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MECHANISTICALLY OPTIMIZED INTRAMOLECULAR CATALYSIS IN THE HYDROLYSIS OF ESTERS. GLOBAL CHANGES INVOLVED IN MOLECULAR REACTIVITY
Author(s) -
Yunes Santiago F.,
Gesser José C.,
Chaimovich Hernan,
Nome Faruk
Publication year - 1997
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199706)10:6<461::aid-poc914>3.0.co;2-7
Subject(s) - chemistry , steric effects , hydrolysis , intramolecular force , reactivity (psychology) , decomposition , isopropyl , reaction rate constant , acid catalysis , medicinal chemistry , solvation , computational chemistry , catalysis , organic chemistry , stereochemistry , kinetics , molecule , medicine , physics , alternative medicine , pathology , quantum mechanics
The hydrolysis of the 2′,2′,2′‐trifluoroethyl monoester of 1,8‐naphthalic acid ( 1 ) proceeds via the monoanion with the intermediate formation of the corresponding anhydride. The rate constant for the formation of 1,8‐naphthalic anhydride ( 2 ) is ca 2500 times faster than its rate of hydrolysis. The isotope effect in the plateau region and theoretical calculations at the PM3 level suggest that elimination of the alkoxide is the rate‐limiting step for the reaction. Accordingly, decomposition of the isopropyl monoester of naphthalic acid proceeds 10 4 times slower than the spontaneous decomposition of 1 . The remarkably high rate of monoester decomposition derives from the special configuration of the substrates and important contributions that arise from relief of torsional strain, which clearly includes electron redistribution due to the decrease in steric hindrance to resonance and the fact that proximity obviates solvation. © 1997 John Wiley & Sons, Ltd.