Electrochemistry of corrosion mitigation of brasses by azoles in basic medium

Modern Approaches to the Synthesis and Transformations of Practically Valuable Benzothiazole Derivatives

The review is devoted to modern trends in the chemistry of 2-amino and 2-mercapto substituted benzothiazoles covering the literature since 2015. The reviewed heterocycles belong to biologically active and industrially demanded compounds. Newly developed synthesis methods can be divided into conventional multistep processes and one-pot, atom economy procedures, realized using green chemistry principles and simple reagents. The easy functionalization of the 2-NH2 and 2-SH groups and the benzene ring of the benzothiazole moiety allows considering them as highly reactive building blocks for organic and organoelement synthesis, including the synthesis of pharmacologically active heterocycles. The review provides a summary of findings, which may be useful for developing new drugs and materials and new synthetic approaches and patterns of reactivity.

Time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy study of 2-phenylimidazole on brass

RATIONALE

This work presents the first surface analysis investigation of 2-phenylimidazole (PhI) as a corrosion inhibitor for brass in a 3 wt.% NaCl solution using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS).

METHODS

A time-of-flight secondary ion mass spectrometer was used to describe the elemental and molecular specific signals on the brass surface. Gas cluster/monoatomic ion beam depth profiling and two-dimensional (2D) imaging showed the surface properties of the PhI surface layer. In addition, detailed XPS was used to describe the element-specific signals on the brass surface. Furthermore, principal component analysis demonstrated the distribution of the different phases of the surface. Finally, the applicability of PhI in hot corrosion studies was suggested by a thermal stability experiment.

RESULTS

TOF-SIMS measurements showed an intense positive-ion TOF-SIMS signal for protonated PhI, i.e. C₉ H₉ N₂ ⁺ at m/z 145.07. Moreover, there was an intense negative-ion TOF-SIMS signal for deprotonated PhI, i.e. C₉ H₇ N₂ ¯ at m/z 143.06. Gas cluster ion beam sputtering associated with the analysis of the XPS-excited Cu L₃ M_4,5 M_4,5 revealed a connection between Cu(I) and PhI to form organometallic complexes.

CONCLUSIONS

The formation of the organometallic complexes with Cu and Zn metal atoms/ions was identified using TOF-SIMS in positive and negative polarity mode: PhI-Cu, PhI-Cu₂ , PhI-Zn, and PhI-Zn₂ complexes were present on the brass surface. The TOF-SIMS measurements were supported by XPS measurements.