- CONTINUOUS PROCESS FOR THE PRODUCTION OF ALKANES
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Continuous reductive dehydroxymethylation process for the preparation of alkanes from primary aliphatic alcohols, having 3 to 25 carbon atoms, in the presence of hydrogen and a catalyst in a reactor at a pressure of ≥ 2 bar, characterized in that the dehydroxymethylation takes place in the vapor phase.
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Page/Page column 12-13
(2021/11/13)
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- Highly stable and selective catalytic deoxygenation of renewable bio-lipids over Ni/CeO2-Al2O3 for N-alkanes
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Ni-based catalysts are easy deactivated in bio-lipids deoxygenation due to metal aggregation and Ni leaching. They also suffer from the hydrocracking of C–C bonds due to strong acidity at high reaction temperature (≥ 300 ℃). Herein, a series of Ni/CeO2-Al2O3 catalysts with different Ce/Al ratio were prepared by one-pot sol-gel method. The characteristic results showed that an appropriate addition of Ce both increase the catalytic activity and stability in bio-lipids deoxygenation. The oxygen vacancies formed by Ce introduction weaken the strong interaction of Ni-Al, thus improving Ni sites dispersion. Additional, Ce-addition in NiCeAl system increases weak and medium acidity and decreases strong acidity, preventing the C–C bond cleavage of hydrocarbon. As the result, the Ni/CeAl-3.0 catalyst afforded a 97.1 % n-C17 yield at 99.9 % MO conversion under 2.5 MPa H2 at 300 ℃ for 6 h. Minor C15-16 alkanes (17 yield). After simple regeneration, n-C17 yield was recovered to 95 %. Furthermore, non-edible bio-lipids (JO and WCO) can be converted to C13-18 alkanes with 95.2 % and 93.8 % yields, respectively.
- Ba, Wenxia,Cui, Huamin,Fu, Lin,Li, Yongfei,Liu, Yuejin
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- Light-Driven Enzymatic Decarboxylation of Dicarboxylic Acids
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Photodecarboxylase from Chlorella variabillis (CvFAP) is one of the three known light-activated enzymes that catalyzes the decarboxylation of fatty acids into the corresponding C1-shortened alkanes. Although the substrate scope of CvFAP has been altered by protein engineering and decoy molecules, it is still limited to mono-fatty acids. Our studies demonstrate for the first time that long chain dicarboxylic acids can be converted by CvFAP. Notably, the conversion of dicarboxylic acids to alkanes still represents a chemically very challenging reaction. Herein, the light-driven enzymatic decarboxylation of dicarboxylic acids to the corresponding (C2-shortened) alkanes using CvFAP is described. A series of dicarboxylic acids is decarboxylated into alkanes in good yields by means of this approach, even for the preparative scales. Reaction pathway studies show that mono-fatty acids are formed as the intermediate products before the final release of C2-shortened alkanes. In addition, the thermostability, storage stability, and recyclability of CvFAP for decarboxylation of dicarboxylic acids are well evaluated. These results represent an advancement over the current state-of-the-art.
- Chen, Bi-Shuang,Liu, Lan,Zeng, Yong-Yi,Zhang, Wuyuan
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p. 553 - 559
(2021/06/25)
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- Production of Bio Hydrofined Diesel, Jet Fuel, and Carbon Monoxide from Fatty Acids Using a Silicon Nanowire Array-Supported Rhodium Nanoparticle Catalyst under Microwave Conditions
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Biodiesel was efficiently produced from biomass fatty acids using renewable gas H2 and a reusable heterogeneous catalyst under low-energy-consumption microwave conditions. As the decarboxylation of fatty acids to alkanes is an important transformation in the production of bio hydrofined diesel (BHD) and jet fuel, we herein report the development of a highly active and reusable Rh nanoparticle catalyst supported by a silicon nanowire array (SiNA-Rh) and its application in the decarboxylation of fatty acids to alkanes under mild conditions. More specifically, SiNA-Rh (500 mol ppm) selectively promoted the hydrogenative decarboxylation reaction at 200 °C under microwave irradiation (～40 W) in a H2 atmosphere (10 bar) to afford the corresponding alkanes in high yields selectively. The only coproduct observed was carbon monoxide, an important and essential staple for the chemical industry. Importantly, carbon dioxide formation was not observed. Moreover, the aldehydes were efficiently converted to alkanes by SiNA-Rh, and this catalyst was reused 20 times without any loss in catalytic activity. Finally, to investigate the effects of microwave irradiation on the enhancement of this chemical transformation based on the Si nanorod structures present in the SiNA-Rh catalyst, the effect of the microwave electric field and magnetic field in the microwave to the reaction was experimentally investigated, and the spatial distribution of the electric field intensity around the surface of the Si nanostructure was simulated using the finite element method.
- Baek, Heeyoel,Fujii, Takashi,Fujikawa, Shigenori,Kashimura, Keiichiro,Sato, Takuma,Tsubaki, Shuntaro,Uozumi, Yasuhiro,Wada, Yuji,Yamada, Yoichi M. A.
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p. 2148 - 2156
(2020/02/11)
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- An unconventional DCOx favored Co/N-C catalyst for efficient conversion of fatty acids and esters to liquid alkanes
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Cobalt (Co) catalysis has recently attracted significant attention in the field of biomass conversion. However, the fabrication of highly dispersive Co nanoparticles at high metal loading with selective facet exposure to achieve specific selectivity is still questionable. In this work, a nitrogen-doped carbon-supported Co catalyst is fabricated for efficient conversion of fatty acids and esters to liquid alkanes. Nitrogen-doping facilitates a highly uniform dispersion of Co nanoparticles even at a high Co loading of 10 wt% and after recycling for 5 runs. The Co/N-C catalyst affords an unconventional decarbonylation/decarboxylation (DCOx) dominant selectivity probably due to partial reduction of cobalt oxides to α-Co0 with only exposure of the (111) facet. Co-existence of Co and N-C leads to strong Lewis acidity and basicity, facilitating the interaction between catalyst and –COOH group, and some important acid-catalyzed step-reactions. The versatility of the Co/N-C catalyst is demonstrated through conversion of various fatty acids and esters.
- Li, Jiang,Liu, Jiaxing,Zhang, Junjie,Wan, Tong,Huang, Lei,Wang, Xintian,Pan, Runze,An, Zhidong,Vlachos, Dionisios G.
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- Photocatalytic degradation of benzothiophene by a novel photocatalyst, removal of decomposition fragments by MCM-41 sorbent
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In this study, a catalyst was synthesized by introduction of ZnO onto the surface of FSM-16 catalyst support (ZnO/FSM-16). Impregnation of catalyst support by ZnO proceeded through reacting of FSM-16 nanoparticles with Zn(CH3COO)2 solution followed by calcination of the product. The synthesized photocatalyst was then identified by different methods, and the optical property of the photocatalyst was studied by the DRS method. The results showed that after deposition of photocatalyst on FSM-16 support, the photocatalyst band gap was shifted to the visible region. The photoluminescence studies revealed lower recombination of electron–holes of the photocatalyst after immobilization on FSM-16. The influence of different variables on the photocatalytic performance of the samples was studied. Under optimized conditions, the high degradation efficiency of 97% was obtained by ZnO/FSM-16. The compounds produced from degradation of benzothiophene were recognized by the GC–MS method, and the products containing sulfur were properly adsorbed by MCM-41 sorbent. The photocatalyst showed high regeneration capability, and its activity was mostly preserved after six regeneration cycles.
- Hosseini, Asma,Faghihian, Hossein
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p. 2383 - 2401
(2019/01/29)
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- Iron-catalysed allylation-hydrogenation sequences as masked alkyl-alkyl cross-couplings
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An iron-catalysed allylation of organomagnesium reagents (alkyl, aryl) with simple allyl acetates proceeds under mild conditions (Fe(OAc)2 or Fe(acac)2, Et2O, r.t.) to furnish various alkene and styrene derivatives. Mechanistic studies indicate the operation of a homotopic catalyst. The sequential combination of such iron-catalysed allylation with an iron-catalysed hydrogenation results in overall C(sp3)-C(sp3)-bond formation that constitutes an attractive alternative to challenging direct cross-coupling protocols with alkyl halides.
- Bernauer, Josef,Wu, Guojiao,Von Wangelin, Axel
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p. 31217 - 31223
(2019/10/19)
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- Chemoselective Hydrodeoxygenation of Carboxylic Acids to Hydrocarbons over Nitrogen-Doped Carbon-Alumina Hybrid Supported Iron Catalysts
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The establishment of catalyst systems for the chemoselective hydrodeoxygenation (HDO) of carboxylic acids to hydrocarbons, such as the HDO of long-chain fatty acids to alkanes, is important for biomass to biofuel conversion. As the most abundant and probably the cheapest transition metal on the earth, iron is a promising non-noble-metal alternative to precious metals for large-scale conversion of biomass. However, it usually suffers from unsatisfactory activity. In this work, a nitrogen-doped carbon-alumina hybrid supported iron (Fe-N-C@Al2O3) catalyst is established for chemoselective HDO of carboxylic acids to hydrocarbons. By using stearic acid HDO as the model reaction, n-octadecane and n-heptadecane are produced with yields of 91.9% and 6.0%, respectively. Triglycerides can also be converted into liquid alkanes with a total molar yield of >92%. In addition, the iron catalyst can chemoselectively catalyze the HDO of the carboxylic acid group in the presence of other functional groups such as an aromatic ring. This chemoselectivity has rarely been seen before because the aromatic ring is usually more easily hydrogenated in comparison to HDO of the carboxylic acid group. The characterization results showed that both the formation of a nitrogen-doped carbon-alumina hybrid and the iron loading are important for the Lewis basicity of these catalysts, in order to adsorb the acid substrates. The addition of melamine as the nitrogen precursor during pyrolysis eliminates undesired reactions between the iron precursor and alumina support to form an inactive hercynite phase, leading to the formation of an Fe3C active phase for the hydrogenation of -COOH to -CH2OH and the hybrid of N-C and alumina for the HDO of -CH2OH to -CH3.
- Li, Jiang,Zhang, Junjie,Wang, Shuai,Xu, Guangyue,Wang, Hao,Vlachos, Dionisios G.
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p. 1564 - 1577
(2019/02/03)
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- Cross-coupling reaction of alkyl halides with alkyl grignard reagents catalyzed by cp-iron complexes in the presence of 1,3-butadiene
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Iron-catalyzed cross-coupling reaction of alkyl halides with alkyl Grignard reagents by the combined use of cyclopentadienyl ligand and 1,3-butadiene additive is described. The reaction smoothly proceeds at room temperature using unactivated alkyl bromides and fluorides via non-radical mechanism, which is in sharp contrast with hitherto known Fe-catalyzed cross-coupling reactions of alkyl halides.
- Iwasaki, Takanori,Shimizu, Ryohei,Imanishi, Reiko,Kuniyasu, Hitoshi,Kambe, Nobuaki
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supporting information
p. 763 - 766
(2018/05/29)
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- Light-Driven Enzymatic Decarboxylation of Fatty Acids
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The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their triglycerides are converted by CvFAP in near-quantitative yield and exclusive selectivity upon illumination with blue light. Very promising turnover numbers of up to 8000 were achieved in this proof-of-concept study.
- Huijbers, Mieke M. E.,Zhang, Wuyuan,Tonin, Fabio,Hollmann, Frank
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supporting information
p. 13648 - 13651
(2018/09/21)
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- Thiol-Catalyzed Radical Decyanation of Aliphatic Nitriles with Sodium Borohydride
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Radical decyanation of aliphatic nitriles was achieved in the presence of NaBH4 and a thiol. The reaction proceeds via a radical mechanism involving borane radical anion addition to nitrile to form an iminyl radical, which undergoes carbon-carbon cleavage. Reductive radical addition to acrylonitrile is followed by decyanation to give a two-carbon homologated product in a net radical ethylation reaction.
- Kawamoto, Takuji,Oritani, Kyohei,Curran, Dennis P.,Kamimura, Akio
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supporting information
p. 2084 - 2087
(2018/04/16)
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- Metathesis of renewable polyene feedstocks – Indirect evidences of the formation of catalytically active ruthenium allylidene species
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Cross-metathesis (CM) of conjugated polyenes, such as 1,6-diphenyl-1,3,5-hexatriene (1) and α-eleostearic acid methyl ester (2) with several olefins, including 1-hexene, dimethyl maleate and cis-stilbene as model compounds has been carried out using (1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)-dichloro(o-isopropoxyphenylmethylene)ruthenium (Hoveyda-Grubbs 2nd generation, HG2) catalyst. The feasibility of these reactions is demonstrated by the observed high conversions and reasonable yields. Thus, regardless of the relatively low electron density, =CH–CH= conjugated units of molecules, including compound 2 as a sustainable, non-foodstuff source, can be utilized as building blocks for the synthesis of various value-added chemicals via olefin metathesis. DFT-studies and the product spectrum of the self-metathesis of 1,6-diphenyl-1,3,5-hexatriene suggest that a Ru η1-allylidene complex is the active species in the reaction.
- Kovács, Ervin,Sághy, Péter,Turczel, Gábor,Tóth, Imre,Lendvay, Gy?rgy,Domján, Attila,Anastas, Paul T.,Tuba, Róbert
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supporting information
p. 213 - 217
(2017/09/12)
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- Insight into forced hydrogen re-arrangement and altered reaction pathways in a protocol for CO2 catalytic processing of oleic acid into C8-C15 alkanes
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A new vision of using carbon dioxide (CO2) catalytic processing of oleic acid into C8-C15 alkanes over a nano-nickel/zeolite catalyst is reported in this paper. The inherent and essential reasons which make this achievable are clearly resolved by using totally new catalytic reaction pathways of oleic acid transformation in a CO2 atmosphere. The yield of C8-C15 ingredients reaches 73.10 mol% in a CO2 atmosphere, which is much higher than the 49.67 mol% yield obtained in a hydrogen (H2) atmosphere. In the absence of an external H2 source, products which are similar to aviation fuel are generated where aromatization of propene (C3H6) oxidative dehydrogenation (ODH) involving CO2 and propane (C3H8) and hydrogen transfer reactions are found to account for hydrogen liberation in oleic acid and achieve its re-arrangement in the final alkane products. The reaction pathway in the CO2 atmosphere is significantly different from that in the H2 atmosphere, as shown by the presence of 8-heptadecene, γ-stearolactone, and 3-heptadecene as reaction intermediates, as well as a CO formation pathway. Because of the highly dispersed Ni metal center on the zeolite support, H2 spillover is observed in the H2 atmosphere, which inhibits the production of short-chain alkanes and reveals the inherent disadvantage of using H2. The CO2 processing of oleic acid described in this paper will significantly contribute to future CO2 utilization chemistry and provide an economical and promising approach for the production of sustainable alkane products which are similar to aviation fuel.
- Xing, Shiyou,Lv, Pengmei,Yuan, Haoran,Yang, Lingmei,Wang, Zhongming,Yuan, Zhenhong,Chen, Yong
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supporting information
p. 4157 - 4168
(2017/09/07)
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- Cerium oxide as a catalyst for the ketonization of aldehydes: Mechanistic insights and a convenient way to alkanes without the consumption of external hydrogen
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The ketonization of aldehydes joins two molecules, with n carbon atoms each, to a ketone with 2n - 1 carbon atoms. When employing cerium oxide as a catalyst with nano-sized crystals (15 nm) the ketone can be obtained in almost 80% yield. In addition, other ketones are observed so that the total ketone selectivity reached almost 90%. Water is consumed during the reaction when the aldehyde is oxidized to the corresponding carboxylic acid, which is established as a reaction intermediate, co-producing hydrogen. Consequently, water has to be co-fed in the reaction to enhance the reaction rate and to improve the catalyst stability with time on stream. In contrast to zirconium oxide which possesses catalytic activity for the aldol condensation liberating water, with cerium oxide water is not abundant on the surface and the reaction kinetics show that the reaction rate depends on the concentration of the water in the gas-phase, in addition to the dependence on the gas-phase concentration of the aldehyde. The liberated hydrogen can be consumed in the hydrodeoxygenation of the ketone product. Doing so, when starting from heptanal, a biomass derived aldehyde, an alkane mixture was obtained with almost 90% diesel content. For the whole cascade reaction with five single steps no reagents are necessary and the only by-product is one molecule of innocuous carbon dioxide (related to two molecules of aldehyde). This shows that cerium oxide possesses a big potential to convert biomass derived aldehydes into biofuels in a very sustainable way.
- Orozco, Lina M.,Renz, Michael,Corma, Avelino
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supporting information
p. 1555 - 1569
(2017/05/10)
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- Fischer–Tropsch synthesis with cobalt catalyst and zeolite multibed arrangement
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The role of zeolite in transformations of hydrocarbons produced from CO and H2 over a Fischer–Tropsch cobalt catalyst under the conditions of multibed arrangement of the cobalt catalyst and the zeolite has been determined. Hydrocarbon conversion over the HBeta zeolite occurs via the bimolecular mechanism, as evidenced by a low methane yield and a high yield of unsaturated gaseous and liquid hydrocarbons. The conversion over the CaA zeolite obeys the unimolecular mechanism, as evidenced by the formation of increased amounts of methane and saturated gaseous C2–C4 hydrocarbons.
- Asalieva, E. Yu.,Kul’chakovskaya,Sineva,Mordkovich,Bulychev
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p. 275 - 280
(2016/06/09)
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- Hydrodeoxygenation of furfural-acetone condensation adducts to tridecane over platinum catalysts
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The total hydrodeoxygenation of furfural-acetone condensation adduct (F2A) for obtaining tridecane is studied in this work. Three different Pt catalysts (using alumina, activated carbon, and graphite-MgZr oxide composite as supports) were tested using acetone as solvent (4.5 mmol/L of adduct) in a stirred batch reactor at 493 K and 5.5 MPa. Best results were obtained with Pt/Al2O3, yielding 21.5% of n-tridecane after 24 h reaction time, with carbon balances close to 96%. The performance of the carbon supported catalysts was poorer (both in terms of conversion, tridecane selectivity and carbon mass balance closure) mainly because of the strong adsorption of reactants and reaction intermediates, whereas the MgZr-HSAG also present activity for the undesired cleavage of C-C bonds of the condensation adducts. A kinetic model, considering serial-parallel reaction steps and first order dependence on the organic reactant has been successfully applied for modelling the results obtained with the three catalysts. The dependence of the kinetic constants on the catalyst properties suggest that metal dispersion and the concentration of weak acid sites are the main parameters affecting catalyst performance.
- Faba, Laura,Díaz, Eva,Vega, Aurelio,Ordó?ez, Salvador
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p. 132 - 139
(2016/05/11)
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- Catalytic Production of Branched Small Alkanes from Biohydrocarbons
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Squalane, C30 algae-derived branched hydrocarbon, was successfully converted to smaller hydrocarbons without skeletal isomerization and aromatization over ruthenium on ceria (Ru/CeO2). The internal CH2-CH2 bonds located between branches are preferably dissociated to give branched alkanes with very simple distribution as compared with conventional methods using metal-acid bifunctional catalysts.
- Oya, Shin-Ichi,Kanno, Daisuke,Watanabe, Hideo,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
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p. 2472 - 2475
(2015/08/24)
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- Stabilization of long-chain intermediates in solution. Tridecyl radicals and cations
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Tetradecanoic acid was decarboxylated by means of lead(IV) acetate (LTA) under thermal (81 °C) and photolytic (r.t.) conditions in benzene solution. The mixture of products, obtained in thermal reaction, consists of esters (acetoxyalkanes and carboxylates
- Teodorovi?, Aleksandar V.,Badjuk, Dalibor M.,Stevanovi?, Nenad,Pavlovi?, Radoslav Z.
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p. 357 - 363
(2015/01/30)
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- Selective Catalytic Hydrogenolysis of Carbon-Carbon σ Bonds in Primary Aliphatic Alcohols over Supported Metals
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The selective scission of chemical bonds is always of great significance in organic chemistry. The cleavage of strong carbon-carbon σ bonds in the unstrained systems remains challenging. Here, we report the selective hydrogenolysis of carbon-carbon σ bonds in primary aliphatic alcohols catalyzed by supported metals under relatively mild conditions. In the case of 1-hexadecanol hydrogenolysis over Ru/TiO2 as a model reaction system, the selective scission of carbon-carbon bonds over carbon-oxygen bonds is observed, resulting in n-pentadecane as the dominant product with a small quantity of n-hexadecane. Theoretical calculations reveal that the 1-hexadecanol hydrogenolysis on flat Ru (0001) undergoes two parallel pathways: i.e. carbon-carbon bond scission to produce n-pentadecane and carbon-oxygen bond scission to produce n-hexadecane. The removal of adsorbed CO on a flat Ru (0001) surface is a crucial step for the 1-hexadecanol hydrogenolysis. It contributes to the largest energy barrier in n-pentadecane production and also retards the rate for n-hexadecane production by covering the active Ru (0001) surface. The knowledge presented in this work has significance not just for a fundamental understanding of strong carbon-carbon σ bond scission but also for practical biomass conversion to fuels and chemical feedstocks.
- Di, Lu,Yao, Sikai,Li, Mengru,Wu, Guangjun,Dai, Weili,Wang, Guichang,Li, Landong,Guan, Naijia
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p. 7199 - 7207
(2015/12/11)
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- Copper-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Alkyl Fluorides and Grignard Reagents
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Copper complexes generated in situ from CuCl2, alkyl Grignard reagents, and 1,3-dienes play important roles as catalytic active species for the 1,2-hydroalkylation of 1,3-dienes by alkyl fluorides through C-F bond cleavage. The alkyl group is introduced to an internal carbon atom of the 1,3-diene regioselectively, thus giving rise to the branched terminal alkene product. Making the switch: A copper-hydride species, generated by the treatment of a copper salt with alkyl Grignard reagents, catalyzes the 1,2-hydroalkylation of 1,3-dienes by alkyl fluorides and Grignard reagents. The alkyl group of the alkyl fluoride is selectively introduced to an internal carbon atom of the 1,3-diene and the Grignard reagent acts as hydride source to give the branched terminal alkene, even in the presence of alkenes and alkynes.
- Iwasaki, Takanori,Shimizu, Ryohei,Imanishi, Reiko,Kuniyasu, Hitoshi,Kambe, Nobuaki
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supporting information
p. 9347 - 9350
(2015/08/06)
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- Copper-catalyzed alkyl-alkyl cross-coupling reactions using hydrocarbon additives: Efficiency of catalyst and roles of additives
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Cross-coupling of alkyl halides with alkyl Grignard reagents proceeds with extremely high TONs of up to 1230000 using a Cu/unsaturated hydrocarbon catalytic system. Alkyl fluorides, chlorides, bromides, and tosylates are all suitable electrophiles, and a TOF as high as 31200 h-1 was attained using an alkyl iodide. Side reactions of this catalytic system, i.e., reduction, dehydrohalogenation (elimination), and the homocoupling of alkyl halides, occur in the absence of additives. It appears that the reaction involves the β-hydrogen elimination of alkylcopper intermediates, giving rise to olefins and Cu-H species, and that this process triggers both side reactions and the degradation of the Cu catalyst. The formed Cu-H promotes the reduction of alkyl halides to give alkanes and Cu-X or the generation of Cu(0), probably by disproportionation, which can oxidatively add to alkyl halides to yield olefins and, in some cases, homocoupling products. Unsaturated hydrocarbon additives such as 1,3-butadiene and phenylpropyne play important roles in achieving highly efficient cross-coupling by suppressing β-hydrogen elimination, which inhibits both the degradation of the Cu catalyst and undesirable side reactions.
- Iwasaki, Takanori,Imanishi, Reiko,Shimizu, Ryohei,Kuniyasu, Hitoshi,Terao, Jun,Kambe, Nobuaki
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p. 8522 - 8532
(2015/01/08)
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- Effect of ligand modification on the reactivity of phosphinoamide-bridged heterobimetallic Zr/Co complexes
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The effect of modifying the N-aryl substituent (aryl = mesityl vs. m-xylyl) of the phosphinoamide ligands linking Zr and Co in tris(phosphinoamide)-linked heterobimetallic complexes has been investigated. Treatment of the metalloligand (iPr2PNXyl)3ZrCl (2) (Xyl = m-xylyl) with CoI2 affords the iodide-bridged product ICo(iPr 2PNXyl)2(μ-I)Zr(η2-iPr2PNXyl) (3) rather than the C3-symmetric isomer observed using the N-mesityl derivative, ICo(iPr2PNMes)3ZrCl. Upon two-electron reduction of complex 3, ligand rearrangement occurs to generate the three-fold symmetric reduced complex N2Co(iPr 2PNXyl)3Zr(THF) (4). Comparison of 4 with the previously reported mesityl-substituted complex N2Co(iPr 2PNMes)3Zr(THF) (1) reveals similar structural features but with a less sterically hindered Zr apical site in complex 4. An obvious electronic difference between these two complexes is also present based on the drastically different infrared N2 stretching frequencies of 1 and 4. These notable differences lend themselves to different reactivity in both stoichiometric and catalytic reactions. Alkyl halide addition to complex 4 results in homo-coupling products resulting from alkyl radicals rather than the alkyl-bridged or intramolecular C-H activation products formed upon addition of RX to 1. This difference in reactivity with alkyl halides renders complex 3 a less effective catalyst for the Kumada cross-coupling of alkyl halides with n-octylMgBr than ICo(iPr2PNMes)3ZrCl, as a greater proportion of homocoupling products are formed under catalytic conditions.
- Zhou, Wen,Saper, Noam I.,Krogman, Jeremy P.,Foxman, Bruce M.,Thomas, Christine M.
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p. 1984 - 1989
(2014/01/17)
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- Decarboxylation and further transformation of oleic acid over bifunctional, Pt/SAPO-11 catalyst and Pt/chloride Al2O3 catalysts
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Catalytic decarboxylation and further conversion of oleic acid to branched and aromatic hydrocarbons in a single process step, over Pt-SAPO-11 and Pt/chloride Al2O3 is presented. An increase of both reaction time and temperature increase the selectivity to heptadecane. Higher selectivity to heptadecane was observed in the presence of hydrogen. Decarboxylation of oleic acid was as high as ～98 wt% (selectivity for heptadecane >30%) at 325 C in the presence of hydrogen. Branched isomers, alkyl aromatics, like dodecyl benzene and cracked (17) paraffins were the other products.
- Ahmadi, Masoudeh,Macias, Eugenia E.,Jasinski, Jacek B.,Ratnasamy, Paul,Carreon, Moises A.
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- Carbon-carbon cross-coupling reactions catalyzed by a two-coordinate nickel(II)-Bis(amido) complex via observable NiI, NiII, and NiIII intermediates
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Recently, the development of more sustainable catalytic systems based on abundant first-row metals, especially nickel, for cross-coupling reactions has attracted significant interest. One of the key intermediates invoked in these reactions is a NiIII-alkyl species, but no such species that is part of a competent catalytic cycle has yet been isolated. Herein, we report a carbon-carbon cross-coupling system based on a two-coordinate Ni II-bis(amido) complex in which a NiIII-alkyl species can be isolated and fully characterized. This study details compelling experimental evidence of the role played by this NiIII-alkyl species as well as those of other key NiI and NiII intermediates. The catalytic cycle described herein is also one of the first examples of a two-coordinate complex that competently catalyzes an organic transformation, potentially leading to a new class of catalysts based on the unique ability of first-row transition metals to accommodate two-coordinate complexes.
- Lipschutz, Michael I.,Tilley, T. Don
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supporting information
p. 7290 - 7294
(2014/07/21)
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- Tandem isomerization/hydroformylation/hydrogenation of internal alkenes to n-alcohols using Rh/Ru dual-or ternary-catalyst systems
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A one-pot three-step reaction, isomerization/hydroformylation/hydrogenation of internal alkenes to n-alcohols, was accomplished by employing a Rh/Ru dual-catalyst system. By using a combination of Rh(acac)(CO)2/ bisphosphite and Shvo's catalyst, (Z)-2-tridecene was converted to 1-tetradecanol in 83% yield with high normal/iso selectivity (n/i = 12). The method was applicable to other internal alkenes, including functionalized alkenes, such as an alkenol and an alkenoate. Furthermore, addition of a third component, Ru3(CO)12, effectively improved the n/i ratio in the tandem isomerization/hydroformylation/hydrogenation of methyl oleate (from n/i = 1.9 to 4.4). Control experiments revealed that the isomerization was mediated by both Rh and Ru and that the coexistence of Rh and Ru was essential for hydrogenation of aldehyde under H2/CO.
- Yuki, Yamato,Takahashi, Kohei,Tanaka, Yoshiyuki,Nozaki, Kyoko
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p. 17393 - 17400
(2014/01/06)
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- Improvement on the catalytic performance of Mg-Zr mixed oxides for furfural-acetone aldol condensation by supporting on mesoporous carbons
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A new procedure for improving the performance of the most common catalysts used in aqueous-phase aldol condensation (Mg-Zr mixed oxides) reactions is presented. This reaction is of interest for upgrading carbohydrate feedstocks. The procedure involves supporting Mg-Zr oxides on non-microporous carbonaceous materials, such as carbon nanofibers (CNFs) or high-surface-area graphites (HSAGs), using either incipient wetness or coprecipitation procedures. The use of HSAGs together with the coprecipitation method provides the best performance. Results obtained for the cross-condensation of acetone and furfural at 323K reveal that the catalyst performance is greatly improved compared to the bulk oxides (96.5 % conversion vs. 81.4 % with the bulk oxide; 87.8 % selectivity for C13 and C8 adducts vs. 76.2 % with the bulk oxide). This difference is even more prominent in terms of rates per catalytically active basic site (four and seven times greater for C8 and C13 adducts, respectively). The improved performance is explained in terms of a more appropriate basic site distribution and by greater interaction of the reactants with the carbon surface. In addition, deactivation behavior of the catalyst is improved by tuning the morphology of the carbonaceous support. An important enhancement of the catalytic stability can be obtained selecting a HSAG with an appropriate pore diameter. With HSAG100 the activity decreased by less than 20 % between successive reaction cycles and the selectivity for the condensation products remained almost unaltered. The decrease is greater than 80 % for the bulk oxides tested at these conditions, with important increases in the selectivity for by-product formation. Copyright
- Faba, Laura,Diaz, Eva,Ordonez, Salvador
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p. 463 - 473
(2013/05/09)
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- Stabilization of long-chain intermediates in solution. octyl radicals and cations
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The rearrangements of 1-octyl, 1-decyl and 1-tridecyl intermediates obtained from thermal lead(IV) acetate (LTA) decarboxylation of nonanoic, undecanoic and tetradecanoic acid were investigated experimentally through analysis and distribution of the products. The relationships between 1,5-, 1,6- and possibly existing 1,7-homolytic hydrogen transfer in 1-octyl-radical, as well as successive 1,2-hydride shift in corresponding cation have been computed via Monte-Carlo method. Taking into account that ratios of 1,5-/1,6-homolytic rearrangements in 1-octyl- and 1-tridecyl radical are approximately the same, the simulation shows very low involvement of 1,7-hydrogen rearrangement (1,5-/1,6-/1,7-hydrogen rearrangement = 85:31:1) in 1-octyl radical.
- Teodorovi?, Aleksandar V.,Badjuk, Dalibor M.,Stevanovi?, Nenad,Pavlovi?, Radoslav Z.
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- Cross coupling reactions of multiple CCl bonds of polychlorinated solvents with Grignard reagent using a pincer nickel complex
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The nickel(II) complex of a bulky pincer-type ligand, N,N′-bis(2,6- diisopropylphenyl)-2,6-pyridinedicarboxamido, was examined for sp 3-sp3 coupling of Grignard reagents with polychlorinated solvents. The nickel(II) complex catalyzed CC coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents. The effective activation of multiple CCl bonds proceeded under ambient reaction conditions and within a short time (20 min). This catalyst displays the highest activity yet reported for this reaction type, with catalyst loading as low as 0.4 mol% and turnover frequency (TOF) as high as 724 h-1. The catalyst is capable of replacing all chlorine atoms with CC bond formations for all of the polychlorinated solvents under investigation. The catalytic process could prove to be an efficient method of remediation of toxic polychlorinated solvents while generating synthetically and commercially important chemicals.
- Gartia, Yashraj,Nasini, Udaya Bhasker,Ghosh, Anindya,Biswas, Abhijit,Stadler, Matthew
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p. 322 - 327,6
(2020/07/30)
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- A novel iron complex for cross-coupling reactions of multiple C-Cl bonds in polychlorinated solvents with grignard reagents
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A novel iron(III) complex (2) of a pincer ligand [1, N2,N6-bis(2,6- diisopropylphenyl)pyridine-2,6-dicarboxamide] was developed and used for remediation of polychlorinated solvents via sp3-sp3 coupling of Grignard reagents with C-Cl bonds. The use of an iron catalyst for such coupling reactions is highly desirable due to its greener and more economical nature. Complex 2 was characterized using various spectroscopic techniques: electrospray ionization mass spectrometer (ESI-MS, m/z 575.1), cyclic voltammetry (E 1/2, 0.03 V and ΔE, 0.97 V), and ultraviolet visible (UV/Vis) spectroscopic techniques. The iron(III) complex showed efficient activation of multiple C-Cl bonds and catalyzing C-C coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents under ambient reaction conditions. Complex 2 showed exceptional activity with reactions approaching near completion in about 5 min. With the required catalyst loading as low as 0.2 mol%, considerably high turnover numbers (TON = 483) and turnover frequency (TOF = 5,800 h-1) were obtained. None of the products detected during the reaction contained any chlorine, indicating an efficient dechlorination method while synthesizing products of synthetic and commercial interest. Interestingly, the catalyst was capable of replacing all chlorine atoms in each polychlorinated solvent under the investigations with high conversion. Springer Science+Business Media, LLC 2012.
- Gartia, Yashraj,Pulla, Sharon,Ramidi, Punnamchandar,Farris, Carolina Costa,Nima, Zeid,Jones, Darin E.,Biris, Alexandru S.,Ghosh, Anindya
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p. 1397 - 1404
(2013/01/15)
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- Synthesis, reactivity, and catalytic application of a nickel pincer hydride complex
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The nickel(II) hydride complex [(MeN2N)Ni-H] (2) was synthesized by the reaction of [(MeN2N)Ni-OMe] (6) with Ph2SiH2 and was characterized by NMR and IR spectroscopy as well as X-ray crystallography. 2 was unstable in solution, and it decomposed via two reaction pathways. The first pathway was intramolecular N-H reductive elimination to give MeN2NH and nickel particles. The second pathway was intermolecular, with H2, nickel particles, and a five-coordinate Ni(II) complex [(MeN2N)2Ni] (8) as the products. 2 reacted with acetone and ethylene, forming [( MeN2N)Ni-OiPr] (9) and [(MeN 2N)Ni-Et] (10), respectively. 2 also reacted with alkyl halides, yielding nickel halide complexes and alkanes. The reduction of alkyl halides was rendered catalytically, using [(MeN2N)Ni-Cl] (1) as catalyst, NaOiPr or NaOMe as base, and Ph2SiH2 or Me(EtO)2SiH as the hydride source. The catalysis appears to operate via a radical mechanism.
- Breitenfeld, Jan,Scopelliti, Rosario,Hu, Xile
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experimental part
p. 2128 - 2136
(2012/06/01)
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- Kinetic studies of the ni-catalyzed cross-coupling of alkyl halides and a tosylate with butyl grignard reagent in the presence of 1,3-butadiene
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Kinetic studies of the nickel-catalyzed cross-coupling reaction of alkyl bromides, iodides, and tosylates with butyl Grignard reagents in the presence of butadiene were performed. The reaction rate was first order with respect to the halides and the nickel catalyst. The butyl Grignard reagent, at concentrations of ca. 0.4M or higher, had little effect on the reaction rate. The relative reactivities and activation parameters were determined for these alkyl halides and a tosylate.
- Iwasaki, Takanori,Tsumura, Asako,Omori, Takehiro,Kuniyasu, Hitoshi,Terao, Jun,Kambe, Nobuaki
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body text
p. 1024 - 1026
(2011/12/05)
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- Cross-coupling of Grignard reagents with alkyl halides or tosylates by the use of nickel or palladium containing perovskite
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Nickel and palladium-containing perovskites, LaFe0.8Ni 0.2O3 (LFNO) and LaFe0.95Pd 0.05O3 (LFPO), could be employed as effective catalyst sources for the cross-coupling of nonactivated alkyl halides and tosylates with Grignard reagents in the presence of conjugated dienes. The reaction proceeded efficiently at room temperature or below using only ca. 1 mol % of catalysts with respect to Ni or Pd and the perovskites were reused without considerable loss of activity.
- Singh, Surya Prakash,Iwasaki, Takanori,Terao, Jun,Kambe, Nobuaki
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experimental part
p. 774 - 776
(2011/03/21)
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- A catalytic application of Co/Zr heterobimetallic complexes: Kumada coupling of unactivated alkyl halides with alkyl grignard reagents
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Tris(phosphanylamide) early/late heterobimetallic Zr/Co complexes, ClZr(R′NPR2)3CoI [R′ = iPr, R = Ph (1), R′ = 2,4,6-trimethylphenyl, R = iPr (2), R′ = R = iPr (3)], have been utilized as catalysts for the cross-coupling of alkyl halides with n-octylmagnesium bromide. While yields are consistently higher for alkyl bromide substrates, it is found that these unusual heterobimetallic complexes are also active towards more challenging alkyl chloride substrates. This is particularly interesting in light of the fact that monometallic cobalt complexes are inert towards these substrates, suggesting that Zr also plays a role in catalysis. Radical trapping studies suggest that a one-electron transfer radical oxidative addition pathway is operative.
- Zhou, Wen,Napoline, Jonathan Wesley,Thomas, Christine M.
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scheme or table
p. 2029 - 2033
(2011/06/25)
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- Radical-mediated intramolecular C-C bond formation and the deoxygenation of alcohols under solvent-free conditions with tributyl methyl ammonium hypophosphite
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A green, solvent-free protocol was developed for the radical-mediated intramolecular cyclization of haloacetals and the deoxygenation of S-methyl dithiocarbonates and cyclic thionocarbonate. This process uses tributyl methyl ammonium hypophosphite as a H-donor in the presence of triethylborane or t-butyl peroxide. This methodology provides eco-friendly reaction conditions.
- Lee, Eun Hwa,Cho, Dae Hyan,Satyender, Apuri,Jang, Doo Ok
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experimental part
p. 6927 - 6929
(2012/02/05)
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- Efficient heterogeneous dual catalyst systems for alkane metathesis
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A fully heterogeneous and highly efficient dual catalyst system for alkane metathesis (AM) has been developed. The system is comprised of an alumina-supported iridium pincer catalyst for alkane dehydrogenation/olefin hydrogenation and a second heterogeneous olefin metathesis catalyst. The iridium catalysts bear basic functional groups on the aromatic backbone of the pincer ligand and are strongly adsorbed on Lewis acid sites on alumina. The heterogeneous systems exhibit higher lifetimes and productivities relative to the corresponding homogeneous systems as catalyst/catalyst interactions and bimolecular decomposition reactions are inhibited. Additionally, using a two-pot device, the supported Ir catalysts and metathesis catalysts can be physically separated and run at different temperatures. This system with isolated catalysts shows very high turnover numbers and is selective for the formation of high molecular weight alkanes.
- Huang, Zheng,Rolfe, Eleanor,Carson, Emily C.,Brookhart, Maurice,Goldman, Alan S,El-Khalafy, Sahar H.,Roy MacArthur, Amy H.
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experimental part
p. 125 - 135
(2010/06/20)
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- Hydrocarbon production from decarboxylation of fatty acid without hydrogen
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Decarboxylation of oleic acid without hydrogen was carried out using hydrotalcites with three different MgO contents (30, 63 and 70 wt%). Effect of MgO content in hydrotalcites and reaction temperatures on the decarboxylation performance in terms of oleic
- Na, Jeong-Geol,Yi, Bo Eun,Kim, Ju Nam,Yi, Kwang Bok,Park, Sung-Youl,Park, Jong-Ho,Kim, Jong-Nam,Ko, Chang Hyun
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experimental part
p. 44 - 48
(2010/12/25)
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- Cobalt-catalyzed cross-coupling reaction between functionalized primary and secondary alkyl halides and aliphatic Grignard reagents
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The coupling of primary and secondary unactivated alkyl bromides with alkyl-Grignard reagents was performed in good yields under mild conditions by using a new catalytic system: consisting of cobalt chloride and tetramethylethylenediamine (CoCl2·2 LiI, 4TMEDA). The reaction is very chemoselective since ketone, ester and nitrile functions are tolerated.
- Cahiez, Gerard,Chaboche, Christophe,Duplais, Christophe,Giulliani, Arianna,Moyeux, Alban
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scheme or table
p. 1484 - 1488
(2009/07/01)
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- Cu-catalyzed regioselective carbomagnesiation of dienes and enynes with sec- and tert-alkyl Grignard reagents
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The carbomagnesiation of dienes and enynes with sec- and tert-alkyl Grignard reagents has been achieved by using copper salts as catalysts. The Royal Society of Chemistry.
- Todo, Hirohisa,Terao, Jun,Watanabe, Hideyuki,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 1332 - 1334
(2008/12/21)
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- CATALYTIC PROCESS FOR CONVERTING RENEWABLE RESOURCES INTO PARAFFINS FOR USE AS DIESEL BLENDING STOCKS
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A process for converting renewable resources such as vegetable oil and animal fat into paraffins in a single step which comprises contacting a feed which is a renewable resources with hydrogen and a catalyst which comprises molybdenum, a non-precious metal and an oxide to produce a hydrocarbon product having a ratio of even-numbered hydrocarbons to odd-numbered hydrocarbons of at least 2:1.
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Page/Page column 8
(2009/01/24)
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- Method for Producing Hydrocarbons
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A process is provided for the production of linear saturated alkanes from one or more primary alcohols, wherein the carbon chain of the one or more primary alcohols has one carbon atom more than the alkane, including conducting reductive dehydroxymethylation of one or more primary fatty alcohols containing 8 to 24 carbon atoms, at a temperature ranging from 100 to 300° C. and pressures from 1 to 250 bar in the presence of hydrogen and a catalyst, and removing water formed during the reaction.
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Page/Page column 2-3
(2008/12/04)
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- Process for hydrogenation of carboxylic acids and derivatives to hydrocarbons
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A process for hydrogenating a carboxylic acid and/or derivative thereof having a carboxylate group represented by the general formula R1COO-, which process comprises feeding hydrogen and the carboxylic acid and/or derivative thereof to a reactor and maintaining conditions within the reactor such that hydrogen reacts with the carboxylic acid and/or derivative thereof to produce a product stream comprising carbon dioxide, carbon monoxide, methane and hydrocarbons represented by general formulae R1H and R1CH3, characterised in that the molar ratio of R1H : R1CH3 is above a pre-determined value and/or the mole ratio of the sum of carbon dioxide, carbon monoxide and methane to carboxylate groups is above a pre-determined value.
- -
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Page/Page column 7-8
(2008/06/13)
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- Copper-catalyzed cross-coupling reaction of Grignard reagents with primary-alkyl halides: Remarkable effect of 1-phenylpropyne
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(Chemical Equation Presented) A general get-together: The Cu-catalyzed cross-coupling reaction of primary-alkyl halides with primary-, secondary-, and tertiary-alkyl and phenyl Grignard reagents proceeds efficiently in THF under reflux in the presence of 1-phenylpropyne (see scheme). The reaction is also applicable to alkyl mesylates (OMs) and tosylates (OTs). The reactivities of alkyl-X with a Grignard reagent increase in the order X = Cl F OMs OTs Br.
- Terao, Jun,Todo, Hirohisa,Begum, Shameem Ara,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 2086 - 2089
(2008/02/14)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Palladium-catalyzed decarboxylation and decarbonylation under hydrothermal conditions: Decarboxylative deuteration
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Equation presented. Decarboxylation of free carboxylic acid was performed by Pd/C catalyst under hydrothermal water (250°C/4 MPa). Under the hydrothermal conditions of deuterium oxide, decarbonylative deuteration was observed to give fully deuterated hydrocarbons from carboxylic acids or aldehydes.
- Matsubara, Seijiro,Yokota, Yutaka,Oshima, Koichiro
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p. 2071 - 2073
(2007/10/03)
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- Semi-volatile and particulate emissions from the combustion of alternative diesel fuels
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Motor vehicle emissions are a major anthropogenic source of air pollution and contribute to the deterioration of urban air quality. In this paper, we report results of a laboratory investigation of particle formation from four different alternative diesel fuels, namely, compressed natural gas (CNG), dimethyl ether (DME), biodiesel, and diesel, under fuelrich conditions in the temperature range of 800-1200°C at pressures of approximately 24 atm. A single pulse shock tube was used to simulate compression ignition (CI) combustion conditions. Gaseous fuels (CNG and DME) were exposed premixed in air while liquid fuels (diesel and biodiesel) were injected using a high-pressure liquid injector. The results of surface analysis using a scanning electron microscope showed that the particles formed from combustion of all four of the above-mentioned fuels had a mean diameter less than 0.1 μm. From results of gravimetric analysis and fuel injection size it was found that under the test conditions described above the relative particulate yields from CNG, DME, biodiesel, and diesel were 0.30%, 0.026%, 0.52%, and 0.51%, respectively. Chemical analysis of particles showed that DME combustion particles had the highest soluble organic fraction (SOF) at 71%, followed by biodiesel (66%), CNG (38%) and diesel (20%). This illustrates that in case of both gaseous and liquid fuels, oxygenated fuels have a higher SOF than non-oxygenated fuels. Motor vehicle emissions are a major anthropogenic source of air pollution and contribute to the deterioration of urban air quality. In this paper, we report results of a laboratory investigation of particle formation from four different alternative diesel fuels, namely, compressed natural gas (CNG), dimethyl ether (DME), biodiesel, and diesel, under fuelrich conditions in the temperature range of 800-1200°C at pressures of approximately 24 atm. A single pulse shock tube was used to simulate compression ignition (CI) combustion conditions. Gaseous fuels (CNG and DME) were exposed premixed in air while liquid fuels (diesel and biodiesel) were injected using a high-pressure liquid injector. The results of surface analysis using a scanning electron microscope showed that the particles formed from combustion of all four of the above-mentioned fuels had a mean diameter less than 0.1 μm. From results of gravimetric analysis and fuel injection size it was found that under the test conditions described above the relative particulate yields from CNG, DME, biodiesel, and diesel were 0.30%, 0.026%, 0.52%, and 0.51%, respectively. Chemical analysis of particles showed that DME combustion particles had the highest soluble organic fraction (SOF) at 71%, followed by biodiesel (66%), CNG (38%) and diesel (20%). This illustrates that in case of both gaseous and liquid fuels, oxygenated fuels have a higher SOF than non-oxygenated fuels.
- Sidhu, Sukh,Graham, John,Striebich, Richard
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p. 681 - 690
(2007/10/03)
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- Fine particle and gaseous emission rates from residential wood combustion
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Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning-communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter(a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and se mivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C8- C20), canister (C2-C12), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and forts were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography. Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter (a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and semivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C8-C20), canister (C2-C12), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence, and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and ions were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography.
- Mcdonald, Jacob D.,Zielinska, Barbara,Fujita, Eric M.,Sagebiel, John C.,Chow, Judith C.,Watson, John G.
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p. 2080 - 2091
(2007/10/03)
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- Synthetic utility of 1,1,2,2-tetraaryIdisilanes: Radical reduction of alkyl phenyl chalcogenides
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Reactivity of tetraaryldisilanes as radical reducing agents of alkyl phenyl chalcogenides initiated by Et3B or AIBN was studied. Here, the reactivity of alkyl sulfide was poor; however, various alkyl phenyl selenides and tellurides were reduced to the corresponding hydrocarbons in good yields with 1,1,2,2-tetraphenyldisilane. The Royal Society of Chemistry 1999.
- Yamazaki, Osamu,Togo, Hidco,Yokoyama, Masataka
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p. 2891 - 2896
(2007/10/03)
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- Copper-catalyzed cross-coupling of alkylsamarium reagents with alkyl halides
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SmI2/HMPA converts alkyl iodides and bromides to alkyl samarium reagents which can be cross-coupled with primary alkyl iodides and bromides and secondary iodides in the presence of Cu(I) halides or Li2CuCl4 at room temperature. The alkylation of primary iodides gives good yields of cross-coupling products with negligible home-coupling produces. The method is especially useful for the small scale cross-coupling reactions.
- Berkowitz, William F.,Wu, Yanzhong
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p. 3171 - 3174
(2007/10/03)
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- Scope and utility of a new soluble copper catalyst [CuBr-LiSPh-LiBr-THF]: A comparison with other copper catalysts in their ability to couple one equivalent of a Grignard reagent with an alkyl sulfonate
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A mixture of equal amounts of CuBr-SMe2, LiBr, and LiSPh in THF at 0°C furnished a new soluble copper catalyst that was highly efficient at coupling primary, secondary, tertiary, aryl, vinyl, and allylic Grignard reagents to primary tosylates and primary Grignard reagents to secondary tosylates and mesylates, all with the use of only 1 equiv of Grignard reagent. The new catalyst was shown to be much more reactive than copper catalysts CuBr and Li2CuCl4 and more efficient in the transference of secondary and tertiary alkyl groups than lower order cuprates (Gilman reagents) and demonstrated more reactivity than the lower order cuprates with its ability to couple primary Grignard reagents to secondary sulfonates. The Grignard reagent/catalyst system was compatible with an ester functionalized tosylate, thus proving to be more chemoselective than a Grignard reagent without the catalyst. The catalyst exhibited good reactivity below room temperature, and with the addition of 6% v/v of HMPA to the catalyst solution, excellent yields of coupled product were obtained within a 25-67°C temperature range. 1H NMR demonstrated that the catalyst solution consisted of several species that most likely were composed of copper ligated with thiophenol, THF, and LiBr in aggregated forms.
- Burns, Dennis H.,Miller, Jeffrey D.,Chan, Ho-Kit,Delaney, Michael O.
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p. 2125 - 2133
(2007/10/03)
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