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To discern which of the three OH groups of GA is the first one undergoing deprotonation, the geometries of the resulting dianions were optimized by using B3LYP hybrid density\u2010functional theory (DFT) and a 6\u201031G(++d,p) basis set, and the results suggest that the OH group at the 4\u2010position is the first one which is deprotonated. The variation of the observed rate constant, <jats:italic>k<\/jats:italic><jats:sub>obs<\/jats:sub>, with the acidity at a given [GA] follows an upward curve suggesting that the reaction takes place with the dianionic form of gallic acid, GA<jats:sup>2\u2212<\/jats:sup>, and rate enhancements of <jats:italic>ca.<\/jats:italic> 23000 fold are obtained on going from pH 3.5 up to pH 7.5. At relatively high acidities, the variation of <jats:italic>k<\/jats:italic><jats:sub>obs<\/jats:sub> with [GA] is linear with an intercept very close to the value for the thermal decomposition of 3MBD; however, a decrease in the acidity leads to saturation\u2010kinetics profiles with nonzero, pH\u2010dependent intercepts. The saturation\u2010kinetics patterns found suggest the formation of an intermediate in a rapid pre\u2010equilibrium step, but the nonzero, pH\u2010dependent intercepts cause the double reciprocal plots of 1\/<jats:italic>k<\/jats:italic><jats:sub>obs<\/jats:sub> <jats:italic>vs.<\/jats:italic> 1\/[GA] to curve. This prompts us to propose an alternative reaction mechanism comprising consecutive equilibrium processes involving the bimolecular, reversible formation of a highly unstable (<jats:italic>Z<\/jats:italic>)\u2010diazo ether which undergoes isomerization to the (<jats:italic>E<\/jats:italic>)\u2010isomer through a unimolecular step. The results obtained indicate the complexity of reactions of arenediazonium ions with nucleophilic arenes containing three or more OH groups.<\/jats:p>","DOI":"10.1002\/hlca.200900080","type":"journal-article","created":{"date-parts":[[2009,10,19]],"date-time":"2009-10-19T16:16:54Z","timestamp":1255969014000},"page":"2009-2023","source":"Crossref","is-referenced-by-count":11,"title":["Reactivity of 3\u2010Methylbenzenediazonium Ions with Gallic Acid. Kinetics and Mechanism of the Reaction"],"prefix":"10.1002","volume":"92","author":[{"given":"Sonia","family":"Losada\u2010Barreiro","sequence":"first","affiliation":[]},{"given":"Carlos","family":"Bravo\u2010D\u00edaz","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2009,10,19]]},"reference":[{"key":"e_1_2_1_1_2","unstructured":"A.\u2005F. Hegarty"},{"key":"e_1_2_1_2_2","unstructured":"K.\u2005H. Saunders R.\u2005L.\u2005M. Allen"},{"key":"e_1_2_1_3_2","unstructured":"H. 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