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81.
Ozonolysis of a Series of Methylated Alkenes: Reaction Rate Coefficients and Gas‐Phase Products 下载免费PDF全文
Tristan Braure Véronique Riffault Alexandre Tomas Romeo Iulian Olariu Cecilia Arsene Yuri Bedjanian Patrice Coddeville 《国际化学动力学杂志》2015,47(9):596-605
The gas‐phase ozonolysis of three methylated alkenes, i.e., trans‐2,2‐dimethyl‐3‐hexene (22dM3H), trans‐2,5‐dimethyl‐3‐hexene (25dM3H), and 4‐methyl‐1‐pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas‐phase product concentrations were determined via online sampling either on three‐bed adsorbent cartridges followed by thermodesorption and GC/FID‐MS analysis or on 2,4‐dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10?17 for 22dM3H and (2.71 ± 0.26) × 10?17 for 25dM3H, both in cm3 molecule?1 s?1 units, have been obtained under pseudo–first‐order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor. 相似文献
82.
András Gy. Németh Renáta Szabó Dr. Attila Domján Prof. György M. Keserű Dr. Péter Ábrányi-Balogh 《ChemistryOpen》2021,10(1):16-27
The development of a new three-component chromatography-free reaction of isocyanides, amines and elemental sulfur allowed us the straightforward synthesis of thioureas in water. Considering a large pool of organic and inorganic bases, we first optimized the preparation of aqueous polysulfide solution from elemental sulfur. Using polysulfide solution, we were able to omit the otherwise mandatory chromatography, and to isolate the crystalline products directly from the reaction mixture by a simple filtration, retaining the sulfur in the solution phase. A wide range of thioureas synthesized in this way confirmed the reasonable substrate and functional group tolerance of our protocol. 相似文献
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π-Extended molecules are key components for the development of materials science. In fact, polyaromatic structures are fundamental for the scientific and technological progress of fields such as organic electronics and bio-applications. Beneficial properties of π-extended structures are absorption in the visible region, often luminescence, high electron mobilities and stability. Common approaches to adjust the properties of polyaromatic structures to functional setups involve changes in shape and size at the molecular level. Recently, incorporating hetero-elements emerged as successful approach. In this regard, organophosphorus conjugated molecules are new materials holding great promise for potential applications. In this review, we comprehensively discuss the design/development of polyaromatic phosphorus materials and their applicability. We establish structure/property/applicability relationships to provide key guidelines for the engineering of newer, future applications. This article thus provides a source of information for the further development of this rapidly evolving field of research. 相似文献
87.
Experimental Mechanics - There have been relatively few studies on mechanical properties of nanomaterials under high strain rates, mainly due to the lack of capable nanomechanical testing devices.... 相似文献
88.
Naphthalimide‐phthalimide derivative based photoinitiating systems for polymerization reactions under blue lights 下载免费PDF全文
Pu Xiao Frédéric Dumur Jing Zhang Bernadette Graff Didier Gigmes Jean Pierre Fouassier Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2015,53(5):665-674
Naphthalimide‐phthalimide derivatives (NDPDs) have been synthesized and combined with an iodonium salt, N‐vinylcarbazole, amine or 2,4,6‐tris(trichloromethyl)‐1,3,5‐triazine to produce reactive species (i.e., radicals and cations). These generated reactive species are capable of initiating the cationic polymerization of epoxides and/or the radical polymerization of acrylates upon exposure to very soft polychromatic visible lights or blue lights. Compared with the well‐known camphorquinone based systems used as references, the novel NDPD based combinations employed here demonstrate clearly higher efficiencies for the cationic polymerization of epoxides under air as well as the radical polymerization of acrylates. Remarkably, one of the NDPDs (i.e., NDPD2) based systems is characterized by an outstanding reactivity. The structure/reactivity/efficiency relationships of the investigated NDPDs were studied by fluorescence, cyclic voltammetry, laser flash photolysis, electron spin resonance spin trapping, and steady state photolysis techniques. The key parameters for their reactivity are provided. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 665–674 相似文献
89.
Immobilized Catalysts for Iridium‐Catalyzed Allylic Amination: Rate Enhancement by Immobilization 下载免费PDF全文
Dr. Chandi C. Malakar Prof. Dr. Günter Helmchen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7127-7134
The first immobilized catalyst for Ir‐catalyzed asymmetric allylic aminations is described. The catalyst is a cationic (π‐allyl)Ir complex bound by cation exchange to an anionic silica gel support. Preparation of the catalyst is facile, and the supported catalyst displayed considerably enhanced activity compared with the parent homogeneous catalyst. Up to 43 consecutive amination runs were possible in recycling experiments. 相似文献
90.
Roberto Morales-Cerrada Dr. Christophe Fliedel Dr. Jean-Claude Daran Dr. Florence Gayet Dr. Vincent Ladmiral Dr. Bruno Améduri Prof. Rinaldo Poli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):296-308
Thermal decarbonylation of the acyl compounds [Mn(CO)5(CORF)] (RF=CF3, CHF2, CH2CF3, CF2CH3) yielded the corresponding alkyl derivatives [Mn(CO)5(RF)], some of which have not been previously reported. The compounds were fully characterized by analytical and spectroscopic methods and by several single-crystal X-ray diffraction studies. The solution-phase IR characterization in the CO stretching region, with the assistance of DFT calculations, has allowed the assignment of several weak bands to vibrations of the [Mn(12CO)4(eq-13CO)(RF)] and [Mn(12CO)4(ax-13CO)(RF)] isotopomers and a ranking of the RF donor power in the order CF3<CHF2<CH2CF3≈CF2CH3. The homolytic Mn−RF bond cleavage in [Mn(CO)5(RF)] at various temperatures under saturation conditions with trapping of the generated RF radicals by excess tris(trimethylsilyl)silane yielded activation parameters ΔH≠ and ΔS≠ that are believed to represent close estimates of the homolytic bond dissociation thermodynamic parameters. These values are in close agreement with those calculated in a recent DFT study (J. Organomet. Chem. 2018 , 864, 12–18). The ability of these complexes to undergo homolytic Mn−RF bond cleavage was further demonstrated by the observation that [Mn(CO)5(CF3)] (the compound with the strongest Mn−RF bond) initiated the radical polymerization of vinylidene fluoride (CH2=CF2) to produce poly(vinylidene fluoride) in good yields by either thermal (100 °C) or photochemical (UV or visible light) activation. 相似文献