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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. August 2002, Volume 1, Number 8, 410-417 |
Use of Quantitative Structure-Property Relationships in
Predicting the Krafft Point of Anionic Surfactants
Mehdi Jalali-Heravi and Elahe Konouz
Internet Electron. J. Mol. Des. 2002, 1, 410-417
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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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