3377-87-5Relevant academic research and scientific papers
Catalytic Bromination of Alkyl sp3C-H Bonds with KBr/Air under Visible Light
Zhao, Mengdi,Lu, Wenjun
supporting information, p. 5264 - 5267 (2018/09/12)
Alkyl sp3C-H bonds of cycloalkanes and functional branch/linear alkanes have been successfully brominated with KBr using air or O2 as an oxidant at room temperature to 40 °C. The reactions are carried out in the presence of catalytic NaNO2 in 37% HCl (aq)/solvent under visible light, combining aerobic oxidations and photochemical radical processes. For various alkane substrates, CF3CH2OH, CHCl3, or CH2Cl2 is employed as an organic solvent, respectively, to enhance the efficiency of bromination.
Preparation of manganese/Graphite oxide composite using permanganate and graphite: Application as catalyst in bromination of hydrocarbons
Suzuki, Hideyuki,Nishina, Yuta
, p. 74 - 78 (2017/08/14)
A highly efficient one-pot preparation of manganese/graphite oxide (MnOX/GO) composite from graphite and KMnO4 is described. Hummers preparation method of GO requires a stoichiometric amount of KMnO4, as a result, the method produces a large amount of reduced Mn species. The Mn residue generally is a waste, therefore, we envisioned converting it to value-Added materials. A MnOX/GO composite was prepared in one-pot by treating the unpurified GO with aqueous KOH. The composite was characterized by XRD, XAFS, SEM and TEM. Among various applications of the MnOX/GO composite, we applied it as a recyclable catalyst for bromination of saturated hydrocarbons, one of the most basic but important chemical transformations. The MnOX/GO composite is expected to be an efficient catalyst because of the high surface area and high accessibility of substrates derived from the 2- dimensional sheet structure. When the reaction of a saturated hydrocarbon and Br2 in the presence of catalytic MnOX/GO was performed under fluorescent light irradiation, a brominated product was formed in high yield in a short reaction time. GO could strongly bind with Mn to prevent elution to the liquid phase, enabling the high recyclability.
Tetrabutylphosphonium Bromide Catalyzed Dehydration of Diols to Dienes and Its Application in the Biobased Production of Butadiene
Stalpaert, Maxime,Cirujano, Francisco G.,De Vos, Dirk E.
, p. 5802 - 5809 (2017/09/15)
We report the use of the ionic liquid tetrabutylphosphonium bromide as a solvent and catalyst for dehydration of diols to conjugated dienes. This system combines stability, high reaction rates, and easy product separation. A reaction mechanism for the model compound 1,2-hexanediol is proposed and experimentally corroborated. This particular mechanism allows for the selective formation of conjugated dienes, in contrast with purely acidic catalysis. Next, the reaction is also performed on various other diols. As a first application, we assessed the biobased production of 1,3-butadiene. With 1,4-butanediol as the starting material, a 94% yield of butadiene was reached at 100% conversion.
Terminal-Selective Functionalization of Alkyl Chains by Regioconvergent Cross-Coupling
Dupuy, Stéphanie,Zhang, Ke-Feng,Goutierre, Anne-Sophie,Baudoin, Olivier
supporting information, p. 14793 - 14797 (2016/11/23)
Hydrocarbons are still the most important precursors of functionalized organic molecules, which has stirred interest in the discovery of new C?H bond functionalization methods. We describe herein a new step-economical approach that enables C?C bonds to be constructed at the terminal position of linear alkanes. First, we show that secondary alkyl bromides can undergo in situ conversion into alkyl zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross-coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross-coupling then provided access to the corresponding linear arylation product in only two steps.
Site-selective aliphatic C-H bromination using N -bromoamides and visible light
Schmidt, Valerie A.,Quinn, Ryan K.,Brusoe, Andrew T.,Alexanian, Erik J.
supporting information, p. 14389 - 14392 (2014/12/10)
Transformations that selectively functionalize aliphatic C-H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C-H functionalization, few intermolecular processes of preparative value exist. Herein, we report an approach to unactivated, aliphatic C-H bromination using readily available N-bromoamide reagents and visible light. These halogenations proceed in useful chemical yields, with substrate as the limiting reagent. The site selectivities of these radical-mediated C-H functionalizations are comparable (or superior) to the most selective intermolecular C-H functionalizations known. With the broad utility of alkyl bromides as synthetic intermediates, this convenient approach will find general use in chemical synthesis.
Direct bromination of hydrocarbons catalyzed by Li2MnO 3 under oxygen and photo-irradiation conditions
Nishina, Yuta,Morita, Junya,Ohtani, Bunsho
, p. 2158 - 2162 (2013/03/13)
A method for the direct bromination of hydrocarbons with Br2 using a ubiquitous and inexpensive catalyst is highly desirable. Herein, we report the selective mono-bromination of hydrocarbons in good yield using Li2MnO3 as a catalyst under irradiation with a fluorescent room light. This new catalyst can be recycled. The effect of light was investigated using action spectra, which revealed that the reaction occurred on the surface of the catalyst.
Bromination of hydrocarbons with CBr4, initiated by light-emitting diode irradiation
Nishina, Yuta,Ohtani, Bunsho,Kikushima, Kotaro
, p. 1663 - 1667 (2013/10/22)
The bromination of hydrocarbons with CBr4 as a bromine source, induced by light-emitting diode (LED) irradiation, has been developed. Monobromides were synthesized with high efficiency without the need for any additives, catalysts, heating, or inert conditions. Action and absorption spectra suggest that CBr4 absorbs light to give active species for the bromination. The generation of CHBr3 was confirmed by NMR spectroscopy and GC-MS spectrometry analysis, indicating that the present bromination involves the homolytic cleavage of a C-Br bond in CBr4 followed by radical abstraction of a hydrogen atom from a hydrocarbon.
Catalytic distillation process for primary haloalkanes
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Page/Page column 9, (2012/02/17)
A process for making primary haloalkanes by catalytic distillation of internal haloalkanes which comprises a) introducing an internal haloalkane feed into a catalytic distillation column; b) isomerizing at least a portion of the internal haloalkane feed in the presence of an internal haloalkane isomerization catalyst at a temperature at or above the boiling point of the internal haloalkanes and below the temperature and pressure at which hydrogen halide is formed to form primary haloalkanes; and removing the primary haloalkanes from the catalytic distillation column.
Highly efficient oxidative bromination of alkanes with the HBr-H 2O2 system in the presence of catalyst
Li, Yujin,Ju, Jie,Jia, Jianhong,Sheng, Weijian,Han, Liang,Gao, Jianrong
experimental part, p. 2428 - 2432 (2011/10/03)
Various cycloalkanes and straight-chain alkanes were efficiently brominated with an aqueous HBr-H2O2 system. This oxidative brominating process was promoted by catalysis and irradiation with light. The cycloalkanes were converted to the corresponding bromo-cycloalkanes in moderate yields and the straight-chain alkanes produced dominantly secondary bromides. This simple but effective bromination method of alkanes is characterized by high atom efficiency, inexpensive reagents and the absence of organic waste, which make it a good alternative to the existing method for Ci￡H activation through bromination. A simple, effective, environmentally friendly method was researched for bromination of alkanes in good yield with HBr as the origin of bromine.
FORMATION OF HETEROATOM CONTAINING DERIVATIVES OF PARAFFINS
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Page/Page column 9-10, (2008/06/13)
A process by which alkyl halides may be reacted (coupled) with nucleophilic materials in the presence of a homogeneous catalyst system. The process comprises reacting (coupling) alkyl halides with a nucleophilic material in the presence of a homogeneous catalyst system to produce derivatives of alkyl halides, wherein the homogeneous catalyst system comprises at least one metal or metal compound which has the ability to form metal-halogen bonds.
