- Strongly Reducing (Diarylamino)benzene-Based Covalent Organic Framework for Metal-Free Visible Light Photocatalytic H2O2Generation
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Photocatalytic reduction of molecular oxygen is a promising route toward sustainable production of hydrogen peroxide (H2O2). This challenging process requires photoactive semiconductors enabling solar energy driven generation and separation of electrons and holes with high charge transfer kinetics. Covalent organic frameworks (COFs) are an emerging class of photoactive semiconductors, tunable at a molecular level for high charge carrier generation and transfer. Herein, we report two newly designed two-dimensional COFs based on a (diarylamino)benzene linker that form a Kagome (kgm) lattice and show strong visible light absorption. Their high crystallinity and large surface areas (up to 1165 m2·g-1) allow efficient charge transfer and diffusion. The diarylamine (donor) unit promotes strong reduction properties, enabling these COFs to efficiently reduce oxygen to form H2O2. Overall, the use of a metal-free, recyclable photocatalytic system allows efficient photocatalytic solar transformations.
- Krishnaraj, Chidharth,Sekhar Jena, Himanshu,Bourda, Laurens,Laemont, Andreas,Pachfule, Pradip,Roeser, Jér?me,Chandran, C. Vinod,Borgmans, Sander,Rogge, Sven M.J.,Leus, Karen,Stevens, Christian V.,Martens, Johan A.,Van Speybroeck, Veronique,Breynaert, Eric,Thomas, Arne,Van Der Voort, Pascal
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- An experimental and theoretical study on imidazolium-based ionic liquid promoted chloromethylation of aromatic hydrocarbons
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The chloromethylation of aromatic hydrocarbons proceeded efficiently using the reusable imidazolium-based ionic liquid as promoter. Mild reaction conditions, enhanced rates, improved yields, recyclability of ionic liquids, and reagents' reactivity which is different from that in conventional organic solvents are the remarkable features observed in ionic liquids. The ionic liquids were recycled in three subsequent runs with no decrease in activity. In addition, the results of calculations with the Gaussian 98 suite of program are in good accordance with the experimental outcomes.
- Wang, Yun,Xi, Yanli
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p. 2196 - 2199
(2014/03/21)
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- New soluble multi-site phase transfer catalysts and their catalysis for dichlorocarbene addition to citronellal assisted by ultrasound - A kinetic study
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Two new soluble multi-site phase transfer catalysts (MPTCs), viz., 1,4-bis-(triethylmethylene ammonium chloride)-2,5-dimethyl benzene (BTMACD) containing di-site and 1,4-bis((3,5-bis(triethylmethyleneammonium chloride)phenoxy)methyl)benzene (TEMACPB) containing tetra-site were prepared and proved by FT-IR, 1H NMR, 13C NMR, mass and elemental analysis. The enhancement of CN peak intensity at 1179 cm-1 noticed in FT-IR, the agreement of m/z values, viz., 405 and 888 for di-site and tetra-site respectively with their theoretical values and the percentage of C, H, N elements noticed in elemental analysis has strongly supported the presence of di-site and tetra-site in the BTMACD and TEMACPB catalysts. Further, the presence of number of active-sites in each catalyst was again confirmed by determining their pseudo-first order rate constant for dichlorocarbene addition to citronellal in the presence of ultrasonic irradiation/mechanical stirring. The comparative study reveals that the kobs determined with the combination of ultrasound and mechanical stirring has shown more activity (3 fold) than with their individual effect. Further, the detailed kinetic study performed with superior tetra-site MPTC (TEMACPB) reveals that the k obs are dependent with the stirring speed, [substrate], [catalyst], [NaOH] and temperature. Based on the kinetic results, thermodynamic parameters are evaluated and an interfacial mechanism is proposed.
- Murugan, Eagambaram,Tamizharasu, Gurusamy
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p. 81 - 89,9
(2020/07/31)
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- Efficient dichloromethylation of some aromatic hydrocarbons catalyzed by a new ionic liquid [C12minPEG800]br under homogeneous catalysis in aqueous media
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A series of new imidazolium-type ionic liquids based on polyethylene glycol have been prepared. The new recyclable temperature-dependant phase-separation system comprised of [C12minPEG800]Br and methylcyclohexane was also developed and successfully applied to the dichloromethylation of some aromatic hydrocarbons to prepare dichloromethyl-substituted hydrocarbons in excellent yields. The ionic liquid could be excellent recycled without any apparent loss of catalytic activity and little loss of weight even after 8 times recycling.
- Hu,Liu,Lu,Lu,Ge,Zhang
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experimental part
p. 131 - 141
(2012/01/03)
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- An inexpensive and efficient synthetic method for the preparation of pyromellitic dianhydride promoted by ionic liquid
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In this article, pyromellitic dianhydride could be successfully obtained in 76.7% total yield by an aerobic oxidation of 1,4-bis(chloromethyl)-2,5- dimethylbenzene or 1,5-bis(chloromethyl)-2,4- dimethylbenzene catalyzed by VO(acac)2/Cu(2-Eth)2/DABCO in [hmim]OTf and a subsequent dehydration of pyromellitic acid upon heating with acetic anhydride. The starting materials including 1,2-bis(chloromethyl)-4,5-dimethylbenzene were prepared by dichloromethylation of their corresponding xylene catalyzed by [C12mim]Br in aqueous media. ARKAT USA, Inc.
- Hu, Yu Lin,Lu, Ming,Liu, Xiao Bin,Zhang, Sheng Bin,Ji, Zhan Hui,Lu, Ting Ting
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experimental part
p. 63 - 74
(2010/10/19)
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- Identification of alkylarene chloromethylation products using gas-chromatographic retention indices
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Gas-chromatographic retention indices on standard nonpolar polydimethylsiloxane stationary phases allow identification of products formed by known organic reactions even without using mass-spectrometric data. The efficiency of this approach was demonstrated by the example of identification of previously uncharacterized chloromethyl derivatives of alkylarenes, including structural isomers of compounds containing several chloromethyl groups, directly in reaction mixtures. Chromatographic analysis of such reaction mixtures allows identification of positional isomers of the starting alkylarenes even when they are present simultaneously. The retention indices were determined for the first time for more than 50 alkyl-(chloromethyl)arenes, by-products of chloromethylation, and chloromethyl derivatives of the simplest alkyl phenyl ketones. Nauka/Interperiodica 2007.
- Zenkevich,Makarov
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p. 611 - 619
(2008/03/18)
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- [emim]BF4-promoted chloromethylation of aromatic hydrocarbons
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The chloromethylation of aromatic hydrocarbons proceeded efficiently using the reusable ionic liquid [emim]BF4 as promoter. The reactions were completed in 5 h at 70°C with good yields and easy workup. Copyright Taylor & Francis Group, LLC.
- Wang, Yun,Shang, Zhi-Cai,Wu, Tian-Xing
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p. 3053 - 3059
(2007/10/03)
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- Scope and Limitations of a New Highly Selective Synthesis of Unsymmetrical Monomers for the Synthesis of Precursors toward Poly(arylenevinylene)s
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In our laboratory a precursor route to poly(p-phenylenevinylene) derivatives is developed in which unsymmetrically substituted p-xylene derivatives, possessing a benzylic sulfinylalkyl group, are used as monomers. Because of this unsymmetry, we were forced to investigate thoroughly the synthesis of these sulfoxides, as we start from symmetric and readily accessible molecules, namely, bis(halomethyl)-p-xylene derivatives. In a former publication, a new extremely effective route for the production of these unsymmetrically substituted sulfinyl monomers was presented. This paper expands upon these previously reported results. To examine the scope and limitations of this elegant route, this new method was applied to the synthesis of various derivatives not included in the initial work.
- van der Borght, Michael,Vanderzande, Dirk,Adriaensens, Peter,Gelan, Jan
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p. 284 - 289
(2007/10/03)
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