Olefination with Sulfonyl Halides and Esters: Synthesis of Unsaturated Sulfonyl Fluorides.

Methanedisulfonyl fluoride, CH2(SO2F)2, transforms aromatic aldehydes into ß-arylethenesulfonyl fluorides, useful substrates for the SuFEx "click"-type transformations. The reaction mimics mechanism of the Horner-Wadsworth-Emmons olefination, which runs via addition of the carbanion, followed by cyclization-fragmentation of the four-membered ring intermediate. In the absence of base, electron-rich aldehydes follow an alternative pathway of the Knoevenagel condensation to provide unsaturated 1,1-disulfonyl fluorides. We demonstrate also trapping of elusive ethene-1,1-disulfonyl fluoride, CH2═C(SO2F)2, with 4-(dimethylamino)pyridine (DMAP) that forms zwitterionic adduct, characterized with X-ray studies.

Stereodivergent synthesis of alkenes by controllable syn-/anti-fragmentation of ß-hydroxysulfonyl intermediates.

The reduction of the carbonyl group in acylated trifluoroethyl alkanesulfonates follows the Felkin-Ahn selectivity, and the so-formed diastereomeric ß-hydroxysulfonyl intermediates undergo syn- and anti-fragmentation, depending on the reaction conditions. In effect, isomeric E- and Z-alkenes are formed in a stereodivergent manner, which mimics the mechanistic manifold of the Peterson olefination.

Ti2C MXene Modified with Ceramic Oxide and Noble Metal Nanoparticles: Synthesis, Morphostructural Properties, and High Photocatalytic Activity.

Among two-dimensional (2D) materials, such as graphene, a new family of 2D anisotropic carbides and nitrides of early transition metals (MXenes) is very interesting because of the potential applications in electronics, medicine, and photocatalysis. In this paper, preparation, morphostructural characterization, band gaps determination, and salicylic acid photodegradation ability of Ti2C MXene and six nanocomposites consisting of the MXene modified by TiO2, Ag2O, Ag, PdO, Pd, and Au are reported. It was confirmed using electron diffraction studies, energy dispersive X-ray spectroscopy, and high-resolution transmission microscopy that metals and metal oxides occur on the MXene flakes as nanoparticles in a shape of spots. The band gaps determined experimentally using Tauc's method are placed in the region of 0.90-1.31 eV. In recent years, the method of photocatalytic decomposition of pollutants using semiconductor photocatalysts and UV-vis energy has become increasingly important. The MXene based nanocomposites revealed high activity in the salicylic acid (SA) photodegradation reaction (86.1-97.1% of degraded SA after 3 h, concentration of SA initial solution 100 µM, the circulation rate of the SA solution 0.875 cm3/min). The interfacial charge transfer mechanism and the role of the metallic and metal oxide nanoparticles in the photocatalytic activity of the MXene based nanocomposites are presented and discussed.

Changes in the microbiological and chemical characteristics of white bread during storage in paper packages modified with Ag/TiO2-SiO2, Ag/N-TiO2 or Au/TiO2.

Microbiological and chemical characteristics of white bread during storage in paper-packages modified with Ag/TiO2-SiO2, Ag/N-TiO2 or Au/TiO2 were investigated. The whiteness and the water retention of the modified packages were slightly superior to those exhibited by the reference sample, as the color of the composite was lighter. The water retention was very good especially for the Ag/TiO2-SiO2-paper. These improvements can be associated with the high specific surface area and with the low agglomeration tendency of Ag nanoparticles in comparison with the Au ones. The preservation activity of the composites for the bread storage is positively influenced by photoactivity and presence of nano-Ag. Packages Ag/TiO2-SiO2-paper and Ag/N-TiO2-paper can find their applicability for extending the shelf life of bread by 2 days as compared with the unmodified paper-package. No influence of the Au/TiO2 on the extending the shelf life of bread was observed.