(equation presented) The pKa values and the geometries of secondary and tertiary amines adjacent to boronic acids were determined using potentiometric and 11B NMR titrations. The studies showed that the secondary ammonium ion has a pKa similar to that of the tertiary ammonium species, which leads to the formation of tetrahedral boron centers at pH values above approximately 5.5. Therefore, secondary amines as well as tertiary amines, when placed proximal to boron centers, can be used to create tetrahedral boronic acids at neutral pH for diol complexation.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry