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1.
Dioxygen Reactivity with a Ferrocene–Lewis Acid Pairing: Reduction to a Boron Peroxide in the Presence of Tris(pentafluorophenyl)borane 下载免费PDF全文
Justin T. Henthorn Prof. Theodor Agapie 《Angewandte Chemie (International ed. in English)》2014,53(47):12893-12896
Ferrocenes, which are typically air‐stable outer‐sphere single‐electron transfer reagents, were found to react with dioxygen in the presence of B(C6F5)3, a Lewis acid unreactive to O2, to generate bis(borane) peroxide. Although several Group 13 peroxides have been reported, boron‐supported peroxides are rare, with no structurally characterized examples of the BO2B moiety. The synthesis of a bis(borane)‐supported peroxide anion and its structural and electrochemical characterization are described. 相似文献
2.
The reaction of tri-O-acetyl-d-glucal with different nitrogen nucleophiles was effectively promoted by a catalytic amount of tris(pentafluorophenyl)borane for the first time in acetonitrile at room temperature to produce a variety of azapseudoglycals via Ferrier rearrangement in good yields and preferential anomeric selectivity. 相似文献
3.
The acylation of alcohols, phenols, amines, and thiophenols was accomplished with 0.5 mol % of tris(pentafluorophenyl)borane [B(C6F5)3] at ambient temperature under solvent-free condition. Major advantages of this method include high yield, short reaction time, simple procedure, compatibility with sensitive protecting groups as well as other functional groups, absence of racemization of optical active compounds, and epimerization of sugars. 相似文献
4.
An efficient acid-catalyzed protection of alcohols as trityl ethers is described using triphenylmethanol in the presence of tris(pentafluorophenyl)borane (3 mol %) in dichloromethane at room temperature. The chemoselectivity of this protocol is demonstrated by studying the tritylation of a primary alcohol in the presence of a secondary alcohol and also the mildness of this catalyst was studied with substrates containing acid labile protecting groups. 相似文献
5.
《Angewandte Chemie (International ed. in English)》2017,56(39):11995-11999
This work showcases a new catalytic cyclization reaction using a highly Lewis acidic borane with concomitant C−H or C−C bond formation. The activation of alkyne‐containing substrates with B(C6F5)3 enabled the first catalytic intramolecular cyclizations of carboxylic acid substrates using this Lewis acid. In addition, intramolecular cyclizations of esters enable C−C bond formation as catalytic B(C6F5)3 can be used to effect formal 1,5‐alkyl migrations from the ester functional groups to unsaturated carbon–carbon frameworks. This metal‐free method was used for the catalytic formation of complex dihydropyrones and isocoumarins in very good yields under relatively mild conditions with excellent atom efficiency. 相似文献
6.
Robert T. Mathers Stewart P. Lewis 《Journal of polymer science. Part A, Polymer chemistry》2012,50(7):1325-1332
Tris(pentafluorophenyl)gallium ( 3 ) and aluminum ( 7 ) are active coinitiators for the production of medium‐high molecular weight (MW) polymers of styrene and isobutene (IB) under aqueous reaction conditions. Strong Brønsted acids formed in situ by reaction of these coinitiators with background moisture present in the monomer droplet ( 5 and 8 , respectively) are believed to be responsible for inducing cationic polymerization of these monomers. Of the two, 7 is the most active for IB polymerization in both aqueous media and anhydrous aliphatic solvents. These results are in contradistinction to tris(pentafluorophenyl)boron ( 2 ), which is incapable of polymerizing IB in aqueous or aliphatic media. The MWs of the polyisobutenes (PIBs) produced under aqueous conditions by either coinitiator greatly exceed those formed under similar reaction conditions by the strongly acidic chelating diborane (1,2‐C6F4[B(C6F5)2]2, 1 ) or diborole (1,2‐C6F4[9‐BC12F8]2, 6 ). Both 3 and 7 are readily synthesized from the corresponding Group 13 halide compounds in conjunction with bis(pentafluorophenyl)zinc ( 4 ). Aqueous polymerization of IB dissolved in aliphatic solvents with 3 or 7 can yield PIBs with relatively narrow polydispersities. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
7.
Preparation and Properties of New Tris(fluoroaryl)boranes B(2-FC6H4)3, B(4-FC6H4)3, B(2,6-F2C6H3)3 and B(C5F4N)3 are prepared from the reactions of RMgX with boron trifluoride, B(OC6F5)3 and B(SC6F5)3 from C6F5XH (X = O, S) and boron trichloride. The synthetic routes and the properties of these mainly new compounds are described. 相似文献
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T. Lewe D. Naumann G. Nowicki H. Schneider W. Tyrra Th. Gilles K.-F. Tebbe 《无机化学与普通化学杂志》1996,622(12):2009-2015
Syntheses and Properties of Some New Tris(fluorophenyl)antimony and -bismuth Compounds. Crystal Structure of Tris(2,6-difluorophenyl)bismuth (2,6-F2C6H3)3Bi, (2,4,6-F3C6H2)3Bi, and (2,6-F2C6H3)3Sb are prepared via Grignard reactions with BiBr3 and SbBr3, respectively. The syntheses and properties of the new compounds and the crystal structure of (2,6-F2C6H3)3Bi are described. From the reaction of BiBr3 with Ag(OCOC6H3F2) the bismuth benzoate Bi(OCOC6H3F2)3 is formed in 83% yield. Attempts to prepare (2,6-F2C6H3)3Bi by decarboxylation of the bismuth benzoate failed. 相似文献
10.
Hui Meng Fengwu Wu Zhike He Liangjie Yuan Qingyao Luo Yune Zeng 《International journal of environmental analytical chemistry》2013,93(3):299-307
Abstract The emission produced by sulfite after oxidation by potassium permanganate in acidic solution in the presence of Ru(phen)3 2+ is used to determine 1.0 × 10?7 to 2.5 × 10?5 mol/L sulfite. The limit of detection is 4.5 × 10?9 mol/L and the relative standard deviation is 3.1% for a 1 × 10?5 mol/L sulfite solution (n=8). The method was also applied satisfactorily to the determination of sulfur dioxide in air by using triethanolamine (TEA) as absorbent material. 相似文献
11.
The ring-opening polymerization of ε-caprolactone (CL) initiated by novel singlelanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity averagemolecular weight about 60 × 103 under quite mild conditions: molar ratio of CL to initiator is 1000,60 ℃, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chainvia the break of acyl-oxygen bond of CL. 相似文献
12.
近年来, 受限路易斯酸碱对(FLPs: Frustrated Lewis Pairs)在小分子的活化以及在催化还原等方面所表现出的独特反应特性, 使得有关FLPs化学的研究受到了国内外广泛的关注. 设计了一种新型的FLPs催化体系, 该体系以三(五氟苯基)硼(BCF)为路易斯酸, 以多种不同取代的有机胺盐酸盐替代常规FLPs中的路易斯碱有机胺. 发现利用该体系与氢化硅烷反应, 不仅可以高产率地制备分离得到相应的伯、仲、叔硼氢化胺盐; 而且还可以这一体系作为催化剂, 以氢化硅烷作为还原剂, 在常温常压下可高选择性地部分或彻底还原大部分含羰基官能团醛酮等有机化合物. 由BCF/2,2,6,6-四甲基哌啶(TMP)盐酸盐组成的催化体系在对CO2催化还原为甲烷的反应中, 亦较相应的BCF/TMP体系显示更高的活性. 还通过核磁共振详细地对比研究了原料有机胺盐酸盐、中间体氯代硼胺盐以及产物氢化硼胺盐中, 胺基氮上质子的核磁共振谱信息, 发现不仅胺基上取代基的位阻效应会影响到具有电四极矩性的14N磁性核的弛豫效应, 而且阴离子基团的配位强弱对胺基氮上质子的化学位移也会产生较大的影响. 相似文献
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Youngchan Jang Dai Seung Choi Shin Han 《Journal of polymer science. Part A, Polymer chemistry》2004,42(5):1164-1173
The activation of a metal alkyl‐free Ni‐based catalyst with B(C6F5)3 was investigated in the polymerization of 1,3‐butadiene. A catalyst of bis(1,5‐cyclooctadiene)nickel (Ni(COD)2)/B(C6F5)3 was found to have high catalytic activity and 1,4‐cis stereoregularity. The catalyst was also found to provide polybutadiene having a molecular weight (Mw) of up to 117,000, even in the absence of AlR3 and MAO. Variations in the mol ratio of B(C6F5)3 to Ni affected catalytic activity, 1,4‐cis stereoregularity, and the Mw of polybutadiene, while the molecular weight distribution (MWD) of polybutadiene showed little correlation with the mol ratio of B(C6F5)3 to Ni. The use of other borane compounds such as B(C6H5)3, BEt3, and BF3 etherate in place of B(C6F5)3 clearly showed the two main functions of B(C6F5)3 in the present catalyst. The high Lewis acidity of B(C6F5)3 enabled it to activate catalytic complexes, thus inducing the polymerization. The steric bulkiness of B(C6F5)3 suppressed chain transfer reactions, contributing to the production of polybutadiene with a high Mw. Kinetic studies showed that the catalyst had an induction period, possibly due to the time needed for the formation of catalytic complexes starting from Ni(COD)2. A plot of ?ln (1?X), where X is the fractional conversion, as a function of time resulted in a linear relationship, showing that the present catalyst system followed first‐order kinetics with respect to monomer concentration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1164–1173, 2004 相似文献
14.
《合成通讯》2012,42(1):33-40
AbstractA new and efficient B(C6F5)3 catalyzed domino strategy has been developed for the synthesis of 2-substituted quinazolinones. The reaction utilizes 2-aminobenzamide and aldehydes for a one-pot protocol. A wide range of substrate scope, functional group tolerance, and operational simplicity with excellent yield are synthetically useful features. 相似文献
15.
Pentafluorophenyliodine(III) Compounds. 2. Fluorine-Aryl Substitution Reactions on Iodinetrifluoride: Synthesis of Pentafluorophenyliodinedifluoride C6F5IF2 and Bis(pentafluorophenyl)iodonium Pentafluorophenylfluoroborates[(C6F5)2I]+[(C6F5)nBF4?n]? Mono- and disubstitution can be achieved in the fluorine-aryl substitution reaction on the low-temperature phase IF3 in CH2Cl2 at ?78°C depending on the aryl transfer reagent. With B(C6F5)3 [(C6F5)2I]+ [(C6F5)nBF4?n]? (68% yield) and with Cd(C6F5)2 C6F5IF2 (97% yield) is obtained whereas with C6F5SiMe3 no fluorine-aryl substitution takes place on IF3 even under basic conditions (EtCN or F? addition). At ?78°C in EtCN solution IF3 does not disproportionate but attacks the solvent under formation of HF. 相似文献
16.
The kinetics of the bromate oxidation of tris(1,10-phenanthroline)iron(II) (Fe(phen)32+) and aquoiron(II) (Fe2+ (aq)) have been studied in aqueous sulfuric acid solutions at μ = 1.0M and with Fe(II) complexes in great excess. The rate laws for both reactions generally can be described as -d [Fe(II)]/6dt = d[Br?]/dt = k[Fe(II)] [BrO?3] for [H+]0 = 0.428–1.00M. For [BrO?3]0 = 1.00 × 10?4M. [Fe2+]0 = (0.724–1.45)x 10?2 M, and [H+]0 = 1.00M, k = 3.34 ± 0.37 M?1s?1 at 25°. For [BrO?3]0 = (1.00–1.50) × 10?4M, [Fe2+]0 = 7.24 × 10?3M ([phen]0 = 0.0353M), and [H+]0 = 1.00M, k = (4.40 ± 0.16) × 10?2 M?1s?1 at 25°. Kinetic results suggest that the BrO?3-Fe2+ reaction proceeds by an inner-sphere mechanism while the BrO?3-Fe(phen)32+ reaction by a dissociative mechanism. The implication of these results for the bromate-gallic acid and other bromate oscillators is also presented. 相似文献
17.
Cui Ping YU Li Fang ZHANG Zhi Quan SHEN Institute of Polymer Science Zhejiang University Hangzhou 《中国化学快报》2003,(10)
The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL. 相似文献
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三草酸合铁(III)酸钾具有工业生产价值,其合成作为化学专业本科生的经典实验项目,按教材实验的效果却不尽人意。本文在严谨的化学平衡理论分析基础上,首次提出提高合成产率的关键是严格控制草酸和草酸钾的用量,改进后的合成条件为:氧化步骤H2O2的浓度为6%,水浴温度为40°C;充分氧化后,微沸2分钟;酸溶步骤中草酸稍微过量,草酸钾过量10%;结晶时做到充分冷却。经此改进,可简化操作,节约原料,实验室平均产率达87%,教学中学生实验平均产率超过70%。 相似文献
20.
Kazem D. Safa Elham Sharifi Shahin Tofangdarzadeh Akbar Hassanpour 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2433-2440
The reactions between a variety of functionalized alcohols and tris(dimethylsilyl)methane, (HMe2Si)3CH, are described. Alcohols such as ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, triethylene glycol monomethyl ether, 2-chloroethanol, 1-octanol, benzyl alcohol, glycidol, and allyl alcohol were converted in the presence of Karstedt's catalyst into the corresponding tris(alkoxydimethylsilyl)methanes, (ROMe2Si)3CH, in a convenient one-pot operation under aerobic conditions. The appearance of the products coincides with the generation of colloidal Pt(0) species. Moreover, poly(4-chloromethyl)styrene containing tris(dimethylsilyl)methyl groups reacts with benzyl alcohol or 2-chloroethanol in the presence of Karstedt's catalyst to give new macromolecules bearing tris(alkoxydimethylsilyl)methyl groups. The reaction rate is greatly influenced by the concentration of catalyst. 相似文献