Computer-augmented modelling of complexes of amino acids in aquo-organic mixtures: Part II-acido-basic equilibria of -alanine and -dopa in aquo-DMF media

Abstract

The solute-solvent interactions of -alanine and -dopa have been studied in 10-70% v/v DMF-water media by pH metric method. The equilibrium constants have been calculated with the computer program MINI-QUAD 75. The selection of the best chemical model of the acido-basic equilibria is based on standard deviation in stability constants and residual analysis based on crystallographic R factor and U (sum of squares of residuals in all mass-balance equations). The linear or quadratic trend of variation of equilibrium constants with 1/D and mol fractions of the solvent mixture has been established with orthogonal polynomial analysis.