Studies On The Calculation Of Thermodynamics Data For Aliphatic Oxygen-containing Organic Compounds

The thermodynamics data of compounds are fundamental in chemical engineering, whichcan be directly obtained by reliable experimental determination. However, there are manydifferent kinds of compounds (especially organic compounds), it is difficult to measure thethermodynamic properties of each compound. While by using the QSAR/QSPR methods, theproperties of compounds are estimated by the molecular structural information extracted directlyfrom its molecular structure. This method will not only have significance in experimentalconditions but also in practice.In a word, the molecular structure of a compound predetermines its properties. One of thefundamental and hot issues in chemistry is how to establish quantitative structure-activityrelationships (QSAR) and quantitative structure–property relationships (QSPR). A major andcrucial task in QSAR/QSPR researches is how to exactly extract sufficient chemical informationwith numerical format from the chemical formula. In this work, The descriptors of thePolarizability Effect Index (PEI), The Number of Effective Carbon (NCeff), the difference of PEI,NCeffbetween the branching chain and and straight chain isomers, ΔPEI, ΔNCeffand etc. arederived from molecular structure.The quantitative structure-property relationship (QSPR) between these descriptors andboiling points of520aliphatic alcohols, ethers, aldehydes, ketones, acids, esters wasperformed respectively. the correlation coefficients R are more than0.99, the standarddeviations (s) are less than6K. the mean absolute deviations MADs are less than5K, the meanrelative deviation MRDs are less than1.2%. Finally, QSPR between these descriptors andboiling points are developed for520aliphatic oxygen-containing organic compound by bestsubsets regression method and SVR method. For training set, the correlation coefficients R is0.9973, the standard deviation (s) is6.70K. For test set, the R is0.928, s is6.10K,respectively. The MRD is1.19%.The QSPR between these descriptors and thermal conductivity of537aliphatic alcohols,ethers, aldehydes, ketones, acids, esters was performed respectively. R is more than0.97, the s is less than0.0033W/(m.K), the MRDs are less than2%. Finally, QSPR between thesedescriptors and thermal conductivity data are developed for520aliphatic oxygen-containingorganic compounds by best subsets regression method and SVR method. For training set, thecorrelation coefficients R is0.9346, the s is0078W/(m.K). For test set, the R is0.9381, s is0.0080W/(m.K), respectively. The MRD is less than5%.The QSPR between these descriptors and121ΔfH°(liquid)data and121ΔfH°(gas)data ofaliphatic alcohols, ethers, aldehydes, ketones, acids, esters was performed respectively. R ismore than0.99, the s is less than5kJ/mol, the MRDs are less than2%. Finally, QSPRbetween these descriptors and ΔfH°(liquid),ΔfH°(gas)data are developed for aliphatic oxygen-containing organic compounds by best subsets regression method and SVR method. For trainingset, the correlation coefficients R is0.9992, the s is5.97kJ/mol. For test set, the R is0.9996, sis4.62kJ/mol, respectively. MRD is l.3%.A software i-SVM which is of great convenience is developed to build the QSPR models.The SVM method showed better results than MLR method.