Evaluation of a Direct 1H NMR Method for Determining Log K and Delta H Values forCrown Ether-Alkylammonium Cation Complexation

摘要

A direct NMR method for determining log K values for crown ether ammonium cation complexation using milligrams of sample was tested and evaluated for accuracy and precision by comparing the results with those obtained using a titration calorimetric method. Log K values for the interactions of a non-chiral crown ether, diketopyridino-18-crown-6 (K2P18C6), with alpha-phenylethylammonium perchlorate in 50%-50% and 90%-10% mixtures of deuterated methanol and deuterated chloroform at four temperatures and, with alpha-naphthyl ethylammonium perchlorate in 50%CD3OD-50%CDCl3 (v/v) at 25 C were determined by a direct NMR method. (JS)