ABSTRACT A general classification procedure for organic solvents is proposed by treating a basis ... more ABSTRACT A general classification procedure for organic solvents is proposed by treating a basis set of eight solvent physiochemical variables (the Kirkwood function (K), molecular refraction (MR), molecular dipole moment (μ), the δ parameter of Hildebrand, index of refraction (n), boiling point (bp), and the energies of HOMO and LUMO) by the Fage nonhierarchical multivariate statistical method. This classification is based on the representation of 83 solvents as points in an eight-dimensional space, solvent similarity being measured from the distance between two points within this space. The original eight-dimensional space may be reduced to a three-dimensional subspace with only an 18% loss of information. This subspace is defined by the principal components F1 (strongly correlated with molecular refraction, refractive index, and HOMO energy), F2 (strongly correlated with the Kirkwood function, dipole moment, and boiling point), and F3 (strongly correlated with LUMO energy). The finding that the HOMO and LUMO energies are important descriptors of solvent properties is an important result. The 83 solvents may be grouped into 9 classes by their clustering of component values: aprotic dipolar (AD), aprotic highly dipolar (AHD), aprotic highly dipolar and highly polarizable (AHDP), aromatic apolar (ARA), aromatic relatively polar (ARP), electron pair donor (EPD), hydrogen bonding (HB), hydrogen bonding strongly associated (HBSA), and miscellaneous (MISC). Among the possible applications of a quantitative classification, the design of new solvents and the semiquantitative evaluation of physicochemical properties (here solubility in water) are specifically considered. Consideration of the regiospecificities of frontier orbitals provides the basis for the ambiclassification of some solvents.
Structure-odor relationships were established for a sample of 99 aliphatic alcohols using a three... more Structure-odor relationships were established for a sample of 99 aliphatic alcohols using a three-layer backpropagation neural network. The molecular structure was described using a common skeleton with six possible substitutions. Substituents were described using only their van der Waals volumes. The discrimination between fruity and camphoraceous odors of 67 compounds gave good results in classification (100%) and prediction (85%) phases. With the global set, the network correctly classified and predicted the camphoraceous character of compounds (100% and 95% respectively) but gave poorer results for the fruity character (87% and 74% respectively). Calculations of pOLs (pOL = -log (olfactory threshold expressed in mol/L)) of 45 camphoraceous compounds were also made. When all camphoraceous compounds were used to establish the model, 91% of the pOLs were correctly estimated. When attempts were made to predict the pOL values of 10% of the compounds from a model designed using 90% of the sample, only 74% of the pOLs were correctly estimated.
... D'autres ont note de fortes correlations de ET avec le paramktre de solubilitC de Hildeb... more ... D'autres ont note de fortes correlations de ET avec le paramktre de solubilitC de Hildebrand, 6 (12), ou avec 6' ou avec In 6 (33). Enfin, rCcemment, le role des forces de dispersion dej5 signale (9) a tte mis en evidence par Haak et Engberts (34). ...
ABSTRACT A general classification procedure for organic solvents is proposed by treating a basis ... more ABSTRACT A general classification procedure for organic solvents is proposed by treating a basis set of eight solvent physiochemical variables (the Kirkwood function (K), molecular refraction (MR), molecular dipole moment (μ), the δ parameter of Hildebrand, index of refraction (n), boiling point (bp), and the energies of HOMO and LUMO) by the Fage nonhierarchical multivariate statistical method. This classification is based on the representation of 83 solvents as points in an eight-dimensional space, solvent similarity being measured from the distance between two points within this space. The original eight-dimensional space may be reduced to a three-dimensional subspace with only an 18% loss of information. This subspace is defined by the principal components F1 (strongly correlated with molecular refraction, refractive index, and HOMO energy), F2 (strongly correlated with the Kirkwood function, dipole moment, and boiling point), and F3 (strongly correlated with LUMO energy). The finding that the HOMO and LUMO energies are important descriptors of solvent properties is an important result. The 83 solvents may be grouped into 9 classes by their clustering of component values: aprotic dipolar (AD), aprotic highly dipolar (AHD), aprotic highly dipolar and highly polarizable (AHDP), aromatic apolar (ARA), aromatic relatively polar (ARP), electron pair donor (EPD), hydrogen bonding (HB), hydrogen bonding strongly associated (HBSA), and miscellaneous (MISC). Among the possible applications of a quantitative classification, the design of new solvents and the semiquantitative evaluation of physicochemical properties (here solubility in water) are specifically considered. Consideration of the regiospecificities of frontier orbitals provides the basis for the ambiclassification of some solvents.
Structure-odor relationships were established for a sample of 99 aliphatic alcohols using a three... more Structure-odor relationships were established for a sample of 99 aliphatic alcohols using a three-layer backpropagation neural network. The molecular structure was described using a common skeleton with six possible substitutions. Substituents were described using only their van der Waals volumes. The discrimination between fruity and camphoraceous odors of 67 compounds gave good results in classification (100%) and prediction (85%) phases. With the global set, the network correctly classified and predicted the camphoraceous character of compounds (100% and 95% respectively) but gave poorer results for the fruity character (87% and 74% respectively). Calculations of pOLs (pOL = -log (olfactory threshold expressed in mol/L)) of 45 camphoraceous compounds were also made. When all camphoraceous compounds were used to establish the model, 91% of the pOLs were correctly estimated. When attempts were made to predict the pOL values of 10% of the compounds from a model designed using 90% of the sample, only 74% of the pOLs were correctly estimated.
... D'autres ont note de fortes correlations de ET avec le paramktre de solubilitC de Hildeb... more ... D'autres ont note de fortes correlations de ET avec le paramktre de solubilitC de Hildebrand, 6 (12), ou avec 6' ou avec In 6 (33). Enfin, rCcemment, le role des forces de dispersion dej5 signale (9) a tte mis en evidence par Haak et Engberts (34). ...
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