Kinetic evidence for high reactivity of 3-nitrophenylboronic acid compared to its conjugate boronate ion in reactions with ethylene and propylene glycols

摘要

The rate constants for a boronate ion were determined for the first time using the reaction systems of 3-nitrophenylboronic acid (3-NO2PhB(OH)(2)) with ethylene glycol (EG) and propylene glycol (PG) in an alkaline solution: the rate constants (25 degrees C, I = 0.10 M) for the reactions of 3-NO2PhB(OH)(3)(-) are 1.2 M-1 s(-1) (EG) and 1.5 M-1 s(-1) (PG), which are at least 103 times smaller than those for the reactions of 3-NO2PhB(OH)(2) [1.0 X 10(4) M-1 S-1 (EG) and 5.8 x 10(3) M-1 S-1 (PG)].