Stabilization of Palladium Nanoparticles by Polyoxometalates Appended with Alkylthiol Tethers and their Use as Binary Catalysts for Liquid Phase Aerobic Oxydehydrogenation

bruyn, Mario De; Neumann, Ronny

doi:10.1002/adsc.200600613

Cited by 39 publications

(18 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Employing our reaction conditions, 11 a is formed from 10 a with ethylbenzene as a byproduct in high conversion and good selectivity as compared to other reports (Table 3, entry 1) 6b. 9, 20 Cyclohexene 10 b was also dehydrogenated to benzene 11 b , which gave comparable results to those reported by Bercaw for this substrate (Table 3, entry 2) 2o. 1‐Isopropylcyclohexene 10 c gives, beside the expected isopropylbenzene 11 c , the unsaturated isopropenylbenzene (i.e., α‐methylstyrene), which suggests the intermediate formation of an exocyclic π‐allyl complex and its subsequent decomposition by β‐hydride elimination prior to aromatization.…”

Section: Resultssupporting

confidence: 51%

See 1 more Smart Citation

Selective Palladium‐Catalyzed Dehydrogenation of Limonene to Dimethylstyrene

2010

View full text Add to dashboard Cite

Conditions for the selective dehydrogenation of (+)‐limonene 1 to the polymer building block dimethylstyrene 2 are described. The reaction occurs smoothly in the presence of Pd(OTFA)2 as catalyst and CuCl2 as oxidant. High selectivity for retaining the exocyclic double bond during aromatization is achieved (>14:1). Initially, variable‐temperature NMR experiments, under stoichiometric conditions, showed a stepwise formation of a π‐allyl intermediate and subsequent reaction to give a mixture of products. However, kinetic experiments showed a sigmoidal curve, pointing to the heterogeneous nature of the catalytically active species. A number of experiments were undertaken to differentiate between homogeneous, molecularly defined catalysis and heterogeneous, nanocluster‐based catalysis. Based on the results, it is proposed that the true catalytic system is heterogeneous in nature.

show abstract

Section: Resultssupporting

confidence: 51%

“…The aim of this work is to investigate a one‐step dehydrogenation of (+)‐limonene to DMS by applying Wacker‐type reaction conditions. In addition, the study on related substrates, such as vinylcyclohexene, outlines the scope of this transformation 9…”

Section: Introductionmentioning

confidence: 99%

Selective Palladium‐Catalyzed Dehydrogenation of Limonene to Dimethylstyrene

2010

View full text Add to dashboard Cite

show abstract

“…43 This will offer complementary stabilization of the anchored metal domains by the inorganic heteropolyanion surface 73. In particular, Neumann and co‐workers synthesized a hybrid POM with two alkyl thiol residues, [(HS‐CH 2 CH 2 CH 2 Si) 2 SiW 11 O 40 ] 4– , enabling the stabilization of palladium colloids 43a. This tethered POM–Pd binary catalyst was effective for the aerobic oxydehydrogenation of vinylcyclohexene and vinylcyclohexane to styrene.…”

Section: N‐heterocyclic Carbene (Nhc) Palladium Complexes Anchorementioning

confidence: 99%

Hybrid Polyoxometalates: Merging Organic and Inorganic Domains for Enhanced Catalysis and Energy Applications

Berardi

Carraro

Sartorel

et al. 2011

Israel Journal of Chemistry

View full text Add to dashboard Cite

Organic–inorganic hybrids based on polyoxometalate scaffolds(POMs) are a unique class of molecular metal-oxides featuring a composite surface, whereby the merging of complementary domains stimulates new functions and enhances performances. The interaction between the organic and inorganic components can be designed via covalent and/or non-covalent strategies, yielding novel molecular systems with key applications in catalysis and materials science. Selected examples of such a rewarding approach will be illustrated, including the synthesis of tailored POM-based catalysts, and their application in homogeneous systems and on electrocatalytic surfaces for water splitting and renewable energy production

show abstract

“…Interestingly, such particles lead to oxydehydrogenation of vinylcylohexene and vinylcyclohexane to styrene via activation of the tertiary carbon-hydrogen bond. Palladium nanoparticles not stabilized in this way led to predominant formation of ethylbenzene via an isomerization-dehydrogenation pathway [124].…”

Section: Rhmentioning

confidence: 99%

Liquid Phase Oxidation Reactions Catalyzed by Polyoxometalates

Neumann

2010

Modern Oxidation Methods

Self Cite

View full text Add to dashboard Cite

j315 and recycling of the catalyst. Following a short introduction to polyoxometalates, their structure and general properties, the major parts of this review deal with three different types of oxidants: (i) mono-oxygen donors, (ii) peroxides and (iii) molecular oxygen. Finally, various systems for catalyst engineering designed to aid in catalyst manipulation, recovery and recycling are discussed. Polyoxometalates (POMs)Research applications of polyoxometalates have over the past two decades become very apparent and important, as reflected by the recent publication of a special volume of Chemical Reviews [1] devoted to these compounds. The diversity of research in the polyoxometalate area is significant and includes their application in many fields, including structural chemistry, analytical chemistry, surface chemistry, medicine, electrochemistry, and photochemistry. However, the most extensive research on the application of polyoxometalates appears to have been in the area of catalysis, where their use as Brønsted acid catalysts and oxidation catalysts has been going on since the late 1970s. Research published over the past decade or two has firmly established the significant potential of polyoxometalates as homogeneous oxidation catalysts. Through the development of novel ideas and concepts, polyoxometalates have been shown to have significant diversity of activity and mechanism that in the future may lead to important practical applications. In recent years, a number of excellent general reviews on the subject of catalysis by polyoxometalates have already been published [2], and while some repetition is inevitable we will attempt to keep the redundancy in the present review to a minimum.A basic premise behind the use of polyoxometalates in oxidation chemistry is the fact that these compounds are oxidatively stable. In fact, as a class of compounds they are thermally stable generally to at least 350-450 C in the presence of molecular oxygen. This, a priori, leads to the conclusion that for practical purposes polyoxometalates would have distinct advantages over widely investigated organometallic compounds that are vulnerable to decomposition due to oxidation of the ligand bound to the metal center. Polyoxometalates, previously also called heteropolyanions, are oligooxide clusters of discrete structure with a general formula [X x M m O y ] qÀ (x m) where X is defined as the heteroatom and M are the addenda atoms. The addenda atoms are usually either molybdenum or tungsten in their highest oxidation state, 6 þ , while the heteroatom can be any number of elements, transition metals and main group elements phosphorus and silicon being the most common heteroatoms. A most basic polyoxometalate, [XM 12 O 40 ] qÀ where (X ¼ P, Si, etc.; M ¼ W, Mo), is that possessing the Keggin structure, Figure 9.1. Such Keggin type polyoxometalates, commonly available in their protic form, are significant for catalysis only as Brønsted acid catalysts.However, since polyoxometalate synthesis is normally carried out in water by mixing ...

show abstract

Stabilization of Palladium Nanoparticles by Polyoxometalates Appended with Alkylthiol Tethers and their Use as Binary Catalysts for Liquid Phase Aerobic Oxydehydrogenation

Cited by 39 publications

References 38 publications

Selective Palladium‐Catalyzed Dehydrogenation of Limonene to Dimethylstyrene

Selective Palladium‐Catalyzed Dehydrogenation of Limonene to Dimethylstyrene

Hybrid Polyoxometalates: Merging Organic and Inorganic Domains for Enhanced Catalysis and Energy Applications

Liquid Phase Oxidation Reactions Catalyzed by Polyoxometalates

Contact Info

Product

Resources

About