Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functio...Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functionalized silica spheres was studied in absence and presence of H2O. The structural properties were adjusted by varying solvents and surfactants during the synthesis and, at constant amine loadings, were found to be the main factor for influencing the CO2 sorption capacities. Under water-free conditions CO2 is bound to the amino groups via the formation of carbamates, which require two neighboring amino groups to adsorb one CO2 molecule. At constant amine concentrations sorbents with lower surface area allow to establish a higher amine density on the surface, which enhances the CO2 uptake capacities under dry conditions. In presence of H2O the CO2 adsorption changes to 1：1 stoichiometry due to stabilization of carbamates by protonation of H2O and formation of further species such as bicarbonates, which should in principle double the adsorption capacities. Low concentrations of physisorbed H2O（0.3 mmol/g） did not impair the adsorption capacity of the adsorbents for CO2, while at higher water uptakes（0.6 and 1.1 mmol/g） the CO2 uptake is reduced, which could be attributed to capillary condensation of H2O or formation of bulky reaction products blocking inner pores and access to active sites.展开更多
The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A ...The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A high toluene conversion(90.7%)and high selectivity of mono-bromotoluene(99.0%)was achieved under the optimal reaction conditions.The UV-Raman spectroscopy was applied for the mechanism study and the result reveals that HTS is efficient for catalyzing the oxidation reaction of HBr with H2O2 to produce abundant active bromine species,which can further facilitate the toluene electrophilic bromination reaction.A two-step toluene bromination reaction mechanism involving the HTS catalyzed active bromine species“generation-conversion-utilization”process is proposed based on the UV-Raman spectroscopy analysis.展开更多
Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing t...Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.展开更多
A facile synthesis of benzo[h]quinolines has been developed via improved Combes reaction. A combination of silica gel, p-toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1-naph...A facile synthesis of benzo[h]quinolines has been developed via improved Combes reaction. A combination of silica gel, p-toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1-naphthylamines with 1,3-diketones under solvent free conditions. In this case, silica gel was used as reaction media, p-toluenesulfonic acid and phosphorus pentoxide were acted as catalyst and dehydrating agent, respectively.展开更多
Neurodegenerative diseases are the consequences of imbalance between the production of oxidative stress and its nullification by cellular defense mechanisms. Hydrogen peroxide(H_2O_2), a precursor of deleterious react...Neurodegenerative diseases are the consequences of imbalance between the production of oxidative stress and its nullification by cellular defense mechanisms. Hydrogen peroxide(H_2O_2), a precursor of deleterious reactive oxygen species, elicits oxidative stress, resulting in severe brain injuries. Bacopa monnieri is well known for its nerve relaxing and memory enhancing properties. The present study was designed to evaluate the protective effects of extracts from Bacopa monnieri against H_2O_2 induced oxidative stress using a cellular model, neuroblastoma IMR32 cell line. The protective potential of methanolic, ethanolic, and water extracts of B. monnieri(BM-MEx, BM-EEx, and BM-WEx) was evaluated using MTT assay. Although, all the B. monnieri extracts were found to protect cells against H_2O_2-mediated stress but BM-MEx showed significantly greater protection. UPLC analysis of BM-MEx revealed various polyphenols, including quercetin, catechin, umbelliferone, and caffeic acid predominance. Further, BM-MEx was found to possess considerable greater neuroprotective potential in comparison to the standard polyphenols such as quercetin, catechin, umbelliferone, and caffeic acid. The levels of antioxidant enzymes were significantly elevated after the pretreatment of BM-MEx and quercetin. The expression levels of oxidative stress markers, such as NF200, HSP70, and mortalin, were significantly alleviated after the pretreatment of BM-MEx as shown by immunofluorescence and RT-PCR. In conclusion, the present study demonstrated the protective effects of BM-MEx, suggesting that it could be a candidate for the development of neuropathological therapeutics.展开更多
基金supported by the German Research Council(DFG)within the priority program(Schwerpunktprogramm),“Poröse Medien mit definierter Porenstruktur in der Verfahrenstechnik–Modellierung,Anwendngen,Synthese”(SPP 1570)under the projects LE 1187/10 and SP 648/4the framework of the DFG Excellence Initiative the Cluster of Excellence“Engineering of Advanced Materials”(DFG EXC 415)funding via the DFG research training group GRK 1896
文摘Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functionalized silica spheres was studied in absence and presence of H2O. The structural properties were adjusted by varying solvents and surfactants during the synthesis and, at constant amine loadings, were found to be the main factor for influencing the CO2 sorption capacities. Under water-free conditions CO2 is bound to the amino groups via the formation of carbamates, which require two neighboring amino groups to adsorb one CO2 molecule. At constant amine concentrations sorbents with lower surface area allow to establish a higher amine density on the surface, which enhances the CO2 uptake capacities under dry conditions. In presence of H2O the CO2 adsorption changes to 1：1 stoichiometry due to stabilization of carbamates by protonation of H2O and formation of further species such as bicarbonates, which should in principle double the adsorption capacities. Low concentrations of physisorbed H2O（0.3 mmol/g） did not impair the adsorption capacity of the adsorbents for CO2, while at higher water uptakes（0.6 and 1.1 mmol/g） the CO2 uptake is reduced, which could be attributed to capillary condensation of H2O or formation of bulky reaction products blocking inner pores and access to active sites.
基金The author thanks for the financial support of SINOPEC Corporation(S413108).
文摘The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A high toluene conversion(90.7%)and high selectivity of mono-bromotoluene(99.0%)was achieved under the optimal reaction conditions.The UV-Raman spectroscopy was applied for the mechanism study and the result reveals that HTS is efficient for catalyzing the oxidation reaction of HBr with H2O2 to produce abundant active bromine species,which can further facilitate the toluene electrophilic bromination reaction.A two-step toluene bromination reaction mechanism involving the HTS catalyzed active bromine species“generation-conversion-utilization”process is proposed based on the UV-Raman spectroscopy analysis.
文摘Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.
文摘A facile synthesis of benzo[h]quinolines has been developed via improved Combes reaction. A combination of silica gel, p-toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1-naphthylamines with 1,3-diketones under solvent free conditions. In this case, silica gel was used as reaction media, p-toluenesulfonic acid and phosphorus pentoxide were acted as catalyst and dehydrating agent, respectively.
基金supported by grants from the Department of Science and Technology (DST), Ministry of Science and Technology, New Delhi under order No. SR/FT/LS-163 and University with Potential for Excellence (UPE) Scheme, University Grants Commission, New Delhi
文摘Neurodegenerative diseases are the consequences of imbalance between the production of oxidative stress and its nullification by cellular defense mechanisms. Hydrogen peroxide(H_2O_2), a precursor of deleterious reactive oxygen species, elicits oxidative stress, resulting in severe brain injuries. Bacopa monnieri is well known for its nerve relaxing and memory enhancing properties. The present study was designed to evaluate the protective effects of extracts from Bacopa monnieri against H_2O_2 induced oxidative stress using a cellular model, neuroblastoma IMR32 cell line. The protective potential of methanolic, ethanolic, and water extracts of B. monnieri(BM-MEx, BM-EEx, and BM-WEx) was evaluated using MTT assay. Although, all the B. monnieri extracts were found to protect cells against H_2O_2-mediated stress but BM-MEx showed significantly greater protection. UPLC analysis of BM-MEx revealed various polyphenols, including quercetin, catechin, umbelliferone, and caffeic acid predominance. Further, BM-MEx was found to possess considerable greater neuroprotective potential in comparison to the standard polyphenols such as quercetin, catechin, umbelliferone, and caffeic acid. The levels of antioxidant enzymes were significantly elevated after the pretreatment of BM-MEx and quercetin. The expression levels of oxidative stress markers, such as NF200, HSP70, and mortalin, were significantly alleviated after the pretreatment of BM-MEx as shown by immunofluorescence and RT-PCR. In conclusion, the present study demonstrated the protective effects of BM-MEx, suggesting that it could be a candidate for the development of neuropathological therapeutics.
