Journal of Molecular Catalysis A: Chemical最新文献_第5页

The KA2 coupling reaction under green, solventless, heterogeneous catalysis 绿色、无溶剂、非均相催化下的KA2偶联反应

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.09.028

Giovanna Bosica, Roderick Abdilla

引用次数: 31

High yields of piperylene in the transfer dehydrogenation of pentane catalyzed by pincer-ligated iridium complexes 钳形连接铱配合物催化戊烷转移脱氢反应中高收率的胡椒烯

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.10.019

Akshai Kumar , Jason D. Hackenberg , Gao Zhuo , Andrew M. Steffens , Oleg Mironov , Robert J. Saxton , Alan S. Goldman

引用次数: 12

Oxidation of aromatic compounds by hydrogen peroxide catalyzed by mononuclear iron(III) complexes 单核铁(III)配合物催化过氧化氢氧化芳香族化合物的研究

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.08.037

Giselle C. Silva , Nakédia M.F. Carvalho , Adolfo Horn Jr. , Elizabeth R. Lachter , Octavio A.C. Antunes

{"title":"Oxidation of aromatic compounds by hydrogen peroxide catalyzed by mononuclear iron(III) complexes","authors":"Giselle C. Silva , Nakédia M.F. Carvalho , Adolfo Horn Jr. , Elizabeth R. Lachter , Octavio A.C. Antunes","doi":"10.1016/j.molcata.2016.08.037","DOIUrl":"https://doi.org/10.1016/j.molcata.2016.08.037","url":null,"abstract":"<div>In the present work, four mononuclear iron(III) complexes containing BMPA (BMPA=bis-(2-pyridylmethyl)amine) and derivative ligands, have been studied as catalyst in toluene oxidation, at 25 °C, using hydrogen peroxide as oxidant and acetonitrile as solvent. All catalysts were able to oxidize toluene with satisfactory yields, producing o-, m-, p-cresols, benzaldehyde and benzyl alcohol, as main products, and traces of 2-methylbenzoquinone and benzoic acid. The catalyst [Fe(BMPA)Cl3] presented the most promising results, reaching yields up to 30.2% at 50 <!-->h. Furthermore, [Fe(BMPA)Cl3] was applied in the oxidation of other aromatic compounds as benzene, ethylbenzene, cumene, n-propylbenzene, p-xylene and anisole. The reaction with H2O2 was monitored by electronic UV–vis spectroscopy in the presence and absence of toluene and its oxidation products, as well as by ESI-(+)-MS/Q-TOF mass spectrometry, in order to provide some information about the reaction mechanism.</div>","PeriodicalId":370,"journal":{"name":"Journal of Molecular Catalysis A: Chemical","volume":null,"pages":null},"PeriodicalIF":5.062,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcata.2016.08.037","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2391731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 31

Effect of oxidative pre-treatment on hydrogen spillover for a Ni/SiO2 catalyst 氧化预处理对Ni/SiO2催化剂氢外溢的影响

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.11.014

Abdel-Ghani Boudjahem , Mohammed M. Bettahar

引用次数: 20

Homogeneous oxidation of alkanes: Role of rhodium–alkyl complexes 烷烃的均相氧化:铑-烷基配合物的作用

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.07.026

E.G. Chepaikin , A.P. Bezruchenko , G.N. Menchikova , А.Е. Gekhman

引用次数: 15

Ordered mesoporous MCo2O4 (M = Cu, Zn and Ni) spinel catalysts with high catalytic performance for methane combustion 有序介孔MCo2O4 (M = Cu, Zn和Ni)尖晶石催化剂具有较高的甲烷燃烧催化性能

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.11.002

Tae Hwan Lim , Su Bin Park , Ji Man Kim , Do Heui Kim

{"title":"Ordered mesoporous MCo2O4 (M = Cu, Zn and Ni) spinel catalysts with high catalytic performance for methane combustion","authors":"Tae Hwan Lim , Su Bin Park , Ji Man Kim , Do Heui Kim","doi":"10.1016/j.molcata.2016.11.002","DOIUrl":"https://doi.org/10.1016/j.molcata.2016.11.002","url":null,"abstract":"<div>Ordered mesoporous MCo2O4 (M=Cu, Zn and Ni) spinel catalysts were synthesized via nano-replication method using mesoporous silica KIT-6 as the hard template. They were applied to methane combustion, in comparison with bulk MCo2O4 spinel catalysts prepared by co-precipitation method. A combined N2 adsorption-desorption, XRD and TEM results clearly confirm that mesoporous MCo2O4 (m-MCo2O4) spinel catalysts contain ordered mesostructure, resulting in the higher BET surface area and pore volume than bulk ones (b-MCo2O4). Moreover, the former catalysts demonstrate the better thermal stability as indicated by larger amount of MCo2O4 phase and smaller size of crystallite domain after calcination at 550°C. Therefore, such excellent properties rationalize that the m-MCo2O4 spinel catalysts reveal higher catalytic activity for methane combustion than bulk counterparts. When it comes to the catalytic performance of the meso catalysts for methane combustion, the m-CuCo2O4 spinel catalyst has superior performance, which is related to the high normalized amount of Co3+ cations on the surface, as evidenced by XPS.</div>","PeriodicalId":370,"journal":{"name":"Journal of Molecular Catalysis A: Chemical","volume":null,"pages":null},"PeriodicalIF":5.062,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcata.2016.11.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2878504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 42

Zeolite catalyzed highly selective synthesis of 2-methoxy-6-acetylnaphthalene by Friedel-Crafts acylation of 2-methoxynaphthalene in acetic acid reaction media 沸石催化2-甲氧基萘在醋酸反应介质中发生Friedel-Crafts酰化反应，高选择性合成2-甲氧基-6-乙酰萘

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.11.012

Tomoyoshi Yamazaki, Makoto Makihara, Kenichi Komura

{"title":"Zeolite catalyzed highly selective synthesis of 2-methoxy-6-acetylnaphthalene by Friedel-Crafts acylation of 2-methoxynaphthalene in acetic acid reaction media","authors":"Tomoyoshi Yamazaki, Makoto Makihara, Kenichi Komura","doi":"10.1016/j.molcata.2016.11.012","DOIUrl":"https://doi.org/10.1016/j.molcata.2016.11.012","url":null,"abstract":"<div>Zeolite catalyzed Friedel-Crafts acetylation of 2-methoxynaphthalene to produce 2-methoxy-6-acetylnaphthalene with high selectivity and conversion has been a challenging task, because the obtained compound is a key intermediate for an anti-inflammatory agent, Naproxen. However, no satisfactory results have been obtained with zeolite catalysts, and harmful solvents have been used to gain a high selectivity together with a high conversion. Here, we report the synthesis of 2-methoxy-6-acetylnaphthalene from 2-methoxynaphthalene with a high selectivity and a high conversion under an unprecedented simple reaction system; acetic anhydride as an acetylating agent, acetic acid as a solvent, and proton-type zeolite catalysts with low acidity. Among the examined zeolites, a proton-type H-MOR (SiO2/Al2O3  <!-->200) with a low acid content shows a conversion of 82% and an 86% selectivity for 2-methoxy-6-acetylnaphthalene. Further, detailed control experiments using H-MOR catalyst in acetic acid solvent were carried out to propose a plausible reaction mechanism.</div>","PeriodicalId":370,"journal":{"name":"Journal of Molecular Catalysis A: Chemical","volume":null,"pages":null},"PeriodicalIF":5.062,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcata.2016.11.012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2878507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 17

Catalytic C-H oxidations by nonheme mononuclear Fe(II) complexes of two pentadentate ligands: Evidence for an Fe(IV) oxo intermediate 两个五齿配体的非血红素单核铁(II)配合物催化C-H氧化:铁(IV)氧中间体的证据

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.10.010

Mainak Mitra , Hassan Nimir , David A. Hrovat , Albert A. Shteinman , Michael G. Richmond , Miquel Costas , Ebbe Nordlander

{"title":"Catalytic C-H oxidations by nonheme mononuclear Fe(II) complexes of two pentadentate ligands: Evidence for an Fe(IV) oxo intermediate","authors":"Mainak Mitra , Hassan Nimir , David A. Hrovat , Albert A. Shteinman , Michael G. Richmond , Miquel Costas , Ebbe Nordlander","doi":"10.1016/j.molcata.2016.10.010","DOIUrl":"https://doi.org/10.1016/j.molcata.2016.10.010","url":null,"abstract":"<div>The oxidation reactions of alkanes with hydrogen peroxide and peracids (peracetic acid (PAA) and m-chloroperoxybenzoic acid (mCPBA)) catalysed by two Fe(II) complexes of pentadentate {N5}-donor ligands have been investigated. Kinetic isotope effect experiments and the use of other mechanistic probes have also been performed. While the total yields of oxidized products are similar regardless of oxidant (e.g. 30–39% for oxidation of cyclohexane), the observed alcohol/ketone ratios and kinetic isotope effects differ significantly with different oxidants. Catalytic reactions in H2O2 medium are consistent with the involvement of hydroxyl radicals in the C<img>H bond cleavage step, and resultant low kinetic isotope effect values. On the other hand, catalytic reactions performed using peracid media indicate the involvement of an oxidant different from the hydroxyl radical. For these reactions, the kinetic isotope effect values are relatively high (within a range of 4.2–5.1) and the C3/C2 selectivity parameters in adamantane oxidation are greater than 11, thereby excluding the presence of hydroxyl radicals in the C<img>H bond cleavage step. A low spin Fe(III)-OOH species has been detected in the H2O2-based catalytic system by UV/Vis, mass spectrometry and EPR spectroscopy, while an Fe(IV)-oxo species is postulated to be the active oxidant in the peracid-based catalytic systems. Computational studies on the C<img>H oxidation mechanism reveal that while the hydroxyl radical is mainly responsible for the H-atom abstraction in the H2O2-based catalytic system, it is the Fe(IV)-oxo species that abstracts the H-atom from the substrate in the peracid-based catalytic systems, in agreement with the experimental observations.</div>","PeriodicalId":370,"journal":{"name":"Journal of Molecular Catalysis A: Chemical","volume":null,"pages":null},"PeriodicalIF":5.062,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcata.2016.10.010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2595829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 25

Improved photocatalytic activity and durability of AgTaO3/AgBr heterojunction: The relevance of phase and electronic structure 提高AgTaO3/AgBr异质结的光催化活性和耐久性:相和电子结构的相关性

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.11.001

Fang Wang , Tingting Wang , Junyu Lang, Yiguo Su, Xiaojing Wang

{"title":"Improved photocatalytic activity and durability of AgTaO3/AgBr heterojunction: The relevance of phase and electronic structure","authors":"Fang Wang , Tingting Wang , Junyu Lang, Yiguo Su, Xiaojing Wang","doi":"10.1016/j.molcata.2016.11.001","DOIUrl":"https://doi.org/10.1016/j.molcata.2016.11.001","url":null,"abstract":"<div>AgTaO3/AgBr heterojunction was constructed for visible light driven photocatalytic purpose in order to investigate the relevance of phase conversion, electronic structure and photocatalytic properties. The result indicated that AgBr grafted on AgTaO3 to form AgTaO3/AgBr heterojunction gave intense visible light absorption, which exhibits highly enhanced photocatalytic performance than their individual counterpart. Theoretical and experimental investigation showed that the matched electronic structure between AgTaO3 and AgBr induced an efficient transfer of photogenerated electrons from AgBr to AgTaO3, leading to efficient charge separation and the subsequent improved photocatalytic activity. Partial AgBr converted to AgBr/Ag during the photocatalytic process, leading to the construction of ternary AgTaO3/AgBr/Ag photocatalyst. Because of the surface plasmon resonance effect of Ag, the resulting AgTaO3/AgBr/Ag exhibited wide range absorption and improved charge separation efficiency, which showed high durability and superior photocatalytic activity toward methyl orange degradation. On the basis of spin resonance measurement and trapping experiment, it is expected that photogenerated electrons, O2−<img>, and OH<img> active species dominate the photodegradation of methyl orange.</div>","PeriodicalId":370,"journal":{"name":"Journal of Molecular Catalysis A: Chemical","volume":null,"pages":null},"PeriodicalIF":5.062,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcata.2016.11.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2660119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

Activation and selective oxy-functionalization of alkanes with metal complexes: Shilov reaction and some new aspects 金属配合物对烷烃的活化和选择性氧官能化:希洛夫反应及其新进展

IF 5.062

Journal of Molecular Catalysis A: Chemical Pub Date : 2017-01-01 DOI: 10.1016/j.molcata.2016.08.020

Аlbert А. Shteinman

{"title":"Activation and selective oxy-functionalization of alkanes with metal complexes: Shilov reaction and some new aspects","authors":"Аlbert А. Shteinman","doi":"10.1016/j.molcata.2016.08.020","DOIUrl":"https://doi.org/10.1016/j.molcata.2016.08.020","url":null,"abstract":"<div>The quest of selective catalytic reactions for direct conversion of alkanes into valued products remains to be the most important task objective of modern chemistry and metal complex catalysis. Nowadays it is adopted that the formation of metal–alkyl intermediates (M<img>R) is a necessary condition for activation and functionalization of alkanes on metal complexes but the mechanism of subsequent reactions of metal alkyls remain obscure, so that effective catalytic systems of this kind are still rare and uncommon. Although it is widely adopted that alkane σ-complexes (M·RH) most frequently are primary hydrocarbon intermediates in these processes, low profile in the literature is given to their reactivity and these are often considered simply just as some ‘collision complexes’. Nevertheless, theoretical and experimental studies provide more and more evidence that the С<img>Н bonds in such complexes may be markedly weakened and/or polarized, thus opening wide horizons for occurrence of subsequent direct homolytic or heterolytic reactions of alkanes. This review addresses the discussion of new routes for activation and oxygenation of saturated hydrocarbons, including those via alkane σ-complexes, without formation of metal–alkyl intermediates.</div>","PeriodicalId":370,"journal":{"name":"Journal of Molecular Catalysis A: Chemical","volume":null,"pages":null},"PeriodicalIF":5.062,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.molcata.2016.08.020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2393924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22