Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.449
Filtrar
1.
Top Curr Chem (Cham) ; 378(1): 11, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31903506

RESUMO

The dramatic increase in atmospheric carbon dioxide (CO2) concentrations has attracted human attention and many strategies about converting CO2 into high-value chemicals have been put forward. Metal-organic frameworks (MOFs), as a class of versatile materials, have been widely used in CO2 capture and chemical conversion, due to their unique porosity, multiple active centers and good stability and recyclability. Herein, we focused on the processes of chemical conversion of CO2 by MOFs-based catalysts, including the coupling reactions of epoxides, aziridines or alkyne molecules, CO2 hydrogenation, and other CO2 conversion reactions. The synthesized methods and high catalytic activity of MOFs-based materials were also analyzed systematically. Finally, a brief perspective on feasible strategies is presented to improve the catalytic activity of novel MOFs-based materials and explore the new CO2 conversion reactions.


Assuntos
Dióxido de Carbono/química , Estruturas Metalorgânicas/química , Alcenos/química , Aminas/química , Aziridinas/química , Catálise , Compostos de Epóxi/química , Hidrogenação , Líquidos Iônicos/química
2.
Bioresour Technol ; 297: 122492, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31796376

RESUMO

In this study, the Mo-promoted Ir/SiO2 (Ir-MoOx/SiO2) catalysts combined with the zeolite HZSM-5 were used for the direct conversion of microcrystalline cellulose (MCC) to liquid fuel (C5/C6 alkanes) in n-dodecane/H2O system. A synergistic effect was formed between the partially reduced MoOx species and the Ir particles, which effectively promoted the catalytic activity of Ir/SiO2 catalyst. When the Mo/Ir molar ratio was 0.5, a high yield of C5/C6 alkanes (91.7%) was achieved at 210 â„ƒ for 12 h. In addition, the main component of C5/C6 alkanes was n-hexane, which was proven to be obtained by the hydrogenolysis of the key intermediate, sorbitol, formed from the hydrolysis and hydrogenation of MCC.


Assuntos
Alcanos , Dióxido de Silício , Catálise , Celulose , Hidrogenação
3.
Biosci Biotechnol Biochem ; 84(1): 37-42, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31578944

RESUMO

The monoterpene, trans-p-menth-3-ene-1,2,8-triol, is a naturally occurring alcohol isolated from several herbal plants. In the present work, the asymmetric synthesis of both enantiomers of this natural product was achieved using Sharpless asymmetric dihydroxylation as the key step. A reversal of enantiofacial selectivity was observed in the asymmetric dihydroxylation.


Assuntos
/química , Extratos Vegetais/química , Extratos Vegetais/síntese química , Cromatografia em Gel , Cristalização , Cromatografia Gasosa-Espectrometria de Massas , Hidrogenação , Hidroxilação , Isomerismo , Conformação Molecular , Extratos Vegetais/isolamento & purificação , Sílica Gel
4.
Chemosphere ; 239: 124740, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31527005

RESUMO

Bromochloroacetic acid is classified as one of the typical disinfection byproducts (DBPs). In this work, supported palladium catalysts on different supports (CeO2, Al2O3, SiO2 and activated carbon (AC)) (labelled as Pd/support) were synthesized via the deposition-precipitation method (D-P method) and their activities for the complete dehalogenation of bromochloroacetic acid by liquid phase catalytic hydrogenation were evaluated. Comprehensive characterizations of the catalysts were conducted by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), point of zero charge (PZC), X-ray photoelectron spectroscopy (XPS) and CO chemisorption. Results indicated that the PZCs of the supports varied with each other. The stronger Pd-support interaction and higher Pd dispersion of Pd/CeO2 and Pd/Al2O3 than those of Pd/AC and Pd/SiO2 were confirmed by X-ray photoelectron spectroscopy and CO chemisorption. Pd/CeO2 had a higher ratio of positively charged Pd to metallic Pd (Pdn+/Pd0) than Pd/Al2O3 and Pd/AC due to a stronger metal-support interaction. Accordingly, a negligible bromochloroacetic acid conversion was observed on Pd/SiO2, whereas bromochloroacetic acid was found to be readily decomposed on Pd/CeO2, Pd/Al2O3 and Pd/AC. However, the dechlorination reaction could not further proceed on Pd/Al2O3 and Pd/AC catalysts after the bromine functionality was removed from bromochloroacetic acid. A complete dehalogenation of bromochloroacetic acid occurred only on Pd/CeO2. Furthermore, the dechlorination rate constants of monochloroacetic acid and bromochloroacetic acid over Pd(1.40)/CeO2 were 0.018 and 0.031 min-1 respectively, confirming an induced synergistic effect due to the existence of bromine atoms. It was worth noting that a stepwise-concerted pathway was verified during the liquid phase catalytic hydrodehalogenation of bromochloroacetic acid.


Assuntos
Acetatos/química , Cério/química , Paládio/química , Poluentes Químicos da Água/química , Monóxido de Carbono/química , Catálise , Carvão Vegetal , Desinfetantes/química , Halogenação , Hidrogenação , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Dióxido de Silício/química , Difração de Raios X
5.
Environ Sci Technol ; 53(21): 12893-12903, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31595750

RESUMO

In the present paper, the mechanisms of N2O reduction by H2 were systemically examined over various polyoxometalate-supported single-atom catalysts (SACs) M1/PTA (M = Fe, Co, Mn, Ru, Rh, Os, Ir, and Pt; PTA = [PW12O40]3-) by means of density functional theory calculations. Among these M1/PTA SACs, Os1/PTA SAC possesses high activity for N2O reduction by H2 with a relatively low rate-determining barrier. The favorable catalytic pathway involves the first and second N2O decomposition over the Os1/PTA SAC and hydrogenation of the key species after the second N2O decomposition. Molecular geometry and electronic structure analyses along the favorable reaction pathway indicate that a strong charge-transfer cooperative effect of metal and support effectively improves the catalytic activity of Os1/PTA SAC. The isolated Os atom not only plays the role of adsorption and activation of the N2O molecule but also works as an electron transfer medium in the whole reaction process. Meanwhile, the PTA support with very high redox stability has also been proven to be capable of transporting the electron to promote the whole reaction. We expect that our computation results can provide ideas for designing new SACs for N2O reduction by using H2 selective catalytic reduction technology.


Assuntos
Teoria da Densidade Funcional , Adsorção , Catálise , Hidrogenação , Ácido Fosfotúngstico
6.
Nat Commun ; 10(1): 4094, 2019 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-31554785

RESUMO

The hydrogen isotope deuterium is widely used in the synthesis of isotopically-labeled compounds and in the fabrication of semiconductors and optical fibers. However, the facile production of deuterium gas (D2) and hydrogen deuteride (HD) in a controlled manner is a challenging task, and rational heterogeneously-catalyzed protocols are still lacking. Herein, we demonstrate the selective production of hydrogen isotope compounds from a combination of formic acid and D2O, through cooperative action by a PdAg nanocatalyst on a silica substrate whose surface is modified with amine groups. In this process, D2 is predominantly evolved by the assist of weakly basic amine moieties, while nanocatalyst particles in the vicinity of strongly basic amine groups promote the preferential formation of HD. Kinetic data and calculations based on semi-classically corrected transition state theory coupled with density functional theory suggest that quantum tunneling dominates the hydrogen/deuterium exchange reaction over the metallic PdAg surfaces.


Assuntos
Formiatos/química , Hidrogênio/farmacologia , Catálise , Preparações de Ação Retardada/farmacologia , Deutério/química , Óxido de Deutério/química , Hidrogenação , Nanopartículas/química , Água/química
7.
Top Curr Chem (Cham) ; 377(5): 27, 2019 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-31559502

RESUMO

The photocatalytic dehydrogenation of formic acid has recently emerged as an outstanding alternative to the traditional thermal catalysts widely applied in this reaction. The utilization of photocatalytic processes for the production of hydrogen is an appealing strategy that perfectly matches with the idea of a green and sustainable future energy scenario. However, it sounds easier than it is, and great efforts have been needed to design and develop highly efficient photocatalysts for the production of hydrogen from formic acid. In this work, some of the most representative strategies adopted for this application are reviewed, paying particular attention to systems based on TiO2, CdS and C3N4.


Assuntos
Formiatos/química , Hidrogênio/química , Catálise , Hidrogenação , Tamanho da Partícula , Processos Fotoquímicos
8.
Phys Chem Chem Phys ; 21(38): 21370-21380, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31531468

RESUMO

Density functional theory modelling has been used to design Mo and W-based catalysts MoIII(tBu)(CO) and WIII(tBu)(CO) for CO2 hydrogenation and HCOOH dehydrogenation, which are bio-mimics of the active site of formate dehydrogenase. Based on DFT calculations, the molybdenum and tungsten based complexes are good catalysts in the +3 oxidation state for CO2 hydrogenation with free energies of 24.03 and 21.31 kcal mol-1, respectively. Such a low barrier indicates that our newly designed Mo and W-based complexes are very efficient for CO2 hydrogenation or HCOOH dehydrogenation catalysis. Overall, our computational results provide in depth insights that can serve as a great tool for the design and development of new and efficient molybdenum and tungsten based catalysts for CO2 hydrogenation or HCOOH dehydrogenation.


Assuntos
Materiais Biomiméticos/química , Dióxido de Carbono/química , Complexos de Coordenação/química , Formiato Desidrogenases/química , Formiatos/química , Modelos Moleculares , Catálise , Domínio Catalítico , Hidrogenação , Ligantes , Molibdênio/química , Oxirredução , Termodinâmica , Tungstênio/química
9.
Molecules ; 24(17)2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31480751

RESUMO

Biotransformations were performed on eight selected yeast strains, all of which were able to selectively hydrogenate the chalcone derivatives 3-(2"-furyl)- (1) and 3-(2"-thienyl)-1-(2'-hydroxyphenyl)-prop-2-en-1-one (3) into 3-(2"-furyl)- (2) and 3-(2"-thienyl)-1-(2'-hydroxyphenyl)-propan-1-one (4) respectively. The highest efficiency of hydrogenation of the double bond in the substrate 1 was observed in the cultures of Saccharomyces cerevisiae KCh 464 and Yarrowia lipolytica KCh 71 strains. The substrate was converted into the product with > 99% conversion just in six hours after biotransformation started. The compound containing the sulfur atom in its structure was most effectively transformed by the Yarrowia lipolytica KCh 71 culture strain (conversion > 99%, obtained after three hours of substrate incubation). Also, we observed that, different strains of tested yeasts are able to carry out the bioreduction of the used substrate with different yields, depending on the presence of induced and constitutive ene reductases in their cells. The biggest advantage of this process is the efficient production of one product, practically without the formation of side products.


Assuntos
Tiofenos/metabolismo , Leveduras/metabolismo , Biotransformação , Células Cultivadas , Chalconas/metabolismo , Hidrogenação , Especificidade por Substrato , Tiofenos/síntese química , Tiofenos/química
10.
J Agric Food Chem ; 67(35): 9916-9925, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31398025

RESUMO

Targeted analysis confirmed the presence of new phytosterol degradation products in fully hydrogenated commercial samples. EI-MS, APCI-MS, and 1D-NMR experiments led to the identification of 10 novel markers of catalytic hydrogenation, among which 5α-sitostan-3-one and 5α-campestan-3-one, isomers of saturated and monounsaturated steroidal hydrocarbons, were reported in edible oils for the first time. Examination of the phytosterol degradation mechanism was done by the catalytic transfer deuteration technique. The mitigation strategy of potentially detrimental compounds included optimization of processing parameters. The effect of catalyst dosage (≤0.1% based on Ni basis) and temperature region (>180 °C) were the most crucial factors in phytosterol degradation control.


Assuntos
Hidrocarbonetos/química , Óleos Vegetais/química , Catálise , Temperatura Alta , Hidrogenação , Isomerismo , Espectroscopia de Ressonância Magnética , Fitosteróis/química , Espectrometria de Massas por Ionização por Electrospray
11.
J Dairy Sci ; 102(11): 9870-9882, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31447159

RESUMO

Effects of culture pH and corn oil (CO) concentration on biohydrogenation (BH) of unsaturated fatty acids and disappearance of neutral detergent fiber (NDF) in batch culture were evaluated in a 2 × 3 factorial design experiment. Culture vessels (100 mL; 4 replicates/treatment per time point) included ground alfalfa hay plus CO at 0, 1, or 2% dry matter inclusion rate and were incubated at pH 5.8 (low pH) or 6.2 (high pH) for 0, 6, 12, 18, or 24 h. Effects of culture pH, CO, time, and their interactions were determined. Adding CO increased total fatty acid concentration in substrates to 1.01, 2.31, and 3.58% dry matter for 0, 1, and 2% CO, respectively. Corn oil concentration interacted with culture pH and resulted in different effects on BH of cis-9,cis-12 18:2 at low or high culture pH. After 24 h of incubation, low pH, compared with high pH, reduced disappearance of NDF by 35% and BH extent of cis-9,cis-12 18:2 by 31%. Increasing CO increased disappearance of NDF across pH treatments and decreased BH extent of cis-9,cis-12 18:2 at low pH and increased it at high pH over 24 h. Compared with high pH, low pH reduced concentrations of 18:0 by 31% and increased concentrations of trans-10,cis-12 18:2 and trans-10 18:1 by 110 and 79% after 24 h, respectively. Adding CO at low pH had greater effect on BH intermediates of cis-9,cis-12 18:2 compared with adding oil at high pH. In particular, increasing CO to 1 and 2% DM at low pH, compared with at high pH, resulted in a 36 and 46% reduction in the concentration of 18:0, an 84 and 131% increase in the concentration of trans-10,cis-12 18:2, and an 81 and 129% increase in the concentration of trans-10 18:1, respectively. Despite the interactions between culture pH and CO concentration, main effects across time were also significant for the response variables of interest. In conclusion, culture pH interacted with CO concentration to affect BH of UFA and disappearance of NDF in batch culture, as the effects were greater at low culture pH than at high culture pH.


Assuntos
Óleo de Milho/química , Fibras na Dieta/metabolismo , Ácidos Graxos Insaturados/química , Ácidos Graxos/química , Leite/química , Ração Animal/análise , Animais , Bovinos/fisiologia , Dieta/veterinária , Suplementos Nutricionais/análise , Feminino , Concentração de Íons de Hidrogênio , Hidrogenação , Lactação , Leite/metabolismo , Rúmen/metabolismo , Rúmen/microbiologia
12.
Molecules ; 24(15)2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31366120

RESUMO

The chiral structure of antibiotic vancomycin (Van) was exploited as an innovative coordination sphere for the preparation of an IrCp* based hybrid catalysts. We found that Van is able to coordinate iridium (Ir(III)) and the complexation was demonstrated by several analytical techniques such as MALDI-TOF, UV, Circular dichroism (CD), Raman IR, and NMR. The hybrid system so obtained was employed in the Asymmetric Transfer Hydrogenation (ATH) of cyclic imines allowing to obtain a valuable 61% e.e. (R) in the asymmetric reduction of quinaldine 2. The catalytic system exhibited a saturation kinetics with a calculated efficiency of Kcat/KM = 0.688 h-1mM-1.


Assuntos
Antibacterianos/química , Complexos de Coordenação/química , Iminas/química , Irídio/química , Vancomicina/química , Catálise , Hidrogenação , Cinética , Oxirredução , Quinaldinas/química , Estereoisomerismo
13.
Molecules ; 24(14)2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31340434

RESUMO

Eupatorin is the major bioactive component of Java tea (Orthosiphon stamineus), exhibiting strong anticancer and anti-inflammatory activities. However, no research on the metabolism of eupatorin has been reported to date. In the present study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with an efficient online data acquisition and a multiple data processing method were developed for metabolite identification in vivo (rat plasma, bile, urine and feces) and in vitro (rat liver microsomes and intestinal flora). A total of 51 metabolites in vivo, 60 metabolites in vitro were structurally characterized. The loss of CH2, CH2O, O, CO, oxidation, methylation, glucuronidation, sulfate conjugation, N-acetylation, hydrogenation, ketone formation, glycine conjugation, glutamine conjugation and glucose conjugation were the main metabolic pathways of eupatorin. This was the first identification of metabolites of eupatorin in vivo and in vitro and it will provide reference and valuable evidence for further development of new pharmaceuticals and pharmacological mechanisms.


Assuntos
Flavonoides/farmacocinética , Glicoconjugados/isolamento & purificação , Microssomos Hepáticos/metabolismo , Orthosiphon/química , Acetilação , Animais , Bile/química , Biotransformação , Fezes/química , Flavonoides/sangue , Flavonoides/urina , Microbioma Gastrointestinal/fisiologia , Glicoconjugados/metabolismo , Hidrogenação , Masculino , Metilação , Oxirredução , Extratos Vegetais/química , Ratos , Ratos Sprague-Dawley , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
14.
Top Curr Chem (Cham) ; 377(4): 20, 2019 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-31273478

RESUMO

Form a green and sustainable chemistry point of view, cross-dehydrogenative coupling (or oxidative cross-coupling) reactions have been recognized as environmentally sustainable and atom economical synthetic routes for the construction of new carbon-carbon and carbon-heteroatom bonds, since no pre-functionalization of starting materials is required. In the past few years, the direct coupling of sp-hybridized C-H bonds with heteroatom-H bonds has received much attention because of the importance of heteroatom-substituted alkynes in organic and medicinal chemistry. This review examines the recent developments in cross-dehydrogenative coupling reactions between C(sp)-H and X-H (X = N, P, S, Si, Sn) bonds, with a particular focus on the mechanistic aspects of the reactions.


Assuntos
Alquinos/química , Carbono/química , Hidrogênio/química , Hidrogenação , Nitrogênio/química , Fósforo/química , Silício/química , Enxofre/química , Estanho/química
15.
Phys Chem Chem Phys ; 21(28): 15400-15407, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31271395

RESUMO

A biomimetic membrane formed by hybrid Janus dendrimers (JDs) which contain hydrogenated and fluorinated dendrons was explored by dissipative particle dynamics simulations. The JD membrane is bilayered and shows a bicontinuous morphology which is also observed in nano-sized dendrimersomes. The thickness of the dendrimersome is significantly less than that of the planar membrane. The co-assembly of lipids with JDs to develop a hybrid membrane was studied as well. Lipids tend to locate in the hydrocarbon domain of the bicontinuous structure of the JD-rich membrane, while 2-dimensional micelles of JDs float in the leaflet of the lipid-rich membrane. The microstructure of the hybrid membrane was quantified by interdigitation lengths in the hydrocarbon, fluorocarbon, and lipid domains. Finally, the influence of lipid concentration on lipid fluidity was examined in terms of lipid diffusivity, which is found to be closely associated with the membrane microstructure.


Assuntos
Dendrímeros/química , Flúor/química , Lipídeos/química , Membranas Artificiais , Simulação por Computador , Hidrogenação , Micelas
16.
Molecules ; 24(14)2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31340614

RESUMO

Photoreactions of acetonitrile solutions of 3,3-diaryl-1,1-dicyano-2-methylprop-1-enes (1a-c) with allyltrimethylsilane (2) in the presence of phenanthrene as a photoredox catalyst and acetic acid as a proton source formed photoallylation (3) and photoreduction (4) products via photoinduced electron transfer pathways. When (S)-mandelic acid was used as the proton source, the reactions proceeded with 3.4 and 4.8 %ee for formation of 3 and 4, respectively. The results of studies of the effect of aryl ring substituents and several chiral carboxylic acids suggested that the enantioselectivities of the reactions are governed by steric controlled proton transfer in intermediate complexes formed by π-π and OH-π interactions of anion radicals derived from 1a-c and chiral carboxylic acids.


Assuntos
Ácidos Carboxílicos/química , Nitrilos/química , Fenantrenos/química , Prótons , Compostos de Trimetilsilil/química , Ácido Acético/química , Alcenos/química , Ânions , Catálise , Radicais Livres , Hidrogenação , Luz , Processos Fotoquímicos , Estereoisomerismo
17.
J Oleo Sci ; 68(7): 615-623, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31178461

RESUMO

The role of Ni-Ag bimetallic magnetic catalysts in the catalytic transfer of hydrogenated soybean oil was studied. First, a Ni-Ag0.15/PVP-DB-171/SiO2/Fe3O4 magnetic catalyst with a magnetic saturation value of 10.431 emu / g was prepared. It was found that the addition of the metal Ag promoter enhanced the dispersion of Ni on the PVP-DB-171/SiO2/Fe3O4 support. The conditions of the catalytic transfer hydrogenation (CTH) (temperature 80°C, catalyst loading 0.23%, donor concentration 0.32 mol /50 mL H2O, and time 90 min) showed the effects of the bimetallic catalysts on the soybean oil hydrogenation process. The hydrogenated soybean oil linolenic acid, linoleic acid and oleic acid reaction rate constants were 4.95×10-2, 8.6×10-3 and 7.54×10-4, respectively. The selectivity of linolenic acid and linoleic acid is as high as 5.75 and 11.4, respectively; the iodine value (IV) of soybean oil after hydrogenation is 102 g I2/100g and the trans fatty acids(TFAs) content is only 1.7%. The use efficiency of the catalyst decreased to 60% after 8 cycles. Catalytic transfer hydrogenation has important research significance and application prospects for the preparation of low-trans hydrogenated oils and fats. This method also provides a theoretical basis for the development of the oil hydrogenation industry.


Assuntos
Magnetismo , Níquel/química , Prata/química , Óleo de Soja/química , Catálise , Hidrogenação
18.
J Oleo Sci ; 68(7): 679-687, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31178468

RESUMO

Hydrotalcite or Mg-Al LDHs were synthesized by co-precipitation method. The Mg-Al mixed oxide was then derived by calcination of hydrotalcite at 450°C. The metal modified catalysts (Mo/Mg-Al and V/Mg-Al) were prepared by incipient wetness impregnation method. The obtained catalysts were characterized by several useful techniques and tested the reactivity for dehydrogenation and oxidative dehydrogenation of ethanol (gas-phase) to produce acetaldehyde. The catalytic reactions were performed at temperature range from 200 to 400°C for both non-oxidative and oxidative atmospheres. The results showed that the vanadium-modified hydrotalcite (V/Mg-Al) exhibited the highest ethanol conversion (34.3%) and acetaldehyde yield (15.5%) at 400℃ in the non-oxidative atmosphere. For the oxidative dehydrogenation of ethanol, the V/Mg-Al catalyst showed the highest activity at 400°C giving the ethanol conversion and acetaldehyde yield of 73.7% and 29.5%, respectively. This result probably related to the highest base density of V/Mg-Al catalyst (6.13 µmol CO2/m2) measured by CO2-TPD. The catalytic activity of Mg-Al catalyst and metal modified catalyst slightly decreased upon time-on-stream test for 10 h on oxidative dehydrogenation of ethanol due to carbon deposition.


Assuntos
Compostos de Alumínio/química , Hidróxido de Alumínio/química , Etanol/química , Compostos de Magnésio/química , Hidróxido de Magnésio/química , Molibdênio/química , Vanádio/química , Compostos de Alumínio/síntese química , Hidróxido de Alumínio/síntese química , Carbono , Catálise , Precipitação Química , Temperatura Alta , Hidrogenação , Compostos de Magnésio/síntese química , Hidróxido de Magnésio/síntese química , Oxirredução
19.
Chem Pharm Bull (Tokyo) ; 67(6): 594-598, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31155565

RESUMO

In this study, the total synthesis of 3-epi-juruenolide C is achieved in 10 steps (longest linear sequence) starting from ethyl (2E,4S,5S)-4,5-dihydroxy-2-hexenoate. The synthetic highlights of our approach include one-pot regioselective bromination, intramolecular carbonylation using bis(triphenylphosphine)dicarbonylnickel, and face-selective hydrogenation using a homogeneous Wilkinson's catalyst.


Assuntos
Dioxóis/síntese química , Lactonas/síntese química , Catálise , Complexos de Coordenação/química , Dioxóis/química , Halogenação , Hidrogenação , Lactonas/química , Níquel/química , Compostos Organofosforados/química , Estereoisomerismo
20.
Mater Sci Eng C Mater Biol Appl ; 102: 458-470, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31147017

RESUMO

The clinical treatment of bone tumors usually brings about residual tumor cells and large bone defects after tumor removal surgery. To solve this problem, it is imperative to develop a novel implant with bi-functions for eliminating the residual tumor cells and repairing bone defects. In this study, hydrogenated black TiO2 (H-TiO2) coating with hierarchical micro/nano-topographies is fabricated by induction suspension plasma spraying (ISPS). The fabricated H-TiO2 coating possessed excellent and controllable photothermal effect in inhibiting the tumor growth under 808 nm NIR laser irradiation in vitro and in vivo. The hierarchical hybrid micro/nano-structured surface and Ti-OH groups improved the adhesion, proliferation, differentiation and osteogenic gene expressions of rat bone mesenchymal stem cells (rBMSCs). These results demonstrate that the H-TiO2 coating may be a promising implant material for the treatment of bone tumors and bone regeneration.


Assuntos
Neoplasias Ósseas/terapia , Regeneração Óssea/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Hipertermia Induzida , Fototerapia , Titânio/farmacologia , Animais , Neoplasias Ósseas/patologia , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Hidrogenação , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/ultraestrutura , Camundongos Endogâmicos BALB C , Camundongos Nus , Osteogênese/efeitos dos fármacos , Espectroscopia Fotoeletrônica , Ratos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA