Syntheses, Characterization, and Application of Tridentate Phenoxyimino-Phenoxy Aluminum Complexes for the Coupling of Terminal Epoxide with CO2: From Binary System to Single Component Catalyst

A series of binuclear aluminum complexes 1–3 supported by tridentate phenoxyimino-phenoxy ligands was synthesized and used as catalysts for the coupling reaction of terminal epoxide with carbon dioxide. The aluminum complex 1, which is catalytically inactive toward the coupling of epoxide with CO2 by itself, shows moderate activity in the presence of excess nucleophiles or organic bases at high temperature. In sharp contrast to complex 1, bifunctional complexes 2 and 3, which incorporate tertiary amine groups as the built-in nucleophile, are able to efficiently transform terminal epoxide with CO2 to corresponding cyclic carbonates as a sole product by themselves at 100 °C. The number of amine groups on the ligand skeleton and the reaction temperature exert a great influence on the catalytic activity. The bifunctional complexes 2 and 3 are also active at low carbon dioxide pressure such as 2 atm or atmospheric CO2 pressure. Kinetic studies of the coupling reactions of chloropropylene oxide/CO2 and styrene oxide/CO2 using bifunctional catalysts under atmospheric pressure of CO2 demonstrate that the coupling reaction has a first-order dependence on the concentration of the epoxide.

ИССЛЕДОВАНИЕ БИОЦИДНОЙ ОБРАБОТКИ КОЖИ СРЕДНЕВЕКОВЫХ КНИЖНЫХ ПЕРЕПЛЕТОВ МЕТОДОМ ДОДУБЛИВАНИЯ АЛЮМИНИЕВЫМ КОМПЛЕКСОМ, СТАБИЛИЗИРОВАННЫМ ТРИМЕТИЛОЛМЕЛЕМОМ

It was shown in the past that different re-tanning agents were used as a repellent to enhance the antifungal properties of the hydrothermal stability of the skins of ancient book covers, including the aluminum sulphate-stabilized complex aluminum salt (Al-ЭDA). Although the skin treatment with this re-tanning agent improves the properties of the skin, the collagen structure cannot be considered very safe, i.e., it was relatively low. An additional biocidal substance, catamine AB, was used to ensure the antifungal properties of the treated leather. That is why, a new aluminum complex material has been synthesized for the skin re-tanning of the covers. As a stabilizer of aluminum sulphate, trimethylmeleme was used, for the production of which the meleme material was taken and reacted with formaldehyde. The resulting trimethylolmeleme, having three methylol groups, can form a complex salt when it interacts with aluminum sulphate. The mentioned complex material was filtered and the water part was removed from the crystals formed from the purified liquid by evaporation. The resulting complex salt is soluble, and the crystals left on the filter are insoluble. Both were tested as re-tanning agent samples on the cover leather samples. Treatment with crystals separated from the filtered liquid completely increases the welding point of the skin treated with the tannin extract of ancient leather up to 1000C and more, and up to 75-770C during re-tanning with the complex salt removed from the filter. The research of antifungal properties of the complexes has identified an expressive activity of the difficulty of dissolving complex II in comparison to the compound used earlier. High hydrothermal stability gives strength, less elasticity and other high-performance properties to the leather

C2-Selective Silylation of Pyridines by a Rhodium–Aluminum Complex

We have developed a C2-selective mono-silylation of a variety of pyridines using a Rh-Al complex. Both the site- and mono-selectivity are controlled via the pyridine coordination to the Lewis- acidic...