Structure-solubility relationships

The correlation between aqueous solubility and molar volume discussed by McAuliffe [5] for hydrocarbons, and the importance of the cavity term in the solvatochromic approach, indicates a significant solubility dependence on the molecular size and shape of solutes. Molecular size and shape parameters frequently used in quantitative structure-water solubility relationships (QSWSRs) are molecular volume and molecular connectivity indices. Moriguchi et al. [33] evaluated the following relationship to estimate Cw of apolar compounds and a variety of derivatives with hydrophilic groups  

Bhatnagar et al. [34] have found a significant correlation between Cw and PvdW for alkanols (C4-C9)  

Patil [35] reports the following correlation for chlorobenzenes and PCBs at 25°C  

Nirmalakhandan and Speece [36] introduced the polarizability factor,, as an additional molecular descriptor. They derived the following model for halogenated alkanes and alkenes, alkylbenzenes, halobenzenes, and alkanols  

This model is based on Sw data spanning 5 log units. Nirmalakhandan and Speece [36,37] discuss the model s validity and robustness in detail. They performed a test using experimental Sw data for esters, ethers, and aldehydes that were not included in the training set. They noted reasonably good agreement between experimental and estimated data for the test set and indicated that eq. 11.5.4 is applicable to dialkyl ethers, alkanals, and alkyl alkanoates, but not for ketones, amines, PAHs, and PCBs. Nirmalakhandan and Speece [37] expanded the model above for the PAHs, PCBs, and PCDDs. However, their model has been criticized by Yalkowsky and Mishra for incorrect and omitted data [38]. The revised model is [38] 

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F. W. Harris and L. H. Lannier, Structure-Solubility Relationships in Polymers, Academic, New York, 1987. 

Also in Structure-Solubility Relationships in Polymers, (eds.) Harris, F. W., Seymour, R. B., Academic Press, N. Y. 1977... 

The solubilities of aromatic compounds in the ionic liquid are dramatically higher than those of saturated compounds. Benzene has a solubility of 4.9mol/mol of ionic liquid, and thiophene has a solubility of 6.7mol/mol of ionic liquid. A dramatic steric effect was observed on the solubility of aromatics the alkyl-substituted aromatics showed reduced solubility. Although the solubility of hexene in the ionic liquid is considerably lower than that of the aromatics, it is still measurably higher than that of hexane. Similar structure-solubility relationships characteristic of organic molecules were observed with the ionic liquids [BMIM]BF4, [BMIM]PFg, and [EMIM]BF4 (Fig. 10) (27). 

Structure-solubility relationships can be used to predict the behavior of the hydrogenation reactions in an ionic liquid. For example ((S(S), the hydrogenation of aromatics in ionic liquids is much faster than that in the aqueous systems because of the higher solubilities of the aromatics in ionic liquids than in water. 

Equilibrium solubility This approach is considered a first attempt to characterize the true thermodynamic solubility of the compound. It is used to rank-order compounds and to extract a structure-solubility relationship within the chemical series. In this assay, compounds are usually equilibrated for 24 h before analysis. One can start from powder, but this is a quite labor-intensive step. In most cases one starts from DMSO stock solutions (usually 10 mM) because it is much more efficient from a compound logistics viewpoint. The solvent is then usually removed and the compound is dried before addition of the buffer medium [15, 16]. 

Alternatively, the structure-solubility relationship estimates solubility using equations that relate solubility to the molecular structures of solutes. The structure-solubility relationship is generally regarded as an empirical method. There is no doubt that an exact theoretical method is preferred over an empirical method forthe study of solubility phenomena. However, owing to the very complicated nature of molecular interactions and the various simpliLcations used in the development of mathematical models, exact thermodynamic approaches may not always provide accurate results without an extensive study of the compound of interest. At the present time, both theoretical and empirical approaches result in similar accuracy, and can be used equally well in the estimation of solubility. 

St Clair TL, St Clair AK, Smith EN (1977) In Harris FW, Seymour RB (eds) Structure-solubility relationships in polymers. Academic Press, New York, p 199... 

H. Hiramatsu, K. Okamura, 1. Tsujioka, S.-l. Yamada, R. Yoshioka, Crystal structure-solubility relationships in optical resolution by diastereomeric salt formation of DL-phenylglycine with (lS)-(+)-camphor-10-sulfonic acid, J. Chem. Soc. Perkin Trans. 2 (2000) 2121-2128. 

Harris, F.W. Seymour, R.B. Eds. Structure-Solubility Relationships in Polymers Academic Press New York, 1977. 

Lesions created in both bovine and human enamel, in an acidified methyl cellulose gel system, displayed many of the same qualitative trends [Lynch, unpubl. data]. After an initial period of approximately 3 days when dissolution was negligible, mineral loss was typically found at a series of discrete locations, with no apparent mineral loss between these pockets of demineralisation. Surface zones were typically poorly defined or absent. After 5 or more days, the isolated pockets had coalesced and lesions were uniform in terms of both depth and mineral loss across the bulk of the lesion body, with well-defined surface zones. When observed under polarised light, these initial pockets of demineralisation were very often coincident with Hunter-Schreger banding. This was particularly noticeable in bovine enamel. Shellis [64] reported variations in solubility related to enamel microstructure and suggested that structure/solubility relationships are likely to influence lesion formation. 

Dubin PL. In Structure-Solubility Relationships in Polymers. New York Academic Press, 1977 135. 

Starkweather, H. W., Chapter 3 in "Structure-Solubility Relationships in Polymers", Harris,... 

Fig. 21.30c). The fact that the latter complex is more soluble than [Ni(Hdmg)2] supports a structure-solubility relationship. 

Polymer Reagents Structure-Solubility Relationship in Polymers... 

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