuracy and are often unreliable. Reported here is the development and testing of a new QSPR (quantitative structure property relation) correlation of e for organic chemicals. On the basis of the regression analysis and tests of the correlation in prediction mode, the average absolute percent error is expected to be less than 3 % when applied to hydrocarbons and nonpolar compounds and less than 18 % when applied to polar compounds with e values ranging from 1.0 to 50.0. The correlation requires values for the dipole moment, solubility parameter, van der Waals area, and refractive index. We show also that density functional calculations of the dipole moment using B3LYP/6-311+G(3df,2p) can be used in the e correlation, wh...
The mutual-diffusion coefficients, Dl2 , of n-hexane, n-heptane, and n-octane in chloroform were ... more The mutual-diffusion coefficients, Dl2 , of n-hexane, n-heptane, and n-octane in chloroform were modeled using equilibrium molecular-dynamics (MD) simulations of simple Lennard-Jones (LJ) fluids. Pure-component LJ parameters were obtained by comparison of simulations to experimental self-diffusion coefficients. While values of "effective" LJ parameters are not expected to simulate accurately diverse thermophysical properties over a wide range of conditions, it was recently shown that effective parameters obtained from pure self-diffusion coefficients can accurately model mutual diffusion in ideal, liquid mixtures. In this work, similar simulations are used to model diffusion in nonideal mixtures. The same combining rules used in the previous study for the cross-interaction parameters were found to be adequate to represent the composition dependence of D~2. The effect of alkane chain length on D12 is also correctly predicted by the simulations. A commonly used assumption in empirical correlations of Oa2, that its kinetic portion is a simple, compositional average of the intradiffusion coefficients, is inconsistent with the simulation results. In fact, the value of the kinetic portion of D12 was often outside the range of values bracketed by the two intradiffusion coefficients for the nonideal system modeled here.
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