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Use of Quantitative Structure-Property Relationships in Predicting the Krafft Point of Anionic Surfactants

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Author(s): Mehdi Jalali-Heravi | Elahe Konouz

Journal: Internet Electronic Journal of Molecular Design
ISSN 1538-6414

Volume: 1;
Issue: 8;
Start page: 410;
Date: 2002;
Original page

ABSTRACT
The Krafft point is the temperature at which the solubility of hydrated surfactants crystals increases sharply with increasing temperature. Also, the concentration at which micelles are formed at the Krafft temperature is the critical micelle concentration (CMC). Therefore, knowing the Krafft point and CMC of the surfactants is important and one should have information about the conditions in which a surfactant acts. This is useful to select an appropriate surfactant for a special application. The linear relationship between the descriptors and Krafft point of anionic surfactants was modeled using multiple linear regression technique. Linear models were generated using a stepwise regression model. A set of 32 linear alkyl sulfates [RSO4Na] and sulfonates [RSO3Na], sulfates and sulfunates with an ether or ester linkage to the hydrophobic tail [R(OCH2CH2)nSO4Na], [RCOO(CH2)nSO3Na] were used for model generation. Among different models, two equations were selected for their good statistical results. Specification of the best model in agreement with the experiment indicates that four descriptors consisting of the Randic index, heat of formation, reciprocal of the dipole moment, and reciprocal of the volume of tail of the molecule play a major role in the prediction of Krafft point of anionic surfactants. The statistics of the best models together with the cross-validation results indicate the capability of both models in predicting the Krafft point of anionic surfactants. Different strategies, including the Akaike Information Criterion (AIC), were used for choosing the best model. It was demonstrated that the Krafft point of these compounds depends on electronic descriptors and topological characteristics, such as compactness and branching of anionic surfactants.
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Tango Jona
Tangokurs Rapperswil-Jona