Figure 4.

Comparison of the protodeboronation rates of hydroxyboronate anions generated from the corresponding boronic acid or ester at pH 13, in 50% aq. dioxane at 70 °C; some structural features are highlighted in color to aid comparison. Vertical axes indicate approximate half-lives (log₁₀-scale). Half-lives for the ester are for direct protodeboronation (k_BE) only, see Figure 1D, and have been extrapolated by reference to their rate-ratio with the corresponding boronic acid at 21 °C. The half-lives at 21 °C can generally be estimated using t_0.5 ≈ 10^{(2.15+1.13log{t})} where {t} is the half-life at 70 °C, in seconds. Data from refs (1), (2), and (30).