In this study, the passivity and pitting corrosion of 316L in simulated concrete pore solutions were investigated through polarization curve, electrochemical impedance spectroscopy (EIS), and MottSchottky (M-S) analyses. In solutions with different pH levels and Cl − concentrations, the corrosion resistance of 316L decreases with decreasing pH and increasing Cl − concentration. The breakdown potential (E b ) is linearly related to the logarithm of Cl − concentration under weak alkaline solutions. The undissolved corrosion product outflow from the corrosion pit would damage the passive film covered by the precipitates. In EIS results, the passive film resistance of 316L in pH 13 is higher than those in pH 9 and 11. In the XPS spectra, the ratios of Cr/(Fe+Cr+Ni) and Fe 3+ / Fe 2+ increase because of the selective dissolution effect on solutions with high Cl − concentration and pH. In M-S data, the passive films under all test solutions are identified as n-type semiconductor. Concrete carbonation and Cl − enrichment can reduce the stability of passive films and increase the corrosion tendency in marine environments.
An efficient synthesis of xanthene/thioxanthene-indole derivatives has been developed through iodine-catalyzed nucleophilic substitution reaction of xanthen-9-ols and thioxanthen-9-ol with indoles.
Represented
is a CuX2- or I2-promoted ring-opening
dual halogenation of cyclopropenones with saturated oxygen heterocycles,
providing an efficient method for the synthesis of 3-haloacrylates.
The ring-opening reaction enables the construction of two C–X
(X = Cl, Br, or I) bonds and a C–O bond as well as the cleavage
of two C–O bonds and a C–C bond in a single step. This
protocol is highly atom economical, has an excellent substrate scope,
and exhibits the ability for gram-scale reaction.
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