ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The β2H scale of solute hydrogen-bond basicity, formulated from 1:1 hydrogen-bond complexation constants in tetrachloromethane, has been used to set up a scale of effective or summation hydrogen-bond basicity, appropriate for the situation in which a solute is surrounded by solvent molecules. The method is based on the equation, \documentclass{article}\pagestyle{empty}\begin{document}$$ \log SP = c + rR_2 + s\pi _2^{\rm H} + a\sum {\alpha _2^{\rm H}} + b\sum {\beta _2 + vVx} $$\end{document} where SP is, in this work, a set of solute water-solvent partition coefficients in a given system. The explanatory variables are solute parameters as follows: R2 is an excess molar refraction, π2H is the solute dipolarity/polarizability, Σα2H and Σβ2 are the effective solute hydrogen-bond acidity and basicity and Vx is McGowan's characteristic volume. Various equations are established using β2H in the equation, and then amended β2H values are back-calculated and new Σβ2H values obtained. It is found that for most solutes, the effective basicity Σβ2H is invariant over the systems used to within an experimental error of around 0·03 units. About 350 Σβ2H values obtained from two or more experimental log P values are listed, together with values for homologous series and a number of singly determined values. For some specific solutes, such as sulphoxides, alkylanilines and alkylpyridines, Σβ2 is not constant, and an additional solute basicity denoted as Σβ2O is needed in order to deal with partitions from water to solvents that are partially miscible with water, such as isobutanol and octanol. Values of Σβ2O, and where possible Σβ2H also, are listed for 80 additional solutes.
Additional Material:
17 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610061204
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