[en] Highlights: • PnBs in the self-assembly of caged pnictogen species were computationally studied. • Such interactions are primarily electrostatic. • Substituents can be used to tune self-assembly structures and processes. In current years, specific rigid caged structures have been designed to facilitate self-assembly via multiple pnictogen bonds (PnBs). On the basis of our survey of the Cambridge Structure Database and recent crystallographic reports, two sets of dimeric complexes of pnictogen alkoxide cages 1-Pn and pnictogen pyrrole crowns 2-Pn were selected to model PnB interactions in the self-assembly of caged pnictogen compounds. Electrostatic interactions play an important role in the formation of these complexes. The introduction of different substituents into the skeleton 1-Pn affects the properties of double Pn⋯O interactions slightly, because of the opposite influence of these substituents on the donor and acceptor abilities. However, the Pn⋯N interaction strength enhances to a large degree with the presence of strong electron-withdrawing substituents into 2-Pn, due to the markedly increased donor ability of pnictogens.

[en] Abstract only

No abstract available

[en] Vanadium phosphates can be easily obtained via the reaction of phosphoric acid with vanadium alkoxides. Well crystallized vanadium phosphate VOPO₄,2H₂O is rapidly precipitated at room temperature from alkoxide precursors. Large anisotropic particles are obtained allowing the deposition of transparent thin films with a marked preferred orientation. Adding water results in longer precipitation times and less anisotropic morphologies. Tertiary alkoxides exhibit a much lower reactivity giving rise to amorphous phases related to the VOPO₄ structure in which some organic groups have not been removed

[en] The preparation and characterization of silicon alkoxide (silicon isopropoxide) from rice husk char has been studied. In the investigation, four kinds of Myanmar paddies were chemically assayed. Analyses showed the silicon contend varies from 73-92% . Based on the silicon content, the process development in the production of silicon isopropoxide was carried out. In the process development, silicon isopropoxide with a yield of 44.21% was achieved by the direct reaction of isopropanol in situ by silicon tetrachloride, which was directly produced by the chlorination of rice husk char at the high temperature range of 900-1100 C. The novelity of the process was that, silicon isopropoxide was achieved in situ and not by using the old process, where generally isopropanol was reacted with silicon tetrachloride. The physiochemical properties of silicon isopropoxide was confirmed by conventional and modern techniques. In the investigation, the starting materials, silica in the reaction products were characterized, identified and confirmed by modren techniques. Silicon isopropoxide can be a sources of pore silica whereby silicon of 97-99% of purity can be achieved.

[en] Short communication

[en] Vanadium pentoxide gels have been synthesized from vanadium alkoxides. The nature of the resulting material mainly depends on the hydrolysis ratio h=H₂O/V. All alkoxy ligands are not hydrolyzed when h≤3 leading to oxopolymers in which organic groups remain bonded to vanadium. Such gels exhibit an orange color. They give rise to amorphous xerogels or transparent films when dried under ambient conditions. An hydrous oxide gel is obtained when hydrolysis is performed with a large excess of water (h=100). It has a red color and exhibits the same layered structure as vanadium pentoxide gels made via the polycondensation of vanadic acid in aqueous solutions. The nature of alkoxy groups also plays a role. Their reactivity towards hydrolysis decreases when their steric hindrance increases

[en] Primary and secondary kinetic hydrogen isotope effects in the elimination of toluene from the alkoxide of 1,2,3-triphenylpropan-2-ol have been determined and are consistent with rate limiting proton transfer in gas phase reaction and with rate limiting carbon-carbon bond cleavage in reaction in dimethyl sulphoxide (DMSO) solution. (author)

[en] The results of experimental studies on ultrapurification of boron and germanium alkoxides are given. On the basis of the obtained data the phase equilibria and the optimum modes for rectification of the studied systems are calculated

[en] Analysis of reactions of 1,3,5-trinitrobenzene (TNB) with alcoholates of primary aliphatic alcohols (substitution of the nitro group or generation of σ^H-complexes at the unsubstituted position of TNB) leads to the conclusion that high basicity of alcoholates (MeONa, EtONa) of unsubstituted primary alcohols promotes formation of σ^H-complexes, thus preventing nucleophilic substitution of a nitro group. Introduction of electron-withdrawing substitutes (R = HC≡C, H₂C = CH, pyridyl) into the alcohol molecule (RCH₂OH) reduces the basicity of their alcoholates which makes substitution of nitro groups possible aff ording the corresponding 1-alkoxy-3,5-dinitrobenzenes in the presence of K₂CO₃ in N-methylpyrrolidone at 80 °C.