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991.
A novel, magnetically recoverable carbonaceous solid acid Fe3O4@C-SO3H catalyst for the conversion of carbohydrates to 5-ethoxymethylfurfural (EMF) was developed. The effect of the DMSO fraction in the ethanol-DMSO binary solvent on the distribution of the reaction products was investigated. The catalyst showed an excellent activity in the synthesis of EMF from fructose and 5-hydroxymethylfurfural (HMF). 5- Ethoxymethylfurfural was also obtained with a high yield of 64.2% in an ethanol–DMSO solvent system via one-step conversion of fructose. After reaction, the catalyst could be recovered by exposure of the reaction mixture to external magnetic field and reused several times without a loss of catalytic activity. 相似文献
992.
Dzh. N. Konshina A. V. Danilova Z. A. Temerdashev S. N. Bolotin A. A. Gurinov V. V. Konshin 《Russian Journal of Applied Chemistry》2016,89(4):590-597
A new sorption material, silica gel with covalently immobilized formazan group, was suggested and characterized. The material was prepared by coupling the immobilized aryldiazonium salt with benzaldehyde phenylhydrazone. The equilibrium and kinetic characteristics of the sorption of Cu(II), Co(II), Ni(II), and Cd(II) from solutions onto the modified silica gel were determined. The material proved to efficiently concentrate Cu(II) from multicomponent solutions. The coordination surrounding of Cu(II) in the complex on the sorbent surface was determined by ESR. 相似文献
993.
A series of Cellulose/poly-ethylene imine (PEI) composites were prepared by grafting hyperbranched PEI onto cellulose chains in alkali/urea aqueous solvent system through “one step” method. The SEM results showed that the Cellulose/PEI composite maintained porous structure. The Cellulose/PEI composites were tested as Cu(II) adsorbents through thermodynamics and kinetics study. The adsorption process followed pseudo-second-order kinetics equation. The adsorption isotherms could be described by both Langmuir and Freundlich isotherm models. The maximum adsorption amount was calculated to be 285.7 mg/g. The composites showed good stability so that they could be used in a wide range of pH and temperature. Besides, the Cu(II) loaded Cellulose/PEI composite could also be easily regenerated by dilute sulfuric acid and still keep a major adsorption capacity. Finally, the adsorption capacities of Celluloes/PEI composite towards other metal ions, such as Zn(II), Ni(II), Cr(III) and Pb(II), were also demonstrated. It will be a new high-performance and environmental friendly material for sewage disposal and metal pollution treatment with promising developmental potential. 相似文献
994.
995.
Wu Wen Shengsheng Yu Chaoqun Zhou Prof. Hao Ma Prof. Zhongyue Zhou Chuangchuang Cao Dr. Jiuzhong Yang Minggao Xu Prof. Fei Qi Prof. Guobin Zhang Prof. Yang Pan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4903-4908
HCHO has been confirmed as an active intermediate in the methanol-to-hydrocarbon (MTH) reaction, and is critical for interpreting the mechanisms of coke formation. Here, HCHO was detected and quantified during the MTH process over HSAPO-34 and HZSM-5 by in situ synchrotron radiation photoionization mass spectrometry. Compared with conventional methods, excellent time-resolved profiles were obtained to study the formation and fate of HCHO, and other products during the induction, steady-state reaction, and deactivation periods. Similar formation trends of HCHO and methane, and their close correlation in yields suggest that they are derived from disproportionation of methanol at acidic sites. In the presence of Y2O3, the amount of HCHO changes, affecting the hydrogen-transfer processes of olefins into aromatics and aromatics into cokes. The yield of HCHO affects the aromatic-based cycle and the formation of ethylene, indicating that ethylene is mainly formed from the aromatic-based cycle. 相似文献
996.
Shuangshuang Ji Xiuzhu Yang Xiaolong Chen Ang Li Doudou Yan Haiyan Xu Hao Fei 《Chemical science》2020,11(34):9126
The development of chemotherapy, an important cancer treatment modality, is hindered by the frequently found drug-resistance phenomenon. Meanwhile, researchers have been enthused lately by the synergistic use of chemotherapy with emerging immunotherapeutic treatments. In an effort to address both of the two unmet needs, reported herein is a study on a series of membrane active iridium(iii) complexed oligoarginine peptides with a new cell death mechanism capable of overcoming drug resistance as well as stimulating immunological responses. A systematic structure–activity relationship study elucidated the interdependent effects of three structural factors, i.e., hydrophobicity, topology and cationicity, on the regulation of the cytotoxicity of the Ir(iii)-oligoarginine peptides. With the most prominent toxicities, Ir-complexed octaarginines (R8) were found to display a progressive oncotic cell death featuring cell membrane-penetration and eruptive cytoplasmic content release. Consequently, this membrane-centric death mechanism showed promising potential in overcoming multiple chemical drug-resistance of cancer cells. More interestingly, the eruptive mode of cell death proved to be immunogenic by stimulating the dendritic cell maturation and inflammatory factor accumulation in mice tumours. Taking these mechanisms together, this work demonstrates that membrane active compounds may become the next generation chemotherapeutics because of their combined advantages.Structure optimized Ir-complexed cyclic octa-arginine shows a potential of “one-drug two-effects” for cancer treatment. 相似文献
997.
Hao Zhang Dr. Benhua Wang Dr. Kai Seehafer Prof. Dr. Uwe H. F. Bunz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(35):7779-7782
A cross-reactive optical sensor array based on poly(p-phenyleneethynylene)s (PPEs) determines Edman degraded amino acids. We report a sensor array composed of three anionic PPEs P1–P3 , and their electrostatic complexes with metal ions (Fe2+, Cu2+, Co2+). We recorded distinct fluorescence intensity response patterns as “fingerprints” of this chemical tongue toward standard phenylthiohydantoin (PTH) amino acids—degradation products of the Edman process. These “fingerprints” were converted into canonical scores by linear discrimination analysis (LDA), which differentiates all of the PTH-amino acids. This array discriminates PTH-amino acid residues degraded from an oligopeptide through Edman sequencing. This approach is complementary to chromatography approaches which rely on mass spectrometry; our array offers the advantage of simplicity. 相似文献
998.
Lars J. Wesenberg Erika Diehl Till J. B. Zähringer Carolin Dörr Dr. Dieter Schollmeyer Dr. Akihiro Shimizu Prof. Dr. Jun-ichi Yoshida Prof. Dr. Ute A. Hellmich Prof. Dr. Siegfried R. Waldvogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17574-17580
The efficient production of many medicinally or synthetically important starting materials suffers from wasteful or toxic precursors for the synthesis. In particular, the aromatic non-protected primary amine function represents a versatile synthetic precursor, but its synthesis typically requires toxic oxidizing agents and transition metal catalysts. The twofold electrochemical amination of activated benzene derivatives via Zincke intermediates provides an alternative sustainable strategy for the formation of new C−N bonds of high synthetic value. As a proof of concept, we use our approach to generate a benzoxazinone scaffold that gained attention as a starting structure against castrate-resistant prostate cancer. Further improvement of the structure led to significantly increased cancer cell line toxicity. Thus, exploiting environmentally benign electrooxidation, we present a new versatile and powerful method based on direct C−H activation that is applicable for example the production of medicinally relevant compounds. 相似文献
999.
M. S. Chernovyants N. V. Aleshina I. N. Shcherbakov Z. A. Starikova 《Russian Journal of General Chemistry》2013,83(5):986-988
The formation by 1H-1,2,4-triazoline-3-thiones in dilute chloroform solution of n-σ*-complex with molecular iodine of the composition C2H2N3S·I2 was studied by electronic spectroscopy in the UV and visible regions (log β = 2.14±0.05). By the XRD method the crystal and molecular structure of the product of chemical interaction of the thione with molecular iodine in ethanol, 1,2-di(1H-1,2,4-triazol-3-yl) disulfide, was determined. 相似文献
1000.
Z. Y. Zhang B. Wu Y. H. Tang Z. X. Li Z. L. Sun L. Y. Chen Y. B. Ji C. H. Ma C. G. Huang 《Journal of Analytical Chemistry》2013,68(8):716-721
To characterize of the constituents in rat urine after oral administration of Radix Astragali decoction, a HPLC-DAD-MS/MS technique had been developed. Urine collected from 0 to 24 h, after administration, was purified using a C18 solid-phase extraction cartridge, and then detected by an on-line MS/MS detector. By comparing the retention times and MS/MS data with those obtained from authentic compounds and the published data, a total of 11 compounds including six flavonoids, one dipeptide, one triterpenoid and three of their metabolites in urine were identified. Compounds daidzein, genistein, quercetin, L-asparamide-D-phenylalanine, 4,2′,4′-trihydroxychalcone, Astragaloside-IV, daidzein sulfate, and kaempferol sulfate were for the first time detected by HPLC-MS/MS technique in urine. The present research results success-fully narrowed the range of effective constituents to be found in Astragalus membranaceus and would be useful for the following action mechanism research of this traditional Chinese medicine in treating various diseases. 相似文献