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Synthesis, Structure, and Acidity Constants of Ligated α-Boryl Acetic Acids
Thomas H Allen1, Anthony R Horner1, Steven J Geib1
1Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Abstract:
Basic hydrolyses of various ligated α-boryl acetic acid esters provided the first ligated derivatives of the unknown compound boroacetic acid (BH2 CH2 CO2 H). Four monoacids (L-BH2 CH2 CO2 H) and one diacid (L-BH(CH2 CO2 H)2 ) were prepared with N-heterocyclic carbene, amine, and pyridine ligands (L). The stable acids were characterized by X-ray crystallography and acidity constant (pKa ) measurements. They rank among the least acidic of all known carboxylic acids. In turn, their conjugate bases are among the strongest of all carboxylates.
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