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Updated: Oct 1, 2026

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile
Published on: October 30, 2018
Intramolecular general base catalyzed ester hydrolysis. The hydrolysis of 2-aminobenzoate esters
Thomas H Fife1, Randhir Singh, Ramesh Bembi
1Department of Biochemistry, University of Southern California, Los Angeles, California 90089-9560, USA. tfife@hsc.usc.edu
Abstract:
Rate constants have been obtained for the hydrolysis of the trifluoroethyl, phenyl, and p-nitrophenyl esters of 2-aminobenzoic acid at 50 degrees C in H(2)O. The pseudo-first-order rate constants, k(obsd), are pH independent from pH 8 to pH 4 (the pK(a) of the amine group conjugate acid). The 2-aminobenzoate esters hydrolyze with similar rate constants in the pH-independent reactions, and these water reactions are approximately 2-fold slower in D(2)O than in H(2)O. The most likely mechanism involves intramolecular general base catalysis by the neighboring amine group. The rate enhancements in the pH-independent reaction in comparison with the pH-independent hydrolysis of the corresponding para substituted esters or the benzoate esters are 50-100-fold. In comparison with the hydroxide ion catalyzed reaction, the enhancement in k(obsd) at pH 4 with the phenyl ester is 10(5)-fold. Intramolecular general base catalyzed reactions are assessed in respect to their relative advantages and disadvantages in enzyme catalysis. A general base catalyzed reaction can be more rapid at low pH than a nucleophilic reaction that has a marked dependence on pH and the leaving group.
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