Formation of Diol Divinyl Diethers in the Synthesis of 1,2-Epoxy-3-(vinyloxyalkoxy)propanes

Russian Journal of Organic Chemistry -     

Study of acid-modified aluminum oxides produced by centrifugal thermal activation in dehydration of ethanol

Possibility of using products formed in centrifugal thermal activation of hydrargillite to obtain alumina catalysts washed to remove admixtures of alkali metals was considered. A comparison of the physicochemical and catalytic properties of the samples demonstrated that washing with water is more favorable than that with nitric acid; the catalytic activity and acid-base properties of the catalyst surface are determined not only by the content of Na, but also by the whole set of catalyst preparation conditions. The most active of the samples obtained in the study has acidity close to that of industrial aluminum oxide produced by the reprecipitation method, but surpasses it in activity: at 370°C, the total yield of ethylene and diethyl ether reaches a value of 88.8 mol %, which is 4% higher than that for the reference sample.     

IR Spectra of Trifluoromethanesulfonamide and Its Self-Associates in the Gas Phase

A labile equilibrium between monomeric trifluoromethanesulfonamide and its trimer and cyclic dimers in the gas phase at 385-485 K was determined by IR spectroscopy and quantum-chemical calculations (B3LYP/6-31G*).     

The structure and proton affinity of N‐benzyl‐N‐(allenyl)trifluoromethanesulfonamide: FT‐IR,DFT and ab initio study,NBO analysis

The first N‐allenyl derivative of trifluoromethanesulfonamide, N‐benzyl‐N‐(allenyl)trifluoromethanesulfonamide ( 1 ), was studied experimentally by the FT‐IR spectroscopy and theoretically at the DFT and MP2 levels of theory. The intramolecular interaction of the nitrogen atom with the triflyl and the allenyl group was studied in comparison with the analogously substituted vinyl derivatives. Compound 1 in heptane solution at 295–183 K exists as an equilibrium mixture of conformational isomers. Protonation at different basic sites in a series of reference molecules is studied theoretically. The central C² atom of the allenyl group in 1 has the highest proton affinity, which is 16 kcal/mol higher than in the N‐vinyl analogues. The relative ability of the allenyl and vinyl groups to conjugation with an electron‐rich and electron‐deficient nitrogen atom lone electron pair is discussed. From the NBO analysis, the conjugation of the nitrogen lone electron pair with the allenyl group is much stronger than with the vinyl group. Copyright © 2013 John Wiley & Sons, Ltd.     

Characteristics optimization of activated alumina desiccants based on product of a centrifugal thermal activation of gibbsite

Activated alumina desiccants modified with NaOH and KOH were synthesized from the product of a centrifugal thermal activation of gibbsite, with the subsequent hydration in an acid or alkaline medium, and their properties were studied. It was shown that the modification makes it possible to raise the dynamic capacity of desiccants produced from pseudoboehmite by up to a factor of 2 via formation of new super-strong basic centers the concentration of which grows with increasing content of an alkaline oxide. A correlation was found between the total concentration of basic centers on the surface of the desiccants and their dynamic capacity in drying of both dry and humid air. Use of the modified desiccants with high static and dynamic capacity will make it possible to improve the drying efficiency.     

Effect of modifying alumina desiccants with sulfuric acid on their physicochemical properties

In the production of alumina desiccants by extrusion, the introduction of sulfuric acid at the stage of preparing a mouldable paste based on hydroxides containing bayerite or pseudoboehmite increases the sorption capacity of the product. This effect is most pronounced for the pseudoboehmite-based materials. The dynamic capacity of these desiccants increases to the level characteristic of the bayerite-containing hydroxide (>5 g H₂O/100 cm³) for a dew point of ?40°C and a contact time of 1.5 s), and their static capacity exceeds this value (increasing from 21.13 to 23.1 g H₂O/100 cm³). This procedure changes the phase composition and textural characteristics of the pseudoboehmite-based desiccants and increases Brønsted acidity and generates strong Lewis acid sites on the surface of all oxides. The dynamic capacity of desiccants with similar textural characteristics depends on the acid-base properties of their surface.     

Oxidation of aryl vinyl sulfides in the ButOOH−Ti(OPri)4−(R,R)-diethyl tartrate system

Oxidation of aryl vinyl sulfides into aryl vinyl sulfoxides in the Bu¹OOH−Ti(OPrⁱ)₄−(R,R)-diethyl tartrate system was studied. The process afforded low optical yields (no more than 5%). A model of the oxidation was proposed that allows interpreting the dependence of the reaction enantioselectivity on the structure of a substrate. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1872–1873, September, 1998.     

Synthesis of aluminum oxides from the products of the rapid thermal decomposition of hydrargillite in a centrifugal flash reactor: II. Physicochemical properties of the products obtained by the centrifugal thermal activation of hydrargillite

A variety of physicochemical methods were used to characterize the product of the rapid thermal decomposition of hydrargillite in a centrifugal flash reactor under the following conditions: the average particle size of the reactant, 80–120 μm; the temperature of the solid heating surface (plate or cylinder), 300–700°C; hot-zone residence time, ～1 s; transfer of the product to the cooled zone of the reactor. The composition of the product and the extent of decomposition of hydrargillite were determined as a function of the processing temperature. The centrifugal thermal activation (CTA) of hydrargillite affords an X-ray-amorphous, highly reactive product with a developed surface and a disordered and inhomogeneous porous structure. This structure is capable of forming different modifications of aluminum hydroxide and oxide. The properties of the CTA product are compared with the properties of the earlier reported hydrargillite rapid decomposition products obtained using a gaseous heat-transfer agent (thermochemical activation product) or a fluidized bed of a granular heat-transfer agent (thermal dispersion product).     

Selective Electrochemical Aromatic Fluorination of Acetophenone and Benzophenone

Electrochemical fluorination of acetofenone and benzophenone was studied in anhydrous HF and in solutions. The electrochemical fluorination of acetophenone in HF occurred exclusively in the ring and furnished ortho- and meta-isomers of fluoroacetophenone, 2,5-difluoroacetophenone, and 1-(3,3,6,6-tetrafluoro-1,4-cyclohexadienyl)-1-ethanone. The fluorination of benzophenone in anhydrous HF furnished predominantly m-fluorobenzophenone, whereas in the presence of chloroform only chlorination products were obtained. The electrochemical fluorination of acetophenone in acetonitrile gave rise only to mono- and difluorinated products. The reasons for readily occurring oxidative fluorination of aromatic compounds into polyfluoro-1,4-cyclohexadienes were discussed, and the decomposition paths of fluorinated products under electron impact were considered.