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1.
Analyst ; 148(6): 1309-1321, 2023 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-36852542

RESUMO

The role of nitrogen functional groups in nitrogen-doped ordered mesoporous carbons (OMCs) toward the spontaneous non-covalent and electrografting was investigated using two home-made ionic liquid-derived ordered mesoporous carbons having different nitrogen concentrations (guanine-rich ionic liquid-derived ordered mesoporous carbon (GIOMC) and ionic liquid-derived ordered mesoporous carbon (IOMC)). The carbonaceous materials were fabricated by the carbonization of a mixture of ionic liquid (1-methyl-3-phenethyl-1H-imidazolium hydrogen sulfate) as a carbon source using SBA-15 as a hard template. Guanine was used during the carbonization of GIOMC as a nitrogen source. The electrode was modified with either GIOMC or IOMC followed by electrochemical surface functionalization with a few electro-active precursors as redox-active molecular models bearing different substituents and electronic properties. The high surface coverage of 5.6(±0.3) × 10-9 mol cm-2 for 4,4-biphenol was obtained for the GIOMC-modified electrode. We seek to explain whether the nitrogen content could indeed exert a dramatic impact on loading electroactive species on the electrode surface. The non-covalent anchoring studies indicated that at higher pH values the loading of electro-active moieties was significantly influenced by the content of nitrogen on the employed OMCs. The adsorption capacity (mg g-1) of the OMCs was studied for catechol as a typical electro-active species in the range of 0.050-0.165 mg ml-1. The adsorption capacity of 0.11 mg g-1 catechol was 42(±4) and 26(±3) mg g-1 for GIOMC and IOMC, respectively. In addition, our observations revealed that electro-grafting efficiency via diazonium ion was restricted by the protonation of nitrogen in the reaction media. Further, the fabricated redox-active/N-doped OMC electrodes showed sensitivity to pH, which was accompanied by either a Nernstian shift of the redox peak potentials (60(±3) mV per pH) in the pH range of 2-13 in the buffer solutions or variations of the redox peak currents (9.7(±0.3) µA per pH) in the pH range of 1-5.5 in the unbuffered situations. The resulting electrodes as voltammetric pH probes showed a simple response to pH in both buffer and unbuffered solutions. In addition, we introduced the fabricated electrode as a zero-gap generator/collector electrode system using a single electrode to recognize proton-dependent electron transfer from the proton-independent electrode process by detecting pH changes quite close to the surface of the electrode. The detailed descriptions are outlined.

2.
Org Biomol Chem ; 21(8): 1692-1703, 2023 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-36734617

RESUMO

A series of metal-free tandem reactions for the synthesis of pharmaceutically important 2-substituted benzoazoles from isothiocyanates and 2-aminothiophenol under catalyst-free conditions in the presence of Et-PMO-Me-PrSO3H (1a) and SBA-15-PrSO3H (1b) as solid acids were carried out in a highly selective way under solvent free conditions. A significant selectivity changeover toward either 2-mercaptobenzoxazole or 2-aminobenzoazole derivatives could be achieved by changing the employed catalyst from the relatively hydrophobic material 1a to the more hydrophilic catalyst 1b. This simple experimental procedure with a novel selective approach toward benzoazoles accompanied by green and reusable catalysts could be considered as an alternative to the existing methods for the synthesis of 2-substituted benzoazole derivatives.

3.
Analyst ; 145(2): 596-606, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31777872

RESUMO

The two-electron oxidation of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) results in highly unstable TMPD2+ in aqueous solutions. Despite its low redox potential, TMPD2+/TMPD couple is not considered as a suitable charge transfer functional group to modify the electrode due to instability of TMPD2+ in aqueous solutions. The main focus of the present paper is to fabricate an efficient redox-active electrode by coupling TMPD with 4-nitroaniline to be utilized for on-surface chemistry. The nitro functional group in the coupling product N2,N2,N5,N5-tetramethyl-4'-nitro-[1,1'-biphenyl]-2,5-diamine (MNPD) was reduced electrochemically to the corresponding amino derivative (MAPD). The oxidized form of MAPD (MAPD2+) exhibited high stability as well as low reduction potential in aqueous solutions. A redox active electrode was designed via the immobilization of the electro-generated MAPD onto a nanofibrillated mesoporous carbon (IFMC) modified glassy carbon electrode (GCE). The redox signal increased several folds with the deposition of IFMC onto glassy carbon electrode compared to bare GCE. Two functionalization routes, electro-grafting and spontaneous physical immobilization, were examined for the attachment of the redox species to the electrode surface. In the first approach, electro-grafting was attained via the electrochemical reduction of MNPD in the presence of sodium nitrite to produce diazonium ions in situ. The redox centers covalently grafted to the surface showed dense deposition and appreciable stability. In the second route, spontaneous adsorption was performed by the same strategy of electro-grafting in the absence of sodium nitrite. In this case, the hydrophobic nanofiber structure of IFMC was capable of robustly trapping MAPD. The anchored MAPD shows high reactivity in Michael addition reactions in ultrafast reaction times. The post-functionalization of the electrodes was easily performed by the oxidation of the redox centers in the presence of species with nucleophilic properties at the electrode/electrolyte interface. In addition, both the constructed electrodes are introduced as suitable mediators in electro-catalytic implications because of their reversibility, stability, and low oxidation potential. The electro-catalytic activity of the electrodes was established for the indirect electrochemical oxidation of homocysteine as a typical substrate.

4.
Mikrochim Acta ; 186(4): 239, 2019 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-30868266

RESUMO

The authors describe the preparation of two kinds of periodic mesoporous organosilicas (PMOs). The first kind is monofunctional and has a bridged alkyl imidazolium framework (PMO-IL). The other is a two-dimensional (2D) hexagonal bifunctional periodic mesoporous organosilica (BFPMO) with bridged IL-phenyl or -ethyl units. The CPMOs were utilized as highly sensitive and stable sorbents for microextraction by packed sorbent. The materials were characterized by SEM, TEM, FT-IR, and N2 adsorption-desorption analysis. The adsorption capacities of the sorbents were investigated by using phenoxy acid herbicides as model analytes. The effects of bifunctionality and type of additional surface groups (phenyl or ethyl) on the efficiency of the extraction is emphasized. Three kinds of environmental contaminants, viz. phenoxy acid herbicides (CPAs), polycyclic aromatic hydrocarbons and chlorophenols were then studied with respect to their extraction by the sorbents. The interactions between the CPAs and the sorbents were evaluated by pH-changing processes to explore the interactions that play a major role. The selectivity of the sorbents was investigated by extraction of other types of analytes of with various polarity and charge. The BFPMOs display the typical good chemical stability of silica materials. The extraction properties are much better compared to commercial silicas. This is assumed to be due to the highly ordered mesoporous structures and the different types of probable interactions with analytes. The performance of the method was evaluated by extraction of CPAs as model analytes from aqueous samples, and quantification by GC with FID detection. Under optimized conditions, low limits of detection (0.1-0.5 µg.L-1) and a wide linearity (0.5-200 µg.L-1) were obtained. The method was applied to the trace analysis of CPAs in farm waters and rice samples. Graphical abstract Monofunctional periodic mesoporous organosilica with bridged alkyl imidazolium frameworks and bi-functional periodic mesoporous organosilica containing bridged ionic liquids and phenyl or -ethyl, have been successfully synthesized and utilized in microextractions by packed sorbent sorbents.

5.
Phytochem Anal ; 30(2): 193-197, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30460725

RESUMO

INTRODUCTION: Research on the volatile oil composition of Thymus kotschyanus Boiss was conducted by applying mesoporous organosilica based on alkylimidazolium ionic liquid (PMO-IL) as a fibre coating material via a method referred to as microwave-assisted headspace solid-phase microextraction (MA-HS-SPME). METHODOLOGY: This technique entails microwave irradiation of the sample and collection of the volatile sample components. These components are further introduced into a gas chromatography-mass spectrometry (GC-MS) injection port for further analysis. A simplex method was used for the optimisation of three different parameters affecting the efficiency of the extraction. CONCLUSION: The MA-HS-SPME method proved to be the most suitable technique in oil determination and extraction from Thymus kotschyanus owing to its advantageous aspects of cost effectiveness, simplicity and solvent independence.


Assuntos
Imidazóis/química , Líquidos Iônicos/química , Micro-Ondas , Óleos Voláteis/análise , Dióxido de Silício/química , Microextração em Fase Sólida/métodos , Thymus (Planta)/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Solventes/química
6.
Int Emerg Nurs ; 72: 101381, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38086282

RESUMO

BACKGROUND: Child resuscitation is a critical and stressful time for family caregivers and healthcare professionals. The aim of this study was to explore caregivers' and healthcare professionals' experiences and perceptions of a parental supporter during pediatric cardiopulmonary resuscitation to provide guidance to healthcare professionals on supporting parents and other family caregivers during resuscitation. METHODS: This study used an exploratory descriptive qualitative approach. The setting was two large referral pediatric governmental hospitals. Participants were 17 caregivers who had experienced their child's resuscitation, and 13 healthcare professionals who served on resuscitation teams in emergency rooms or intensive care wards. Semi-structured, in-depth interviews were conducted and data were analyzed using thematic analysis. COREQ guidelines were followed. RESULTS: Participants shared their experiences and perceptions of a parental supporter during pediatric resuscitation in three themes: 1) Requirement for the presence of a parental supporter, 2) Expectations of the parental supporter, and 3) Characteristics of the parental supporter. CONCLUSIONS: Study findings highlight the need for a parental supporter during pediatric resuscitation; however, there is no defined parental supporter role in current guiding policies due to limited research on this role. More research on the parental supporter role is needed so effective policies and protocols can be developed to enhance family-centered care practices in pediatric emergency and acute care settings.


Assuntos
Reanimação Cardiopulmonar , Cuidadores , Humanos , Criança , Pesquisa Qualitativa , Pais , Atitude do Pessoal de Saúde
7.
Chemistry ; 19(31): 10142-5, 2013 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-23787963

RESUMO

Go Mannich! A highly efficient and enantioselective method for the direct asymmetric reaction of dibenzyl malonate with N-tert-butoxycarbonyl aldimines in the presence of Yb(OTf)3 and iPr-pybox complexes is described (see scheme; pybox = pyridine bisoxazoline).


Assuntos
Iminas/química , Malonatos/química , Mesilatos/química , Compostos Organometálicos/química , Piridinas/química , Catálise , Estrutura Molecular , Estereoisomerismo , Temperatura
8.
Analyst ; 138(6): 1740-4, 2013 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-23359870

RESUMO

A novel and simple method for the electrochemical modification of ordered mesoporous silica is described. A well-organized thin film of amine-functionalized ordered mesoporous silica has been deposited electrochemically on the electrode surface. The resulting amine-functionalized electrodes were then subjected to post-functionalization with catechol moieties through electrochemical generation of reactive o-quinone followed by covalent bonding to the anchored amine groups inside the mesoporous channels of silica to afford the corresponding modified electrodes bearing aminocatechol electroactive groups. This simply obtained nanoporous modified electrode with adequate loading of electroactive groups shows very good electrochemical responses.

9.
Org Biomol Chem ; 11(3): 416-9, 2013 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-23208696

RESUMO

A new binary photocatalyst was easily prepared based on incorporation of amorphous titania into the periodic mesoporous organosilicate framework bearing photoresponsive isocyanurate species. The catalyst was found to be highly active in photocatalytic deoximation reaction under sunlight irradiation.


Assuntos
Aldeídos/síntese química , Cetonas/síntese química , Compostos de Organossilício/química , Oximas/química , Luz Solar , Titânio/química , Aldeídos/química , Catálise , Cetonas/química , Estrutura Molecular , Processos Fotoquímicos , Porosidade , Propriedades de Superfície
10.
Sci Rep ; 13(1): 14736, 2023 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-37679477

RESUMO

Chiral chloro-indeno pybox has served as a new ligand for the Yb(OTf)3-catalyzed asymmetric Friedel-Crafts alkylation reaction of indoles with nitroalkenes. The tunable nature of pybox ligands enables the rational design of catalysts for optimal performance in terms of both activity and stereoselectivity in a Friedel-Crafts-type reaction. Good to excellent yields and enantioselectivities were obtained for a relatively wide range of substrates, including sterically hindered compounds, under optimized reaction conditions.

11.
Chemistry ; 18(28): 8634-40, 2012 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-22707318

RESUMO

A novel nano-fibrillated mesoporous carbon (IFMC) was successfully prepared via carbonization of the ionic liquid 1-methyl-3-phenethyl-1H-imidazolium hydrogen sulfate (1) in the presence of SBA-15. The material was shown to be an efficient and unique support for the palladium nanoparticle (PdNP) catalyst Pd@IFMC (2) in aerobic oxidation of heterocyclic, benzylic, and heteroatom containing alcohols on pure water at temperatures as low as 40 °C for the first time and giving almost consistent activities and selectivities within more than six reaction runs. The catalyst has also been employed as an effective catalyst for the selective oxidation of aliphatic and allylic alcohols at 70-80 °C. The materials were characterized by X-ray photoelectron spectroscopy (XPS), N(2) adsorption-desorption analysis, transmission electron microscopy (TEM), and electron tomography (ET). Our compelling XPS and ET studies showed that higher activity of 2 compared to Pd@CMK-3 and Pd/C in the aerobic oxidation of alcohols on water might be due to the presence of nitrogen functionalities inside the carbon structure and also the fibrous nature of our materials. The presence of a nitrogen heteroatom in the carboneous framework might also be responsible for the relatively uniform and nearly atomic-scale distribution of PdNPs throughout the mesoporous structure and the inhibition of Pd agglomeration during the reaction, resulting in high durability, high stability, and recycling characteristics of 2. This effect was clearly confirmed by comparing the TEM images of the recovered 2 and Pd@CMK-3.


Assuntos
Álcoois/química , Carbono/química , Nanopartículas/química , Paládio/química , Água/química , Catálise , Oxirredução , Espectroscopia Fotoeletrônica , Dióxido de Silício/química
12.
Chemistry ; 18(42): 13520-30, 2012 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-22945297

RESUMO

The preparation and characterization of a set of periodic mesoporous organosilicas (PMOs) that contain different fractions of 1,3-bis(3-trimethoxysilylpropyl)imidazolium chloride (BTMSPI) groups uniformly distributed in the silica mesoporous framework is described. The mesoporous structure of the materials was characterized by powder X-ray diffraction, transmission electron microscopy, and N(2) adsorption-desorption analysis. The presence of propyl imidazolium groups in the silica framework of the materials was also characterized by solid-state NMR spectroscopy and diffuse-reflectance Fourier-transform infrared spectroscopy. The effect of the BTMSPI concentration in the initial solutions on the structural properties (including morphology) of the final materials was also examined. The total organic content of the PMOs was measured by elemental analysis, whereas their thermal stability was determined by thermogravimetric analysis. Among the described materials, it was found that PMO with 10% imidazolium content is an effective host for the immobilization of perruthenate through an ion-exchange protocol. The resulting Ru@PI-10 was then employed as a recyclable catalyst in the highly efficient aerobic oxidation of various types of alcohols.


Assuntos
Álcoois/química , Imidazóis/química , Compostos de Organossilício/química , Compostos de Rutênio/química , Adsorção , Catálise , Líquidos Iônicos/química , Compostos de Organossilício/síntese química , Oxirredução , Porosidade , Dióxido de Silício/química
13.
Org Biomol Chem ; 10(23): 4531-6, 2012 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-22569627

RESUMO

A novel SBA-15 functionalized palladium complex partially confined with 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid (Material 4) was found to be a very efficient and reusable catalyst in the Suzuki-Miyaura coupling reaction of aryl halides including aryl chlorides and heteroaryl halides with different aryl boronic acids under aqueous conditions without any organic co-solvents. Our studies showed that 4 is a more efficient catalyst in comparison with the catalyst not containing IL or catalyst with a higher ratio of IL. The materials were characterized by N(2)-sorption analysis, TGA and transmission electron microscopy before and after catalysis. While our studies showed that the catalyst can be successfully recycled and reused in at least 4 reaction runs, in contrast, several poisoning experiments and kinetic studies provide the notion that homogeneous (dissolved) species are responsible for the observed catalysis.

14.
ACS Omega ; 7(35): 30989-31002, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36092616

RESUMO

A macroporous dual-functional acid-base covalent organic polymer catalyst poly(St-VBC)-NH2-SO3H was prepared using high internal phase emulsion polymerization using vinylbenzyl chloride (VBC), styrene (St), and divinylbenzene (DVB) as substrates toluene as a porogenic solvent, and subsequent modification with ethylenediamine and 1,3-propane sultone. The role of various amounts of toluene as the porogenic solvent as well as the amount of 1,3-propane sultone (different ratio of acid/base sites) on the structure of the prepared materials have been carefully investigated. The prepared materials were characterized by Fourier transform infrared (FT-IR), CHNS elemental analysis, energy-dispersive X-ray (EDX), elemental mapping, field emission scanning electron microscopy (FE-SEM), and thermalgravimetric analysis (TGA). The catalytic activity of the poly(St-VBC)-NH2-SO3H series with different acid/base densities was assessed for one-pot cascade C-C bond-forming reactions involving deacetylation-Henry reactions. The poly(St-VBC)-NH2-SO3H(20) sample bearing 1.82 mmol/g of N (base site) and 1.16 mmol/g (acid site) showed the best catalytic activity. The catalyst demonstrated superior activity compared to the homogeneous catalysts, poly(St-DVB)-SO3H+EDA, poly(St-VBC)-NH2+chlorosulfonic acid, and poly(St-DVB)-SO3H+poly(St-VBC)-NH2 as the catalyst system. The optimized catalyst showed excellent catalytic performance with 100% substrate conversion and 100% yield of the final product in the one-pot production of ß-nitrostyrene from benzaldehyde dimethyl acetal under cascade reactions comprising acid-catalyzed deacetalization and base-catalyzed Henry reactions. It was shown that these catalysts were reusable for up to four consecutive runs with a very slight loss of activity. The excellent performance of the catalyst was attributed to the excellent chemical and physical properties of the developed support since it provides an elegant route for preparing site-isolated acid-base dual heterogenized functional groups and preventing their deactivation via chemical neutralization.

15.
Inorg Chem ; 50(13): 6063-72, 2011 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-21648445

RESUMO

The preparation and characterization of a number of main-chain organometallic polymers (NHC-Pd MCOP) with different N-alkyl substituted groups such as benzyl (3a), n-hexyl (3b), and n-dodecyl (3c) are described. Among these polymers, 3c bearing the more lipophilic group n-dodecyl was found to be a more reactive and recoverable catalytic system in the Suzuki-Miyaura cross-coupling reaction of chloroarenes, including both deactivated and hindered aryl chlorides with different types of arylboronic acids under aqueous conditions. While the catalysts seem to be highly recyclable, on the contrary, we have provided much compelling evidence, such as kinetic monitoring, poisoning experiments, and average molecular weight determination before and after catalysis, that shows that the described organometallic polymers might be indeed the source of production of active soluble Pd species in the form of either Pd nanoparticles or fragmented NHC-Pd complexes. Our studies showed that in order to assess whether the catalysts are functioning in a heterogeneous pathway or they are simply a source of production of active Pd species, it is crucial to devise a suitable and highly efficient poison that could capture essentially soluble catalytic species. In this regard, we interestingly found that among a variety of well-known catalyst poisons such as Hg(0), SBA-15-PrSH, and cross-linked poly(4-vinylpyridine) (PVP), only PVP could efficiently quench catalysis, thus providing clear evidence of the formation soluble Pd species in our protocol. In addition, several experiments such as bright-field microscopy, dynamic light scattering (DLS) of the reaction mixture, and kinetic monitoring of the reaction at an early stage confirm not only that the described organometallic polymers could be a source of production of trace amounts of Pd nanoparticles but the capsular structures of these lipophilic polymers in water provides a means of entrapment of nanoclusters in a hydrophobic region, thus accelerating the reaction in pure water in the absence of any co-organic solvent.

16.
Org Biomol Chem ; 9(11): 4194-8, 2011 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-21505706

RESUMO

A novel SBA-15-functionalized TEMPO confined ionic liquid [BMIm]Br was found to be a highly efficient and recyclable catalyst system for the transition-metal-free aerobic oxidation of a wide range of structurally diverse alcohols. Thanks to the strong physical confinement of the ionic liquid inside the mesochannels of SBA-15-supported TEMPO, the resulting solid catalyst showed improved selectivity in the aerobic oxidation of allylic alcohols. The catalyst can be recovered and re-used for at least 11 reaction runs without significant loss of either activity or confined IL.


Assuntos
Álcoois/química , Óxidos N-Cíclicos/química , Líquidos Iônicos/química , Dióxido de Silício/química , Elementos de Transição/química , Aldeídos/síntese química , Aldeídos/química , Catálise , Cetonas/síntese química , Cetonas/química , Estrutura Molecular , Oxirredução , Estereoisomerismo
17.
Org Biomol Chem ; 9(21): 7420-6, 2011 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-21904726

RESUMO

The application of a novel palladium containing ionic liquid based periodic mesoporous organosilica (Pd@PMO-IL) catalyst in the aerobic oxidation of primary and secondary alcohols under molecular oxygen and air atmospheres is investigated. It was found that the catalyst is quite effective for the selective oxidation of several activated and non-activated alcoholic substrates. The catalyst system could be successfully recovered and reused several times without any significant decrease in activity and selectivity. Moreover, the hot filtration test, atomic absorption spectroscopy (AA) and kinetic study with and without selective catalyst poisons showed that the catalyst works in a heterogeneous pathway without any palladium leaching in reaction solution. Furthermore, nitrogen-sorption experiment and transmission electron microscopy (TEM) image proved the superior stability of high-ordered PMO-IL mesostructure during reaction process. TEM image also confirmed the presence of well-distributed Pd-nanoparticles in the uniform mesochannels of the material. These observations can be attributed to the ionic liquid nature of PMO-IL mesostructure which facilitates the reaction through production, chemical immobilization and stabilization of active palladium nanoparticles, as well as preventing Pd-agglomeration during overall process.


Assuntos
Álcoois/química , Imidazóis/química , Cetonas/síntese química , Compostos Organometálicos/química , Compostos de Organossilício/química , Paládio/química , Catálise , Cetonas/química , Estrutura Molecular , Compostos Organometálicos/síntese química , Oxirredução , Tamanho da Partícula , Porosidade , Propriedades de Superfície
18.
J Colloid Interface Sci ; 589: 474-485, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33486283

RESUMO

HYPOTHESIS: It is expected that incorporation of 2, 2, 6, 6-tetra-methyl piperidine-N-oxyl radical (TEMPO) and an imidazolium bromide bearing hydrophilic triethylene glycol (TEG) groups on Fe3O4@SiO2 core-shell may not only result in a novel highly water-dispersible/magnetically separable multi-functional catalyst system for metal-free aerobic oxidation of alcohols, which operates through a synergistic relay pathway, but it could potentially provide a strong platform for simultaneous separation and recycling of all components. EXPERIMENTS: The catalyst was prepared by anchoring TEMPO moieties onto a magnetic core-shell Fe3O4@SiO2 functionalized with an ionic liquid bearing TEG groups. The materials was characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, thermal gravimetric analysis, and elemental analysis. The performance of the catalyst was evaluated and quantitatively measured in the aerobic oxidation of alcohols in water. FINDINGS: The catalyst exhibited excellent and stable colloidal dispersion in water and high performance in the aerobic oxidation of various types of alcohols under metal- and halogen-free reaction conditions. As hypothesized, strong synergistic effect between functionalized components was seen in the described reaction. The catalyst displayed excellent dual-adjustable-selectivity in the oxidation of primary alcohols to either the corresponding aldehydes or carboxylic acids by tuning the reaction solvent and/or reaction time and excellent recycling behavior through a "double-separation-strategy".

19.
Chem Commun (Camb) ; 57(71): 8897-8900, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34486604

RESUMO

The ABNO@PMO-IL-Br material obtained by anchoring 9-azabicyclo[3.3.1]nonane-3-one N-oxyl (keto-ABNO) within the mesopores of periodic mesoporous organosilica with bridged imidazolium groups is a robust bifunctional catalyst for the metal-free aerobic oxidation of numerous primary and secondary alcohols under oxygen balloon reaction conditions. The catalyst, furthermore, can be successfully employed in the first metal-free self-esterification of primary aliphatic alcohols affording valued esters.

20.
Talanta ; 235: 122724, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517592

RESUMO

In this study, a sensitive solid phase microextraction (SPME) coating was developed based on two kinds of plugged and non-plugged bifunctional periodic mesoporous organosilicas (BFPMO) with ionic liquid and ethyl units. The extraction efficiency of all plugged and unplugged sorbents was investigated for the extraction of chlorophenols (CPs) in water and honey samples by emphasizing the effect of different physicochemical properties. The separation and determination of the CPs was performed by gas chromatography-mass spectrometry (GC-MS). The extraction results showed that plugged BFPMO coating exhibited outstanding enrichment ability for the extraction of CPs as model analytes with different polarities. This can be attributed to a valuable hydrophobic-hydrophilic balance in the mesochanels of the plugged BFPMO, which is the result of the combination of plug technology and bridged organic groups. Low limits of detection in the range of 5-70 ng L-1, wide linearity, and good reproducibility (RSD = 8.1-10.1 % for n = 6) under the optimized extraction conditions were achieved. Finally, the BFPMOs coated fiber was successfully used for determination of CPs in real water samples. The relative recoveries for the five CPs were in the range of 92.3-104.0 %, which proved the applicability of the method.


Assuntos
Clorofenóis , Poluentes Químicos da Água , Clorofenóis/análise , Cromatografia Gasosa-Espectrometria de Massas , Reprodutibilidade dos Testes , Microextração em Fase Sólida , Poluentes Químicos da Água/análise
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