Highly efficient visible-light photocatalytic ethane oxidation into ethyl hydroperoxide as a radical reservoir

Photocatalytic ethane conversion into value-added chemicals is a great challenge especially under visible light irradiation. The production of ethyl hydroperoxide (CH₃CH₂OOH), which is a promising radical reservoir for regulating the oxidative stress in cells, is even more challenging due to its facile decomposition. Here, we demonstrated a design of a highly efficient visible-light-responsive photocatalyst, Au/WO₃, for ethane oxidation into CH₃CH₂OOH, achieving an impressive yield of 1887 μmol g_cat⁻¹ in two hours under visible light irradiation at room temperature for the first time. Furthermore, thermal energy was introduced into the photocatalytic system to increase the driving force for ethane oxidation, enhancing CH₃CH₂OOH production by six times to 11 233 μmol g_cat⁻¹ at 100 °C and achieving a significant apparent quantum efficiency of 17.9% at 450 nm. In addition, trapping active species and isotope-labeling reactants revealed the reaction pathway. These findings pave the way for scalable ethane conversion into CH₃CH₂OOH as a potential anticancer drug.

Highly efficient visible-light driven photocatalytic oxidation of ethane into ethyl hydroperoxide was realized for the first time over Au/WO₃.     

丙烯酸酯类与亚麻纤维接枝共聚反应的研究

Abou-Zeid等人曾报道以Fe(~2+)-H_2O_2体系引发丙烯腈等单体与黄麻纤维的接枝共聚反应,Misra等人报道了以S_2O_8_2-TU为引发体系,甲基丙烯酸甲酯与黄麻纤维的接枝共聚,最近,我们报道了以Ce(Ⅳ)引发甲基丙烯酸甲酯、丙烯酸乙酯(EA)分别与苧麻及亚麻纤维的接枝共聚。亚麻纤维与丙烯酸酯类单体接枝改性后,仲长率有所提高,加强了结合力,改善了成纱品质,因此引起人们的重视。本文以过硫酸钾-硫脲(KPS-TU)为引发体系,研究丙烯酸甲酯(MA)、EA及丙烯酸丁酯(BA)与亚麻纤维的接枝共聚反应规律,用IR、SEM、X射     

Microdynamics of solid anilinium chloride

Intraionic C₃ reorientation of the anilinium NH⁺₃ group was evidenced by measurements of the temperature dependence of the proton spin—lattice relaxation time, by rotating frame experiments and cw NMR data. Analysis of the results yielded a rotor hindering potential E = 33.6 kJ/mole and τ_o = 4 × 10⁻¹³ s.     

Thermal decompositions of zinc(II) benzenedicarboxylates

The thermal decompositions of zinc(II)benzenedicarboxylates were studied in air atmosphere at a heating-rate of 10 deg min^–1. Zinc phthalate and isophthalate were dehydrated in one step and next decomposed directly to ZnO. Zinc terephthalate was dehydrated in two steps and then decomposed directly to ZnO.

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Zusammenfassung Bei einer Aufheizgeschwindigkeit von 10°-min^–1 wurde die thermische Zersetzung von Zink(II)benzoldikarboxylat in Luft untersucht. Zinkphtalat und -isophtalat wird zunächst in einem Schritt dehydratisiert und anschließend zu ZnO zersetzt. Zinkterephtalat wird vor der endgültigen Zersetzung zu ZnO in zwei Schritten dehydratisiert.

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Creation of nematic and reentrant nematic phases in bi- and multi-component smectic mixtures

Abstract

Experimental results referring to the transformation of smectic phases, mainly smectic A, into nematic and reentrant nematic phases are reviewed. A new explanation of some experimental results is proposed. Factors which are responsible for the depression of smectic phases in mixtures of polar mesogens are discussed and the possibility of forming mixtures with a broad temperature range of nematic phase from smectic compounds, which can be useful for liquid crystal displays (LCDs), is shown. A nematic gap observed in some cases between monolayer (S_A1) or monolayer and partially bilayer (S_Ad) smectics results from the differences in the organization of the molecules in the smectic layers. It is concluded that polar phase from smectic A₁ phases can be divided into two groups: (a) the first one is characteristic for compounds with the -NCS, -F, -CI, -I or ?COC _m H_{2m + 1} terminal group. The spacing of the smectic layer slowly expands with the increase in alkyl chain length and the structure of the smectic A₁ phase slowly changes to be more like the smectic A_d phase (d/1 > 1). It is proposed that such a smectic is called an enhanced monolayer smectic (S_A1e (b) the second one is typical for compounds with the -CN terminal group. This kind of smectic A₁ phase is rapidly transformed into the smectic A_d phase with increasing alkyl chain length. These latter monolayer mesogens easily form the reentrant nematic phase when they are mixed with other polar smectic mesogens.     

Efficient Syntheses of Traumatic Lactone and Rhizobialide

Herein, we report the total synthesis of traumatic lactone and rhizobialide by utilizing allenoic acid to construct the lactone ring. The key starting materials, allenoic acids, could be prepared by the ATA (allenation of terminal alkynes) of a terminal alkyne with an aldehyde that contained a protected hydroxyl group followed by hydrolysis. Importantly, the asymmetric synthesis could be realized just by replacing racemic diphenylprinol with (R)- or (S)-diphenylprinol to deliver the optically active allenoate.     

Isobutane Dehydrogenation Assisted by CO2 over Silicalite‐1‐Supported ZnO Catalysts: Influence of Support Crystallite Size

The ZnO catalysts supported on Silicalite‐1 zeolites with different crystallite sizes (0.08, 0.35, 1 and 1.7 μm, respectively) and 5% Zn were synthesized via an incipient wetness method. The catalysts were characterized by XRD, N₂ adsorption, SEM, TEM‐EDX, DRIFT spectra and NH₃‐TPD, and their catalytic performance in isobutane dehydrogenation assisted by CO₂ was investigated. The catalytic activity is strongly dependent on the crystallite size of Silicalite‐1 support. The ZnO/S‐1‐0.35 catalyst with ca. 0.35 μm crystallite size displays the highest activity, affording an initial isobutane conversion of 51.0% and 74.5% isobutene selectivity. This can be attributed to a higher amount of acid sites present on this catalyst as well as the largest amount of nest silanols possessed by the S‐1‐0.35 support.     

Direct Pyridazine Ring Synthesis from β-Cyano Esters. A Facile Synthesis of the Derivatives of Tetrahydro-3,6-pyridazinedione 3-Hydrazone

4-Substituted tetrahydro-3,6-pyridazinedione 3-hydrazones (2) (or their 3-hydrazino tautomers 3), useful intermediates in the synthesis of bicyclic pyridazine derivatives, were prepared in satisfactory yields in the reaction of the corresponding alkyl 3-substituted 3-cyanopropionates with hydrazine hydrate.     

Synthesis and characterization of 6,6″′-bis(anthracen-9-yl)-2,2′;6′,2″;6″,2″′-quaterpyridine

New bianthracene-quaterpyridine ligand 6,6″′-bis(anthracen-9-yl)-2,2′;6′,2″;6″,2″′-quaterpyridine L has been obtained in a multistep synthesis using Suzuki–Miyaura and Stille-type coupling reactions. The dianthracene ligand L has four nitrogen-donor atoms and can form different supramolecular architectures with transition metal ions. Ligand L and intermediate compounds have been characterized by spectroscopic methods and elemental analyses. 2-(Anthracen-9-yl)-6-bromopyridine and 6-(anthracen-9-yl)-6′-bromo-2,2′-bipyridine have been also characterized by X-ray crystallography.