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https://www.readbyqxmd.com/read/28330256/immobilized-lipase-catalyzing-glucose-stearate-synthesis-and-their-surfactant-properties-analysis
#1
A Maria Sebatini, Manisha Jain, P Radha, S Kiruthika, Krishnamurthi Tamilarasan
Sugar fatty acid esters are practical importance and have a variety of applications that include surfactants and as an emulsifying agent. In this study, we report glucose stearate synthesis using lipase-Fe3O4 nanoparticles catalyst. The influence of various reaction factors, such as silica gel concentration, molar ratio of sugar/acid, reaction temperature and speed of agitation on esterification by immobilized enzyme was analyzed. The glucose stearate esterification degree of 87.2 % was obtained under the optimized condition: 1:2 molar ratio of glucose/stearic acid, 2 % (w/v) of silica gel at 120 rpm and 40 °C...
December 2016: 3 Biotech
https://www.readbyqxmd.com/read/28330198/pretreatment-and-enzymatic-process-modification-strategies-to-improve-efficiency-of-sugar-production-from-sugarcane-bagasse
#2
Siddhartha Pal, Shereena Joy, Kalpana D Trimukhe, Pramod S Kumbhar, Anjani J Varma, Sasisanker Padmanabhan
Pretreatment and enzymatic hydrolysis play a critical role in the economic production of sugars and fuels from lignocellulosic biomass. In this study, we evaluated diverse pilot-scale pretreatments and different post-pretreatment strategies for the production of fermentable sugars from sugarcane bagasse. For the pretreatment of bagasse at pilot-scale level, steam explosion without catalyst and combination of sulfuric and oxalic acids at low and high loadings were used. Subsequently, to enhance the efficiency of enzymatic hydrolysis of the pretreated bagasse, three different post-pretreatment process schemes were investigated...
December 2016: 3 Biotech
https://www.readbyqxmd.com/read/28329760/low-temperature-hydrogen-production-from-water-and-methanol-using-pt-%C3%AE-moc-catalysts
#3
Lili Lin, Wu Zhou, Rui Gao, Siyu Yao, Xiao Zhang, Wenqian Xu, Shijian Zheng, Zheng Jiang, Qiaolin Yu, Yong-Wang Li, Chuan Shi, Xiao-Dong Wen, Ding Ma
Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM)...
March 22, 2017: Nature
https://www.readbyqxmd.com/read/28329727/theoretical-study-on-the-alkylation-of-o-xylene-with-styrene-in-alcl3-ionic-liquid-catalytic-system
#4
Bobo Cao, Jiuyao Du, Ziping Cao, Haitao Sun, Xuejun Sun, Hui Fu
To explore sustainable catalysts with innovative mechanisms, the alkylation mechanism of o-xylene with styrene was studied using DFT method in AlCl3-ionic liquid catalytic system. The reaction pathway was consisted of CC coupling and a hydrogen shift, in which two transition states were found and further discussed. The reactive energy catalyzed by superelectrophilic AlCl2(+) (12.6kcal/mol) was distinctly lower than AlCl3 (43.0kcal/mol), which was determined as the rate-determining step. Mulliken charge along IRC gave a comprehensive understanding of charge distribution and electron transfer in dynamic progress...
March 6, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28328225/palladium-catalyzed-%C3%AE-mesylation-of-simple-amide-via-primary-sp-3-c-h-activation
#5
Ren Zhao, Wenjun Lu
A β-mesylation of primary sp(3) C-H bonds from simple amides with methanesulfonic anhydride (Ms2O) has been established successfully at 80 °C in a Pd(OAc)2 (catalyst)/K2S2O8 (oxidant)/CF3CH2OH (solvent) system. These amide substrates involve N-monosubstituted linear, branch, or cyclic alkanes, and electron-deficient benzyl compounds. The β-mesylated amide products can be converted easily to β-fluoroamides or β-lactams through inter- or intramolecular SN2 processes.
March 22, 2017: Organic Letters
https://www.readbyqxmd.com/read/28328163/chemoselective-hydrazine-mediated-transfer-hydrogenation-of-nitroarenes-by-co3-o4-nanoparticles-immobilized-on-an-al-si-mixed-oxide-support
#6
P Linga Reddy, Mohit Tripathi, R Arundhathi, Diwan S Rawat
Cobalt oxide nanoparticles (size 2 to 3.5 nm) were successfully impregnated on an alumina-silica (mixed oxide) support through an experimentally viable and easily reproducible protocol. The prepared material was well characterized by XRD, HR-TEM, BET surface area, EDX and XPS analyses. Porous alumina-silica having a high surface area served as a protective heterogeneous support on which the well-dispersed Co3 O4 nanoparticles served as an active catalytic species for the hydrazine-mediated transfer hydrogenation of nitroarenes...
March 22, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28328101/asymmetric-synthesis-of-spiropyrazolones-by-rhodium-catalyzed-c-sp-2-h-functionalization-annulation-reactions
#7
Jun Zheng, Shao-Bo Wang, Chao Zheng, Shu-Li You
Rhodium-catalyzed C(sp(2) )-H functionalization reactions of 4-aryl-5-pyrazolones followed by [3+2] annulation reactions with alkynes provide rapid access to highly enantioenriched five-membered-ring 4-spiro-5-pyrazolones. The use of a chiral SCpRh catalyst enabled the synthesis of a large range of spiropyrazolones with all-carbon quaternary stereogenic centers in up to 99 % yield and 98 % ee from readily available substrates.
March 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28328085/an-efficient-and-reusable-embedded-ru-catalyst-for-the-hydrogenolysis-of-levulinic-acid-to-%C3%AE-valerolactone
#8
Zuojun Wei, Jiongtao Lou, Chuanmin Su, Dechao Guo, Yingxin Liu, Shuguang Deng
To achieve a higher activity and reusability of a Ru-based catalyst, Ru nanoparticles were embedded in N-doped mesoporous carbon through a hard-template method. The catalyst showed excellent catalytic performance (314 h(-1) turnover frequency) and recyclability (reusable five times with 3 % activity loss) for the hydrogenolysis of levulinic acid to γ-valerolactone. Compared with the mesoporous carbon without N-doping and conventional activated carbon, the introduction of N-dopant effectively improved the dispersion of Ru nanoparticles, decreased the average size of Ru nanoparticles to as small as 1...
March 22, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28328073/surfactant-assisted-stabilization-of-au-colloids-on-solids-for-heterogeneous-catalysis
#9
Wangcheng Zhan, Yuan Shu, Yujie Sheng, Huiyuan Zhu, Yanglong Guo, Li Wang, Yun Guo, Jinshui Zhang, Guanzhong Lu, Sheng Dai
The stabilization of surfactant-assisted synthesized colloidal noble metal nanoparticles (NPs, such as Au NPs) on solids is a promising strategy for preparing supported nanocatalysts for heterogeneous catalysis because of their uniform particle sizes, controllable shapes, and tunable compositions. However, surfactant removal to obtain clean surfaces for catalysis through traditional approaches (such as solvent extraction and thermal decomposition) can easily induce the sintering of NPs, greatly hampering their use in synthesis of novel catalysts...
March 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28327736/a-dnp-supported-solid-state-nmr-study-of-carbon-species-in-fluid-catalytic-cracking-catalysts
#10
Deni Mance, Johan van der Zwan, Marjolein E Z Velthoen, Florian Meirer, Bert M Weckhuysen, Marc Baldus, Eelco T C Vogt
A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles...
March 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28327728/in-situ-fe2n-n-doped-porous-carbon-hybrids-as-superior-catalysts-for-oxygen-reduction-reaction
#11
Xiaoxiao Huang, Ziyu Yang, Bing Dong, Yazhou Wang, Tianyu Tang, Yanglong Hou
Developing efficient and economical noble-metal free catalysts for oxygen reduction reaction (ORR) is one of the essential factors for the industrialization of fuel cells. Recent studies on transition metal ORR catalysts have become the priority to practical low-temperature fuel cells. Herein, we proposed a novel in situ design, Fe2N nanoparticles (NPs) in an N doped porous carbon matrix (Fe2N@NPC) derived from metal organic frameworks (MOFs) as high-performance ORR catalysts. The decorated Fe2N NPs increase the amount of Fe-N/C bonding as catalytic site...
March 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28327721/palladium-catalyzed-highly-regioselective-hydroaminocarbonylation-of-aromatic-alkenes-to-branched-amides
#12
Jinping Zhu, Bao Gao, Hanmin Huang
Pd(t-Bu3P)2 has been successfully identified as an efficient catalyst for the hydroaminocarbonylation of aromatic alkenes to branched amides under relatively mild reaction conditions. With hydroxylamine hydrochloride as an additive, both aliphatic and aromatic amines could be used as coupling partners for the present reaction, leading to production of branched amides in high yields with excellent regioselectivities.
March 22, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28327715/recent-advances-in-cataluminescence-based-optical-sensing-systems
#13
Si Wang, Zhiqin Yuan, Lijuan Zhang, Yanjun Lin, Chao Lu
Cataluminescence (CTL) is a specific chemiluminescence (CL) occurring on the surface of solid catalysts during heterogeneous catalytic oxidation reactions, and it is still a young technique compared to conventional CL. In recent years, CTL-based sensors have been widely used in the detection of various analytes. We have witnessed many developments in CTL-based sensing systems for the enhancement of sensitivity or selectivity. This review provides a thorough introduction to the history and development of CTL-based sensing systems...
March 22, 2017: Analyst
https://www.readbyqxmd.com/read/28327708/facile-embedding-of-single-vanadium-atoms-at-the-anatase-tio2-101-surface
#14
Stig Koust, Logi Arnarson, Poul G Moses, Zheshen Li, Igor Beinik, Jeppe V Lauritsen, Stefan Wendt
To understand the structure-reactivity relationships for mixed-metal oxide catalysts, well-defined systems are required. Mixtures of vanadia and titania (TiO2) are of particular interest for application in heterogeneous catalysis, with TiO2 often acting as the support. By utilizing high-resolution scanning tunneling microscopy, we studied the interaction of vanadium (V) with the anatase TiO2(101) surface in the sub-monolayer regime. At 80 K, metallic V nucleates into homogeneously distributed clusters onto the terraces with no preference for nucleation at the step edges...
March 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28327700/development-of-an-enantioselective-amine-silver-co-catalyzed-conia-ene-reaction
#15
M Blümel, D Hack, L Ronkartz, C Vermeeren, D Enders
The development of a novel cooperative catalytic system for an amine-silver co-catalyzed Conia-ene reaction of alkyne-tethered C-H-acidic compounds is reported. By using a cost-effective silver salt and a small diamine for the 5-exo-dig-cyclization the cyclopentane products are obtained in very good yields. The enantioselectivity of the reaction could be controlled by exchanging the diamine co-catalyst with a cinchona-derived primary amine.
March 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28327642/surface-chemistry-of-rare-earth-oxide-surfaces-at-ambient-conditions-reactions-with-water-and-hydrocarbons
#16
Elçin Külah, Laurent Marot, Roland Steiner, Andriy Romanyuk, Thomas A Jung, Aneliia Wäckerlin, Ernst Meyer
Rare-earth (RE) oxide surfaces are of significant importance for catalysis and were recently reported to possess intrinsic hydrophobicity. The surface chemistry of these oxides in the low temperature regime, however, remains to a large extent unexplored. The reactions occurring at RE surfaces at room temperature (RT) in real air environment, in particular, in presence of polycyclic aromatic hydrocarbons (PAHs), were not addressed until now. Discovering these reactions would shed light onto intermediate steps occurring in automotive exhaust catalysts before reaching the final high operational temperature and full conversion of organics...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28327599/metal-organic-framework-templated-synthesis-of-ultrasmall-catalyst-loaded-zno-znco2o4-hollow-spheres-for-enhanced-gas-sensing-properties
#17
Won-Tae Koo, Seon-Jin Choi, Ji-Soo Jang, Il-Doo Kim
To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2-3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28326782/synthesis-and-properties-of-triarylhalostibonium-cations
#18
Mengxi Yang, François P Gabbaï
As part of our fundamental interest in the chemistry of main-group Lewis acids, we have decided to target stibonium cations whose Lewis acidity is enhanced by the presence of a halogen substituent directly bound to antimony. Starting from Ph3Sb(OTf)2 (1) and Mes3Sb(OTf)2 (2), we successfully prepared the triflate derivatives Ph3SbF(OTf) (3) and Mes3SbF(OTf) (4). We also synthesized the hexachloroantimonate salt of [Mes3SbCl](+) (6), an analogue of the known [Ph3SbCl][SbCl6] (5). The structures of these complexes have been investigated experimentally as well as computationally using density functional theory methods...
March 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28326774/%C3%AE-functionalization-of-indolin-2-one-derived-aliphatic-acids-for-the-divergent-synthesis-of-spirooxindole-%C3%AE-butyrolactones
#19
Jing Cao, Shuding Dong, Delu Jiang, Peiyu Zhu, Han Zhang, Rui Li, Zhanyi Li, Xuanyu Wang, Weifang Tang, Ding Du
β-Functionalization of indolin-2-one-derived aliphatic acids has been applied in formal [3+2] annualtions for catalyst-free and divergent synthesis of two series of structurally interesting 3, 3'-spirooxindole γ-butyrolactones that may be attractive for potential drug discovery. These findings also pave the way for further diversity-oriented synthesis of spirooxindoles starting from indolin-2-one-derived aliphatic acids or their derivatives.
March 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28326679/synthesis-of-pyridine-zinc-based-porous-organic-polymer-for-cocatalyst-free-cycloaddition-of-epoxides
#20
He Li, Chunzhi Li, Jian Chen, Lina Liu, Qihua Yang
Synthesis of solid catalysts for co-catalyst free CO2 cycloaddition reaction has attracted much research attention. Herein we report a hierarchical porous organic polymer, Py-Zn@MA which could catalyze cycloaddition reaction with epoxides and CO2 without using any additives or co-catalyst to afford turnover frequency (TOF) as high as 250 and 97 h-1 at 130 oC using pure and diluted CO2 (a simulating flue gas), respectively. These results are superior to most ever reported heterogeneous co-catalyst free systems...
March 22, 2017: Chemistry, An Asian Journal
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