- Magnetically separable mesoporous silica-supported palladium nanoparticle-catalyzed selective hydrogenation of naphthalene to tetralin
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A novel magnetically separable mesoporous silica-supported palladium catalyst was designed and prepared for the selective hydrogenation of naphthalene to tetralin, which is an important transformation from a practical viewpoint. In the catalyst, Pd nano grains were dispersed uniformly and protected within the mesoporous silica shells being coated on the Fe3O4 core, so that the durability of the catalyst could be significantly improved.
- Yang, Yonghui,Xu, Bolian,He, Jie,Shi, Jianjun,Yu, Lei,Fan, Yining
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- Cp?Ir-Catalyzed Acceptorless Dehydrogenation of Carbon-Carbon Single Bonds
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Pentamethylcyclopentadienyl (Cp?) iridium(III) chloride catalyzed acceptorless dehydrogenation of α-tetralone is reported. Cp? iridium chloride showed higher activity in comparison to other Cp? iridium complexes having bromide, iodide, or hydride or complexes without a Cp ring. The desired product, naphthol, was obtained in up to 71% yield from α-tetralone. The dehydrogenation by Cp? iridium catalyst could be applied to not only α-tetralone but also dihydrocoumarin, dihydroquinolinone, dimethylcyclohexanone, dihydrobenzofuran and 1-isochromanone, although the conversion stayed moderate. The catalytic turnover was not limited by the increased concentration of the product but by catalyst decomposition.
- Ando, Hideaki,Kusumoto, Shuhei,Wu, Weiwei,Nozaki, Kyoko
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- Treatment of naphthols with B(C6F5)3: Formation and characterization of the Lewis acid adducts of their keto isomers
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With the strong Lewis acid B(C6F5)3, the keto tautomers from a variety of naphthol derivatives are obtained (e.g. α- naphthol, see scheme). The adducts of the tautomers were characterized by X-ray structure analysis, and the first attempts at hydrozirconation of the adducts were made.
- Vagedes, Dominik,Froehlich, Roland,Erker, Gerhard
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- Hydrogenation of Aromatics in Diesel Fuels on Pt/MCM-41 Catalysts
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The hydrogenation activity of Pt supported on two mesoporous MCM-41 samples differing in their chemical composition has been studied by following the kinetics of the hydrogenation of naphthalene at 225-275°C reaction temperature and 5.0 MPa total pressure and by comparing the kinetic parameters obtained with Pt supported on a mesoporous amorphous silica-alumina (MSA) and other conventional supports, such as commercial amorphous silica-alumina (ASA), zeolite USY, γ-alumina, and silica. The two mesoporous MCM-41 and MSA materials having very high surface areas allowed for a better dispersion of the Pt particles, and they showed a superior overall hydrogenation activity as compared to the other supports. However, Pt/USY displayed the highest turnover (activity per exposed surface Pt), owing to the interaction of small Pt aggregates in the supercage of the zeolite with the strong Broensted acid sites associated to framework aluminum forming electron-deficient Pt species of known enhanced activity. Moreover, both the Al-MCM-41 and USY-based catalysts presented the highest sulfur tolerance during the hydrogenation of a naphthalene feed containing 200 ppm sulfur added as dibenzothiophene. The high metal dispersion and the interaction of the small Pt clusters with the mildly acidic sites present in Al-MCM-41 may account for its high sulfur tolerance. The superior hydrogenation activity and sulfur tolerance of Pt-MCM-41 catalyst observed in the naphthalene experiments were further confirmed during the hydrogenation of a hydrotreated light cycle oil (LCO) feed containing ca 70 wt% aromatics and 400 ppm sulfur.
- Corma,Martinez,Martinez-Soria
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- Synthesis of Ni–W aromatic hydrocarbon hydrogenation catalysts by the ex situ and in situ decomposition of a precursor based on a dendrimer network
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A Ni–W precursor supported on a dendrimer-containing crosslinked polymer (42 wt % of a third-generation polypropylenimine dendrimer) has been first synthesized. The precursor has been subjected to the ex situ and in situ decomposition in a hydrocarbon feedstock to prepare an unsupported Ni–W sulfide catalyst. The activity of the resulting catalyst in the hydrogenation of aromatic hydrocarbons has been studied using the example of naphthalene. The process has been conducted in an autoclave-type reactor in a temperature range of 350–400°C at a hydrogen pressure of 5.0 MPa. It has been shown that the in situ synthesis of a Ni–W catalyst leads to the formation of particles exhibiting higher activity in the hydrogenation of naphthalene. The in situ synthesized Ni–W particles have been characterized by TEM and XPS.
- Sizova,Kulikov,Zolotukhina,Serdyukov,Maksimov,Karakhanov
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- The cyclization of parent and cyclic hexa-1,3-dien-5-ynes - A combined theoretical and experimental study
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The thermal cycloisomerization of both parent and benzannelated hexa-1,3-dien-5-yne, as well as of carbocyclic 1,3-dien-5-ynes (ring size 7-14), was investigated by using pure density functional theory (DFT) of Becke, Lee, Yang, and Parr (BLYP) in connection with the 6-31G* basis set and the Brueckner doubles coupled-cluster approach [BCCD(T)] with the cc-pVDZ basis set for the parent system. The initial cyclization product is the allenic cyclohexa-1,2,4-triene (isobenzene), while the respective biradical is the transition structure for the enantiomerization of the two allenes. Two consecutive [1,2]-H shifts further transform isobenzene to benzene. For the benzannelated system, the energetics are quite similar and the reaction path is the same with one exception: the intermediate biradical is not a transition state but a minimum which is energetically below isonaphthalene. The cyclization of the carbocyclic 1,3-dien-5-ynes, which follows the same reaction path as the parent system, clearly depends on the ring size. Like the cyclic enediynes, the dienynes were found to cyclize to products with reduced ring strain. This is not possible for the 7- and 8-membered dienynes, as their cyclization products are also highly strained. For 9- to 11-membered carbocycles, all intermediates, transition states, and products lie energetically below the parent system; this indicates a reduced cyclization temperature. All other rings (12- to 14-membered) have higher barriers. Exploratory kinetic experiments on the recently prepared 10- to 14-membered 1,3-dien-5-ynes rings show this tendency, and 10- and 11-membered rings indeed cyclize at lower temperatures.
- Prall, Matthias,Krueger, Anke,Schreiner, Peter R.,Hopf, Henning
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- THE SILICON-MODIFIED METAL AMMONIA REDUCTION OF AROMATIC COMPOUNDS
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A trimethylsilyl substituent is used to control regiochemistry in the metal-ammonia reduction of several naphthalenes, and is subsequently removed resulting in a " Misoriented Birch Reduction."
- Rabideau, Peter W.,Karrick, Gregory L.
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- Reduction of polycyclic aromatic hydrocarbons promoted by cobalt or manganese nanoparticles
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A new methodology for the partial reduction of polycyclic aromatic and heteroaromatic hydrocarbons under mild reaction conditions is presented, the process being a reasonable alternative to the catalytic hydrogenation or the Birch reaction. The reduction protocol described is based on the use of cobalt or manganese nanoparticles generated in situ in a simple and economic way, by reduction of commercially available CoCl2·6H2O or MnCl2·2H2O in the presence of lithium sand and the corresponding PAH, acting itself as an electron carrier. The use of a deuterium-oxide-containing cobalt(II) salt allows the simple preparation of deuterium labeled products. The regiochemistry and degree of reduction in the case of 1-substituted naphthalene derivatives markedly depends on the nature of the metal-NPs used.
- Nador, Fabiana,Moglie, Yanina,Vitale, Cristian,Yus, Miguel,Alonso, Francisco,Radivoy, Gabriel
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- The hydrogenation of aromatic compounds under mild conditions by using a solid Lewis acid and supported palladium catalyst
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Al2O3 or SiO2 particles with abundant surface hydroxyl groups can prevent side reactions of aromatic compounds with AlCl3 completely; this Lewis acid can potentially destroy the stable structure of aromatic comp
- Zhang, Peng,Wu, Tianbin,Hou, Minqiang,Ma, Jun,Liu, Huizhen,Jiang, Tao,Wang, Weitao,Wu, Congyi,Han, Buxing
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- Catalyses of Fe and FeS2 on the Reaction of Di(1-naphthyl)methane
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Reactions of di(1-naphthyl)methane (DNM) over Fe and FeS2 at 300 deg C were carried out to investigate the catalytic activities and selectivities of the two catalysts.Both catalysts showed high activities for the reaction of DNM but Fe catalyzed DNM hydrogenation whereas FeS2 catalyzed DNM hydrocracking.This difference can be ascribed to the presence of sulfur.
- Wei, Xian-yong,Ogata, Eisuke,Niki, Etsuo
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- Swelled plastics in supercritical CO2 as media for stabilization of metal nanoparticles and for catalytic hydrogenation
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Swelled plastics in supercritical carbon dioxide provide unique environments for stabilizing palladium and rhodium nanoparticles and for catalytic hydrogenation. Complete hydrogenation of benzene to cyclohexane can be achieved in 10 minutes using the plastic stabilized Rh nanoparticles at 50°C in supercritical CO2. High efficiency, reusability, and rapid separation of products are some advantages of the plastic stabilized metal nanoparticles for catalytic hydrogenation in supercritical CO2.
- Ohde, Hiroyuki,Ohde, Mariko,Wai, Chien M.
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- Selective hydrogenation of 1-naphthol on USY-supported NiB nanocatalyst
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Selective hydrogenation of 1-naphthol to 5,6,7,8-tetrahydro-1-naphthol was investigated over several Ni- and Pd-based supported catalysts such as supported Ni/γ-Al2O3, Pd/C, and NiB/ultrastable Y zeolite (USY). It was found that USY-
- Wang, Bo,Liu, Hui
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- Promotion of Ni/SBA-15 catalyst for hydrogenation of naphthalene by pretreatment with ammonia/water vapour
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The activities of nickel supported on SBA-15 catalysts, which were prepared by pretreatment with ammonia/water vapour, were investigated by hydrogenation of naphthalene. Comparing with the un-pretreated catalysts, the pretreated catalysts exhibited significant activity, and naphthalene conversion was improved approximately 100% over the un-pretreated catalysts. The formation of NH4NO3 during pretreatment, which helped to reduce NO 2/O2 generation thus enhancing the dispersion of NiO, was considered to be the main reason for the increased Ni0 dispersion and the enhanced activity of the catalyst pretreated with ammonia/water vapour.
- Ren, Shibiao,Zhang, Ping,Shui, Hengfu,Lei, Zhiping,Wang, Zhicai,Kang, Shigang
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- Water as an additive to enhance the ring opening of naphthalene
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Use of water as a reaction medium or additive to enhance reaction efficiency is an important topic in green chemistry, and ring opening and contraction reactions of aromatics are crucial for upgrading diesels. In this work, we investigated the effect of water on the yields of ring opening and contraction reactions of naphthalene. A series of catalysts, such as Rh 2O3/HY zeolite, Mo-Ni oxide and their physical mixtures, were used as the catalysts. The influences of the amount of water, hydrogen pressure, reaction temperature and reaction time on the yields of the ring opening and contraction products (ROCP) were studied. It was found that Rh 2O3/HY and Mo-Ni oxide showed an excellent synergistic effect for catalyzing the reaction, and water could be used as a green and efficient additive for enhancing the yield of the ROCP. At the optimized conditions, the yield of the ROCP could be as high as 63.3%. The mechanism for the effect of water on the reactions was discussed on the basis of control experiments.
- Wang, Qian,Fan, Honglei,Wu, Suxiang,Zhang, Zhaofu,Zhang, Peng,Han, Buxing
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- Deep hydrogenation of coal tar over a Ni/ZSM-5 catalyst
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We have developed a Ni/ZSM-5 catalyst and utilised it to completely hydrogenate a series of condensed arenes, including naphthalene, anthracene and phenanthrene, under relatively mild conditions. The yields of decalin, perhydroanthracene and perhydrophenanthrene reached 100%, 98.8% and 25.8%, respectively. By analyzing the isomer distribution of the perhydroarenes, we proposed a mechanism of biatomic hydrogen transfer, which was further proven via the hydrogenation of 9,10-diphenylanthracene. Through hydrotreatment over the Ni/ZSM-5 catalyst, both high-temperature coal tar rich in condensed arenes and low-temperature coal tar mixing arenes with alkanes were greatly upgraded. The majority of arenes in the coal tars were deeply and even completely hydrogenated, which may open up a route for further processing and application of coal tar as clean fuels.
- Qi, Shi-Chao,Zhang, Lu,Wei, Xian-Yong,Hayashi, Jun-Ichiro,Zong, Zhi-Min,Guo, Lu-Lu
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- Hydrodearomatization catalysts based on molybdenum hexacarbonyl Mo(CO)6 supported on mesoporous aromatic frameworks
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A method for synthesizing fine hydrodearomatization catalysts based on the immobilization of molybdenum carbonyl into the pores of mesoporous aromatic frameworks is proposed. It is shown that the amount of the deposited metal and the average size of the resulting particles depend on the support and the deposition method characteristics. The catalytic activity of the synthesized materials in the hydrogenation of bicyclic hydrocarbons at a hydrogen pressure of 5.0 MPa in a temperature range of 330–500°C is studied using the example of naphthalene, methylnaphthalenes, and biphenyl as model substrates.
- Maksimov,Karakhanov,Kulikov,Terenina
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- (2,7)TROPONOPHANE
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The title compound 5 and its dehydro analog 6 were synthesized from 10 and 9, respectively, and their physical properties were examined.Tropone ring in these compounds are deeply bent to tub shapes and conjugation of the carbonyl group is greatly reduced.
- Fujise, Yutaka,Shiokawa, Toshihiro,Mazaki, Yasuhiro,Fukazawa, Yoshimasa,Fujii, Mitsuharu,Ito, Sho
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- Iterative Preparation of Platinum Nanoparticles in an Amphiphilic Polymer Matrix: Regulation of Catalytic Activity in Hydrogenation
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We demonstrate that iteration of the seeded preparation of platinum nanoparticles dispersed in an amphiphilic polystyrene-poly(ethylene glycol) resin (ARP-Pt) regulates their catalytic activity in the hydrogenation of aromatic compounds in water. The catalytic activity of the fifth generation of ARP-Pt [G5] prepared through four iterations of the seeded preparation was far superior to that of the initial ARP-Pt [G1] in the hydrogenation of aromatic compounds in water.
- Hamasaka, Go,Osako, Takao,Srisa, Jakkrit,Torii, Kaoru,Uozumi, Yasuhiro
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- Preparation of Ni - W aromatic hydrocarbon hydrogenation catalysts by breaking reverse emulsions or suspensions of a precursor in hydrocarbon feedstock
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Reverse emulsions (hydrocarbon feedstock)/(aqueous precursor solution) for synthesizing aromatic hydrocarbon hydrogenation catalysts have been prepared using the water-soluble salts (NH4)2WS4 and Ni(NO3)2·6 H2O as precursors. It has been found that the optimum stabilizer for the emulsions is the nonionic surfactant SPAN-80. The resulting emulsions exhibit low catalytic activity in the hydrogenation of aromatic hydrocarbons; it has been shown that the activity of the systems in hydrodearomatization reactions is adversely affected by the presence of water. A procedure for preparing suspensions of solid precursor particles in a hydrocarbon feedstock by the removal of water from the resulting reverse emulsions has been developed. The catalytic activity of the resulting suspensions in the hydrogenation of aromatic hydrocarbons has been studied using naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene as examples. It has been shown that the catalytic activity of the suspensions is higher than that of the reverse emulsions of the same composition. It has been found that the feedstock should be subjected to additional sulfurization with elemental sulfur for further sulfiding the surface of the nickel - tungsten catalyst. The W: Ni molar ratio of 1: 1 has been found to be optimum.
- Sizova,Serdyukov,Maksimov
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- Nickel–molybdenum sulfide catalysts supported on an ordered mesoporous polymer for hydrogenating–hydrocracking of model biaromatic petroleum compounds
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Nickel–molybdenum sulfide catalysts have been synthesized in situ in a hydrocarbon medium by the decomposition of the [(n-Bu)4N]2Ni(MoS4)2 precursor complex supported on an ordered mesoporous phenol–formaldehyde polymer in the presence of a sulfiding agent (dimethyl disulfide). The catalytic properties of the samples have been studied in a batch reactor at 380°C and a hydrogen pressure of 5.0 MPa using the example of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene. The tests have shown that the conversion of biaromatic substrates is close to quantitative and the use of dimethyl disulfide as a sulfiding agent leads to an increase in the amount of complete hydrogenation products, as evidenced by the high content of the active phase in this case.
- Karakhanov,Boronoev,Ignat’eva,Kardasheva, Yu. S.,Filippova, T. Yu.,Maksimov
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- Disproportionation of dihydroarenes by sol-gel entrapped RhCl3-quaternary ammonium ion pair catalysts
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The ion pairs generated from RhCl3 · 3H2O and the quaternary ammonium salts [(C8H17)3NMe]Cl (Aliquat 336) and [Me3N(CH2)3Si(OMe)3]Cl were physically and chemically entrapped, respectively, in SiO2 sol-gel matrices under mild conditions. The resulting immobilized ion pairs proved to be stable, leach-proof, and recyclable catalysts for disproportionation of 1,3-cyclohexadiene and several other vic-dihydroarenes. In these reactions, equimolar quantities of the respective tetrahydro-and fully aromatic compounds were obtained. The entrapped catalysts, in most cases, proved to be more efficient and more selective than their homogeneous analogues. The reaction rates and conversions were shown to depend strongly on steric effects of substituents and on the bulkiness of the substrate skeleton. The recorded first order kinetics in the substrates (organic reactants) suggests that the mechanism involves stepwise addition of two molecules of the dihydroarenes to the rhodium nucleus, and that the addition of the first substrate molecule is rate limiting.
- Rosenfeld, Ayelet,Blum, Jochanan,Avnir, David
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- Facile in situ Encapsulation of Highly Dispersed Ni@MCM-41 for the Trans-Decalin Production from Hydrogenation of Naphthalene at Low Temperature
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Ni@MCM-41 catalyst that has uniformly distributed, highly dispersed Ni nanoparticles (about 2.3 nm) was designed and successfully synthesized by in situ encapsulation of Ni in the channels of MCM-41. This catalyst exhibits excellent thermal stability and hydrogenation activity. Water insoluble nickel acetylacetonate (Ni(acac)2) was first dissolved aqueous solution of cetyltrimethyl ammonium bromide (CTAB) and encapsulated in micelles of CTAB. Sodium silicate was used as a silicon source to rapidly hydrolyze and then wrap on the micelle surface to synthesize the MCM-41 zeolite. The MCM-41 zeolite encapsulating Ni(acac)2 was synthesized within a short time (4 h) at 120 °C. Compared with conventional supported catalysts, thus 3 wt.% Ni@MCM-41 has ultra-small uniformly distributed Ni nanoparticles and exhibits improved activity for the hydrogenation of naphthalene to decalin at very low reaction temperatures. The TOF and the apparent activation energy of Ni@MCM-41 and the conventional catalysts (Ni/MCM-41 and Pt/MCM-41) were evaluated and compared. And the catalysis mechanism was analyzed. Furthermore, this Ni@MCM-41 catalyst offers an additional advantage of selectivity in decalin isomerization; 92 % trans-decalin selectivity was achieved at a wide temperature range.
- Song, Xiaoyun,Guan, Qingxin,Shu, Yu,Zhang, Xiaojing,Li, Wei
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- Naphthalene Hydrogenation over Catalysts Formed In Situ from Ruthenium-Containing Thiosalts
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Abstract: Ruthenium-containing 1-butyl-1-methylpiperidinium thiosalts are synthesized; their decomposition in situ in a hydrocarbon medium makes it possible to form catalysts active in the hydrogenation of naphthalene. It is shown that the modification of thiosalts with nickel leads to the formation of more active catalyst systems. A thermally stable ionic liquid 1-butyl-1-methylpiperidinium trifluoromethanesulfonate is synthesized. It is shown that the hydrogenation catalyst may be prepared by the decomposition of thiosalts in the ionic liquid and that it can be reused in several cycles without any loss in activity.
- Onishchenko,Suzova,Maximov
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- FeS2-Catalyzed Hydrocracking of Di(1-naphthyl)methane. Effects of Hydrogen Pressure, Catalyst Feed and Reaction Temperature, and Kinetic Study
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Hydrocracking of di(1-naphthyl)methane (DNM) in the temperature range of 150-300 deg C was studied.In the presence of FeS2 and pressurized hydrogen, DNM hydrocracking took place over 175 deg C.FeS2 selectively catalyzed the cleavage of C-C linkage in DNM to give 1-methylnaphthalene and naphthalene.The rate for DNM hydrocracking strongly depended on hydrogen pressure, FeS2 feed and reaction temperature.Kinetic study indicates that DNM hydrocracking in the temperature range of 200-300 deg C could be considered as a first order reaction.Under the reaction condition (DNM 7.5 mol, decalin 30 ml, FeS2 0.5 g, sulfur 0.05 g, initial hydrogen pressure 10 MPa), the activation energy and frequency factor for DNM hydrocracking were 19 kcal mol-1 and 5.3*107 h-1, respectively.
- Wei, Xian-Yong,Ogata, Eisuke,Niki, Etsuo
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- MoCx species embedded in ordered mesoporous silica framework with hierarchical structure for hydrogenation of naphthalene
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An integrated route to accomplish the incorporation of MoCx species into ordered mesoporous silica framework (OMSF) was presented. The MoVI-melamine hybrids were used as the single-source precursors for molybdenum carbides and partic
- Pang, Min,Chen, Xiaozhen,Xu, Qinying,Liang, Changhai
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- Synthesis of cyclo-1,3-dien-5-ynes
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Cyclo-1,3-dien-5-ynes with ring sizes from 10 to 14 (6a-e) have been prepared for the first time by using a five-step synthesis starting from the alkynols 7a-e. The final ring-closure was achieved by McMurry coupling of the α,ω-dialdehydes 12a-e with the complex TiCl3(DME)1.5. Thermal isomerization of the cyclodienynes leads to the corresponding benzocycloalkenes, and it has been shown that the ring size has a considerable influence on the temperature necessary for thermocylization.
- Hopf, Henning,Krueger, Anke
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- Enhanced selectivity to decalin in naphthalene hydrogenation under supercritical carbon dioxide
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A charcoal-supported rhodium catalyst was highly active and selective to decalin for the hydrogenation of naphthalene at very low temperature (333 K) under supercritical carbon dioxide. Copyright
- Hiyoshi, Norihito,Miura, Ritsuko,Rode, Chandrashekhar V.,Sato, Osamu,Shirai, Masayuki
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- Promotion of hydrogenation activity and sulfur resistance over Ni/ASA catalyst by support modification simultaneously with P and USY
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Individual and simultaneous P and USY promoted amorphous SiO2-Al2O3 (ASA) supported Ni catalysts were prepared using the hydrothermal synthesis method with the assistance of cis-9-octadecenylamine. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption and desorption, UV-vis diffuse reflectance spectroscopy, FTIR spectroscopy of adsorbed pyridine (Py-IR), transmission electron microscopy (TEM), temperature-programmed hydrogen reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The effects of P and USY loading on the activity of naphthalene hydrogenation were evaluated in a fixed bed reactor under the following reaction conditions: P = 4 MPa, GHSV = 16 h-1, H2/oil = 600 volume ratio, T = 200, 240, 280 and 320 °C. Experimental results verified that all individual P and USY modified catalysts displayed higher hydrogenation activity than the freely P and USY decorated catalyst at 200-280 °C. Furthermore, the catalyst simultaneously modified with 1.0 wt% P and 10 wt% USY had the highest hydrogenation activity and sulfur tolerance. Multiple effects, such as metal dispersion, acid amount, surface exposure of the active Ni° species and the [NiOh2+]/[NiTd2+] ratio were responsible for the high hydrogenation activity of P and USY-promoted catalysts.
- Cui, Sha,Ge, Jiaqi,Wang, Genggeng,Yang, Ying,Liu, Baijun
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- Naphthalene hydrogenation over nickel–tungsten sulfide catalysts synthesized in situ from DMSO–hydrocarbon medium emulsions
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A method for synthesizing unsupported nickel–tungsten sulfide hydrodearomatization catalysts by breaking SPAN-80 surfactant-stabilized nonaqueous emulsions of solutions of different precursors in dimethyl sulfoxide (DMSO) in situ in a hydrocarbon medium h
- Sizova,Antonov,Serdyukov,Maksimov
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- Chemical treatment of CNTs in acidic KMnO4 solution and promoting effects on the corresponding Pd-Pt/CNTs catalyst
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Carbon nanotubes (CNTs) were chemically treated in acidic KMnO4 solution. XRD, nitrogen physisorption, FTIR and chemical titration were used to investigate the influence of the treatment conditions on the surface structure, the bulk structure,
- Chen, Jiuling,Chen, Qinghai,Ma, Qing,Li, Yongdan,Zhu, Zhonghua
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- Properties of Nanosized Cobalt-Molybdenum Sulfide Catalyst Formed In Situ from Sulfonium Thiosalt
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Abstract: A cobalt-molybdenum-containing sulfonium thiosalt is prepared; when decomposed in situ, it forms the catalyst active in hydrogenation and hydrodesulfurization. The possibility of catalyst isolation and reuse in several hydrogenation cycles is shown. It is found that a lower selectivity for naphthalene hydrogenation products in catalyst recycling is associated with decrease in the dispersity of molybdenum sulfide nanoparticles and reduction in the degree of their promotion by cobalt atoms.
- Knyazeva,Panyukova,Maximov
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- Carbon Dioxide Copolymerization Study with a Sterically Encumbering Naphthalene-Derived Oxide
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Poly(1,4-dihydronaphthalene carbonate) has been prepared via the catalytic coupling of carbon dioxide and 1,4-dihydronaphthalene oxide using chromium(III) catalysts. The copolymer formation is found to be greatly dependent on the steric environment around the metal center. Traditional (salen)CrIIIX/cocatalyst systems bearing bulky t-butyl groups hinder the approach of the large monomer, significantly diminishing polymer chain growth and providing the entropically favored cyclic byproduct in excess. In contrast, employing the sterically unencumbered azaannulene-derived catalyst, (tmtaa)CrIIIX/cocatalyst system (tmtaa = tetramethyltetraazaannulene) shows polymer selectivity close to 90% with three times the activity (TOF = 20-30 h-1). With the use of a bifunctional (salen)CrIII catalyst, even higher polymer selectivity (>90%) can be observed. The complete synthesis of a new bifunctional tetraazaannulene ligand for a more effective catalyst is also described herein.
- Darensbourg, Donald J.,Kyran, Samuel J.
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- Visible Light-Driven, Room Temperature Heck-Type Reaction of Alkyl Halides with Styrene Derivatives Catalyzed by B12 Complex
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A visible light driven Heck-type coupling reaction of alkyl halides with styrene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ru(bpy)3]Cl2 photosensitizer at room temperature is reported. The catalytic efficiencies of the B12 catalyst were compared to that of other cobalt complexes such as cobaloxime. Various control experiments supported a radical-based mechanism similar to those for typical B12 model reactions. A unique coupling reaction combined with 1,2-migration of the functional group is also reported. Mild reaction conditions using an environmentally benign cobalt catalyst derived from the natural B12 provided a practical protocol for the synthetic organic chemistry of the B12 catalyzed reaction system. (Figure presented.).
- Chen, Li,Hisaeda, Yoshio,Shimakoshi, Hisashi
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- From lignocellulosic biomass to renewable cycloalkanes for jet fuels
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A novel pathway was investigated to produce jet fuel range cycloalkanes from intact biomass. The consecutive processes for converting lignocellulosic biomass into jet fuel range cycloalkanes principally involved the use of the well-promoted ZSM-5 in the process of catalytic microwave-induced pyrolysis and RANEY nickel catalysts in the hydrogen saving process. Up to 24.68% carbon yield of the desired C8-C16 aromatics was achieved by catalytic microwave pyrolysis at 500 °C. We observed that solvents could assist in the hydrogenation reaction of naphthalene; and the optimum result for maximizing the carbon selectivity (99.9%) of decalin was obtained from the reaction conducted in the n-heptane medium. The recovery of organics could reach ～94 wt% after the extraction process. These aromatics in the n-heptane medium were eventually hydrogenated into jet fuel range cycloalkanes. Various factors were analyzed to determine the optimal result under mild conditions. An increased catalyst loading, reaction temperature, and prolonged time could enhance the hydrogenation reactions to improve the selectivity of jet fuel range cycloalkanes. Three types of hydrogenation catalysts (NP Ni, RANEY Ni 4200, home-made RANEY Ni) were chosen to evaluate the catalytic performance. The results indicated that the home-made RANEY nickel is the optimal catalyst to obtain the highest selectivity (84.59%) towards jet fuel range cycloalkanes. These cycloalkanes obtained can be directly used as additives to synthesize the desired jet fuels by blending with other hydrocarbons. Hence integration of catalytic processes and conversion of lignocellulosic biomass paved a new avenue for the development of green bio-jet fuels over inexpensive catalysts under mild conditions.
- Zhang, Xuesong,Lei, Hanwu,Zhu, Lei,Wu, Joan,Chen, Shulin
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- (4)PARACYCLOPHANE INTERCEPTED
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Irradiation (254 nm) of 1,4-tetramethylene(Dewar benzene) (1a) at -20 deg C in THF leads to (4)paracyclophane (2a).In the absence of acid, 2a polymerizes immediately.In the presence of CF3COOH, adducts 6 and 7 are formed by protonation of 2a at a bridgehead carbon atom to give benzenonium ion 9a, followed by addition of a nucleophile, i.e., CF3COO(-) or THF, respectively, at the other bridgehead carbon, leading to a bridged 1,4-dihydrobenzene.The corresponding methanol adduct 8 is formed on irradiation of 1a in methanol solution in the presence of CF3COOH.The difference in behavior between 2a and its higher homologue is discussed on the basis of calculated charge densities.
- Kostermans, Gerardus B.M.,Bobeldjik, Marcel,Wolf, Willem H. de,Bickelhaupt, Friedrich
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- NOVEL POLYHYDRONAPHTHALENIC STRUCTURES
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Novel 1,7-dihydro- or 1,2,6,7-tetrahydronaphthalene derivatives were obtained from naphthalene through a polysilylation/oxidation process as well as 1,4,6,7-tetrakis(trimethylsilyl)naphthalene, a regiospecific precursor of 1,4,6,7-tetrafunctional naphthalenes.
- Laguerre, Michel,Dunogues, Jacques,Calas, Raymond
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- Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions
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Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (～10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.
- Chen, Yuzhuo,Chen, Zhirong,Gong, Yutong,Mao, Shanjun,Ning, Honghui,Wang, Yong,Wang, Zhenzhen
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p. 3069 - 3084
(2021/11/16)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- Supported noble metal catalyst with a core-shell structure for enhancing hydrogenation performance
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Supported noble metal nanoparticles are a kind of high efficiency of catalysts in aromatics hydrogenation, and the properties and structures of supports are of great importance to improve hydrogenation behaviors. In this work, an efficient Pd/S-1@ZSM-5 core-shell catalyst with an enhanced naphthalene hydrogenation ability was prepared by building acidic nano-ZSM-5 shells surrounding silicalite-1 supported Pd NPs. The acidic nano-ZSM-5 shell can strengthen the spillover hydrogenation due to the increase of the strong acid sites around Pd NPs, and the strong acid sites around metal NPs can be regulated by controlling the coverage of nano-ZSM-5 shell. Additionally, the formed mesoporous structure of nano-ZSM-5 shell is beneficial for the diffusion of bulky reactants. These are the two important factors for enhancing hydrogenation ability of Pd/S-1@ZSM-5 catalyst. Furthermore, Pd/S-1@ZSM-5 catalyst also shows good sulfur-tolerance in the presence of thionaphthene. This work presents an elegant example for enhancing hydrogenation abilities of noble metal catalysts by constructing a core-shell structure.
- Lu, Ningyue,Zhao, Jiaxin,Dong, Qi,Zhao, Yanpeng,Fan, Binbin
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-
- Catalyzed transfer hydrogenation by 2-propanol for highly selective PAHs reduction
-
Catalytic hydrogenation of mono-, di- and trinuclear aromatic compounds has been studied under hydrogen transfer conditions at 150 °C and 82 °C in 2-PrOH as a hydrogen donor and with Raney nickel as a catalyst. In contrast to conjugated or condensed aromatic rings, isolated ones demonstrated low reactivity in transfer hydrogenation (TH) that can be used to increase the hydrogenation selectivity of the reaction. So, naphthalene and biphenyl are partially hydrogenated into tetralin and cyclohexylbenzene, respectively, with excellent conversion (≥ 96 %) and selectivity (≥ 98 %) for 5–6 h at 82 °C. Increasing the reaction temperature to 150 °C results expectedly in the hydrogenation of second aromatic ring, which occurs slowly enough. Only 8 % of decaline and 42 % of dicyclohexyl, correspondingly, were obtained after 5 h at 150 °C. At the same time, TH of trinuclear anthracene and phenanthrene at 150 °C resulted in the formation of deeper hydrogenated octahydro-anthracenes and -phenanthrenes, respectively.
- Philippov,Chibiryaev,Martyanov
-
-
- Effect of Lanthanum Doping on the reactivity of unsupported CoMoS2 catalysts
-
In the present study, catalytic systems based on La-doping were developed to improve the activity and performance of CoMoS2 hydrodesulfurization catalysts. Lanthanum-doped at 5, 10, or 25% of the Co content in CoMoS2 hydrodesulfurization catalysts were synthesized through a solvothermal process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses confirmed the catalysts were triphasic consisting of Co9S8, MoS2, and La2S3. The La doped catalysts showed enhanced catalytic activity compared with CoMoS2 synthesized under the same conditions. The CoMoS2 prepared under solvothermal synthesis conditions showed a catalytic activity of 6.80 mol g-1 s-1, however, the La0.05Co0.95MoS2 doping showed a catalytic activity of 6.51 mol g -1 s-1 whereas the La0.1Co0.9MoS2 and La0.25Co0.75MoS2 samples showed catalytic activities of 10.7 mol g-1 s-1. The reaction products indicated the major reaction pathway was direct desulfurization. The La0.25Co0.75MoS2 catalyst after one reaction cycle showed a lower amount of carbon, than the undoped CoMoS2 catalyst.
- Valdes, Carolina,Gonzalez, Diego,Flores, Kenneth,Eubanks,Valle, John,Hernandez, Carlos,Lopez, Jorge,Alcoutlabi, Mataz,Parsons
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-
- Photoredox catalysis on unactivated substrates with strongly reducing iridium photosensitizers
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Photoredox catalysis has emerged as a powerful strategy in synthetic organic chemistry, but substrates that are difficult to reduce either require complex reaction conditions or are not amenable at all to photoredox transformations. In this work, we show that strong bis-cyclometalated iridium photoreductants with electron-rich β-diketiminate (NacNac) ancillary ligands enable high-yielding photoredox transformations of challenging substrates with very simple reaction conditions that require only a single sacrificial reagent. Using blue or green visible-light activation we demonstrate a variety of reactions, which include hydrodehalogenation, cyclization, intramolecular radical addition, and prenylationviaradical-mediated pathways, with optimized conditions that only require the photocatalyst and a sacrificial reductant/hydrogen atom donor. Many of these reactions involve organobromide and organochloride substrates which in the past have had limited utility in photoredox catalysis. This work paves the way for the continued expansion of the substrate scope in photoredox catalysis.
- Shon, Jong-Hwa,Kim, Dooyoung,Rathnayake, Manjula D.,Sittel, Steven,Weaver, Jimmie,Teets, Thomas S.
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p. 4069 - 4078
(2021/04/06)
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- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
-
The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
- -
-
Paragraph 0094-0095; 0106-0113
(2021/05/29)
-
- N-Atom Deletion in Nitrogen Heterocycles
-
Excising the nitrogen in secondary amines, and coupling the two residual fragments is a skeletal editing strategy that can be used to construct molecules with new skeletons, but which has been largely unexplored. Here we report a versatile method of N-atom excision from N-heterocycles. The process uses readily available N-heterocycles as substrates, and proceeds by N-sulfonylazidonation followed by the rearrangement of sulfamoyl azide intermediates, providing various cyclic products. Examples are provided of deletion of nitrogen from natural products, synthesis of chiral O-heterocycles from commercially available chiral β-amino alcohols, formal inert C?H functionalization through a sequence of N-directed C?H functionalization and N-atom deletion reactions in which the N-atom can serve as a traceless directing group.
- Cai, Wangshui,Guo, Ting,Li, Guigen,Lu, Hongjian,Qin, Haitao,Wang, Shuang
-
supporting information
p. 20678 - 20683
(2021/08/25)
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- Modular Synthesis of Carbazole-Substituted Phthalimides as Potential Photocatalysts
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The modular synthesis of carbazole functionalized phthalimides (PIs) and their applicability as catalyst in selected photocatalytic transformations are reported. The developed synthetic approach provides high variability of phthalimide considering that the synthesis of the phthalimide core can be easily performed. Starting from fluorophthalic acid anhydrides, the corresponding fluorophthalimides were prepared with various amines, and the fluoro function ensured the introduction of carbazoles into the phthalimide framework through aromatic nucleophilic substitution. Besides the synthetic developments, some of the carbazolyl phthalimides were tested in four different photocatalytic transformations, which showed attractive and comparable activity to the known 4-CzIPN and noble metal complexes.
- F?ldesi, Tamás,Gonda, Zsombor,Nagy, Bálint,Novák, Zoltán
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supporting information
(2021/11/22)
-
- Uniformly sized Pt nanoparticles dispersed at high loading on Titania nanotubes
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A range of Pt loadings (0.9–21.5 wt. %) on titania nanotubes (TNT) catalysts were prepared with a view to address metal-support interaction effects on Pt nanoparticles (size, dispersion, shape) and were prepared by a vapor-phase impregnation method using Pt(acac). The reduced catalysts were characterized by XRD, TEM, H2-TPD, CO adsorption FTIR and examined as catalysts in naphthalene hydrogenation. Pt nanoparticles have a very uniform size between 1.4–2.2 nm for Pt loadings 0.9–21.5 wt% as indicated by TEM, H2-TPD and CO-adsorption FTIR. A strong metal-support interaction between Pt and TNT support hinder Pt nanoparticles to agglomerate into larger particles, even at high Pt loadings. Both Pt edge sites and exposed surface total Pt sites are highest at 10.2 wt.% Pt loading and parallels naphthalene hydrogenation activity which peaks at this loading.
- Chávez, C. Angeles,Cortés-Jácome, M. A.,Encarnación-Gómez, C.,García, J. R. Vargas,Hernández-Cortéz, J. G.,Hernández-Cruz, M. G.,López, I. Cuauhtémoc,Medina-Mendoza, A. K.,Salinas, E. López,Toledo-Antonio, J. A.
-
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- Preparation of highly active unsupported Ni–Si–Mo catalyst for the deep hydrogenation of aromatics
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A mesoporous nickel-silicon-molybdenum composite oxide with the phase of ammonium nickel (or silicon) molybdate was synthesized by chemical precipitation and unsupported nickel-silicon-molybdenum sulfide catalysts with various Ni/Si ratios were obtained by sulfidation of the oxide precursors. The oxide precursors and unsupported sulfide catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TPR, and HRTEM. The unsupported nickel-silicon-molybdenum sulfide catalysts were tested in the hydrogenation of naphthalene. It was found that the introduction of Si could increase the specific surface area and improve the pore structure of precursors, and reduce the reduction temperature of Mo species. The results of naphthalene hydrogenation showed that the introduction of Si could significantly improve the hydrogenation activity of the catalysts, especially the Ni9.5Si0.5Mo10 catalyst exhibited the highest aromatic hydrogenation activity at low temperature. Interestingly, it is found that the tetralin selectivity is 100% in the low temperature range (220–260 °C) over Si10Mo10 catalyst, which might be attractive in the production of tetralin and other industrial application.
- Dong, Chengwu,Li, Fan,Liu, Chenguang,Liu, Dong,Wu, Tongtong,Yin, Changlong
-
-
- Ultrasmall Particle Sizes of Walnut-Like Mesoporous Silica Nanospheres with Unique Large Pores and Tunable Acidity for Hydrogenating Reaction
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The large particle sizes, inert frameworks, and small pore sizes of mesoporous silica nanoparticles greatly restrict their application in the acidic catalysis. The research reports a simple and versatile approach to synthesize walnut-like mesoporous silica nanospheres (WMSNs) with large tunable pores and small particle sizes by assembling with Beta seeds. The as-synthesized Beta-WMSNs composite materials possess ultrasmall particulate sizes (70 nm), large radial mesopores (≈30 nm), and excellent acidities (221.6 mmol g?1). Ni2P active phase is supported on the surface of Beta-WMSNs composite materials, and it is found that the obtained composite spherical materials can reduce the Ni2P particle sizes from 8.4 to 4.8 nm with the increasing amount of Beta seeds, which can provide high accessibilities of reactants to the active sites. Furthermore, the unique large pores and ultrasmall particle sizes of Beta-WMSNs samples facilitate the reduction of the diffusion resistance of reactants due to the short transporting length, thus the corresponding Ni2P/Beta-WMSNs composite catalysts show the excellent hydrogenating activity compared to the pure Ni2P/WMSNs catalyst.
- Duan, Aijun,Hu, Di,Li, Huiping,Liu, Cong,Mei, Jinlin,Meng, Qian,Shi, Yu,Wang, Gang,Xiao, Chengkun
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- One-pot dual catalysis for the hydrogenation of heteroarenes and arenes
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A simple dinuclear monohydrido bridged ruthenium complex [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] acts as an efficient and selective catalyst for the hydrogenation of various heteroarenes and arenes. The nature of the catalytically active species was investigated using a combination of techniques including in situ reaction monitoring, kinetic studies, quantitative poisoning experiments and electron microscopy, evidencing a dual reactivity. The results suggest that the hydrogenation of heteroarenes proceeds via molecular catalysis. In particular, monitoring the reaction progress by NMR spectroscopy indicates that [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] is transformed into monomeric ruthenium intermediates, which upon subsequent activation of dihydrogen and hydride transfer accomplish the hydrogenation of heteroarenes under homogeneous conditions. In contrast, carbocyclic aryl motifs are hydrogenated via a heterogeneous pathway, by in situ generated ruthenium nanoparticles. Remarkably, these hydrogenation reactions can be performed using molecular hydrogen under solvent-free conditions or with 1,4-dioxane, and thus give access to a broad range of saturated heterocycles and carbocycles while generating no waste.
- Chatterjee, Basujit,Kalsi, Deepti,Kaithal, Akash,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
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p. 5163 - 5170
(2020/09/07)
-
- Reductive Deamination with Hydrosilanes Catalyzed by B(C6F5)3
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The strong boron Lewis acid tris(pentafluorophenyl)borane B(C6F5)3 is known to catalyze the dehydrogenative coupling of certain amines and hydrosilanes at elevated temperatures. At higher temperature, the dehydrogenation pathway competes with cleavage of the C?N bond and defunctionalization is obtained. This can be turned into a useful methodology for the transition-metal-free reductive deamination of a broad range of amines as well as heterocumulenes such as an isocyanate and an isothiocyanate.
- Fang, Huaquan,Oestreich, Martin
-
supporting information
p. 11394 - 11398
(2020/05/25)
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- Method to convert lignin 4-O-5 diaryl ethers and their model compounds into organic chemicals
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It is provided a method of converting a diaryl ether source such as lignin and/or polyphenylene oxide (PPO) containing 4-O-5 linkages and an inorganic chemical such as ammonia into an organic compound, comprising reacting said diaryl ether source with the inorganic chemical in presence of a catalyst, preferably palladium, transforming the 4-O-5 linkages of said diaryl ether source into the organic compound. It is provided a palladium-catalyzed synthesis of aniline derivatives from 4-O-5 linkage lignin model compounds and cheap industrial inorganic chemical ammonia via dual C(Ar)—O bond cleavage.
- -
-
Paragraph 11-13
(2020/09/18)
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- Scalable Wolff-Kishner Reductions in Extreme Process Windows Using a Silicon Carbide Flow Reactor
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A safe and scalable continuous flow strategy for Wolff-Kishner reductions that employs methanol as the solvent has been developed. The use of low-cost hydrazine as the reducing agent in combination with a caustic base provides an atom-efficient, environmentally friendly method for the deoxygenation of aldehydes and ketones to alkanes. Because of the required harsh and corrosive reaction conditions (200 °C, 50 bar), reactor materials such as stainless steel, glass, or any type of polymer have compatibility problems, rendering this process problematic on a production scale. The use of corrosion-resistant silicon carbide (SiC) as the reactor material opens up the possibility of performing Wolff-Kishner reductions on scale with a considerably improved safety profile. Methanol as the solvent significantly simplifies the workup procedure compared with the generally employed high-boiling solvents such as diethylene glycol. The continuous flow protocol was applied to a number of substrates and provided the desired products in good to high yields with space-time yields of up to 152 g L-1 h-1. In addition, a pharmaceutically valuable active pharmaceutical ingredient precursor was synthesized by employing this higherature/pressure Wolff-Kishner protocol.
- Znidar, Desiree,O'Kearney-Mcmullan, Anne,Munday, Rachel,Wiles, Charlotte,Poechlauer, Peter,Schmoelzer, Christoph,Dallinger, Doris,Kappe, C. Oliver
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p. 2445 - 2455
(2019/11/03)
-
- Mild and efficient rhodium-catalyzed deoxygenation of ketones to alkanes
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A new and simple method for the deoxygenation of ketones to alkanes is presented. Most substrates are reduced under mild conditions by triethylsilane in the presence of catalytic amounts of [Rh(μ-Cl)(CO)2]2. This system selectively provides the methylene hydrocarbons in good to excellent yields starting from acetophenones and diaryl ketones. A rapid examination of the reaction pathway suggests that the ketone is first converted into an alcohol, which then undergoes hydrogenolysis to give the alkane.
- Argouarch, Gilles
-
supporting information
p. 11041 - 11044
(2019/07/31)
-
- Carbonyl and olefin hydrosilylation mediated by an air-stable phosphorus(iii) dication under mild conditions
-
The readily-accessible, air-stable Lewis acid [(terpy)PPh][B(C6F5)4]21 is shown to mediate the hydrosilylation of aldehydes, ketones, and olefins. The utility and mechanism of these hydrosilylations are considered.
- Andrews, Ryan J.,Chitnis, Saurabh S.,Stephan, Douglas W.
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supporting information
p. 5599 - 5602
(2019/05/21)
-
- Synthesis of hierarchical zeolites by solid state crystallization of aluminosilicate nanogels
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Hierarchically porous ZSM-5 zeolites, having macropores, mesopores, and micropores are formed using a solid-state crystallization process. An aluminosilicate nanogel prepared with precursors, solvent, and a structure-directing agent is provided. The solvent is evaporated from the aluminosilicate nanogel at room temperature. The dried aluminosilicate nanogel is then heated to promote crystallization. The crystallized zeolites are calcined to remove the structure-directing agent.
- -
-
Page/Page column 9; 10; 15
(2019/07/19)
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- Nickel–Tungsten and Nickel–Molybdenum Sulfide Diesel Hydrocarbon Hydrogenation Catalysts Synthesized in Pores of Aromatic Polymer Materials
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Abstract: Porous aromatic polymer materials based on tetraphenylmethane molecules linked by methylene groups have been synthesized. By impregnating these materials with nickel–tungsten and nickel–molybdenum thiosalts, catalysts for the hydrogenation of bicyclic aromatic hydrocarbons of the diesel fraction have been prepared. Nanoparticles of the active sulfide phase are formed in support pores during the reaction; it is assumed that after the formation of the nanoparticles, the support material will undergo partial degradation to rearrange the mesoporous structure into a macroporous structure providing the best diffusion of substrates to the surface of the sulfide nanoparticles. The synthesized catalysts have been tested in the hydrogenation of naphthalene and naphthalene derivatives at a hydrogen pressure of 5 MPa and a temperature of 380°C.
- Batryshin,Makeeva,Kulikov,Kardasheva, Yu. S.,Maksimov,Karakhanov
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p. 575 - 580
(2019/06/24)
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- Synthesis and Reactivity of [PCCP]-Coordinated Group 5 Alkyl and Alkylidene Complexes Featuring a Metallacyclopropene Backbone
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The R2P-functionalized tolanes 1a (R = Ph) and 1b (R = iPr) were employed for the synthesis of [PCCP]-coordinated group 5 complexes. In the case of vanadium, the d1-configured dialkyl species [PCCP]V(CH2SiMe3)2 (3a and 3b) were prepared and found to be resistant toward oxidation, i.e., the corresponding alkylidene complexes were not observed upon treatment with various oxidants. For niobium and tantalum, however, the high-valent d0-configured alkyl-alkylidene complexes [PCCP]M(=CHSiMe3)(CH2SiMe3) (M = Nb: 6b, M = Ta: 7b) were obtained for the iPr2P-substituted ligand. Both these alkylidenes, i.e., 6b and 7b, were employed for ring-opening metathesis polymerizations (ROMP) of strained olefins. Although the ??2-alkyne motifs in 6b and 7b are best described as metallacyclopropenes, the unsaturated ligand backbone was neither degraded nor copolymerized over the course of these polymerizations. Upon hydrogenolysis of 7b, however, the metallacyclopropene backbone was partially hydrogenated, and the dinuclear (μ-H)3-bridged tantalum(V) complex 8 featuring a metallacyclopropane substructure was formed. An intermediate in this reaction was shown to catalytically hydrogenate one or both arenes in naphthalene, while the isolated dimeric species 8 was found to be inactive under identical reaction conditions.
- Federmann, Patrick,Richter, Tim,Wadepohl, Hubert,Ballmann, Joachim
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p. 4307 - 4318
(2019/11/03)
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
-
- Birch-Type Photoreduction of Arenes and Heteroarenes by Sensitized Electron Transfer
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The direct reduction of arenes and heteroarenes by visible-light irradiation remains challenging, as the energy of a single photon is not sufficient for breaking aromatic stabilization. Shown herein is that the energy accumulation of two visible-light photons allows the dearomatization of arenes and heteroarenes. Mechanistic investigations confirm that the combination of energy-transfer and electron-transfer processes generates an arene radical anion, which is subsequently trapped by hydrogen-atom transfer and finally protonated to form the dearomatized product. The photoreduction converts planar aromatic feedstock compounds into molecular skeletons that are of use in organic synthesis.
- Chatterjee, Anamitra,K?nig, Burkhard
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supporting information
p. 14289 - 14294
(2019/08/30)
-
- Stereoselective Aromatic Ring Hydrogenation over Supported Rhodium Catalysts in Supercritical Carbon Dioxide Solvent
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The combination of supported rhodium metal catalysts and supercritical carbon dioxide solvent was effective for the stereoselective ring hydrogenations of aromatic compounds at low temperature. Higher solubility of hydrogen in supercritical carbon dioxide provides higher concentration of hydrogen on the rhodium surface, but lower that of the intermediate on rhodium surface, which suppresses the flipping of surface intermediate, leading to higher catalyst activities and cis selectivities to the corresponding ring-hydrogenated products as compared with those in organic solvents.
- Shirai,Hiyoshi,Rode
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p. 1926 - 1934
(2019/01/05)
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- Decarboxylative Intramolecular Arene Alkylation Using N-(Acyloxy)phthalimides, an Organic Photocatalyst, and Visible Light
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An intramolecular arene alkylation reaction has been developed using the organic photocatalyst 4CzIPN, visible light, and N-(acyloxy)phthalimides as radical precursors. Reaction conditions were optimized via high-throughput experimentation, and electron-rich and electron-deficient arenes and heteroarenes are viable reaction substrates. This reaction enables access to a diverse set of fused, partially saturated cores which are of high interest in synthetic and medicinal chemistry.
- Sherwood, Trevor C.,Xiao, Hai-Yun,Bhaskar, Roshan G.,Simmons, Eric M.,Zaretsky, Serge,Rauch, Martin P.,Knowles, Robert R.,Dhar, T. G. Murali
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p. 8360 - 8379
(2019/09/03)
-
- Room Temperature Chemoselective Deoxygenation of Aromatic Ketones and Aldehydes Promoted by a Tandem Pd/TiO2 + FeCl3 Catalyst
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A rapid and practical protocol for the chemoselective deoxygenation of various aromatic ketones and aldehydes was described, which used a tandem catalyst composed of heterogeneous Pd/TiO2 + homogeneous FeCl3 with the green hydrogen source, polymethylhydrosiloxane (PMHS). The developed catalytic system was robust and scalable, as exemplified by the deoxygenation of acetophenone, which was performed on a gram scale in an atmospheric environment utilizing only 0.4 mol % Pd/TiO2 + 10 mol % FeCl3 catalyst to give the corresponding ethylbenzene in 96% yield within 10 min at room temperature. Furthermore, the Pd/TiO2 catalyst was shown to be recyclable up to three times without an observable decrease in efficiency and it exhibited low metal leaching under the reaction conditions. Insights toward the reaction mechanism of Pd-catalyzed reductive deoxygenation for aromatic ketones and aldehydes were investigated through operando IR, NMR, and GC-MS techniques.
- Dong, Zhenhua,Yuan, Jinwei,Xiao, Yongmei,Mao, Pu,Wang, Wentao
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p. 11067 - 11073
(2018/09/12)
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- Chlorotrimethylsilane and Sodium Iodide: A Remarkable Metal-Free Association for the Desulfurization of Benzylic Dithioketals under Mild Conditions
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A novel metal-free process allowing the reductive desulfurization of various benzylic dithioketals to afford diarylmethane and benzylester derivatives with good to excellent yields is reported. At room temperature, this mild reduction process requires only the use of TMSCl and NaI in CH2Cl2 and tolerates a large variety of functional groups. (Figure presented.).
- Zhao, Guangkuan,Yuan, Ling-Zhi,Alami, Mouad,Provot, Olivier
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p. 2522 - 2536
(2018/05/14)
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- Ruthenium nanoparticles ligated by cholesterol-derived NHCs and their application in the hydrogenation of arenes
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Herein we present ruthenium nanoparticles (Ru-NPs) stabilized with two rigid NHC ligands derived from cholesterol. The obtained nanoparticles were fully characterized and applied in the hydrogenation of various aromatic compounds under mild conditions. Interestingly, the more bulky ligand gives a slightly lower ligand coverage and a faster catalyst.
- Rakers, Lena,Martínez-Prieto, Luis M.,López-Vinasco, Angela M.,Philippot, Karine,Van Leeuwen, Piet W. N. M.,Chaudret, Bruno,Glorius, Frank
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p. 7070 - 7073
(2018/07/05)
-
- Hydrogenation of naphthalene and anthracene on Pt/C catalysts
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Hydrogenation of naphthalene and anthracene deposited on Sibunit and active carbon was studied. The reactions were carried out at a temperature of 280 °C and a pressure of 90 atm. The directions for the complete hydrogenation of the investigated substrates were studied. Correlations between the structures of naphthalene and anthracene and their activity in hydrogen absorption are presented. The hydrogenation rates decrease as the substrate is saturated with hydrogen.
- Kalenchuk,Koklin,Bogdan,Kustov
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p. 1406 - 1411
(2018/10/31)
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- Birch Reduction of Aromatic Compounds by Inorganic Electride [Ca2N]+?e- in an Alcoholic Solvent: An Analogue of Solvated Electrons
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Birch reduction of aromatic systems by solvated electrons in alkali metal-ammonia solutions is widely recognized as a key reaction that functionalizes highly stable π-conjugated organic systems. In spite of recent advances in Birch reduction with regard to reducing agent and reaction conditions, there remains an ongoing challenge to develop a simple and efficient Birch reaction under mild conditions. Here, we demonstrate that the inorganic electride [Ca2N]+?e- promotes the Birch reduction of polycyclic aromatic hydrocarbons (PAHs) and naphthalene under alcoholic solvent in the vicinity of room temperature as a solid-type analogy to solvated electrons in alkali metal ammonia solutions. The anionic electrons from electride [Ca2N]+?e- are transferred to PAHs and naphthalene via alcoholysis in a polar cosolvent medium. It is noteworthy that a high conversion yield to the hydrogenated products is ascribed to the extremely high electron transfer efficiency of 98%. This simple protocol utilizing an inorganic electride offers a direct and practical strategy for the reduction of aromatic compounds and provides an outstanding reducing agent for synthetic chemistry.
- Yoo, Byung Il,Kim, Ye Ji,You, Youngmin,Yang, Jung Woon,Kim, Sung Wng
-
supporting information
p. 13847 - 13853
(2018/11/23)
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- Nickel-Catalyzed Reductive Cleavage of Carbon-Oxygen Bonds in Anisole Derivatives Using Diisopropylaminoborane
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The catalytic removal of a methoxy group on an aromatic ring allows this group to be used as a traceless activating and directing group for aromatic functionalization reactions. Although several catalytic methods for the reductive cleavage of anisole derivatives have been reported, all are applicable only to π-extended aryl ethers, such as naphthyl and biphenyl ethers, while monocyclic aryl ethers cannot be reduced. Herein, we report a nickel-catalyzed reductive cleavage reaction of C-O bonds in aryl ethers using diisopropylaminoborane as the reducing agent. Unlike previously reported methods, this reducing reagent allows effective C-O bond reduction in a much wider range of aryl ether substrates, including monocyclic and heterocyclic ethers bearing various functional groups.
- Igarashi, Takuya,Haito, Akira,Chatani, Naoto,Tobisu, Mamoru
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p. 7475 - 7483
(2018/07/21)
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- Novel electronic salt system and method for reducing unsaturated hydrocarbon compound
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The invention discloses an electronic salt system and a method for reducing unsaturated hydrocarbon compounds by using the electronic salt system, belongs to the field of organic synthesis, and solvesthe problems such as complicated operation, harsh conditions, easy generation of complex over-reduction products of methods for reducing the unsaturated hydrocarbon compounds in the prior art. An electron salt may be synthesized by an alkali metal reagent, an ether and an alcohol, the ether can be a crown ether or a cryptand; and the method adopts the electronic salt system, the unsaturated hydrocarbon compounds is reduced by the electronic salt system in an organic solvent. The method for reducing the unsaturated hydrocarbon compounds is used for reducing the unsaturated hydrocarbon compounds.
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Paragraph 0145-0149
(2018/09/08)
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- Formal Cross-Coupling of Diaryl Ethers with Ammonia by Dual C(Ar)-O Bond Cleavages
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The conversion of renewable resources and inexpensive inorganic chemicals directly into higher value-added organic chemicals is becoming more and more important for our society's future sustainable development. Lignin, being the second most abundant organic carbon renewable resource on Earth, has been treated as waste in the pulp and paper industry. The 4-O-5 linkage diaryl ether bond is the strongest among the three types of ether linkages in lignins. Selective cleavage of this linkage can potentially generate smaller processable bio-based aromatic polymeric materials and compounds. Furthermore, there has been a long synthetic interest in coupling reactions with aryl ethers via C(Ar)-O bond cleavage, for example, for polyphenylene oxide (PPO) waste recycling. On the other hand, ammonia is a very inexpensive industrial inorganic chemical. Herein, we report a direct conversion of diaryl ethers and ammonia into aniline derivatives and arenes, providing a model for selective lignin 4-O-5 linkage modification and PPO recycling with inexpensive ammonia. Both symmetrical and unsymmetrical diaryl ethers were successfully cross-coupled with ammonia via dual C(Ar)-O bond cleavages, generating the corresponding cyclohexylanilines and arenes.
- Cao, Dawei,Zeng, Huiying,Li, Chao-Jun
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p. 8873 - 8878
(2018/09/12)
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- Method for converting diaryl ether to N-cyclohexylaniline compound
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The invention discloses a method for converting diaryl ether to an N-cyclohexylaniline compound. The method comprises the following steps of under the effect of a catalyst, through reaction of a diaryl ether compound with ammonia water and a reducer, forming a drug or a skeletion N-cyclohexylaniline as a natural product, with important physiological activity and a derivative. The method provided by the invention is simple and available in raw material, high in conversion rate, important in product and good in yield and has a wide application prospect of degradation as well as deep developmentand utilization of lignin and polydiphenyl ether plastics.
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Paragraph 0067; 0068; 0069
(2019/01/14)
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- The synthesis and mechanistic studies of a highly active nickel phosphide catalyst for naphthalene hydrodearomatization
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Although HDS and HDN reactions over transition metal phosphides have been widely studied, few publications about aromatic hydrodearomatization (HDA) over transition metal phosphides are found. Using ordered mesoporous Al-MCM-41 (Al-M) as the support, a series of supported nickel phosphide catalysts with different Ni/P molar ratios and loadings have been prepared by a temperature-programmed reduction and characterized. The HDA activity of naphthalene was measured in a fixed bed reactor at 250-330 °C and 3 MPa. The results showed that the catalyst with initial Ni/P molar ratio of 1.25 and 15 wt% loading displayed the highest HDA activity as well as 99.0% of selectivity of decalin at 270 °C, which is even higher than that of 0.5 wt% Pt-Al-M catalyst. As a comparison, the HDA performance of various catalysts was also examined. The results revealed that the presence of framework aluminum favors HDA processes and a synergistic effect between nickel phosphide and the suitable acidity resulted in an improvement of the catalytic activity. Finally, the possible reaction pathway of naphthalene hydrogenation (HYD) on nickel phosphide catalysts was proposed. Taking into consideration the high catalytic activity, Al-M supported nickel phosphide can be considered as a very efficient HDA catalyst to decrease the contents of aromatics in the fuels.
- Yun, Guoxia,Guan, Qingxin,Li, Wei
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p. 8677 - 8687
(2017/02/10)
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- Nickel–molybdenum sulfide naphthalene hydrogenation catalysts synthesized by the in situ decomposition of oil-soluble precursors
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Nickel–molybdenum sulfide catalysts for the hydrogenation of aromatic hydrocarbons have been prepared by the in situ decomposition of oil-soluble precursors Mo(CO)6 and Ni(С7H15СOO)2 in a hydrocarbon feedstock and characterized by HRTEM and XPS. The resulting Ni–Mo sulfide material exhibits high catalytic activity in the naphthalene hydrogenation reaction. An optimum Mo/Ni ratio of 1/2 has been selected.
- Sizova,Maksimov
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p. 595 - 599
(2017/07/22)
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- Ruthenium-nickel-nickel hydroxide nanoparticles for room temperature catalytic hydrogenation
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Improving the utilization of metals in heterogeneous catalysts with excellent catalytic performance, high selectivity and good stability represents a major challenge. Herein a new strategy is disclosed by enabling a nanoscale synergy between a transition metal and a noble metal. A novel Ru/Ni/Ni(OH)2/C catalyst, which is a hybrid of Ru nanoclusters anchored on Ni/Ni(OH)2 nanoparticles (NPs), was designed, prepared and characterized. The Ru/Ni/Ni(OH)2/C catalyst exhibited a remarkable catalytic activity for naphthalene hydrogenation in comparison with existing Ru/C, Ni/Ni(OH)2/C and Ru-Ni alloy/C catalysts. This is mainly attributed to the interfacial Ru, Ni and Ni(OH)2 sites of Ru/Ni/Ni(OH)2/C, where hydrogen is adsorbed and activated on Ru while Ni transfers the activated hydrogen species (as a "bridge") to the activated naphthalene on Ni(OH)2 sites, producing decalin through a highly effective pathway.
- Zhu, Lihua,Shan, Shiyao,Petkov, Valeri,Hu, Weiwei,Kroner, Anna,Zheng, Jinbao,Yu, Changlin,Zhang, Nuowei,Li, Yunhua,Luque, Rafael,Zhong, Chuan-Jian,Ye, Hengqiang,Yang, Zhiqing,Chen, Bing H.
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p. 7869 - 7875
(2017/07/13)
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- Pd/C-Al-water facilitated selective reduction of a broad variety of functional groups
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The chemoselective reduction of a broad variety of functional groups by a Pd/C-Al-H2O system is described. The reduction is based on the reaction of Al with the solvent water that in situ produces hydrogen that is utilized by the supported Pd catalyst toward the hydrogenation of the target functional groups. The hydrogenations are carried out under mild conditions and provided the products in high yields and selectivity. The reduction system appeared to be effective for a broad range of functional groups, including C-C, C-N, C-O and N-O multiple bonds, aromatic rings, hydrogenolysis of C-O, C-N and C-Halogen bonds. The appropriate selection of the reaction conditions allowed the selective preparation of different products from the same substrate. The simplicity, cost, tunability and the environmentally benign character of the catalytic system offer numerous advantages over the currently available methods.
- Sch?fer,Ellstrom,Cho,T?r?k
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p. 1230 - 1234
(2017/03/20)
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- Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
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The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.
- Gieshoff, Tim N.,Chakraborty, Uttam,Villa, Matteo,Jacobi von Wangelin, Axel
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supporting information
p. 3585 - 3589
(2017/03/21)
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