title: Relative kinetic reactivity of boronic acid and boronate ion towards Tiron, 2,2'-biphenol, and propylene glycol.
abstract: Reaction systems of boronic acid (RB(OH2), R = phenyl or 3-fluorophenyl) with diols and no proton ambiguity were elaborately set up, and kinetic measurements were conducted to elucidate the relative reactivities of RB(OH)2 and RB(OH)3(-). In the reactions of phenylboronic and 3-fluorophenylboronic acids with propylene glycol, the reactivity order was: RB(OH)2 >> RB(OH)3(-), whereas in the reactions of 3-pyridylboronic acid with Tiron and 2,2'-biphenol, the reactivity of RB(OH)2 was comparable to that of RB(OH)3(-). These results are in contrast to those that have been previously reported, and widely accepted for over thirty years, that concluded that the reactivity of RB(OH)3(-) is several orders of magnitude higher than that of RB(OH)2. The reactivity of Tiron with 3-pyridylboronic acid is affected by the protonation of one of its sulfonate groups.
authors.affiliation: Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Watanabe
authors.forename: Chiaki
authors.initials: C
authors.lastname: Miyamoto
authors.forename: Asumi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Kenzo
authors.initials: K
authors.lastname: Iizuka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwatsuki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Inamo
authors.forename: Hideo D
authors.initials: HD
authors.lastname: Takagi
authors.forename: Koji
authors.initials: K
authors.lastname: Ishihara