Tetrahedron

Synthesis and acidity constants of 13 CO 2 H-labelled mono and dipyrrole carboxylic acids. pK a from 13 C-NMR

DL Holmes, DA Lightner

Index: Holmes, Darren L.; Lightner, David A. Tetrahedron, 1995 , vol. 51, # 6 p. 1607 - 1622

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Citation Number: 30

Abstract

Six monocarboxylic acids were prepared highly enriched with 13C in their CO2H groups, and their pKa values were determined at low concentrations 10− 4− 10− 5M in H2O and in H2O-(CD3) 2SO mixtures by analysis of pH-dependent 13CO2H NMR chemical shifts. Plots of the variation of CO2H (CO2−) 13C-NMR chemical shift vs pH gave a typical titration curve from which pKa's for [1-13C]-phenylpropionic (1) and [1-13C]-phenylacetic (2) acids were ...