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Five-membered pyrroline nitroxides with high-potential is fascinating as catholyte for aqueous organic redox flow batteries (AORFBs), however, it suffers from a primary deficiency of insufficient stability due to ring-opening side reaction. Herein we report a spatial structure regulation strategy by host-guest chemistry, encapsulating 3-carbamoyl-2,2,5,5-tetramethylpyrroline-1-oxyl (CPL) into hydrosoluble cyclodextrins (CDs) with an inclusion structure of N-O· head towards cavity bottom, to boost the solubility and cyclability of pyrroline nitroxides significantly. The armor-clad CPL (CPL⊂HP-β-CD) catholyte in 0.05-0.5 M presents a battery capacity fade rate as low as 0.002 %/cycle (0.233 %/day) compared to the sole CPL in 0.05 M (0.039 %/cycle or 5.23 %/day) over 500 cycles in assembled AORFBs. The optimized reclining spatial structure with N-O· head towards CD cavity bottom effectively inhibits the attack of Lewis base species on the hydrogen abstraction site in pyrroline ring, and thus avoids the ring-opening side reaction of pyrroline nitroxides. [ABSTRACT FROM AUTHOR]

We demonstrate that sequential disproportionation reactions can enable selective aggregation of two- or four electron–holes at a hypervalent iodine center. Disproportionation of an anodically generated iodanyl radical affords an iodosylbenzene derivative. Subsequent iodosylbenzene disproportionation can be triggered to provide access to an iodoxybenzene. These results demonstrate multielectron oxidation at the one-electron potential by selective and sequential disproportionation chemistry. [ABSTRACT FROM AUTHOR]

We explore the nature of the metal-insulator transition in the two-dimensional organic compound β"-(BEDT-TTF)2Hg(SCN)2Cl by x-ray, electrical transport, ESR, Raman, and infrared investigations. Magnetic and vibrational spectroscopy concurrently reveal a gradual dimerization along the stacking direction (a-b)(a-b), setting in already at the crossover temperature of 150 K from the metallic to the insulating state. A spin gap of Δσ=47 meV is extracted. From the activated resistivity behavior below T = 55 K, a charge gap of Δρ=60 meV is derived. At TCO = 72 K, the C=C vibrational modes reveal the development of a charge-ordered state with a charge disproportionation of 2δρ=0.34e. In addition to a slight structural dimerization, charge-order causes stripes most likely perpendicular to the stacks. [ABSTRACT FROM AUTHOR]

For countless applications in science and technology, light must be concentrated, and concentration is classically achieved with reflective and refractive elements. However, there is so far no efficient way, with a 2D detector, to detect photons produced inside an extended volume with a broad or isotropic angular distribution. Here, with theory and experiment, we propose to stochastically transform and concentrate a volume into a smaller surface, using a high-albedo Ulbricht cavity and a small exit orifice through cavity walls. A 3D gas of photons produced inside the cavity is transformed with a 50% number efficiency into a 2D Lambertian emitting orifice with maximal radiance and a much smaller size. With high-albedo quartz-powder cavity walls ( ρ = 99.94 % ), the orifice area is 1 / (1 - ρ) ≈ 1600 times smaller than the walls' area. When coupled to a detectivity-optimized photon-counter ( D = 0.015 photon - 1 s 1 / 2 cm ) the detection limit is 110 photon s - 1 L - 1 . Thanks to this unprecedented sensitivity, we could detect the luminescence produced by the non-catalytic disproportionation of hydrogen peroxide in pure water, which has not been observed so far. We could also detect the ultraweak bioluminescence produced by yeast cells at the onset of their growth. Our work opens new perspectives for studying ultraweak luminescence, and the concept of stochastic 3D/2D conjugation should help design novel light detection methods for large samples or diluted emitters. [ABSTRACT FROM AUTHOR]

Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to generate a pair of radicals comprising a one-electron reduced and a one-electron oxidized species. Our evidence is based on the measurement of two marker proton hyperfine couplings, Aiso(H(6α)) and Aiso(H(8α)), which we correlated to predictions from density functional theory. The ratio of these two hyperfine couplings is reversed in the oxidized and the reduced radical species. Observation of the dismutation reaction is facilitated by the exceptional C-H acidity of the methyl group at position 7 of 6,7,8-trimethyllumazine and the slow proton exchange associated with it, which leads to NMR-distinguishable anionic (TML-) and neutral (TMLH) protonation forms. [ABSTRACT FROM AUTHOR]

The degree of shrinkage of particle stabilised bubbles of various sizes, in a polydisperse bubble dispersion, has been investigated in the light of the finite adsorption times for the particles and the disproportionation kinetics of the bubbles. For the case where the system contains an abundance of particles we find a threshold radius, above which bubbles are stabilised without any significant reduction in their size. Bubbles with an initial radius below this threshold on the other hand undergo a large degree of shrinkage prior to stabilisation. As the ratio of the available particles to the bubbles is reduced, it is shown that the final bubble size, for the larger bubbles in the distribution, becomes increasingly governed by the number of particles, rather than their adsorption time per se. For systems with "adsorption controlled" shrinkage ratio, the final bubble distribution is found to be wider than the initial one, while for a "particle number controlled" case it is actually narrower. Starting from a unimodal bubble size distribution, we predict that at intermediate times, prior to the full stabilisation of all bubbles, the distribution breaks up into a bimodal one. However, the effect is transient and a unimodal final bubble size distribution is recovered, when all the bubbles are stabilised by the particles. [ABSTRACT FROM AUTHOR]

The nature of charge disproportionation in orthorhombic lanthanum orthoferrites La1-xCaxFeO3-δ (x=0.4 and 0.5) has been investigated by kilohertz mechanical spectroscopy. Contrast to rhombohedral La1-xSrxFeO3-δ (x=0.5), no elastic softening was observed in La1-xCaxFeO3-δ above charge disproportionation. This different behavior of elastic modulus in La1-xCaxFeO3-δ and La1-xSrxFeO3-δ unveils the implicit orbital effect. Below charge disproportionation, an internal friction peak around 140K was observed in La1-xCaxFeO3-δ, which is similar to that in La1-xSrxFeO3-δ. This peak is ascribed to an elastic manifestation of charge freezing and can be used as an indirect indication of CD in doped LaFeO3. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stannate salts are versatile precursors to explore hydrolysis chemistry and dismutation reactions. • Tetra(aqua) diorganotin dications are stabilized as multicomponent molecular crystals. • Structural chemistry reveals the role of alkanesulfonates as both coordinating and non-coordinating ligands. The reactions between diphenyl/di- n -butyltin oxide, dialkyl sulfite, and tetra- n -butylammonium iodide (120 °C, 20 h) proceed via isomerization of the sulfite to sulfonate anion and afford the stannate salts, [ n -Bu 4 N][Ph 2 Sn(OSO 2 Et) 3 ] (1) and [ n -Bu 4 N][ n -Bu 2 Sn(OSO 2 n -Pr) 3 ] (2). The solutions of 1 and 2 in acetonitrile upon exposure to atmospheric conditions resulted in the isolation of multicomponent molecular crystals, [Ph 2 Sn(H 2 O) 4 ][ n -Bu 4 N] 3 [OSO 2 Et] 5 ·3H 2 O (3), [ n -Bu 2 Sn(H 2 O) 4 ][ n -Bu 4 N] 2 [OSO 2 n -Pr] 4 ·H 2 O (4) and [ n -Bu 2 Sn(μ -OH)(H 2 O) 2 ] 2 [ n - Bu 4 N ] 2 [ OSO 2 n - Pr ] 4 (5). In the solid state, the diorganotin cations in 3 – 5 owe their stability to O H---O hydrogen bonds with non-coordinating sulfonate anions. Reactions of the previously reported stannate salt, [ n -Bu 4 N][Ph 2 Sn(OSO 2 Me) 3 ] (6) with N -donor ligands provide a manifestation of phenyl group dismutation to afford new coordination assemblies, [Ph 3 Sn(OSO 2 Me)H 2 O][4,4′-bipy] (7) and [Ph 3 Sn(OSO 2 Me)] (8). X-ray crystallographic studies reveal affinity of the alkanesulfonates to function in both primary and secondary coordination sphere that enables the formation of anionic, cationic, and neutral organotin frameworks. [ABSTRACT FROM AUTHOR]

Highlights • The reverse disproportionation process is proofed in transesterification system. • An existing conclusion about a constant rate of reverse disproportionation was break. • An more accurate information about the thermodynamic and kinetic was offered. • The available Sn-based intermediate is demonstrated to play a real catalytic role. Abstract The extensive researches about the thermodynamic and intrinsic kinetic of disproportionation reaction of methyl phenyl carbonate to diphenyl carbonate were investigated independently with dibutyltin oxide as a catalyst, at a temperature range of 433.15–473.15 K and different catalyst concentrations in a stirred batch reactor, for a deeper knowledge of reaction essence. This reaction was found endothermic and showed hardly any reaction in the absence of catalyst which indicate an inferior kinetic characteristics. The reaction rate increases with an increasing catalyst concentration until the concentration went to 8.08 × 10−4 mol mol−1. A possible mechanism involving an in-situ Sn-based species was proposed and finally verified by a good agreement between experimental and simulated data. The available Sn-based species was then demonstrated to play a real catalytic role by extra experiments. All results can also be further utilized to explore the essence of transesterification reaction network. [ABSTRACT FROM AUTHOR]

Abstract A seed-induced rapid synthesis of submicron ZSM-5 zeolites from acid-leached illite clay was achieved via solid-like state conversion. The optimal synthesis conditions and crystallization mechanism were investigated. The synthesized ZSM-5 zeolites were characterized using X-ray diffraction, scanning electron microscopy, N 2 adsorption–desorption, X-ray fluorescence, NH 3 temperature-programmed desorption, and 27Al MAS NMR. The results clearly indicated that well-dispersed submicron-size ZSM-5 zeolites were synthesized in the relatively short period of 6 h. In the solid-like state conversion synthesis system induced by crystal seeds, the sample gradually transformed from amorphous to well-dispersed submicron ZSM-5 as the crystallization time increased. Aluminum entered the ZSM-5 zeolites framework to provide acidic sites. The obtained ZSM-5 zeolites showed slightly better catalytic performance in toluene disproportionation than ZSM-5 seeds. Graphical abstract Image 1 Highlights • Highly crystalline submicron ZSM-5 is obtained via solid-like state conversion. • Highly crystalline submicron ZSM-5 is obtained by the seed-assisted method. • Highly crystalline submicron ZSM-5 can be synthesized within 6 h. • High-valued utilization of natural illite. • Synthetic ZSM-5 has high catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract Three CuZn-superoxide dismutase (SOD) functional mimics, [CuZn(dien) 2 (μ-Im)](ClO 4) 3 (1), [Cu 2 (dien) 2 (μ-Im)](ClO 4) 3 (2) (Im = imidazole, dien = diethylenetriamine), and [CuZn(salpn)Cl 2 ] (3) (H 2 salpn = 1,3-bis(salicylideneamino)propane), were successfully inserted into the nanochannels of SBA-15 type mesoporous silica with retention of the silica mesostructure. X-ray absorption spectroscopic studies indicate that the encapsulated complexes keep unchanged the first-shell environment of Cu(II) and Zn(II) ions. Magnetic measurements suggest that the nanochannels constrain the geometry of the μ -imidazolate-Cu(II) 2 core modifying the relative orientation of the two copper coordination planes. Confinement imposed by the silica nanochannels upon encapsulation of complexes 1 and 2 leads to stable hybrid materials at physiological pH with enhanced SOD activity relative to the free complexes. Unlike the imidazolato-bridged compounds, insertion of 3 in mesoporous silica leads to a less stable hybrid material exhibiting partial release into the aqueous solution and O 2 •− dismutation rate slower than the free complex. The covalent binding of a mononuclear Cu(dien)Im+ moiety to the mesoporous silica showed lower SOD activity than encapsulated imidazolato-bridged CuZn and Cu 2 complexes. The results emphasize the positive effect of encapsulation on SOD activity of imidazolato-bridged dinuclear complexes. Graphical abstract Image 1 Highlights • Biomimetic hybrid materials as potential therapeutic agents against oxidative stress. • Confinement enhances SOD activity of imidazolato-bridged CuZn and Cu 2 catalysts. • Stable catalytic systems with no significant metal leaching at physiological pH. • Encapsulation keeps the silica mesostructure and catalyst integrity. [ABSTRACT FROM AUTHOR]

A thermodynamic modeling of phase diagrams and thermodynamic properties of the La-Co-O system is presented. Special attention is given to the perovskite LaCoO3−δ phase, due to its outstanding practical importance. In addition to phase equilibria, defect chemistry and charge disproportionation of lanthanum cobaltite were considered during the modeling and are discussed with respect to their thermo-chemical and electrochemical applications. Two sets of optimized parameters are obtained, one for high charge disproportionation (2Co3+ → Co2+ + Co4+) and one for low charge disproportionation. By analyzing both oxygen nonstoichiometry and ion distribution results, it is decided that the parameters for low charge disproportionation will be used in the extensions to multi-component system database (e.g. La-Sr-Co-Fe-O). Calculations with the presented thermodynamic database deliver fundamental materials properties for the optimization of technological materials for industrial applications, including SOFC and oxygen membrane. [ABSTRACT FROM AUTHOR]

Abstract Nanosized niobium carbide (NbC) powder was successfully synthesized by disproportionation reaction of Nb(IV) species in NaCl-KCl molten salt at 800–900 °C for 0.5–5 h by using a mixture of Nb, NbCl 5 , and acetylene black as raw materials. Effects of molar ratio of NbCl 5 /Nb, temperature, and reaction time on NbC preparation were also investigated. The composition and microstructure of the product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM). Homogenous NbC powder with a particle size of ~50 nm is in-situ synthesized on template of acetylene black by disproportionation reaction of Nb(IV) species in NaCl-KCl molten salt. In addition, NbC formation is dramatically influenced by molar ratio of NbCl 5 /Nb and temperature, a higher temperature and higher molar ratio of NbCl 5 /Nb are more preferable for nanosized NbC powder formation. [ABSTRACT FROM AUTHOR]

Abstract SmFe 12 -based compounds possess promising intrinsic magnetic properties, even superior to those of Nd 2 Fe 14 B phase at elevated temperatures. However, the remaining challenge is to demonstrate that those intrinsic properties can be further developed into practically relevant extrinsic ones by proper processing. Here we have employed hydrogenation disproportionation desorption recombination (HDDR) process for preparation of ultrafine-grained SmFe 12 -based alloys with the tetragonal ThMn 12 -type crystal structure. The effect of alloying elements and grain boundary phase on disproportionation rate is investigated and experimental HDDR process phase diagram is proposed. Due to the high vapor pressure of Sm as well as the competing phases, recombination into phase-pure samples can be realized only in a narrow processing parameters window. The resultant phase constitutions, chemical composition, microsctructure and crystallographic relations at different process steps are discussed. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Highlights • A high-pressure electronic disproportionation transformation. • Stable high pressure disproportionation phases of CO 2 and CO. • The van der Waals space of compression for a high-pressure transformation. • Simulation design of high-pressure disproportionation phases. Abstract First-principles enthalpy minimization simulations with target pressures suggest that dense-packed disproportionation phases of CO 2 and CO can be transformed from selected molecular precursors under hydrostatic compression. In transformations, electrons are pushed from oxygen to carbon atoms to form electronic disproportionation phases with their chemical formulas of C−2O 2 + and C−O+. Simulations indicate that the space packing properties of reactive groups in a molecular crystal precursor, including the orientation and the number of bonding partners of each reactive group, mainly control transformation bonding pathways. Phonon dispersion spectra and molecular dynamic simulations confirm the metastability of both electronic disproportionation phases under high pressures. [ABSTRACT FROM AUTHOR]

Abstract Vanadium acetylacetonate, or V(acac) 3 , provides a model chemistry for investigating the performance of nonaqueous disproportionation flow batteries. A flow reactor was developed to implement studies of efficiency, energy capacity, and power capability with respect to electrolyte flow rate and current density. Reactors incorporating a porous separator allowed V(acac) 3 to be cycled without appreciable capacity fade at current densities up to 100 mAcm−2. Experiments at the lowest flow rate, 12.5 mLmin–1, revealed limitations imposed by residence time within the reactor, which manifested as high charging overpotentials. These overpotentials vanish above 25 mLmin–1. A higher flow rate of 50 mLmin–1 yielded performance similar to cells at 25 mLmin–1, but could improve performance at current densities above 100 mAcm−2. Extrapolation of power density's dependence on current suggests a maximum power of 0.22 Wcm−2 for cells run at 206 mAcm−2. Energy efficiency passes through a maximum of 71% at 40 mAcm−2 and the corresponding energy density suggests that the chemistry can, in principle, deliver above 13 WhL−1 in acetonitrile solutions and above 24 WhL−1 in mixed-solvent solutions with higher V(acac) 3 solubility. A V(acac) 3 cell run at 40 mAcm−2 is shown to exhibit stable capacity and performance for more than 150 cycles. Highlights • A new reactor design resolves materials compatibility issues in nonaqueous RFBs. • Effects of flowrate and power on disproportionation electrochemistry are elucidated. • Vanadium acetylacetonate cycles stably, supporting charge/discharge for >150 cycles. • The nonaqueous support does not strictly limit power; cells tolerate 100 mAcm−2. [ABSTRACT FROM AUTHOR]

The mechanism of the H2O2 disproportionation catalyzed by the manganese catalase (MnCat) KatB was studied using the hybrid density functional theory B3LYP and the quantum chemical cluster approach. Compared to the previous mechanistic study at the molecular level for the Thermus thermophilus MnCat (TTC), more modern methodology was used and larger models of increasing sizes were employed with the help of the high-resolution X-ray structure. In the reaction pathway suggested for KatB using the Large chemical model, the O-O homolysis of the first substrate H2O2 occurs through a μ-η1:η1 coordination mode and requires a barrier of 10.9 kcal/mol. In the intermediate state of the bond cleavage, two hydroxides form as terminal ligands of the dimanganese cluster at the Mn2(III,III) oxidation state. One of the two Mn(III)-OH− moieties and a second-sphere tyrosine stabilize the second substrate H2O2 in the second-sphere of the active site via hydrogen bonding interactions. The H2O2, unbound to the metals, is first oxidized into HO2· through a proton-coupled electron transfer (PCET) step with a barrier of 9.5 kcal/mol. After the system switches to the triplet surface, the uncoordinated HO2· replaces the product water terminally bound to the Mn(II) and is then oxidized into O2 spontaneously. Transition states with structural similarities to those obtained for TTC, where μ-η2-OH−/O2− groups play important roles, were found to be higher in energy. [ABSTRACT FROM AUTHOR]

α-Amino acids (α-AAs) are in extremely high demand in nearly every sector of the food and health-related chemical industries and continue to be the subject of intense multidisciplinary research. The self-disproportionation of enantiomers (SDE) is an emerging and one of the least studied areas of α-AA or enantiomeric properties, critically important for their production and application. In the present work, we report a detailed study of the SDE via achiral, gravity-driven column chromatography for a set of N-acylated, N-carbonylated, N-fluoroacylated, and N-thioacylated α-amino acid esters. As well as thioacylation, attention was paid to the effect of altering the R group of the ester functionality, the side chain, or that of the acyl group attached to the amide nitrogen, whereby it was found that electron-withdrawing groups in the latter moiety had a pronounced effect on the magnitude and behavior of the resulting SDE phenomenon. Intriguingly, in the case of N-fluoroacylated derivatives, by favoring the formation of dimeric associates and effecting a strong bias toward homochiral associates over heterochiral associates, the SDE magnitude was greatly reduced contrary to intuitive expectations. Energy estimates resulted from DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the sulfur (S) disproportionation tendencies in a sulfur packed bed reactor for perchlorate bio-autotrophic reduction at different temperatures. The reactor was operated with over 99% efficiency for 21.00 ± 1.40 mg L−1 perchlorate removal when the hydraulic retention time (HRT) ranged from 12.00 h to 0.75 h at 27 ± 2 °C. When HRT was controlled at 1.00 h, the perchlorate removal efficiency was only 8 ± 1% as the temperature dropped to 6 ± 1 °C. The half-order model fit both perchlorate removal and S disproportionation reaction well. Compared with S disproportionation, the decrease of temperature had a greater influence on perchlorate reduction. As the temperature dropped from 27 ± 2 °C to 6 ± 1 °C, the 1/2 K 1/2 v ,R for perchlorate reduction decreased from 7.37 mg1/2 L−1/2 h−1 to 0.19 mg1/2 L−1/2 h−1. Meanwhile, the 1/2 K 1/2 v ,S for S disproportionation decreased from 3.04 mg1/2 L−1/2 h−1 to 1.96 mg1/2 L−1/2 h−1. The reaction activation energy of perchlorate reduction and S disproportionation was 120.28 kJ mol−1 and 13.44 kJ mol−1, respectively. The S disproportionation reaction proceeded remarkably at the beginning of the reduction, a longer HRT and higher temperature promoted S disproportionation, resulting in excessive sulfate generation and alkalinity consumption. Besides, the spatial distribution of the microbial communities and the dominant bacteria function under different HRTs was analyzed using high-throughput sequencing. Graphical abstract Image 1 Highlights • The acceleration of S disproportionation was discovered. • 21.00 mg/L ClO 4 − was removed >99% at HRT 0.75 h (27 ± 2 °C). • 1/2 kinetics model fit both perchlorate removal and S disproportionation well. • Spatial distribution of the microbial communities was analyzed. • Bacterial α and β diversity, and dominant genus was investigated. [ABSTRACT FROM AUTHOR]

Classical halides of the heavier Group 14 homologues germanium, tin, and lead are common precursors for the synthesis of exciting compounds, such as polyhedral clusters. To get access to larger metalloid cluster compounds of Group 14, the disproportionation reaction of metastable monohalide solutions, accessible through a preparative co‐condensation reaction, proved to be quite successful. As the identity of the subvalent halides within the metastable solutions were yet unknown the reaction course from a monohalide precursor to a metalloid cluster was mostly unidentified. This might change now, as a first subhalide cluster [Ge14Br8(Et3P)4] could be characterized, being the first trapped intermediate of the disproportionation reaction of Group 14 subhalides. All these aspects are included within this Minireview, together with a short historical overview, dealing with the development of the preparative co‐condensation technique out of the matrix isolation technique, being the essential first step of the synthesis of metastable monohalide solutions of the heavier Group 14 elements Ge and Sn. Metastable solutions of monohalides of germanium and tin open the door for the synthesis of element‐rich metalloid clusters by means of a disproportionation reaction. In this Minireview recent developments are discussed, highlighting the first structurally characterized metalloid subhalide cluster of Group 14—[Ge14Br8(Et3P)4]—giving first insight into the complex reaction mechanism of the disproportionation reaction. [ABSTRACT FROM AUTHOR]

Abstract Influence diagnostics are used to identify data points that have a disproportionate impact on model parameters, performance and/or predictions, providing valuable information for use in model calibration. Regression-theory influence diagnostics identify influential data by combining the leverage and the standardised residuals, and are computationally more efficient than case-deletion approaches. This study evaluates the performance of a range of regression-theory influence diagnostics on ten case studies with a variety of model structures and inference scenarios including: nonlinear model response, heteroscedastic residual errors, data uncertainty and Bayesian priors. A new technique is developed, generalised Cook's distance, that is able to accurately identify the same influential data as standard case deletion approaches (Spearman rank correlation: 0.93–1.00) at a fraction of the computational cost (<1%). This is because generalised Cook's distance uses a generalised leverage formulation which outperforms linear and nonlinear leverage formulations due to less restrictive assumptions. Generalised Cook's distance has the potential to enable influential data to be efficiently identified on a wide variety of hydrological and environmental modelling problems. Highlights • Influential data points have a disproportionate impact on model predictions. • A new generalised Cook's distance accurately identifies influential data points. • More efficient (<1% computational cost) than standard case-deletion approaches. • Applies to nonlinear regression and hydrological models with heteroscedastic errors. • Can be used in a Bayesian framework with priors or data uncertainty. [ABSTRACT FROM AUTHOR]

Highlights • Nanocrystalline Ce 13 Fe 81 B 6 alloy powder is synthesized through a new process. • Microstructure transformation of the alloy powder during the process is studied. • The effects of microstucture on the magnetic properties of materials are researched. Abstract Nanocrystalline Ce 13 Fe 81 B 6 alloy powder was synthesized by mechanically driven disproportionation-recombination processing. The microstructure transformation of the alloy during different processing stages was characterized by XRD and TEM. The magnetic properties of the nanocrystalline powder were measured by VSM. The results showed that the Ce 2 Fe 14 B matrix phase of the Ce 13 Fe 81 B 6 alloy was disproportionated into the nanostructured CeH 2.51 , α-Fe, and Fe 2 B phases by ball milling in hydrogen for 20 h, and that these nanostructured phases could be desorbed and recombined to nanocrystalline Ce 2 Fe 14 B phase again by subsequent vacuum annealing, with the remanence, coercivity, and maximum energy product of the as-synthesized alloy powders achieving 8.1 kGs, 6.02 kOe, and 8.51 MGOe, respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The variety of catalysts based on supported ionic liquid-like phases was investigated for disproportionation of trichlorosilane. • To compare the catalytic activity, different catalysts modified by different tritic ammonium functional groups with the subsequent activation. • Activation energy value indicates the heterogeneous nature of the thermal decomposition. Abstract The variety of catalysts based on macroporous supported ionic liquid-like phases using chloromethyl styrene cross-linked with divinylbenzene (CMS/DVB) and different NR 3 cations was investigated for disproportionation of trichlorosilane in a continuous-flow reactor. To determine the optimal conditions for conducting a complex catalytic process, the primary task is to determine the thermodynamical equilibrium state of the reaction system. Increase in the concentration of DCS in the system occurs from 5 to 10%, which in turn is promising in terms of considering DCS as the main precursor for the processes of epitaxial silicon growth. In addition, the maximum attainable temperature is thermodynamically optimal for the process. In the first stage, the thermal stability of the catalyst supports was determined using evolved gas analysis and all samples have a similar thermal stability 475 К. All samples have been carefully studied by SEM, AFM, EGA and nitrogen physisorption. To compare the catalytic activity of different catalytic systems on the basis of macroporous supports modified by different tritic ammonium functional groups with the subsequent activation, the kinetics of the TCS disproportionation on the catalyst sample having the highest catalytic activity was studied. The results obtained indicate that the introduction of acceptor substituents increases catalytic activity in the disproportionation of TCS. To assess the feasibility of using dichlorosilane (DCS) as a raw material for the creation of semiconductor structures, the kinetics of thermal decomposition of DCS in a mixture with hydrogen was studied at a temperature of 1200–1500 K. According to the obtained kinetic results, the activation energy of the process is determined, which is in the temperature range of 1220–1320 K and the concentration of DCS in hydrogen 9–28.6 mol.%, is 112.9 kJ/mol. Activation energy value indicates the kinetical mode of the thermal decomposition. [ABSTRACT FROM AUTHOR]

Each of the three new hydrazobenzenes consisting of a hydrazobenzene conjugated with a 5-membered heterocyclic ring (furan or thiophene) at its two para positions, prepared from corresponding azo precursors, was used in the acid-catalyzed benzidine rearrangements. Both rearrangement and disproportionation occurred and product structures were characterized by spectroscopic data such as NMR, MS, and with CHN analysis. We confirm the largest [9, 9]-sigmatropic benzidine-type rearrangement in each case as a prominent pathway accompanied by disproportionation. [ABSTRACT FROM AUTHOR]

2,6-Dimethylnaphthalene (2,6-DMN) is one of the crucial intermediates for the synthesis of polybutylenenaphthalate and polyethylene naphthalate (PEN). The complex synthesis procedure and the high cost of 2,6-DMN production significantly reduce the commercialisation of PEN even though PEN demonstrates superior properties compared with polyethylene terephthalate. 2,6-DMN can be produced by methylation of 2-methylnaphthalene (2-MN) and/or naphthalene, disproportionation of 2-MN, and/or isomerisation of dimethylnaphthalenes (DMNs). In this study, synthesis of 2,6-triad DMN isomers consisting of 2,6-DMN, 1,6-DMN, and 1,5-DMN have been investigated with the disproportionation of 2-MN over unmodified and Zr-modified mesoporous MCM-41 zeolite catalysts. In contrast to other DMN isomers, both 1,5-DMN and 1,6-DMN can be effectively isomerised to be profitable 2,6-DMN. The disproportionation of 2-MN experiments were carried out in a catalytic fixed-bed reactor in the presence of 1 g of catalyst at a temperature range of 350-500 °C and weight hourly space velocity between 1 to 3 h−1. The results demonstrated that mesoporous MCM-41 zeolite catalyst has a selective pore shape for 2,6-triad DMN isomers, which may allow a decrease in the production cost of 2,6-DMN. Additionally, 2,6-DMN was successfully synthesised by the disproportionation of 2-MN over MCM-41 zeolite catalyst. Furthermore, both the conversion of 2-MN and the selectivity of 2,6-DMN were considerably enhanced by the Zr impregnation on MCM-41. [ABSTRACT FROM AUTHOR]

The development of hydrogen fuel cells is greatly hindered by the unwanted generation of H2O2 at the cathode. A non‐Pt cathode catalyst is now shown to be capable of simultaneously reducing both O2 and H2O2, thus rendering H2O2 a useful part of the feed stream. The applicability of this unique catalyst is demonstrated by employing it in a fuel cell running on H2/CO and O2/H2O2. Peroxide allowed: The development of hydrogen fuel cells is greatly hindered by the unwanted generation of H2O2 at the cathode. A non‐Pt cathode catalyst is now shown to be capable of simultaneously reducing both O2 and H2O2, thus rendering H2O2 a useful part of the feed stream. The applicability of this unique catalyst is demonstrated by employing it in a fuel cell running on H2/CO and O2/H2O2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Microporous/mesoporous materials were prepared using Beta nanozeolite precursors of varying crystallinity. • Zeolite precursors quenching by acid followed by hydrothermal treatment raises mesopore volume preserving chemical properties. • Adding Beta precursors to a gel containing non–ionic surfactant renders a mixture of preformed Beta nanocrystals and SBA–15. • Beta precursors treatments hardly modify p/o and i/d selectivities in m–xylene isomerization/disproportionation. Abstract Hierarchical Beta nanozeolites with the properties of both Beta nanozeolite and mesoporous material were prepared by two different methods: (1) Direct Hydrothermal Method (DHM) by the assembly of nanocrystals of preformed Beta seeds in the presence of the surfactant P123 under hydrothermal conditions, (2) Acidification of Beta seeds suspension (without the use of the mesopore directing agent). For the two methods, the effect of crystallization time of Beta nanozeolite precursor (seeds) was studied: 6, 12 and 24 h. The obtained materials were characterized using nitrogen sorption measurements, thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), ammonia Temperature Programmed Desorption (NH 3 -TPD) and adsorption/desorption of pyridine monitored by FTIR. The characterization results show that acidification of Beta seeds suspension leads to best structured nano-Beta (Beta nanoparticles). However, with the DHM method physical mixtures of Beta nanoparticles and mesoporous SBA-15 phases were obtained. The m-xylene isomerization/disproportionation reaction in gas-phase was carried out over all the synthesized solids in order to explore their catalytic properties. It was found that the m-xylene conversion and isomerization/disproportionation ratio were closely related to the crystallization time of Beta zeolite precursors, mesopores creation in hierarchical Beta zeolite nanoparticles and the method used to produce the extra meso-porosity. [ABSTRACT FROM AUTHOR]

The effect of an initial alloy on microstructure and magnetic properties of Nd–Fe–B hydrogenation–disproportionation–desorption–recombination (HDDR) magnets during hot-deformation process have been studied with strip-casting alloy of composition Nd12.5FebalCo0.3Nb0.2B6.4 which have different microstructures. HDDR powders were produced by HDDR process with strip-casting alloy after pre-annealing or no pre-annealing. Obtained HDDR powders were subjected to hot-pressing at 700 °C under 400 MPa in vacuum and subsequently to die-upsetting at 800 °C with deformation conditions such as strain rate of 0.01 s−1 and height reduction of 77%. The microstructure of the initial alloys showed a large difference depending on the presence or absence of pre-annealing. The coercivity of HDDR powders using alloy after pre-annealing and no pre-annealing was different about 2 kOe. In addition, the remanence of hot-deformed magnet using HDDR powder produced with no pre-annealing alloy was higher than that with pre-annealing alloy although the hot deformation was conducted under the same condition and the remanence of two kinds of starting HDDR powder was almost the same. It was confirmed that the microstructure and magnetic properties of hot-deformed magnet depend on the microstructure of the initial alloy. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Phenytoin sodium (PS) is a narrow therapeutic index drug that dictates maintenance of narrow plasma concentration of the drug. This requires a good quality product that meets regulatory specifications throughout shelf-life as well as during the usage period. Quality of the drug product may change if not develop in a scientific fashion which may have ramifications on clinical outcome. The focus of the study was to understand the effect of process variables and storage conditions on the disproportionation and phase transformation of the drug, and dissolution of extended-release capsules of PS. Four formulations were prepared to contain either powder blend or granules of PS with commonly used excipients. The granules were prepared in a high shear mixture by granulating with water, ethanol or mixture thereof. The capsules were stored in pharmacy vials for 4-weeks at 40 °C/75% RH and 30 °C/65% RH. Formulations were characterized by spectroscopies (FTIR, NIR, and chemical imaging), X-ray powder diffraction (XRPD), dissolution and assay. Granules filled capsule did not meet USP dissolution specifications and there was a significant decrease in dissolution on exposure to stability conditions. Dissolution decreased from 77.56 ± 3.83% to 42.34 ± 4.31%, and 63.96 ± 6.12 to 46.53 ± 2.91 in physical mixture and water granulated formulations, respectively, after four weeks exposure at 40 °C/75% RH. Spectroscopic (NIR, FTIR, and chemical imaging) data indicated disproportionation of the drug during the storage period. Moreover, XRPD data explained a decrease in dissolution in the initial granules filled capsules as well as temperature and humidity exposed samples. It indicated the phase transformation of the drug and/or excipients, disproportionation and/or interactions. These changes further accelerated on exposure to stability conditions. In conclusion, our studies indicated the significant effect of process variables and stability conditions on the critical quality attributes of PS extended-release capsule that has the potential impact on the clinical performance of the product. [ABSTRACT FROM AUTHOR]

Abstract: Sodium complexes of aminotroponiminate (ATI) ligands have been reacted with a range of neutral donor ligands. Upon addition of crown ethers, they undergo an unusual ligand‐induced disproportionation reaction with formation of [Na(ATI)2]− sodiate complex anions. The same structural motif has also been found in the first well‐defined mixed‐metal ATI complexes, which have been accessed starting from monometallic sodium and potassium species. The mixed‐metal compounds confirm the possibility of ATIs to act as ditopic ligands. Using the polymerization of ϵ‐caprolactone as a model system, structure‐reactivity‐relationships in sodium and mixed‐metal ATI compounds have been studied by comparing the reactivity of [Na(ATI)] and [Na(ATI)2]− structural motifs. These studies revealed trends in the catalyst activity depending on the nuclearity of the complex and the substitution pattern at the ATI ligand. Exceptionally high activities were obtained for dinuclear sodium sodiates of type [Na(crown)2][Na(ATI)2], making them the most active alkali metal initiators for this reaction. The organometallic and polymeric compounds presented in this work have been characterized by techniques including (VT‐)NMR spectroscopy, single‐crystal X‐ray diffraction, gel permeation chromatography, mass spectrometry, and DFT calculations. [ABSTRACT FROM AUTHOR]

A combined experimental and theoretical study on the reaction of Si2Br6 with N‐heterocyclic carbenes is reported. Employment of an imidazole‐2‐ylidene with methyl groups in C4‐ and C5‐position results in the disproportionation of Si2Br6 into the adducts NHC→SiBr2 and NHC→SiBr4. According to expectation, the hydrogenated derivative 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene forms analogous disproportionation products of Si2Br6 at low temperatures, whereas reaction at higher temperatures furnishes the 4‐SiBr3‐substituted NHC. The underlying formation mechanism explored by means of density functional theory calculations features an abnormal carbene intermediate. [ABSTRACT FROM AUTHOR]

Elemental sulfur is commonly regarded as the product of oxidative sulfur cycling in the sediment. However, reports on the occurrence of elemental sulfur in seepage areas are few and thus its origin and mechanisms controlling its distribution are insufficiently understood. Here, we analyzed the multiple sulfur isotopic compositions for elemental sulfur and pyrite from an iron-dominated gas hydrate-bearing sedimentary environment of the South China Sea to unravel the impact of sulfate-driven anaerobic oxidation of methane (SO 4 -AOM) on the formation of elemental sulfur. The multiple sulfur isotopes reveal variable ranges for both elemental sulfur and pyrite (δ 34 S: between −15.7 and +23.3‰ for elemental sulfur and between −35.3 and +34.4‰ for pyrite; Δ 33 S: between −0.08 and +0.06‰ for elemental sulfur and between −0.03 and +0.15‰ for pyrite). The enrichment of 34 S in pyrite throughout the sediment core suggests pronounced SO 4 -AOM in paleo-sulfate-methane transition zones (SMTZ). In addition, the occurrence of seep carbonates with very negative δ 13 C values (as low as −57‰, V-PDB) coincides with the inferred paleo-SMTZs and agrees with formerly locally pronounced SO 4 -AOM. Interestingly, the multiple sulfur isotopic composition of elemental sulfur reveals a different pattern from that of pyrite derived from organoclastic sulfate reduction (i.e., with low δ 34 S and high Δ 33 S values for the latter). In comparison to coexisting pyrite, most of the elemental sulfur reveals higher δ 34 S values (as much as +28.9‰), which is best explained by an enrichment of 34 S in the residual pool of dissolved sulfide generated by SO 4 -AOM. As an intermediate sulfur phase, elemental sulfur can form via sulfide oxidation coupled to iron reduction, but it can only persist in the absence of free sulfide. Therefore, the occurrence of 34 S enriched elemental sulfur is likely to represent an oxidative product after hydrogen sulfide had vanished due to vertical displacement of the SMTZ. Our observations suggest that elemental sulfur may serve as a useful recorder for reconstructing the dynamics of sulfur cycling in modern and possibly ancient seepage areas. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) was synthesized during combustion in a diesel engine by adding catalyst sources into fuel. Fuel used in this study was a mixture of normal dodecane/ethanol, methyl laurate/ethanol, and 1-decanol/ethanol. The analysis of an exhaust gas using a gas chromatograph revealed that the amount of carbon monoxide was most influential on the CNT formation than other factors such as adiabatic combustion temperatures and/or the amount of low molecular weight hydrocarbons like acetylene and ethylene. The significance of carbon monoxide in our system was also suggested by simulated and modeling works. Simulations of combustion reactions inside a cylinder were performed through CHEMKIN-PRO software for a qualitative evaluation. Modeling works of CNT growth rates were carried out by means of not only CO related reactions but also ethylene and acetylene related reactions as a source of carbon deposition. It was suggested that carbon monoxide had stronger connection with CNT synthesis in a diesel engine compared with other potential CNT precursors such as ethylene and acetylene. Furthermore, we proposed CNT growth route in our system by considering characteristics of combustion in a diesel engine. [ABSTRACT FROM AUTHOR]

The work outlined in this paper demonstrates significant improvements in ductility during the Hydrogen Ductilisation Process (HyDP) [1] of a Neomax-type alloy and, for the first time, complete ductility of a sub-stoichiometric alloy. In previous studies, the uniformity of the ductilisation transformation was limited by the presence of the NdFe 4 B 4 phase not undergoing complete disproportionation, which left extremely brittle, micron-scale islands in a highly ductile disproportionated matrix. The present works investigated the influence of a significantly longer (18 h) hydrogen treatment of the Neomax-type alloy to observe whether the completely disproportionated NdFe 4 B 4 phase is as ductile as the disproportionated matrix. It has been observed that, when the NdFe 4 B 4 phase is completely disproportionated, it exhibits similar ductility to that of the disproportionated matrix, showing no sign of cracking under a compressive load. However, inhomogeneity in the book mould material leads to varying quantities of NdFe 4 B 4 phase and thus, varying levels of disproportionation. Despite this, significant improvements were observed in the mechanical behaviour of the Neomax-type alloy. The longer disproportionation treatment also results in larger grains and thus, a lower final coercivity in the recombined state than that of the previous 5 h treatment. For comparison, the mechanical behaviour of a sub-stoichiometric alloy, which did not contain any NdFe 4 B 4 phase, has also been studied. The compression behaviour of this sub-stoichiometric alloy in the disproportionated state was found to be completely ductile. It is clear from this work that it is possible to create a completely ductile NdFeB material directly from the solid cast alloy which, in the future, could have significant implications for NdFeB magnet production. [ABSTRACT FROM AUTHOR]

The disproportionation of ethylbenzene and toluene have been compared on two zeolites, H-mordenite and HY. The online examination of products as a function of time on stream reflect the different processes occurring on the two zeolites. The relative activities expressed on a unit aluminium center basis, are in line with their relative cracking (n-heptane) activities reported by others, showing that no extraneous factors affect activity. The data set provides a baseline for the activity of these two zeolites for future use in comparing other more complex alkylation reactions involving mononuclear and binuclear aromatic molecules. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of a pentamethylcyclopentadienyl‐substituted dialane with a variety of Lewis bases results in unexpected disproportionation of the dialane into AlI and AlIII species. Use of a transition‐metal Lewis base allows for the formation of metal‐only Lewis pairs. Furthermore, the synthesis of a Lewis base bis‐adduct was successful with the Lewis base 4‐dimethylaminopyridine. [ABSTRACT FROM AUTHOR]

Here, we report a synthesis of Cu nanocubes by photoreduction of CuSO4. Because synthetic saponite (one of the layered clay minerals) was used as the adsorbent, the nanocubes contained no capping agents or protectants, and the disproportionation reaction of Cu2O with H2SO4 was found to be the key for morphological control. [ABSTRACT FROM AUTHOR]

Copper/carbon dot nanohybrids (Cu/CD NHs) were prepared via a facile precipitation method through a disproportionation reaction. The surface characterization was performed by various techniques such as XRD, FTIR and TEM. Then, water-based nanofluids composed of Cu/CD NHs at 0.1 and 0.5 mass% were prepared, and their thermo-physical properties including thermal conductivity, viscosity, density and specific heat were evaluated at various temperatures. The water-based Cu/CD nanofluid demonstrated to be a potential heat transfer fluid with a high stability. It was found that the thermal conductivity can be enhanced by increasing the nanoparticle concentration and temperature. Almost 1.25-fold increase in thermal conductivity has been achieved by raising the temperature up to 50 °C and at the concentration of 0.5 mass%. The heat capacity was found to increase with increasing concentration. Moreover, by increasing temperature the density and viscosity of the as-prepared nanofluid decreased, whereas the heat capacity showed an increasing trend. [ABSTRACT FROM AUTHOR]

Abstract: In this study, one‐pot hydrothermal synthesis of sheet‐like ZSM‐5 as a high‐performance catalyst for toluene disproportionation was carried out using binary surfactants. In the dual template, tetraethylammonium hydroxide was used to construct the microporous structure of ZSM‐5, and cationic surfactant (e.g., octadecyltrimethylammonium chloride (C18TMAC), hexadecyltrimethyl ammonium bromide (C16TMAB), and tetradecyltrimethylammonium bromide, (C14TMAB)) can change the growth habits of the ZSM‐5 crystals by hindering the regular stacking of zeolite layers from their longer hydrophobic chain. From the XRD pattern of the as‐synthesized samples which were hydrothermally treated for different time, it was found that a lamellar mesostructured intermediate gradually transformed into the sheet‐like ZSM‐5 during hydrothermal process. With a proper amount of cationic surfactant, the thickness of the sheet‐like ZSM‐5 could be controlled to less than 30 nm. Concerning the catalyst application, the toluene disproportionation performance over the sheet‐like ZSM‐5 is 1.5 times higher than that of the commercial ZSM‐5. The higher conversion is ascribed to the faster diffusion amount due to the sheet‐like ZSM‐5. [ABSTRACT FROM AUTHOR]

Anisotropic Pr13Fe80B7 magnetic powders are obtained by shortening the disproportionation time of the hydrogenation disproportionation desorption recombination (HDDR) process. The magnetic powders with a disproportionation time of 30 min have the magnetic properties of Br=0.93 T and Mr/Ms=0.75, and show a high degree of crystal texture along the c axis, whereas the magnetic powders obtained with a prolonged disproportionation time are isotropic. A rodlike structure is observed in the 30 min-disproportionation products and is transformed into spherical morphology with a prolonged disproportionation time. It suggests that the rodlike disproportionated microstructure is very important for the formation of crystal texture in the conventional HDDR powders. [ABSTRACT FROM AUTHOR]

A Kerr microscope that uses ultraviolet (UV) light for high-resolution domain observation was built, and the domain structure and magnetization process of hydrogenation disproportionation desorption recombination (HDDR) powder were examined. The UV Kerr microscope could observe nanometer-sized domain patterns. Applying a dc field of 1.0 kOe to HDDR powder at a desorption recombination (DR) time of 12 min produced abrupt wall motion. The pinning force exerted by the grain boundaries is inadequate for producing high coercivity because the Nd-rich phase layers along these boundaries are absent at a DR time of 12 min. For HDDR powder at a DR time greater than 14 min, changing the magnetic field by up to 1.0 kOe produced no observable wall motion. It follows that the high coercivity of HDDR powder is due to domain wall pinning at the grain boundaries. [ABSTRACT FROM AUTHOR]

Excipients are crucial components of most pharmaceutical formulations. In the case of a solid oral dosage formulation containing the salt form of a weakly ionizable drug, excipient selection is critical, as some excipients are known to cause salt disproportionation (conversion of salt to the free form). Therefore, robust formulation design necessitates an in-depth understanding of the factors impacting salt disproportionation during processing or storage as this can negatively impact product quality and performance. To date, there is an incomplete understanding of key excipient properties influencing salt disproportionation. Specifically, the potential roles of amorphous excipient glass transition temperature and excipient hygroscopicity, if any, on salt disproportionation are still not well understood. Furthermore, the relationship between the compression and the extent of salt disproportionation is an unknown factor. Herein, by utilizing various grades of polyvinylpyrrolidone (PVP), its copolymer, copovidone (PVPVA), and magnesium stearate, a systematic investigation of disproportionation was performed using pioglitazone HCl as a model salt of a weak base. It was observed that there was a poor correlation between excipient hygroscopicity and the rate and extent of disproportionation. However, powder compression into compacts enhanced the rate and extent of disproportionation. This work focused on disproportionation of the salt of a weak base, as basic drugs are more prevalent, however, salts of weak acids may have similar tendencies under relevant conditions. The knowledge gained from this study will help in understanding the role of various excipients with respect to salt disproportionation, paving the way for designing stable salt formulations. [ABSTRACT FROM AUTHOR]

Abstract: The sodium oxygen battery is a promising metal–air battery; however, the discharge process is not well understood and the major discharge product is still under debate. The discharge products determined the theoretical specific energy and electrochemical performance of the battery. Now it is demonstrated that NaO2 spontaneously disproportionates to Na2O2, no matter whether it is dissolved in solution or stays on the surface. The behaviors of NaO2 in solution and on the surface are different. Solvents play a crucial effect on the disproportionation of dissolved NaO2 species, which is fast in low donor number (DN) solvents such as acetonitrile but sluggish in high DN solvents such as DMSO. In situ XRD results exhibited the different product growing processes in various solvents. Surface NaO2 would slowly disproportionate to Na2O2 anyway, but this process is relatively slow compared to the time span of discharge process and it does not affect the major product on discharge. [ABSTRACT FROM AUTHOR]

Abstract: The sodium oxygen battery is a promising metal–air battery; however, the discharge process is not well understood and the major discharge product is still under debate. The discharge products determined the theoretical specific energy and electrochemical performance of the battery. Now it is demonstrated that NaO2 spontaneously disproportionates to Na2O2, no matter whether it is dissolved in solution or stays on the surface. The behaviors of NaO2 in solution and on the surface are different. Solvents play a crucial effect on the disproportionation of dissolved NaO2 species, which is fast in low donor number (DN) solvents such as acetonitrile but sluggish in high DN solvents such as DMSO. In situ XRD results exhibited the different product growing processes in various solvents. Surface NaO2 would slowly disproportionate to Na2O2 anyway, but this process is relatively slow compared to the time span of discharge process and it does not affect the major product on discharge. [ABSTRACT FROM AUTHOR]

The reduction of free‐base naphthalocyanine (H2Nc) with sodium fluorenone ketyl and an excess of bis(triphenylphosphoranylidene)ammonium chloride (PPN+)(Cl–) unexpectedly results in the synthesis of the (PPN+)2(H2Nc2–) salt (1). As sodium fluorenone ketyl can generate only H2Nc·– radical anions, the formation of H2Nc2– is most probably realized through the disproportionation of H2Nc·– to H2Nc0 and H2Nc2–. The H2Nc2– dianions in 1 form layers in which π–π stacks of H2Nc2– are formed along the a direction with a short interplanar distance of 3.30 Å and a HOMO–HOMO (HOMO = highest occupied molecular orbiatl) overlap integral of 3.1 × 10–3. The H2Nc2– macrocycle is distorted owing to the formation of alternate short and long C–N(imine) bonds. The distortion of the macrocycle increases with the negative charge on H2Nc owing to the occupation of the lowest unoccupied molecular orbital (LUMO). Calculations indicate that the distortion disappears in the triplet state of H2Nc2– as the occupation of the LUMO and LUMO+1 orbitals averages their effects on the geometry of the macrocycle. The optical spectrum of 1 shows a lowest energy absorption band at λ = 1230 nm, which is attributed to the HOMO → LUMO+1 excitation and a blueshift of the Q‐band of H2Nc. The elecron paramagnetic resonance (EPR) silence of 1 indicates the diamagnetic singlet state of the H2Nc2– dianions. The DFT calculations indicate that the open‐shell broken‐symmetry singlet state is lower in energy than the corresponding closed‐shell singlet and triplet states. The large singlet–triplet energy gap indicates that the corresponding triplet state is thermally inaccessible. [ABSTRACT FROM AUTHOR]

The radiolysis of diethylene glycol dimethyl ether (diglyme) in a boiling state has been studied for the first time. Boiling facilitates the cleavage of internal C-O bonds, weakens the cage effect and diglyme regeneration processes, and facilitates the exchange and dimerization reactions of radicals. As compared with radiolysis at room temperature, the amount of unsaturated products of diglyme fragmentation formed during irradiation in the boiling state is smaller by a factor of 4, and the disproportionation products of heavy radicals are found in negligible amounts, if any. The yield of radiolytic decomposition of diglyme under boiling conditions is ∼15 molecule/100 eV, which is higher than that at room temperature by a factor of almost 1.5. [ABSTRACT FROM AUTHOR]

Drywall manufactured in China released foul odors attributed to volatile sulfur compounds. These included hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Given that calcium sulfate is the main component of drywall, one would suspect bacterial reduction of sulfate to sulfide as the primary culprit. However, when the forensics, i.e., the microbial and chemical signatures left in the drywall, are studied, the evidence suggests that, rather than dissimilatory sulfate reduction, disproportionation of elemental sulfur to hydrogen sulfide and sulfate was actually the primary cause of the malodors. Forensic evidence suggests that the transformation of elemental sulfur went through several abiological and microbial stages: (1) partial volatilization of elemental sulfur during the manufacture of plaster of Paris, (2) partial abiotic disproportionation of elemental sulfur to sulfide and thiosulfate during the manufacture of drywall, (3) microbial disproportionation of elemental sulfur to sulfide and sulfate resulting in neutralization of all alkalinity, and acidification below pH 4, (4) acidophilic microbial disproportionation of elemental sulfur to sulfide and sulfuric acid, and (5) hydrogen sulfide volatilization, coating of copper fixtures resulting in corrosion, and oxidation to sulfur dioxide. [ABSTRACT FROM AUTHOR]

In this work, the NdFeB ribbons (Nd 13.5 Fe 73 Co 7·5 B 6 ) were first subjected to the hydrogenation disproportionation (HD) to prepare disproportionation Nd Fe B precursor and subsequently cryomilled for different times. The submicron NdFeB particles with ultrafine nanocrystalline were finally obtained after desorption recombination (DR) process. The results indicated that with the increase of the cryomilling time, Nd 2 Fe 14 B grains were refined to nanoscale, but the coercivity decreased due to the strong exchange coupling between the nano-grains. The optimized nanocrystalline NdFeB particles have a size of 40 nm or less and present a coercivity of 6.63 kOe after cryomilling for 10 h followed by DR treatment at 800 °C for 10 min. To further improve the magnetic properties, Ca was added into HD powders in the course of cryomilling process to protect the powders from oxidation and a noticeable coercivity of 9.49 kOe was obtained. Finally, the mechanism of magnetic interactions and coercivity enhancement were discussed. [ABSTRACT FROM AUTHOR]

The disproportionation of formic acid to methanol catalyzed by a half-sandwich iridium complex, [Cp*Ir(bpy-Me)OH2]2+, was computationally investigated by using density functional theory. A newly proposed mechanism features three interrelated catalytic cycles, the dehydrogenation of formic acid to CO2 and H2, the hydrogenation of formic acid to formaldehyde with the formation of water, and the hydrogenation of formaldehyde to methanol. Methanol assisted proton transfer and direct C-O bond cleavage after hydroxyl deprotonation in two competitive pathways for the formation of formaldehyde are the rate-determining steps in the whole catalytic reaction. Calculation results indicate that the formation of formaldehyde from methanediol through direct cleavage of a C-O bond after hydroxyl deprotonation has a free energy barrier of 25.9 kcal/mol, which is 1.9 kcal/mol more favorable than methanol assisted proton transfer. [ABSTRACT FROM AUTHOR]