化学
电位滴定法
外推法
水溶液
离解常数
乙腈
色谱法
滴定法
酸离解常数
甲醇
离解(化学)
分析化学(期刊)
无机化学
有机化学
离子
数学分析
生物化学
受体
数学
作者
Gergely Völgyi,Rebeca Ruiz,Karl Box,John Comer,Elisabeth Bosch,Krisztina Takács‐Novák
标识
DOI:10.1016/j.aca.2006.10.015
摘要
In this paper the validation of pKa determination in MDM-water mixtures is presented. The MDM-water mixture is a new multicomponent cosolvent mixture (consisting of equal volumes of methanol, dioxane and acetonitrile, as organic solvents) that dissolves a wide range of poorly water-soluble compounds. The cosolvent dissociation constants (p(s)Ka) of 50 chemically diverse compounds (acids, bases and ampholytes) were measured in 15-56 wt% MDM-water mixtures by potentiometric or spectrophotometric titration and the aqueous pKa values obtained by extrapolation. Three different extrapolation procedures were compared in order to choose the best extrapolation in MDM-water mixture using a sub-set of 30 water-soluble compounds. The extrapolated results are in good agreement with pKa values measured in aqueous medium. No significant difference was found among these extrapolation procedures thus the widely used Yasuda-Shedlovsky plot was proposed for MDM cosolvent also. Further we also present that the single point estimation based on measurement in 20%/v MDM-mixture using a general calibration equation may be suitable for rapid pKa determination in the early phase of drug research.
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