Ma Peisheng

Position Group Contribution Method for Estimation of Melting Point of Organic Compounds

Abstract A new method is proposed based on the position group contribution additivity for the prediction of melting points of covalent compounds. The characteristics of this method are the use of position distribution function, which could distinguish between most isomers including cis or trans structure of organic compounds. Contributions for hydrocarbons and hydrocarbon derivatives containing oxygen, nitrogen, chlorine, bromine and sulfur, are given. Results are compared with those by the most commonly used estimating methods. The average derivation for prediction of normal melting temperature of 730 compounds is 14.46 K, compared to 29.33 K with the method of Joback, and 27.81 K with the method of Constantinou-Gani. The present method is not only more accurate, but also much simpler and more stable.

Measurement and Correlation for Solubility of Adipic Acid in Several Solvents

Abstract Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure solvents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N -dimethylformamide, N,N -dimethylacetamide, and dimethylsulfoxide at the temperature range from 293.15K to 353.15K. All these data were regressed by λ h , NRTL, Wilson, and the modified Wilson models. For the study of six, Δ h , NRTL, and the modified Wilson models were found to provide an accurate mathematical representation of the experimental results, with overall average absolute relative deviations between measured and calculated values as 1.74%, 2.06%, and 3.06%, respectively. The results showed that the Δ h model is the most suitable for description of the solid-liquid equilibrium containing adipic acid.

Position Group Contribution Method for Predicting the Normal Boiling Point of Organic Compounds

A new position group contribution model is proposed for the estimation of normal boiling data of organic compounds. involving a carbon chain from C2 to C18. The characteristic of this method is the use of position distribution function. It could distinguish most of isomers that include cis-or trans-structure from organic compounds. Contributions for hydrocarbons and hydrocarbon derivatives containing oxygen nitrogen chlorine bromine and sulfur, are given. Compared with the predictions, results made use of the most common existing group contribution methods, the overall average absolute difference of boiling point predictions of 417 organic compounds is 4.2K; and the average absolute percent derivation is 1.0%, which is compared with 12.3 K and 3.2% with the method of Joback, 12.1K and 3.1% with the method of Constantinou-Gani. This new position contribution groups method is not only much more accurate but also has the advantages of simplicity and stability.

Solubility of Glutaric Acid in Cyclohexanone, Cyclohexanol, Their Five Mixtures and Acetic Acid

Abstract By using the laser-monitoring technique, solid-liquid equilibrium data of glutaric acid in cyclohexanol, cyclohexanone, their five mixed solvents and acetic acid were measured within the temperature range from 292.15K to 354.60K by dynamic method. Empirical formula and λh equation were used to correlate the solubilities of glutaric acid in eight solvents. The maximal average relative deviations were 1.15% and 2.20% by using the empirical formula and λh equation to correlate the solubility data. The results showed that the empirical formula and λh model could correlate the solubility data of glutaric acid in eight solvents. In addition, the solubility data of glutaric acid in five mixtures (cyclohexanone+cyclohexanol) could be predicted with the NRTL equation utilizing the parameters of the binary systems. The total average relative deviation was 3.60%. The results indicate that the NRTL equation could well predict the solubilities of glutaric acid in the mixed solvents of cyclohexanone and cyclohexanol.

Estimation of liquid viscosity of pure compounds at different temperatures by a corresponding-states group-contribution method

A new equation for estimating liquid viscosity of pure compounds in a corresponding-state group-contribution method (CSGC) is presented. Group-contribution parameters of 84 groups were obtained by correlating experimental liquid viscosity data at different temperatures (a total of 2777 data points) of 366 compounds including various alkanes, alkenes, cyclohydrocarbons, aromatic and oxygenated hydrocarbons as well as compounds containing sulfur, nitrogen and halogen. The new method demonstrates significant improvement in accuracy.

Viscosities of Pure Water, Acetic Acid + Water, and p-Xylene + Acetic Acid + Water at Different Temperature and Pressure

Abstract The viscosities of pure water, the acetic acid + water binary system, and the p -xylene + acetic acid + water ternary system at different concentrations were determined with a rolling-ball viscometer at temperatures from 313.15 to 473.15 K and pressures from 0.10 to 3.20 MPa. The viscosity data were fitted by a correlation equation for the estimation of the mixture viscosities. The average absolute deviations (AAD) of the correlation for binary and ternary systems are 2.48% and 1.77%, respectively.

Solid-Liquid Equilibria of Benzoic Acid Derivatives in 1-Octanol

Abstract The solid-liquid equilibrium of benzoic acid derivatives in 1-octanol was first determined in this article. Using a laser monitoring observation technique, the solubility data of 0 -amino-benzoic acid, p -amino-benzoic acid, 0 -chloro-benzoic acid, and m -nitro-benzoic acid in 1-octanol were measured by the polythermal method in the temperature range of 20–50°C. The experimental data were regressed with the Wilson equation and the λH equation. The experimental results showed that the solubility of the four chemicals in 1-octanol increased significantly with temperature. The results indicate that the molecular structure and interactions affect the solubility significantly. The solubility order of the benzoic acid derivatives is as follows: m -nitro-benzoic acid > 0 -chloro-benzoic acid > 0 -amino-benzoic acid > p -amino-benzoic acid. Both the Wilson equation and λH equation are in good agreement with the experimental data.

Correlation of Viscosities for Alkane, Aromatic and Alcohol Family at High Pressure by Modified Tait Equation

Abstract A new model was proposed to calculate the viscosity of fluids under the pressure ranging from 0.1 to 110MPa by improving the Tait equation, in which the viscosity μ of liquids was linked with activation volume V ≠ . The model with two adjustable parameters α and β was applied in calculating viscosities for alkane, aromatic and alcohol family at high pressure. Results show that calculated values of viscosity are in good agreement with the experimental ones, and the average relative deviations for alkanes, aromatics and alcohols are 0.56%, 0.31% and 0.66%, respectively. Besides, the errors correlated by the model proposed in this paper were equivalent to the ones from the pure empirical Tait equation, and obviously superior to those from Eyring equation.

A Modification of α in SRK Equation of State and Vapor-Liquid Equilibria Prediction

Abstract Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor α in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified α had a better precision than that with the original one.

Densities and Viscosities of 1-butyl-3-methylimidazolium Hexafluorophosphate [bmim][PF6] + CO2 Binary System: Determination and Correlation

Abstract A gas-dissolving device was designed and connected to the falling-body viscometer, which was used to determine the viscosities of liquids in our lab before. The equipment can be used to determine the gas composition, the densities and viscosities of the solution at the same time. The densities and viscosities of [bmim][PF 6 ] + CO 2 binary system were determined in the temperature range of 313.2 to 413.2 K and pressure range of 5.0 to 25.0 MPa by the equipment. Then the viscosities of [bmim][PF 6 ] + CO 2 binary system at constant temperature, constant pressure, and different temperature and pressure were correlated, respectively. For the correlation at different temperature and different pressure for different concentration mixtures the average relative deviation ARD is 0.037.