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Testing catalytic activity of ruthenium(III) acetylacetonate in the presence of trialkylphosphite or trialkylphosphine in hydrogen generation from the hydrolysis of sodium borohydride
Araştırma Makalesi

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Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Saim Ozkar , Tuelin Demiralp , Mehdi Masjedi
Yıl :
2009
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Catalytic activity of Ru(acac)(3) in the presence of different phosphorus compounds (P(OMe)(3), P(OPh)(3), PPh3 and dppe) was investigated for the first time in the hydrolysis of NaBH4. Phosphorus compound, usually known as poison in catalysis, is involved in the formation of a species which has higher catalytic activity in comparison with Ru(aCaC)(3) alone. Varying the phosphorus compound affects the catalytic activity and lifetime of the catalyst as well as the kinetics and the activation parameters of the hydrolysis of NaBH4. For all of the phosphorus compounds, the hydrogen generation was found to be zero-order with respect to the substrate concentration and first-order regarding the catalyst concentration. The catalyst system with P(OMe)3 shows the highest catalytic activity and provides the largest total turnover number (TTON = 20,700 over 72 h) in the hydrolysis of NaBH4. The highest activation energy and enthalpy values were obtained for the catalyst with dppe (E-a = 59 +/- 2. Delta H-# = 60 +/- 2 kJ/mol) while the lowest values were found for the catalyst system with PPh3 (E-a = 46 +/- 2, Delta H-# = 43 +/- 1 kJ/mol). (C) 2009 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2009.05.022
Sayi :310
issue :1-2
Sayfa :59-63
Sınıflandırma :
2
Palladium(0) nanoclusters stabilized by poly(4-styrenesulfonic acid-co-maleic acid) as an effective catalyst for Suzuki-Miyaura cross-coupling reactions in water
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Saim Ozkar , Murat Aydemir , Feyyaz Durap , Onder Metin
Yıl :
2011
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Palladium(0) nanoclusters stabilized by poly(4-styrenesulfonic acid-co-maleic acid), PSSA-co-MA, were generated in situ during the hydrolysis of ammonia-borane (AB) from the reduction of potassium tetrachloropalladate(II) in aqueous solution at room temperature. They were isolated from the reaction solution and characterized by UV-visible electronic absorption spectroscopy, TEM, SAED and XRD techniques. The PSSA-co-MA stabilized palladium(0) nanoclusters were used as catalyst in Suzuki-Miyaura cross-coupling reactions of various of arylbromides or aryl iodide with phenylboronic acid in water without any purification process after catalytic hydrolysis of AB. They show excellent catalytic activity in coupling of series of aryl bromides or aryl iodide with phenylboronic acid under the optimized reaction conditions in water. PSSA-co-MA stabilized palladium(0) nanoclusters provided turnover frequency of 1980 and 5940h(-1) in Suzuki-Miyaura coupling reactions of phenylboronic acid with p-bromoacetophenone or p-iodobenzene, respectively, which are the highest values ever reported for the Suzuki-Miyaura coupling reactions in water as sole solvent. (C) 2011 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2011.01.011
Sayi :337
issue :1-2
Sayfa :39-44
Sınıflandırma :
3
A skeletal rearrangement study of a carbon-13 labelled 3-methylpentane on doped sulphated zirconia catalysts
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Francois Garin , Umit Bilge Demirci
Yıl :
2006
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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The isomerization on sulphated zirconias of the 3-methyl(3-(13)C)pentane, molecule chosen to distinguish between the methyl and ethyl migrations, is studied.
DOI : 10.1016/j.molcata.2006.05.023
Sayi :258
issue :1-2
Sayfa :46-58
Sınıflandırma :
4
Investigation of ruthenium-copper bimetallic catalysts for direct epoxidation of propylene: A DFT study
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Isik Onal , Selim Senkan , Ali Can Kizilkaya
Yıl :
2010
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Propylene epoxidation reactions are carried out on Ru-Cu(1 1 1) and Cu(1 1 1) surfaces with periodic density functional theory (DFT) calculations. Ru-Cu(1 1 1) surface is modeled as Cu(1 1 1) monolayer totally covering the Ru(0 0 0 1) surface underneath, in accordance with the literature. It is shown that the Ru-Cu(1 1 1) surface is ineffective for propylene oxide formation since it has a lower energy barrier (0.48 eV) for the stripping of the allylic hydrogen of propylene and a higher energy barrier (0.92 eV) towards oxametallacycle formation compared to Cu(1 1 1) surface which has a barrier of 0.83 eV for hydrogen stripping and 0.75 eV for oxametallacycle formation. The reason behind this ineffectiveness is shown to be the higher basicity of the atomic oxygen adsorbed on Ru-Cu(111) compared to Cu(1 11), evaluated by the adsorption of sulfur dioxide onto the systems. The results are consistent both with recent publications about propylene epoxidation and previous studies performed about the structure of Ru-Cu catalysts. (C) 2010 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2010.07.008
Sayi :330
issue :1-2
Sayfa :107-111
Sınıflandırma :
5
Novel homogeneous catalyst comprising ruthenium and trimethylphosphite for the hydrolysis of sodium borohydride
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Saim Ozkar , Leyla Tatar Yildirim , Mehdi Masjedi
Yıl :
2012
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Homogeneous catalytic hydrolysis of sodium borohydride starting with Ru(acac)(3) (acac = acetylacetonate) and P(OMe)(3) was followed by monitoring the hydrogen evolution and the UV-vis electronic absorption spectra which shows the conversion of all ruthenium(III) to a ruthenium(II) species, most likely acting as catalyst. This active catalyst is alive only under reducing conditions and converted mainly to Ru(acac)(3) along with other minor complexes when the catalytic reaction is over. A ruthenium(II) complex was isolated from the reaction solution after the complete catalytic hydrolysis of sodium borohydride and characterized to be [Ru{P(OMe)(3)}(4)H-2] by single crystal XRD, MS. UV-vis, FTIR, H-1, C-13 and P-31 NMR spectroscopy. [Ru{P(OMe)(3)}(4)H-2] complex crystallizes in the triclinic space group P-1 with a = 10.066(2)angstrom, b = 19.108(3)angstrom, c = 20.938(4)angstrom, alpha = 78.839(14)degrees, beta = 87.308(16)degrees and gamma = 79.506(14)degrees. This ruthenium(II) complex was found not to be the active catalyst in the hydrolysis of sodium borohydride, rather one of its conversion products after catalysis. Although the active catalyst could not be isolated from the reaction solution, it could be stabilized by adding chelating 2,2'-bipyridine into the solution during the catalysis. Thus, a stabilized form of the active catalyst, [Ru(acac)(bipy){P(OMe)(3)}H], could be isolated and characterized by MS, UV-vis, FTIR, H-1, C-13 and P-31 NMR spectroscopy. [Ru(acac)(bipy){P(OMe)(3)}H] is expectedly not as active as the ruthenium(II) species formed in situ during the catalysis. Taking all the results together reveals that the active catalyst is a ruthenium(II) complex, either [Ru(acac){P(OMe)(3)}(3)H] or most likely its dissociation product, [Ru(acac){P(OMe)(3)}(2)H]. Control experiments showed that 2,2'-bipyridine can replace only the trimethylphosphite ligands but not the acetylacetonato ligand in the ruthenium(II) complex. (C) 2011 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2011.12.015
Sayi :355
Sayfa :186-191
Sınıflandırma :
6
Graphene-supported NiPd alloy nanoparticles: A novel and highly efficient heterogeneous catalyst system for the reductive amination of aldehydes
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Bela Toeroek , Arif Dastan , Onder Metin , Khadijeh Ganjehyan , Bilal Nisanci
Yıl :
2015
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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A novel and highly efficient heterogeneous catalytic reductive amination of aldehydes is described. The recently developed graphene supported NiPd alloy nanoparticle (G-NiPd) catalyst using ammonia borane (AB) as a green, stable and safe hydrogen donor was used in a water/methanol mixture (v/v=2/3) under ambient conditions. The catalytic system was successfully applied in the reductive amination of various substituted aldehydes with amines and the corresponding products were obtained in (up to) 99% yield in 6 h. The G-NiPd catalyst could be recycled up to five times without any significant loss in the product yield. (C) 2015 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2015.08.022
Sayi :409
Sayfa :191-197
Sınıflandırma :
Kimya %100
Kataliz %97
7
Synthesis, characterization and investigation of homogeneous oxidation activities of peripherally tetra-substituted Co(II) and Fe(II) phthalocyanines: Oxidation of cyclohexene
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Halit Kantekin , Serpil Gokce , Ece Tugba Saka , Zekeriya Biyiklioglu
Yıl :
2013
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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The synthesis and characterization of novel peripherally tetra-substituted iron(II) 4 and cobalt(II) 5 phthalocyanines are described for the first time in this study. All the new compounds are characterized by a combination of IR, H-1 and C-13 NMR, mass and UV-vis spectroscopy techniques. Complexes 4 and 5 served as catalyst for the oxidation of cyclohexene using different types of oxidants, such as tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (m-CPBA), aerobic oxygen and hydrogen peroxide (H2O2). During the oxidation process the products formed are 2-cyclohexene-1-ol, 2-cyclohexene-1-one and cyclohexene oxide. The selectivity for 2-cyclohexene-1-ol is favored when iron(II) and cobalt(II) phthalocyanine catalysts are employed. The higher conversion is obtained as catalyst iron(II) phthalocyanine (96%). TBHP was determined as the successful oxidant with the minimum demolition of the catalyst, superior selectivity and conversion in the oxidation products. (c) 2013 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2013.06.009
Sayi :378
Sayfa :156-163
Sınıflandırma :
Kimya %100
Kataliz %98
8
An EPR and NMR study on Mo/HZSM-5 catalysts for the aromatization of methane: Investigation of the location of the pentavalent molybdenum
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Younes Ben Taarit , Ayse Erdem-Senatalar , Alper Sarioglan , Vu Thi Thu Ha
Yıl :
2013
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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EPR and Al-27 NMR were used to probe the nature of the phases that formed during the conversion of methane at high temperature on the Mo/HZSM-5 catalyst. It was shown that ammonium 6-molybdoaluminate III supported over silica gave rise, when reduced, to an EPR signal due to Mo5+ ions with the odd electron interacting with the nonzero nuclear spin of aluminum in much the same way as in HZSM-5. Therefore, the occurrence of this particular spin interaction should not be taken as evidence of the location of the Mo5+ ions at the exchange sites of the zeolites. Rather, combined Al-27 NMR and EPR investigation of the reduction of a pure polycrystalline aluminum molybdate suggested that the observed signal in the case of the zeolite composite catalyst was due to Mo5+ ions formed within the Al-2(MoO4)(3) extra phase that formed upon dealumination of the zeolite in the presence of molybdenum. (c) 2013 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2013.06.020
Sayi :378
Sayfa :279-284
Sınıflandırma :
Kimya %95
Kataliz %95
9
Highly active and long lived homogeneous catalyst for the dehydrogenation of dimethylamine borane starting with ruthenium(III) acetylacetonate and oleylamine precatalyst
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Saim Ozkar , Mehdi Masjedi , Sibel Duman
Yıl :
2016
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Herein, we report the results of our study on the homogeneous catalytic dehydrogenation of dimethylamine borane in the presence of Ru(acac)(3) and oleylamine (OAm) in toluene solution. The precatalyst system comprising Ru(acac)(3) and 3 equivalent OAm shows the high catalytic activity in hydrogen generation from dimethylamine borane solution. Monitoring the hydrogen evolution shows the presence of an induction period during which the homogeneous catalyst is formed, and then the hydrogen evolution continues almost linearly until the complete dehydrogenation of dimethylamine borane. UV-vis spectroscopic observation implies on the formation of a ruthenium(II)species. Using UV-vis, FTIR, Mass, H-1 and C-13 NMR spectroscopies we could identify the presence of trans-[Ru(acac)(2)(OAm)(2)] in the solid residue obtained after the catalytic reaction. This complex might be a stable form of the active catalyst as it shows similar catalytic activity in dehydrogenation of dimethylamine borane as before. The precatalyst system comprising Ru(acac)(3) and 3 equivalent OAm provides 15,000 turnovers over 8 days with a constant turnover frequency of TOP = 77.8 h(-1) in hydrogen generation from the dehydrogenation of dimethylamine borane in toluene solution at 60.0 +/- 0.1 degrees C. Adding 3 equivalent OAm per Ru into the precatalyst solution increases the catalytic activity by a factor of similar to 5 and the lifetime of the catalyst by a factor of >9 compared to the ones obtained by using sole Ru(acac)(3). Kinetics of catalytic dehydrogenation of dimethylamine borane starting with Ru(acac)(3) and 3 equivalent OAm in toluene solution were studied depending on catalyst concentration, substrate concentration and temperature. The catalytic reaction was found to be first-order with respect to each of both Ru(acac)(3) and dimethylamine borane concentrations. The activation energy for the catalytic dehydrogenation is E-a = 58 +/- 2 kJ/mol. (C) 2015 Published by Elsevier B.V.
DOI : 10.1016/j.molcata.2015.08.006
Sayi :411
Sayfa :9-18
Sınıflandırma :
10
Synthesis of surfactant-assisted FeVO4 nanostructure: Characterization and photocatalytic degradation of phenol
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Gulin Selda Pozan Soylu , Beysim Ozturk
Yıl :
2015
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Pure triclinic FeVO4 catalysts Were synthesized by hydrothermal method and modified with Hexadecyltrimethylammonium Bromide (HTAB), Sodium Dodecyl Sulfate, Polyethylene Glycol (PEG) as surfactant. The materials were characterized by XRD, BET, FT-IR, DRS and SEM techniques. These catalysts were used for the photocatalytic degradation of phenol (Ph) under natural solar light irradiation. The effect of preparation parameters on the photocatalytic activity was also examined. It is found that the surfactant and pH value a significant influence on the particle morphology and even the crystalline structure of the product. Surfactant added products resulted an improve efficiency of the triclinic FeVO4. With HTAB as surfactant at an hydrothermal temperature of 75 degrees C and the pH 3 value of the precursor solution the highest percentage of phenol degradation (100%) and highest reaction rate (1.24 mgl(-1) min(-1)) were obtained in 45 min. It is concluded that the excellent photocatlytic activity of the HTAB-assisted FeVO4 catalyst, with rod-like shaped morphology, was associated its small particle size, large surface area, the presence of more surface OH groups and lower band gap energy than pure FeVO4. (C) 2014 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2014.11.013
Sayi :398
Sayfa :65-71
Sınıflandırma :
11
Mechanism of CuAAC reaction: In acetic acid and aprotic conditions
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Nurcan Senyurt Tuzun , Cihan Ozen
Yıl :
2017
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Kaydet Alıntıla
Protonation of copper-triazolide is a distinctive and final part in CuAAC reaction which has kinetic importance such that it can even affect the product distribution. In the context of this study, the protonation mechanism of copper-triazolide was investigated with quantum mechanical calculations to have a deeper understanding of the mechanism. In aprotic conditions where the alkyne is considered as proton donor, the key finding of DFI' calculations performed in this study is that the activation energy barrier for the protonation step is greater than the cycloaddition step. In the absence of a strong proton donor the final protonation step is coupled with the alkyne deprotonation step in the catalytic cycle, which slows down the reaction. A conceivable pathway for acetic acid promoted CuAAC reaction on the basis of experimental and computational studies was also sought. With acetate as ligand, cycloaddition is a facile reaction and the energetics shows that it speeds up the cycloaddition step. Acetic acid in CuAAC reaction provides proton for the final protonation step in the catalytic cycle, decouples the protonation/deprotonation step by acting as a strong proton donor in the last step and facilitates protonation. The energetics presented herein are in accordance with the experimental proposals on rate-determining step in aprotic conditions and decreased reaction times obtained in the experiments in the presence of acetic acid. (C) 2016 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2016.11.010
Sayi :426
Sayfa :150-157
Sınıflandırma :
12
Double carbonylation of iodobenzene in a microfluidics-based high throughput flow reactor
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Rita Skoda-Foeldes , Jozsef Bakos , Ferenc Darvas , Laszlo Uerge , Arpad Kuik , Janos Balogh
Yıl :
2009
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Double carbonylation of iodobenzene in the presence of amines were carried out effectively in a microfluidics-based flow reactor (X-Cube (TM)) of high throughput capability using immobilized Pd(PPh3)(4) catalyst. By the proper tuning of the reaction conditions alpha-ketoamides could be synthesized with 70-96% selectivities depending on the choice of the nucleophile. The highest yields of double carbonylation products were obtained at relatively low temperature (80 degrees C) and using DBU as the base with primary amines as the reaction partners. Imine formation was observed only at higher temperatures. (C) 2008 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2008.11.035
Sayi :302
issue :1-2
Sayfa :76-79
Sınıflandırma :
13
Rhodium nanoparticles stabilized by sulfonic acid functionalized metal-organic framework for the selective hydrogenation of phenol to cyclohexanone
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Mehmet Zahmakiran , Mehmet Yurderi , Ahmet Bulut , Mehmet Gulcan , Ilknur Efecan Ertas
Yıl :
2015
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Kaydet Alıntıla
Rhodium(0) nanoparticles stabilized by sulfonic acid functionalized metal-organic framework (Rh@SMIL-101) were prepared, for the first time, by using a direct cationic exchange approach and subsequent reduction with sodium borohydride at room temperature. The characterization of the resulting Rh@SMIL-101 material was done by using multi pronged analyses including ICP-OES, EA, P-XRD, XPS, DR-UV-vis, BFFEM, HRTEM, STEM-EDX and N2-adsorption-desorption technique, which revealed that the formation of rhodium(0) nanoparticles (2.35 +/- 0.9 nm) stabilized by the framework of S-MIL-101 by keeping the host framework intact (Rh@S-MIL-101). The catalytic performance of Rh@S-MIL-101 in terms of activity, selectivity and stability was demonstrated in the hydrogenation of phenol under mild conditions (at 50 degrees C and 5 bar initial H-2 pressure). We found that Rh@S-MIL-101 catalyst selectively hydrogenated phenol to cyclohexanone with high activity (initial TOF= 78 mol cyclohexanone/mol Rh x h) and selectivity (>92%) at almost complete conversion (>95%). Moreover, the resulting rhodium nanopartides were found to be highly stable against leaching and sintering, which makes Rh@S-MIL-101 reusable heterogeneous catalyst without losing of significant activity and selectivity. (C) 2015 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2015.09.025
Sayi :410
Sayfa :209-220
Sınıflandırma :
Kimya %100
Kataliz %82
14
One-pot synthesis of 1,2/3-triols from the allylic hydroperoxides catalyzed by zeolite-confined osmium(0) nanoclusters
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Onder Metin , Saim Ozkar , Mehmet Serdar Gultekin , Serdar Akbayrak , Digdem Dalmizrak , Haydar Goksu
Yıl :
2013
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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Kaydet Alıntıla
A facile, efficient and eco-friendly method for the one-pot synthesis of 1,2/3-triols from the allylic hydroperoxides were developed by using zeolite-confined osmium(0) nanoclusters as reusable catalyst and without using any co-oxidant (H2O2, (BuOOH)-Bu-t, NMO, etc.) in water/acetone (v/v = 1/4) mixture at room temperature. In this method, the oxygen atom of the allylic hydroperoxide group was transferred to the double bond of the same molecule via zeolite-confined osmium(0) nanoclusters. The method has been successfully applied to various allylic hydroperoxides and the corresponding 1,2/3-triols were obtained in high chemical yield. Moreover, a plausible mechanism was proposed for the catalytic oxidation of allylic hydroperoxide to the respective 1,2/3-triols in the presence of zeolite-Os-0 catalyst gathering all the results collected by testing a variety of allylic hydroperoxides in the presence of zeolite-Os-0 catalyst. (c) 2013 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2013.06.013
Sayi :378
Sayfa :142-147
Sınıflandırma :
15
In situ modification of the Grubbs first generation catalyst: A highly controllable metathesis catalyst bearing tridentate Schiff base ligands
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Solmaz Karabulut , Emel Bucak , Bengi Ozgun Ozturk
Yıl :
2013
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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In this study, a practical and inexpensive procedure for the modification of the Grubbs first generation catalyst is reported. A highly controllable metathesis catalyst system was obtained by in situ modification of the Grubbs catalyst with tridentate Schiff base (O-N-O) ligands. The latent catalyst was activated by the addition of HCl, which allowed control of its initiation rate by varying the HCl/Ru ratio. Due to the superior control over the catalyst initiation step, improved molecular weight control in the ring-opening metathesis polymerization (ROMP) of cyclooctene (COE) was achieved using these complexes. ROMP polymers obtained by these catalyst systems have relatively narrow molecular weight distributions, and the molecular weight of the polymers can be controlled on a wide scale. In addition, the reversible inhibition and activation of the catalysts were studied the in ring-closing metathesis reaction (RCM) of diethyldiallylmalonate. RCM of diethyldiallylmalonate can be halted by the introduction of tridentate Schiff base ligands to the reaction medium. The reaction can be switched on again by the introduction of trace amounts of HCL. (C) 2013 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2013.04.010
Sayi :376
Sayfa :53-62
Sınıflandırma :
16
Reaction pathway analysis for CO oxidation over anionic gold hexamers using DFT
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Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Ramazan Yildirim , A Erhan Aksoylu , Tugba Davran-Candan
Yıl :
2009
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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 Piri Tam Metin Bulucu
Kaydet Alıntıla
The reaction pathways for CO oxidation over anionic gold hexamer(Au-6(-)) as a model catalyst were studied using unrestricted density functional theory (UDFT). The reaction mechanisms for two possible initial structures, in which either CO or O-2 was adsorbed on the apex site while the other was on the nearest lateral site, were analyzed. The reaction proceeds through a typical Langmuir-Hinshelwood mechanism taking place in two steps for both initial structures. First, CO reacts with the molecular O-2 leading to the first CO2 molecule and Au-O complex through the formation of a four-centered intermediate structure (CO-OO). This is followed by the elimination of the remaining O on the cluster by another CO. It was found that the energy barriers for the formation of the intermediate and its decomposition into CO2 and Au-O complex were much lower when O-2 was bonded to the apex site. The second step, on the other hand, was found to be identical for both initial structures. (C) 2009 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2009.02.034
Sayi :306
issue :1-2
Sayfa :118-122
Sınıflandırma :
17
Photocatalytic degradation of ciprofloxacin by synthesized TiO2 nanoparticles on montmorillonite: Effect of operation parameters and artificial neural network modeling
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Semra Karaca , Alireza Khataee , Aydin Hassani
Yıl :
2015
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yayıncı Web Sitesi
 Piri Tam Metin Bulucu
Kaydet Alıntıla
TiO2/MMT nanocomposite was synthesized and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Energy-dispersive Xray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray fluorescence (XRF) and Brunauer-Emmett-Teller (BET) techniques. The average size of TiO2 nanoparticles was decreased from 60-80 nm to 40-60nm through the immobilization on MMT. The main influential factors such as the TiO2/MMT dose, ciprofloxacin (CIP) concentration, pH of the solution, UV light regions, reusability of the catalyst and electrical energy determination were studied. The addition of radical scavengers (e.g. chloride, iodide, sulfate and bicarbonate) and enhancers (e.g. hydrogen peroxide, potassium iodate and peroxydisulfate) on the degradation efficiency was studied. The predicted data from the designed artificial neural network model were found to be in a good agreement with the experimental data (R-2=0.9864). The main intermediates of CIP degradation were determined by GC-Mass spectrometry. (C) 2015 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2015.08.020
Sayi :409
Sayfa :149-161
Sınıflandırma :
Kimya %100
Kataliz %75
18
An insight toward the photocatalytic activity of S doped 1-D TiO2 nanorods prepared via novel route: As promising platform for environmental leap
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Caue Ribeiro , Shahzad Abu Bakar
Yıl :
2016
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yayıncı Web Sitesi
 Piri Tam Metin Bulucu
Kaydet Alıntıla
The photocatalytic applications of the S-doped titanium dioxide (TiO2) are of great importance due to photon-to-carrier conversion ability of S-doping in the energy region below the band gap of pure TiO2. Therefore, 1D (one dimensional) S-doped TiO2 anatase nanorods were synthesized first time by facile, low temperature and template free oxidant peroxide method (OPM). The addition of thiourea as sulfur precursor favored the formation of better crystalline anatase TiO2 and S atoms favorably crystalized the anatase structure. It was found that substitution of Ti4+ by S6+ in the lattice of S doped TiO2 nanorods increased the number of adsorbed active groups (hydroxyl radical) at the surface of catalyst and also gave rise to the visible-light response. The formation of Ti-O-S bond favors the partial transfer of electrons from S to 0 atoms. It helps the electron-deficient S atoms to hold/capture electrons and thus reduce the recombination rate of photogenerated electron-hole pairs. The preferred anatase {1 0 1} facets could also act as beneficiary reservoirs to decrease the recombination probability of electron-hole pairs. Methylene blue (MB) was used as target organic molecule for evolution of photocatalytic activity by photocatalytic oxidation reaction under visible-light. The mineralization products of MB were detected using High Performance Liquid Chromatography (HPLC) and GC/MS spectroscopy that gave the pattern of possible degraded fragments from the mineralization of MB. The role of active species in the degradation process was identified with the help of Mott-Schottky measurement, addition of different scavengers and the band structure obtained from the UV-vis diffuse reflectance spectrum. It was found that holes and hydroxyl radicals played major role in the photo-degradation of MB. The fundamental mechanism for enhanced photocatalytic performance of S doped TiO2 nanorods was discussed in detail and attributed to the S doping and morphology engineering that may improve the electron-hole pair separation efficiency for enhanced photocatalytic performance under visible-light irradiation. This work may provide an insight into the synthesis of S doped TiO2 photocatalysts that showed good stability after four cycles and have great potential for environmental purification of organic pollutants. (C) 2015 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2015.12.002
Sayi :412
Sayfa :78-92
Sınıflandırma :
Kimya %69
Kataliz %78
19
Carboxymethyl chitosan Schiff base supported heterogeneous palladium(II) catalysts for Suzuki cross-coupling reaction
Araştırma Makalesi

Araştırma Makalesi
Open Access
Kaynak :
Aperta - TÜBİTAK Açık Arşivi
Dergi:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yazar(lar) :
Ayfer Mentes , Eda Aciksoz , Talat Baran
Yıl :
2015
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Yayıncı Web Sitesi
 Piri Tam Metin Bulucu
Kaydet Alıntıla
In this study, two new O-carboxymethyl chitosan Schiff bases supported Pd(II) catalyst were synthesized (OCMCS-3aPd and OCMCS-4aPd). The catalysts were characterized with FTIR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV vis, magnetic moment and molar conductivity. The catalytic activities of these catalysts were tested in the synthesis of biaryl compounds by Suzuki cross-coupling reactions. Characterizations of the biaryls were performed with GC MS and H-1 NMR. In synthesis of the biaryl compounds in the presence of the Pd(II) catalyst, high selectivity was observed; no homo-coupling byproducts were detected in the spectra. A reusability test demonstrated that the catalysts were highly efficient even after ten run. The mercury poisoning and leaching tests indicated that the catalysts have heterogeneous nature. (C) 2015 Elsevier B.V. All rights reserved.
DOI : 10.1016/j.molcata.2015.06.008
Sayi :407
Sayfa :47-52
Sınıflandırma :
20
Catalytically active species in new metathesis systems Wn+(Mon+)–ionic liquid–olefin: A quantitative ESR study
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
A.V. Kucherov , A.V. Vasnev , A.A. Greish , L.M. Kustov
Yıl :
2005
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
For the first time, a quantitative approach is successfully used in the ESR study of new catalysts for olefin metathesis prepared by dissolution of WCl6 and MoCl5 in ionic liquids (hmimBF4, hpyrBF4, etc.). ESR monitoring of frozen probes taken upon interaction between the phases of an ionic liquid and hex-1-ene permits one to elucidate the key role of isolated paramagnetic complexes of W5+ and Mo5+ ions in catalysis. The use of MoCl5 as a starting reagent opens a way for a quantitative observation of paramagnetic active species in two liquid phases. It is shown that the reaction in the biphasic system proceeds as a heterogeneous catalytic process: virtually all the isolated W5+ or Mo5+ species are located in the ionic liquid. The kinetics of formation/accumulation of the isolated paramagnetic W5+ species at the initial slow step of W6+ reduction by an olefin agrees closely with the kinetics of metathesis leading to the formation of a C8 product. No induction period is observed in the case of Mo5+ ions. The number of the ESR-visible isolated paramagnetic Mo5+ complexes reaches ∼90% of the total number of molybdenum ions in the sample. Thus, the Mo(V) state of the active sites localized in ionic liquids is responsible for the further catalytic process. The same seems to be true for the W(V) species accumulated in the ionic liquid at the end of the first step of the reaction.
DOI : 10.1016/j.molcata.2005.04.045
Anahtar Kelimeler : Olefin metathesis, Ionic liquids, W5+ and Mo5+ ions, ESR, Quantitation of paramagnetic species
ISSN: 1381-1169
Sayı: 1-2
Cilt: 237
Sayfa: 165-171
Sınıflandırma :
21
A simple, economical, and highly efficient synthesis of β-hydroxynitriles from epoxide under solvent free conditions
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
Bahareh Mirmashhori , Najmodin Azizi , Mohammad R. Saidi
Yıl :
2006
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
A simple, rapid, and highly regioselective green protocols for the synthesis of β-hydroxylnitriles by the direct reaction of epoxides with trimethylsilyl cyanide in the presence of catalytic amount of lithium perchlorate under solvent free conditions in high to quantitative yield is reported.
DOI : 10.1016/j.molcata.2005.11.042
Anahtar Kelimeler : β-Hydroxylnitriles, Regioselective, Trimethylsilyl cyanide, Lithium perchlorate
ISSN: 1381-1169
Sayı: 1-2
Cilt: 247
Sayfa: 159-161
Sınıflandırma :
Kimya %100
Kataliz %67
22
Oxidation of crotyl alcohol using Ti-β and Ti-MCM-41 catalysts
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
Lucinda J Davies , Paul McMorn , Donald Bethell , Philip C Bulman Page , Frank King , Frederick E Hancock , Graham J Hutchings
Yıl :
2001
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
A comparative study of the oxidation of the crotyl alcohol using hydrogen peroxide and tert-butyl hydroperoxide as oxidants with TS-1, Ti-β, Ti-Alβ, Ti-MCM-41, Ti-Al-MCM-41 and Ti-grafted-MCM-41 as catalysts is described and discussed. With hydrogen peroxide as oxidant, significant Ti-leaching is observed with all the catalysts except TS-1 (Ti-Alβ>Ti-grafted- MCM-41>Ti-MCM-41>Tiβ>Ti-Al-MCM-41⪢TS-1). For Ti-Alβ, Ti-grafted- MCM-41 and Ti-Al-MCM-41, initial heterogeneously catalysed formation of the epoxide was observed. However, the formation of a Ti-species in solution is shown to contribute to competing homogeneously catalysed formation of ether diols and triol. Using tert-butyl hydroperoxide as oxidant the Ti-leaching was minimised and selective epoxide formation was observed with Ti-β, Ti-Alβ and Ti-MCM-41 as heterogeneous catalysts, although, with Ti-Alβ, the ether diols and triol products dominated due to acid catalysed solvolysis of the epoxide.
DOI : 10.1016/s1381-1169(00)00430-1
Anahtar Kelimeler : Crotyl alcohol oxidation, Hydrogen peroxide, Tert-butylhydroperoxide, TS-1, Ti-β, Ti-Alβ, Ti-MCM-41, Ti-grafted- MCM-41, Ti-Al-MCM- 41, Ti-leaching
ISSN: 1381-1169
Sayı: 1-2
Cilt: 165
Sayfa: 243-247
Sınıflandırma :
23
AUTHOR INDEX
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yıl :
2001
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
DOI : 10.1016/s1381-1169(01)00044-9
ISSN: 1381-1169
Sayı: 1-2
Cilt: 167
Sayfa: 247-248
Sınıflandırma :
24
Influence of impregnation times on the dispersion of CuO on anatase
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
Haiyang Zhu , Yong Wu , Xi Zhao , Haiqin Wan , Lijuan Yang , Jianming Hong , Qing Yu , Lin Dong , Yi Chen , Can Jian , Jun Wei , Penghui Xu
Yıl :
2006
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
X-ray diffraction (XRD), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the dispersion of copper oxide in CuO/TiO2 samples prepared by one and double-step impregnations and the NO + CO activities of CuO/TiO2 samples were also tested. The results indicate that the dispersion capacity of copper oxide in CuO/TiO2 samples with one-step impregnation and double impregnations are about 0.52 and 0.98 mmol/100 m2 TiO2, respectively, which should be related to the shielding effect of accompanying NO3− anions during the impregnations. Therefore, the dispersion capacity of copper oxide on anatase with double impregnations could approach to 1.16 mmol/100 m2 TiO2, i.e. a value corresponding to the density of vacant sites on the (0 0 1) surface of TiO2. The NO + CO activities of CuO/TiO2 samples suggest that dispersed copper oxide species in these catalysts is the mainly active species and the increasing amount of dispersed copper oxide would enhance their activities. It seems to suggest that, for the supported catalysts, double or multiple impregnations would result in better activity than those prepared by one-step impregnation. In addition, the coordination environment of the dispersed copper oxide species existed on the anatase surface has been discussed by the incorporation model [Y. Chen, L.F. Zhang, Catal. Lett. 12 (1992) 51].
DOI : 10.1016/j.molcata.2005.08.021
Anahtar Kelimeler : Copper oxide species, Anatase, Dispersion capacity, Impregnation, Incorporation model
ISSN: 1381-1169
Sayı: 1
Cilt: 243
Sayfa: 24-30
Sınıflandırma :
Kimya %100
Kataliz %100
25
Catalytic oxidation of alkenes with ruthenium(II) perchlorate complexes
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
A.S Kanmani , S Vancheesan
Yıl :
1997
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Ruthenium(11) perchlorate complexes,.Ru(dppm)3(Cl04)]Cl04, 1, Ru(dppe)3(Cl04)]Cl04, 2, [Ru(dpae)3(Cl04)]Cl04, 3, catalyse the oxidation of cyclohexene in the presence of cumene hydroperoxide (CHP) under homogeneous liquid phase. The products of oxidation are 2-cyclohexen-I-ol and 2-cyclohexenone. Linear alkenes like 1-heptene and 1-octene are not efficiently oxidised under these conditions. Solvent influences the rate of oxidation considerably. N-methylmorpholine-N-oxide (NMO) and CHP are compared for their oxidising ability.
DOI : 10.1016/s1381-1169(97)00087-3
Anahtar Kelimeler : Ruthenium(II) perchlorate, Homogeneous, Catalyst, Cyclohexene, Oxidation
ISSN: 1381-1169
Sayı: 2-3
Cilt: 125
Sayfa: 127-134
Sınıflandırma :
26
Catalytic activity of solvated and unsolvated lanthanide halides in Friedel–Crafts acylations
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
Denise Barbier-Baudry , Alain Dormond , Stéphanie Richard , Jean Roger Desmurs
Yıl :
2000
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Anhydrous lanthanide halides — chlorides and bromides — can act as homogeneous catalysts of Friedel–Crafts acylations. The catalytic activity is related to the solubility of these anhydrous salts. More soluble THF or dioxane (Diox.) neodymium and samarium adducts are more active catalysts.
DOI : 10.1016/s1381-1169(00)00285-5
Anahtar Kelimeler : Friedelu2013Crafts acylation, Lanthanides, Homogeneous catalysis, Neodymium, Samarium
ISSN: 1381-1169
Sayı: 1-2
Cilt: 161
Sayfa: 23-29
Sınıflandırma :
27
Reduction of ketones by dihydrogen or hydrogen transfer catalysed by a ruthenium complex of the hydridotris (3,5-dimethyl)pyrazolyl borate ligand
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
Consuelo Vicente , Georgyi B. Shul'pin , Beatriz Moreno , Sylviane Sabo-Etienne , Bruno Chaudret
Yıl :
1995
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
The hydride complexes Tp∗RuH(H2)2 (1) and Tp∗RuH(COD) (2) (Tp∗ = hydridotris(3,5-dimethyl)pyrazolyl borate) show good catalytic activity for the reduction of unactivated ketones either by dihydrogen or by hydrogen transfer from alcohols in basic media.
DOI : 10.1016/1381-1169(95)00045-3
Anahtar Kelimeler : Hydrogen, Ketones, Pyrazolyl derivative, Reduction, Ruthenium
ISSN: 1381-1169
Sayı: 1
Cilt: 98
Sayfa: L5-L8
Sınıflandırma :
28
Volume contents
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yıl :
2006
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
DOI : 10.1016/s1381-1169(05)00717-x
ISSN: 1381-1169
Sayı: 1-2
Cilt: 244
Sayfa: 283-284
Sınıflandırma :
29
Mesoporous MCM41-heterogenised (salen)Mn and Cu complexes as effective catalysts for oxidation of sulfides to sulfoxidesIsolation of a stable supported Mn(V)O complex, responsible of the catalytic activity
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
V AYALA , A CORMA , M IGLESIAS , F SANCHEZ
Yıl :
2004
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Chiral salen manganese and copper complexes immobilised on mesoporous silica supports (silica, MCM-41) have been investigated as catalysts in the sulfide to sulfoxide oxidation; the supported catalysts are highly suited to reactions leading to high yields and high sulfoxide/sulfone selectivity while moderate asymmetric induction (up to 30%) was observed. The presence of stable manganyl [Mn(V)O] complexes into support channels have been established, being responsible for catalytic activity. The recovery and reusability of heterogenised Mn- and Cu-catalysts have been studied.
DOI : 10.1016/s1381-1169(04)00461-3
Anahtar Kelimeler : Immobilised salen, Heterogenisation, Sulfide oxidation, Manganese, Copper
ISSN: 1381-1169
Sayı: 1-2
Cilt: 221
Sayfa: 201-208
Sınıflandırma :
Kimya %100
Kataliz %84
30
Kinetics and selectivity of the copper-catalysed oxidative coupling of 4-(2′,6′-dimethylphenoxy)-2,6-dimethylphenol
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Journal of Molecular Catalysis A: Chemical
Yayıncı:
Elsevier
Yazar(lar) :
P Baesjou
Yıl :
1999
Journal of Molecular Catalysis A: Chemical
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
The kinetics of the copper/N-methylimidazole catalysed oxidative coupling reaction with the C–O coupled dimer of 2,6-dimethylphenol (DMP or monomer), viz. 4-(2′,6′-dimethylphenoxy)-2,6-dimethylphenol (dimer), as the substrate have been studied. The reaction was found to obey Michaelis–Menten kinetics. The dimer is more easily oxidised than the monomer, but the formation of a copper–substrate complex is more difficult. The reaction rates are higher than in the case of the monomer, and the amounts of diphenoquinone (DPQ) formed are much lower. With the dimer as the substrate, the order of the reaction in copper is 2, confirming that the formation of a dinuclear copper complex is an important step in the reaction mechanism. The amount of DPQ formed is proportional to the initial amount of the dimer. A slight, but clear preference for the dimer over the monomer as the substrate has been observed from experiments with mixtures of monomer and dimer. The amount of DPQ formed decreases exponentially with an increase in the fraction of dimer in the mixture, which can be ascribed mainly to a statistical effect.
DOI : 10.1016/s1381-1169(98)00240-4
Anahtar Kelimeler : Dioxygen uptake, Dimer, Phenol oxidation, Homogeneous copper catalysis, Michaelisu2013Menten, Reaction mechanism, N-Methylimidazole
ISSN: 1381-1169
Sayı: 3
Cilt: 140
Sayfa: 241-253
Sınıflandırma :

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