Electrocatalytic Synthesis of Nylon-6 Precursor at Almost 100 % Yield

Synthesis of cyclohexanone oxime via the cyclohexanone-hydroxylamine process is widespread in the caprolactam industry, which is an upstream industry for nylon-6 production. However, there are two shortcomings in this process, harsh reaction conditions and the potential danger posed by explosive hydroxylamine. In this study, we presented a direct electrosynthesis of cyclohexanone oxime using nitrogen oxides and cyclohexanone, which eliminated the usage of hydroxylamine and demonstrated a green production of caprolactam. With the Fe electrocatalysts, a production rate of 55.9 g h⁻¹ g_cat⁻¹ can be achieved in a flow cell with almost 100 % yield of cyclohexanone oxime. The high efficiency was attributed to their ability of accumulating adsorbed hydroxylamine and cyclohexanone. This study provides a theoretical basis for electrocatalyst design for C−N coupling reactions and illuminates the tantalizing possibility to upgrade the caprolactam industry towards safety and sustainability.     

The Pr-Ga system in the 66.7–100 at.% Ga range

Reinvestigation of the Pr-Ga system by X-ray diffraction, differential thermal analysis, metallography, scanning electron microscopy and diffusion couples established that gallium has a wide solid solubility range in PrGa₂ (78 at.% Ga) and that PrGa₆, which forms peritectically at 466 ± 6 °C, exists. The possible existence of PrGa₄ is postulated on the basis of indirect experimental evidence.     

The fabrication and mechanical properties of Ta-V (0–60 at.%) alloys

Commercial purity Ta-V alloys containing 0–60 at.% V were fabricated into wire at room temperature. Reductions in area of greater than 99% were possible without intermediate annealing. TaV₂ was present in the 50 and 60 at.% V alloys. Recrystallization and mechanical property data are given. Alloys containing 0–40 at.% V have a low rate of work hardening and good properties at 1000°C and they do not show a ductile-to-brittle transition down to −195°C.     

The HfNi and ZrNi systems in the region 65 – 80 at.% Ni

The HfNi and ZrNi systems have been examined in the region 65 – 80 at.% Ni by microscope and X-ray analyses.In the HfNi system the following intermediate phases were observed: Hf₃Ni₇, Hf₈Ni₂₁, HfNi₃(h. t.), HfNi₃(l. t.) and Hf₂Ni₇. Hf₃Ni₇, which is formed peritectically at 1250 ± 20 °C, decomposes eutectoidally at 1016 ± 3 °C into Hf₇Ni₁₀ and HfNi₃(l. t.). Hf₈Ni₂₁ is stable from 1300 ± 20 °C, where it forms peritectically, to 1175 ± 10 °C where it decomposes eutectoidally into Hf₃Ni₇ and HfNi₃(l. t.). HfNi₃(h. t.) is a high temperature phase, forming peritectically at 1350 ± 20 °C and transforming into HfNi₃(l. t.) below 1200 ± 10 °C. Hf₂Ni₇ melts congruently. A eutectic between Hf₇Ni₁₀and Hf₃Ni₇ occurs at 1190 ± 10 °C.In the ZrNi system only one phase forming peritectically exists; this is Zr₈Ni₂₁, which is stable at least down to 800 °C. ZrNi₃ is formed in a reaction between Zr₈Ni₂₁ and Zr₂Ni₇ at 920 ± 10 °C. Crystallographic data for the intermediate phases in the HfNi and ZrNi systems in the region 65–75 at.% Ni are presented.     

Enthalpies of formation of SmCo alloys in the composition range 10–22 at. % Sm

Several intermetallic compounds exist in the composition range 10–22 at.% Sm(Sm₂Co₁₇, SmCo₅, Sm₂Co₇) but their preparation as single-phase specimens is very difficult. In order to determine the enthalpies of formation of these compounds, measurements were carried out on four alloys containing respectively 12.9 at.% Sm, 16.4 at.% Sm, 17 at.% Sm and 19.8 at.% Sm, annealed in the temperature range 950–1100 °C. The compositions of the phases present in each specimen were deduced from the characterization of the measured alloys by scanning electron microscopy, electron microanalysis and X-ray diffraction.The heats of formation were deduced from solution calorimetry in molten tin. The variation of the experimental results as a function of the samarium content enabled the enthalpy of formation of SmCo₅ ( − 40.8 kJ mol⁻¹) to be determined. The same ΔH_f value as determined for the phase quenched from 950 °C was measured for SmCo₅ kept at room temperature after very slow cooling. This result did not confirm the eutectoid decomposition previously reported for SmCo₅.The extrapolation of the measured values for the higher and lower samarium contents leads to the evaluation of the enthalpies of formation of Sm₂Co₁₇ (−152 kJ mol⁻¹) and Sm₂Co₇ (−99kJ mol⁻¹).     

BaO-BiO1.5 phase diagram in the region 80–100 mol % BiO1.5 at p o 2 = 21 kPa

The phase equilibria in the region from 80 to 100 mol % BiO_1.5 are studied in the BaO-BiO_1.5 system in air and under an argon atmosphere using visual polythermal analysis (VPA), X-ray powder diffraction, differential thermal analysis (DTA), electron diffraction (ED), and elemental analysis in a transmission electron microscope (EA/TEM). A series of discrete layered rhombohedral phases (RPs) with the composition Ba₂Bi_8+n O_y, where n = 0, 1, 2, 4, 8, or 10, is discovered. The melting character is determined for these RPs: the 1: 4 phase melts congruently; the 2: 9, 1: 5, 1: 6, and 1: 8 phases melt incongruently. The crystallization fields are 10–30°C. At p _{o 2} = 21 kPa, the 1: 4 phase in the subsolidus region decomposes into a 4: 13 perovskite-like phase and the 2: 9 phase. The other rhombohedral phases decompose into stages to yield Bi₂O₃ and a neighboring RP that is richer in barium. The Ba₂Bi_8+n O_y oxides are stable in argon and experience a first-order phase transformation at about 560°C.     

Microchemical and Microstructural Characterization of the Early Stages of the Discontinuous Precipitation Reaction in Al-22 at.% Zn Alloy

High-spatial energy dispersive X-ray (EDX) microanalysis has been applied in order to reveal changes of chemical composition accompanying the formation of the lamellar structure due to discontinuous precipitation reaction in Al-22at.% Zn alloy. The line-scans performed in the reaction zone have shown that the region left behind the grain boundary (GB) after its displacement from the original position is solute depleted, similar to the de-alloying case of diffusion induced grain boundary migration. This enables the allotriomorphs to be transformed into solute-rich lamellae and development of lamellar + structure, especially if the GB moves in the direction perpendicular to its original location. If the direction of movement is strongly inclined to the original location of the GB, the growth usually stops after a short period of time, mainly due to formation of the precipitation free zone (PFZ) ahead of the reaction front. The detailed EDX examination revealed that there is a sharp change in solute content at the lamella/PFZ and PFZ/matrix alloy interfaces. The solute content in the PFZ is lower than in the neighbouring lamella and it corresponds to the equilibrium state. Therefore, one can suppose that the PFZ is formed due to backward movement of the reaction front in order to consume the excess of solute atoms stored in the lamellae in comparison with the equilibrium state. As soon as the equilibrium state is attained within the PFZ, the growth of the colony is completed.     

Phase Equilibrium System of CsCl-YCl3-（9.5%）HCL-H2O at T=298.15 K and Its Compounds

Introduction In a series of papers the authors reported the spec-troscopy results on upconversion luminescence of the double salts between the alkali metal (Rb,Cs) halide and rare earth metal trihalide (REX3).1-4 Consequently, ex-tensive syntheses of new double salts and studies on optical properties of such species have received much more attention.5-12 Although a number of these double salts have been synthesized, the formation in alkali metal halide/rare earth metal halide double salts s…     

数显式分光光度计0%、100%失调的处理

介绍了数显式分光光度计 0 %、10 0 %失调的原因及处理方法     

数显式分光光度计0%,100%失调的处理

介绍了数显式分光光度计０％、１００％失调的原因及处理方法。     

Kinetics of Crystalline Iodine Dissolution in Ethanol at Room Temperature and at 60°С

The kinetics of crystalline iodine dissolution in ethanol at room temperature and 60°C is studied using the electronic absorption spectra of iodine solutions. Dissolution is shown to proceed for more than three months. It is found that the process begins with the formation of hydroiodic acid HI and is complete with the formation of I ₃ ^? anions.     

“Speed” Marvel at DuPont

Before beginning the technical subject, I'd like to take a few minutes to review Professor Marve?s long association with DuPont. Professor Marvel is known simply as “Speed” at DuPont, and I will refer to him by that title of respect. Speed has been a consultant for DuPont since February 1928, a little more than 55 years. In that time, we estimate he has made 260 trips to Wilmington or other DuPont locations from Urbana and Tucson, held 19,000 individual consulting conferences, stayed 1308 nights in the DuPont hotel (= 3.58 years), and surely, established many records for a consulting relationship, both in duration and breadth.     

Solid water at room temperature?

Previously, we have shown that water adjacent to many hydrophilic substances excludes colloidal and molecular solutes. It was labelled “exclusion zone” (EZ) or “fourth phase” water. A salient feature is its characteristic light absorbance at or near 270 nm. In this study, EZ water formed against three chemically distinct surfaces, Nafion, ghee, and Whatman-5 filter paper was extracted, characterized by UV–Visible absorbance spectroscopy, and solidified either by lyophilizing or evaporation in an oven. The resulting highly stable solid was dissolved in water and confirmed as EZ water by its characteristic absorbance at 270–280 nm. We used mass spectroscopy to verify the absence of ionizable contaminants that could reproduce the characteristic “signature EZ” spectra in the three liquid preparations, or in the solids formed from desiccated EZ water that had been reconstituted in deionized water. Hence, a solid form of EZ water may, indeed, exist at room temperature.     

The o-chlorotoluene photodissociation at 266 nm

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Effect of oxidation of nitride coatings on corrosion properties of Ti-6Al-4V alloy in 0.9% NaCl at 40°C

The corrosion properties of Ti-6Al-4V alloy with oxidized thermodiffusion nitride coatings were investigated in isotonic 0.9% solution of NaCl at temperature of 40°C. It was shown that modification of nitride coatings by oxygen leads to a deterioration of the protective properties of nitrided surface of Ti-6Al-4V alloy. The protective properties of the alloy with nitride coatings modified by oxygen are determined by the composition of formed surface oxynitride film.      

Phase Equilibrium of the System TbCl3-CdCl2-HCl(7.92 wt %)-H2O at 298.15 ± 0.1 K 1

The equilibrium solubility of the quaternary system TbCl₃-CdCl₂-HCl(7.92 mas. %)-H₂O was determined at 298K and the corresponding equilibrium diagram was constructed. The quaternary system is complicated by the three equilibrium solid phases: CdCl₂ · H₂O, TbCd₄Cl₁₁ · 14H₂O (4: 1 type), and TbCl₃ · 6H₂O, of which the new compound Cd₄TbCl₁₁ · 14H₂O was found to be congruently soluble in the system. The new compound obtained was identified and characterized by the method of X-ray diffraction and the thermal analysis methods of thermogravimetry-differential thermogravimetry (TG-DTG). This article was submitted by the authors in English.     

Molybd?n (1%) in 3% Uran enthaltenden Thoriumoxiden

Ohne Zusammenfassung     

Unexpected ipso-Substitutions at the β-Carboline Nucleus

Abstract

Minisci-type radical carbamoylation of 1-bromo-β-carboline (1) gives the 3-substituted product in low yield, whereas 1-acetyl-β-carboline (3a) reacts under ipso-substitution of the acetyl group. Cyanations of the N-oxides of 1 and 3a occur under clean ipso-substitution of the groups in 1-position. 1-Methyl derivatives show no tendency to react under ipso-substitution.     

Molecular electronics at electrode–electrolyte interfaces

Four contemporary examples, all published in recent years, of studies of molecular electronics at electrode–electrolyte interfaces are reviewed in this opinion article. The first illustrative example involves the switching of the redox active molecular wire between redox states, with concomitant changes in molecular conductance. This example illustrates how molecular electronics at electrode–electrolyte interfaces can be used to analyse mechanisms of electron transfer, to distinguish electrolyte effects and to provide details not readily available from ensemble measurements. The second example shows that the fluctuations of molecular conductance of a redox active molecular wire can be followed as a function of electrode potential. This shows how the stochastic kinetics of individual reaction events at electrode–electrolyte interfaces can be followed. The third example demonstrates how electrochemistry can be used to control quantum interference in single molecular wires. The fourth example shows a single-molecule electrochemical transistor concept for well-defined metal cluster containing molecular wires.     

Argon–water system at low temperatures

The molecular dynamics method is used to simulate argon solutions in water and a thin water film–argon system at low temperatures. The correlation in motions of two closely spaced argon atoms is of another nature than the correlation of two neon atoms in a neon solid solution in ice II. The structure of hydrate shells of argon atoms contains five-membered rings composed of water molecules. The solubility of argon in a water film at low temperatures is noticeably higher than at room temperature. If a water film is first cooled to the glassy state and then argon atoms are added to it, then approximately as many argon atoms are absorbed on the film surface as they are present in a cooled film in equilibrium with the argon atmosphere. Argon atoms migrate from one pit to another on the rough surface of a solid water film.