Xi:Irritant;
111-87-5Relevant articles and documents
Nametkin,Tanewa
, (1943)
Regioselective addition of stannylcyanocuprates to acetylenic ethers: A chemical and spectroscopic study
Cabezas,Oehlschlager
, p. 432 - 442 (1994)
The reactions of acetylenic ether 1 with higher order cuprates 2a, 2b and 2c were studied chemically and spectroscopically. Conditions were developed to efficiently and regioselectively prepare α- and β-stannylvinyl ethers. 1H and 13C NMR studies of these reactions suggest that in the presence of HMPA, higher order stannylcyanocuprate, (Bu3Sn)2Cu(CN)Li2, 2a, exists in equilibrium with Gilman cuprate, (Bu3Sn)2CuLi.
Highly selective and stable ZnO-supported bimetallic RuSn catalyst for the hydrogenation of octanoic acid to octanol
Hidajat, Marcel Jonathan,Hwang, Dong-Won,Yun, Gwang-Nam
, (2021)
The chemoselective hydrogenation of biomass-derived carboxylic acids is promising for the development of biorefineries. Herein, the selective conversion of octanoic acid to octanol over bimetallic RuSn/ZnO in a fixed-bed continuous reactor system, is reported. Almost complete conversion (99.4 %) of octanoic acid was achieved, with a remarkably high selectivity to octanol (93.0 %), when using specific reaction conditions (300°C, a weight hourly space velocity (WHSV) of 2 h?1, and 30 atm H2). Characterizations of the catalysts by BET, CO pulse chemisorption, ICP-AES, XRD, XPS and STEM-EDS revealed that the addition of Sn to Ru/ZnO resulted in the formation of a Ru3Sn7 alloy phase as well as SnOx. Comparison with Ru/ZnO catalyst gives an insight that the presence of Ru3Sn7 alloy was most likely the active site and it significantly improved the hydrogenation activity and selectivity to octanol. The SnOx and ZnO favored the formation of octyl octanoate by esterification of the formed octanol and octanoic acid, although it was successfully suppressed by optimizing the reaction conditions. Long-term stability tests revealed that RuSn/ZnO retained its activity for 1000 h with no coke formation. This study reveals the potential of RuSn/ZnO for the valorization of medium-chain fatty acids into value-added chemicals.
A facile zirconium(IV) chloride catalysed selective deprotection of t-butyldimethylsilyl (TBDMS) ethers
Sharma,Srinivas,Radha Krishna, Palakodety
, p. 4689 - 4691 (2003)
A simple and efficient protocol for the selective deprotection of t-butyldimethylsilyl (TBDMS) ethers using 20 mol% ZrCl4 in 20-45 min and in high yields, is reported, wherein it is demonstrated that acid and base sensitive groups and allylic and benzylic groups are unaffected.
Intrinsic isotope effects suggest that the reaction coordinate symmetry for the cytochrome P-450 catalyzed hydroxylation of octane is isozyme independent
Jones,Rettie,Trager
, p. 1242 - 1246 (1990)
The mechanism of the ω-hydroxylation of octane by three catalytically distinct, purified forms of cytochrome P-450, namely, P-450(b), P-450(c), and P-450(LM2), was investigated by using deuterium isotope effects. The deuterium isotope effects associated with the ω-hydroxylation of octane-1,1,1-2H3, octane-1,8-2H2, and octane-1,1,8,8-2H4 by all three isozymes were determined. From these data the intrinsic isotope effects were calculated and separated into their primary and secondary components. The primary intrinsic isotope effect for the reaction ranged from 7.69 to 9.18 while the secondary intrinsic isotope effect ranged from 1.13 to 1.25. Neither the primary nor secondary isotope effect values were statistically different for any of the isozymes investigated. These data are consistent with a symmetrical transition state for a mechanism involving initial hydrogen atom abstraction followed by hydroxyl radical recombination which is essentially independent of the specific isozyme catalyzing the reaction. It is concluded that (1) in general the porphyrin-[FeO]3+ complex behaves as a source of a triplet-like oxygen atom, (2) the regioselectivity for the site of oxidation is dictated by the apoprotein of the specific isozyme of cytochrome P-450 catalyzing the reaction, and (3) the maximum primary intrinsic isotope effect for any cytochrome P-450 catalyzed oxidation of a carbon center is about 9, assuming no tunneling effects.
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Gingras,Waters
, p. 3508,3511 (1954)
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2-pyridylsilyl group as a multifunctional 'phase tag' for solution phase synthesis
Yoshida, Jun-ichi,Itami, Kenichiro,Mitsudo, Koichi,Suga, Seiji
, p. 3403 - 3406 (1999)
2-Pyridyldimethylsilyl (2-PyMe2Si) group was found to serve as effective 'phase tag' for acid-base extraction for solution phase synthesis. Acid-base extraction of octyl(2-pyridyl)dimethylsilane gave rise to 98% recovery. The introduction of 2-PyMe2Si group to organic molecules was easily accomplished by Rh catalyzed hydrosilylation of alkenes with 2- PyMe2SiH. The removal of 2-PyMe2Si group was achieved by the oxidation with H2O2/KF (Tamao oxidation). In order to demonstrate the utility of 2- PyMe2Si group as a 'phase tag', a sequential multi-step transformation was conducted. The products of each steps were easily isolated by acid-base extraction, and were sufficiently pure for the direct use in the next step of the sequence.
Novel Cu and Cu2In/aluminosilicate type catalysts for the reduction of biomass-derived volatile fatty acids to alcohols
Harnos, Szabolcs,Onyestyak, Gyoergy,Barthos, Robert,Valyon, Jozsef,Stolcova, Magdalena,Kaszonyi, Alexander
, p. 1954 - 1962,9 (2012)
This work relates to the consecutive reduction of short chain carboxylic acids (volatile fatty acids, VFAs) to alcohols as main products. Acetic acid (AA) was used as a reactant to model the VFAs that can be produced by either thermochemical or biological biomass degradation. The amorphised zeolite supported copper catalysts (Cu/SiAl), especially the In-modified CuIn/SiAl catalysts, showed high hydroconversion activity and selectivity for alcohol, ester and aldehyde. Catalysts containing dispersed copper particles in amorphous aluminosilicate were obtained by dehydrating and H2-reducing Cu-forms of low-silica synthetic zeolites (A, X, P). The activity of the highly destructed Cu-aluminosilicates was found to depend on the structure of the zeolite precursor. The formation of ethyl acetate could be suppressed by adding water to the AA feed and by modifying the catalyst, e.g. by In2O 3 additive. In the catalysts modified by In2O3 additive formation of copper-indium alloy phase (Cu2In intermetallic compound) was detected resulting in a different selectivity than the one recorded for the Cu/SiAl.
Modulation of photodeprotection by the sunscreen protocol
Eivgi, Or,Levin, Efrat,Lemcoff, N. Gabriel
, p. 740 - 743 (2015)
A protocol for the selective photoremoval of alcohol protecting groups modulated by the presence of auxiliary light absorbing molecules is presented. Thus, by this method, a single light source was used to selectively remove a specific protecting group in the presence of another chromophore with a lower molar absorption coefficient. The use of a molecular sunscreen, either internal or external, was found to be crucial to achieve high selectivities.
Smith
, p. 25,39 (1974)
Pentaco-ordinate Silicon Compounds in Synthesis: Chemo- and Stereo-selective Reduction of Carbonyl Compounds using Trialkoxy-substituted Silanes and Alkali Metal Alkoxides
Hosomi, Akira,Hayashida, Hisashi,Kohra, Shinya,Tominaga, Yoshinori
, p. 1411 - 1412 (1986)
Carbonyl compounds are reduced with trialkoxy-substituted silane to the corresponding alcohols chemo- and stereo-selectively in the presence of alkali metal alkoxide under mild conditions; reduction occurs very smoothly by using an alkoxide derived from pinacol as a bidentate ligand.
Bacterial CYP153A monooxygenases for the synthesis of omega-hydroxylated fatty acids
Honda Malca, Sumire,Scheps, Daniel,Kuehnel, Lisa,Venegas-Venegas, Elena,Seifert, Alexander,Nestl, Bettina M.,Hauer, Bernhard
, p. 5115 - 5117 (2012)
CYP153A from Marinobacter aquaeolei has been identified as a fatty acid ω-hydroxylase with a broad substrate range. Two hotspots predicted to influence substrate specificity and selectivity were exchanged. Mutant G307A is 2- to 20-fold more active towards fatty acids than the wild-type. Residue L354 is determinant for the enzyme ω-regioselectivity.
Nickel catalyzed hydroboration with catecholborane
Kabalka,Narayana,Reddy
, p. 1019 - 1023 (1994)
Hydroborations of alkenes and alkyne with catecholborane were found to be catalyzed by activated nickel powder.
Deprotection of Acetals and Silyl Ethers Using Some ?-Acceptors
Tanemura, Kiyoshi,Suzuki, Tsuneo,Horaguchi, Takaaki
, p. 290 - 292 (1994)
Hydrolysis of dodecanol dimethyl acetal and dodecyl silyl ethers in MeCN-H2O was examined using a catalytic silyl amount of ?-acceptors such as 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), tetracyanoethylene (TCNE), 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF4), and chloranil (CA).Cleavage of dodecyl triethylsilyl ether with TCNQ and CA was caused by room light.By application of DDQ-catalyzed deprotection of acetals to hydrolysis of tetrahydropyranyl ethers, the corresponding alcohols were obtained in quantitative yields.
Effects of Organic Modifiers on a Palladium Catalyst in the Competitive Hydrogenation of 1-Octene Versus Octanal: An Evaluation of Solid Catalysts with an Ionic Liquid Layer
Miller, Stuart F.,Friedrich, Holger B.,Holzapfel, Cedric W.,Dasireddy, Venkata D. B. C.
, p. 2628 - 2636 (2015)
The competitive hydrogenation between 1-octene and octanal has been investigated with a ≈5% palladium on alumina catalyst prepared in situ with the following organic modifiers: pyridine, 1-methylimidazole, 1,3-dimethylimidazole methylsulfate, 1,3-dimethylimidazole bis(trifluoromethylsulfonyl)imide and methyltri-sec-butylphosphonium methylsulfate. The results of these investigations indicate that the ionic liquid modifiers have significant and specific effects on catalytic performance, for example, certain systems can completely suppress octanal conversion. In addition, analytical techniques reveal that the matrix and quantity of organic species on the used catalysts are different if different ionic liquids are used as modifiers. Surface studies also reveal that the modifiers have a noticeable effect on the crystallite size and chemisorption properties of the catalysts.
Highly active and selective platinum(0)-carbene complexes. Efficient, catalytic hydrosilylation of functionalised olefins
Marko, Istvan E.,Sterin, Sebastien,Buisine, Olivier,Berthon, Guillaume,Michaud, Guillaume,Tinant, Bernard,Declercq, Jean-Paul
, p. 1429 - 1434 (2004)
Readily available N-heterocyclic platinum-carbene complexes 1 are highly efficient catalysts for the regioselective hydrosilylation of alkenes. These novel organometallics tolerate a wide range of functional and protecting groups, can be stored for prolonged periods of time and are particularly active (TON > 106).
Improving the catalytic behavior of Ni/Al2O3 by indium in reduction of carboxylic acid to alcohol
Onyestyák, Gy?rgy,Harnos, Szabolcs,Kalló, Dénes
, p. 184 - 188 (2011)
Octanoic acid (OA) was used as reactant with medium chain length to model the aliphatic carboxylic acids which can be produced by catalytic, thermochemical or biological degradation of biomass. A flow through reactor was applied at 21 bar total pressure (in general 20 bar hydrogen and 1 bar octanoic acid partial pressures) and 240-360°C. Fatty acid conversion activity of alumina supported Ni catalysts and the yield of selectively produced alcohol can be increased drastically by In2O3 doping. Appearance of metallic indium can effectively direct the step by step catalytic reduction to alcohol formation over partly reduced Ni catalysts instead of chain shortening hydrodecarbonylation. On comparing a commercial, conventionally used Adkins catalyst (consisting of 72 wt.% CuCr2O4 and 28 wt.% CuO) and novel bimetallic alumina supported composite (InNi/Al2O 3) producing alcohol with high selectivity, the chromium-free, environmental benign hydrogenation catalyst seems to be much more active.
Alkyne [2 + 2 + 2] Cyclotrimerization Catalyzed by a Low-Valent Titanium Reagent Derived from CpTiX3 (X = Cl, O- i-Pr), Me3SiCl, and Mg or Zn
Okamoto, Sentaro,Yamada, Takeshi,Tanabe, Yu-Ki,Sakai, Masaki
, p. 4431 - 4438 (2018)
Inter-, partially intra-, and intramolecular [2 + 2 + 2] cycloadditions of alkynes were catalyzed by a low-valent titanium species generated in situ from the reduction of CpTi(O-i-Pr)3, CpTiCl3, or Cp?TiCl3 with Mg or Zn powder in the presence of Me3SiCl. The role of Me3SiCl as an additive in the reaction mechanism is discussed.
Amides as Nucleophiles: Reaction of Alkyl Halides with Amides or with Amides and Water. A New Look at an Old Reaction
Brace, Neal O.
, p. 1804 - 1811 (1993)
Heating of formamide with an alkyl halide (with or without water) affords a mild, nonhydrolytic, high-yield synthesis of alcohols and formate esters.Yet the way in which substitution on the alkyl halide actually occurs remains obscure.To explore this question, thermal reaction of 1-bromooctane (1a) with formamides (HC(O)NHR, R=H, Me; 2a, 2b) was studied quantitatively.Major products are 1-octanol (3) and n-octyl formate (5); minor products are 1-octene (4), di-n-octyl ether (6), and N-octylformamide (7, from 2a, only).Solid coproduct is HC(=NR)NHR + Br(1-) (e.g., 8a, R=H, methanimidamide hydrobromide).Analogously, 1a and N-methylformamide (2b) give alkylated products 3,5, and 6 along with 8b (R=Me). 1-Iodooctane (1b) reacts similarly.Probe samples show that 1-octanol (3) is first formed, followed by 5 and 6.Occurence of 8a-c is key to a mechanistic interpretation of the reaction.An imidate ("salt I"), e.g., from 1a and 2b, is first formed and reacts with amide 2b to give and 3.Now alcohol 3 is converted to ester 5 and 8b by reaction with this same formylamidine.Water, if present, adds to the imidate and gives a new tetrahedral intermediate that cleaves to ester 5 and amide salt, RNH3X.Analogous reaction steps are proposed to generate side products 4, 6, and 7.Alkylation of formamide by C6F13CH2CH2I (1c) is considerably slower and less efficient than alkylation by 1-bromooctane.This result stands in sharp contrast to fast, efficient reaction of 1c with N-methylformamide or with DMF and water.
Thexylchloroborane. A Versatile Reagent for the Preparation of Mixed Thexyldiorganoboranes
Zweifel, George,Pearson, Norman R.
, p. 5919 - 5920 (1980)
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Unveiling the dual role of the cholinium hexanoate ionic liquid as solvent and catalyst in suberin depolymerisation
Ferreira, Rui,Garcia, Helga,Sousa, Andreia F.,Guerreiro, Marina,Duarte, Filipe J. S.,Freire, Carmen S. R.,Calhorda, Maria Jose,Silvestre, Armando J. D.,Kunz, Werner,Rebelo, Luis Paulo N.,Silva Pereira, Cristina
, p. 2993 - 3002 (2014)
Disruption of the three-dimensional network of suberin in cork by cholinium hexanoate leads to its efficient and selective isolation. The reaction mechanism, which likely involves selective cleavage of some inter-monomeric bonds in suberin, was still unanswered. To address this question, the role of the ionic liquid during suberin depolymerisation and during cleavage of standard compounds carrying key chemical functionalities was herein investigated. A clear demonstration that the ionic liquid catalyses the hydrolysis of acylglycerol ester bonds was attained herein, both experimentally and computationally (DFT calculations). This behaviour is related to cholinium hexanoate capacity to activate the nucleophilic attack of water. The data showed also that the most favourable reaction is the hydrolysis of acylglycerol ester bonds, with the C2 position reporting the faster kinetics, whilst most of the linear aliphatic esters remained intact. The study emphasises that the ionic liquid plays the dual role of solvent and catalyst and leads to suberin efficient extraction through a mild depolymerisation. It is also one of the few reports of ionic liquids as efficient catalysts in the hydrolysis of esters.
MOF-derived Cu@C catalyst for the liquid-phase hydrogenation of esters
Zhao, Yujun,Wu, Xiaoqian,Zhou, Jiahua,Wang, Yue,Wang, Shengping,Ma, Xinbin
, p. 883 - 886 (2018)
MOF derived core-shell Cu@C was prepared by the pyrolysis of Cu-BTC and applied in the liquid-phase hydrogenation of ester. The severe aggregation of copper species was inhibited by the carbon shell. Compared with traditional Cu/AC-H2 catalyst, Cu@C-N2 displayed higher activity in the hydrogenation of butyl butyrate due to its higher Cu dispersion. Further reduction of Cu@C-N2 catalyst in H2 greatly improved the activity, as a result of the appropriate ratio of Cu+/Cu0, which can activate both ester and H2 molecules.
Electrocatalytic hydrogenation of octyl aldehyde over Pd catalysts
Cirtiu, Ciprian M.,Menard, Hugues
, p. 475 - 478 (2007)
The electrocatalytic hydrogenation (ECH) of octyl aldehyde (octanal) to octyl alcohol (octan-1-ol) was investigated using commercial Pd/alumina catalysts in aqueous ethanol. The influence of different parameters, such as catalyst support, current intensity, polarity of solvent, supporting electrolyte, and octanal concentration, on the electrocatalytic hydrogenation of octanal was studied.
A Remarkably Simple Class of Imidazolium-Based Lipids and Their Biological Properties
Wang, Da,Richter, Christian,Rühling, Andreas,Drücker, Patrick,Siegmund, Daniel,Metzler-Nolte, Nils,Glorius, Frank,Galla, Hans-Joachim
, p. 15123 - 15126 (2015)
A series of imidazolium salts bearing two alkyl chains in the backbone of the imidazolium core were synthesized, resembling the structure of lipids. Their antibacterial activity and cytotoxicity were evaluated using Gram-positive and Gram-negative bacteria and eukaryotic cell lines including tumor cells. It is shown that the length of alkyl chains in the backbone is vital for the antibiofilm activities of these lipid-mimicking components. In addition to their biological activity, their surface activity and their membrane interactions are shown by film balance and quartz crystal microbalance (QCM) measurements. The structure-activity relationship indicates that the distinctive chemical structure contributes considerably to the biological activities of this novel class of lipids. Lipids! A series of imidazolium salts bearing two alkyl chains in the backbone were synthesized, resembling the structure of lipids. The biological activity resulting from their surface activity and membrane interaction are shown (see figure), which were determined by the alkyl chain length.
Novel hydroborating agents from Silylamine-boranes
Soderquist, John A.,Medina, Jesus R.,Huertas, Ramon
, p. 6119 - 6122 (1998)
Exhibiting a broad spectrum of hydroboration reactivities, seven (7) new silylamine-borane complexes (1) were efficiently prepared from diborane and the corresponding silylated amines (2). Most are crystalline solids which are air-stable, concentrated borane sources. All provide convenient alternatives to other hydroborating agents, 2 undergoing complete hydrolysis to volatile and/or water soluble by-products upon aqueous work-up, thereby greatly facilitating the isolation of the borane-derived reaction products.
Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex
De Vries, Johannes G.,Gandini, Tommaso,Gennari, Cesare,Jiao, Haijun,Pignataro, Luca,Stadler, Bernhard M.,Tadiello, Laura,Tin, Sergey
, p. 235 - 246 (2022/01/03)
The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-To-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.
Radical Chain Reduction via Carbon Dioxide Radical Anion (CO2?-)
Hendy, Cecilia M.,Jui, Nathan T.,Lian, Tianquan,Smith, Gavin C.,Xu, Zihao
supporting information, p. 8987 - 8992 (2021/07/01)
We developed an effective method for reductive radical formation that utilizes the radical anion of carbon dioxide (CO2?-) as a powerful single electron reductant. Through a polarity matched hydrogen atom transfer (HAT) between an electrophilic radical and a formate salt, CO2?- formation occurs as a key element in a new radical chain reaction. Here, radical chain initiation can be performed through photochemical or thermal means, and we illustrate the ability of this approach to accomplish reductive activation of a range of substrate classes. Specifically, we employed this strategy in the intermolecular hydroarylation of unactivated alkenes with (hetero)aryl chlorides/bromides, radical deamination of arylammonium salts, aliphatic ketyl radical formation, and sulfonamide cleavage. We show that the reactivity of CO2?- with electron-poor olefins results in either single electron reduction or alkene hydrocarboxylation, where substrate reduction potentials can be utilized to predict reaction outcome.
