EBC-232 and 323: A Structural Conundrum Necessitating Unification of Five In Silico Prediction and Elucidation Methods

Structurally unique halimanes EBC-232 and EBC-323, isolated from the Australian rainforest plant Croton insularis, proved considerably difficult to elucidate. The two diastereomers, which consist an unusual oxo-6,7-spiro ring system fused to a dihydrofuran, were solved by unification and consultation of five in silico NMR elucidation and prediction methods [i.e., ACDLabs, olefin strain energy (OSE), DP4, DU8+ and TD DFT CD]. Structure elucidation challenges of this nature are prime test case examples for empowering future AI learning in structure elucidation.     

Comparison of Various Options for Designing the Direct Oxidation of Methane to Methanol

Russian Journal of Applied Chemistry - Various options for designing the direct oxidation of natural gas to methanol are considered: flow-through, with a distributed supply of the oxidizer along...     

Study of the products of platinum-catalyzed hydrogenation of chlorinated nitro and amino aromatic compounds at high degree of dehalogenation

The kinetics of formation and consumption of the dehalogenation products during hydrogenation of 3,4-dichloronitrobenzene under static and gradient-free flow conditions and hydrogenation of p-chloroaniline under static conditions were studied in the presence of platinum supported on active carbon. In the former case, p-chloroaniline and aniline are the primary dehalogenation products; in the presence of the catalyst, they can react with each other giving biphenyl derivatives, whose synthesis and accumulation in the reaction mixture occur with a considerable delay and have not been investigated before.     

Production of Ethylene,CO, and Hydrogen by Oxidative Cracking of Oil Refinery Gas Components

Flowsheets based on the results of experimental studies and detailed kinetic modeling were suggested for oxidative cracking of oil refinery gas components to obtain ethylene, CO, and hydrogen. The calculations show that oxidative cracking alone does not allow production of ethylene and СО in ratios required for the further catalytic carbonylation and hydroformylation of ethylene. Matrix conversion of a part of oxy-cracking products is suggested as an additional step for producing CO and hydrogen.

     

Weak antilocalization in a three-dimensional topological insulator based on a high-mobility HgTe film

The up-conversion luminescence of Er³⁺ from the ²H_11/2, ⁴S_3/2, and ⁴F_9/2 levels in nanocrystals of Y_0.95(1?x)Yb_0.95xEr_0.05PO₄ (x = 0, 0.3, 0.5, 0.7, 1) orthophosphates activated with Er³⁺ ions has been studied under the excitation of Yb³⁺ ions to the ²F_5/2 level by 972-nm cw laser radiation. Broadband radiation in the wavelength range of 370–900 nm has been observed at certain power densities of exciting laser radiation; this broadband radiation is absent in the case of excitation of the powders under study by pulsed laser radiation with a wavelength of 972 nm at a pulse repetition frequency of 10 Hz and a duration of a pulse of 15 ns. Experimental data indicating that this radiation is thermal in nature have been presented.     

Liquid-phase catalytic hydrogenation of 3,4-dichloronitrobenzene over Pt/C catalyst under gradient-free flow conditions in the presence of pyridine

Experimental data on nitro compound uptake, the intermediate product accumulation, and the corresponding amine compound generation were obtained on hydrogenating 3,4-dichloronitrobenzene over Pt/C catalyst in the gradient-free flow regime in the presence and absence of pyridine. In addition, a side reaction of dehalogenation was investigated. The role of pyridine admixture on every step of the process was analyzed and the rate of hydrogenation of the nitro compound was determined both in the presence and in the absence of inhibitor.

     

Thermally activated transformation of magnetization-reversal modes in ultrathin nanoparticles

The influence of thermal fluctuations on magnetization-reversal processes in ultrathin magnetic particles is investigated on the basis of a numerical solution of the Landau-Lifshitz-Gilbert equations taking account the thermal-activation fluctuation field. It is shown that for nanoparticles there exists a region of magnetic and geometric parameters where a strong jump-like instability of the critical field for magnetization reversal arises. This instability is due to the thermally activated transformation of magnetization configurations far from the switching threshold. The thermal-instability mechanism described is important for particles of much larger sizes than for the single-mode Néel-Brown instability. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 8, 555–560 (25 April 1999)     

Polariton dynamics of a one-dimensional gyrotropic magnetic photonic crystal in a dc electric field: I. Peculiarities of refraction

It is shown that both TE and TM waves incident on the surface of a semi-infinite one-dimensional thin-layer gyrotropic magnetic photonic crystal of the magnetic-nonmagnetic dielectric type can experience a number of refraction anomalies in an external electric field due to the effect of hybridization of evanescent waves in magnetic and nonmagnetic layers. These anomalies are absent under the same conditions in spatially homogeneous media consisting of the same materials as the photonic crystal.     

Impact of phase composition on water adsorption on inorganic hybrids "salt/silica"

The effect of a "guest-host" interaction on the phase composition and sorption properties of the composite sorbents "salt in a porous host matrix" has been studied. The matrix was a mesoporous silica of KSK type, while the confined salts were CaCl(2), CuSO(4), MgSO(4), and Na(2)SO(4). Both structure and properties of the composites were studied by X-ray diffraction, titration in the pH range of 2-9, differential dissolution, and TG techniques. Chemical interaction between the silica surface and the salt during preparation results in the formation of the salt surface complexes and stabilization of the dispersed salt in two phases, namely, a crystalline phase and an X-ray amorphous phase. The water sorption properties of the composites depend on the phase composition and can be intently modified by using variation of the preparation conditions.     

Enthalpy and heat capacity of the intermetallic compound CsBi<Subscript>2</Subscript> in the solid and liquid states

Enthalpy of solid and liquid intermetallic compound CsBi₂ in the temperature range of 430–1225 K was measured by massive isothermal drop calorimeter. Approximation equations were obtained, and isobaric heat capacity and enthalpy change on melting were determined. The tables of recommended values of caloric properties in the range from 298.15 K to 1225 K were developed. The experimental uncertainty of enthalpy and heat capacity measurements were estimated to be within 0.35 and 1.0%, respectively. The obtained results were compared with the calculations according to the laws of ideal solutions.