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Nanopalladium on Amino-Functionalized Mesocellular Foam: An Efficient Catalyst for Suzuki Reactions and Transfer Hydrogenations
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Organic Chemistry.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
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2013 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 2, 612-618 p.Article in journal (Refereed) Published
Abstract [en]

The applications of a heterogeneous Pd0-AmP-MCF nanoparticle catalyst in Suzuki cross-coupling reactions and transfer hydrogenations of alkenes are described. The catalyst was highly efficient for both transformations, resulting in 1)coupling of a wide range of aryl halides with various boronic acids in high yields and 2)chemoselective reduction of a variety of alkenes with the use of 1-methyl-1,4-cyclohexadiene as hydrogen donor. Moreover, the catalyst can be recycled several times without any significant decrease in activity or leaching of metal into solution, making the protocol economical and environmentally friendly. In the case of the Suzuki cross-coupling, a 15-fold increase in reaction rate was observed if the reaction was performed under microwave irradiation compared to conventional heating in an oil bath.

Place, publisher, year, edition, pages
2013. Vol. 5, no 2, 612-618 p.
Keyword [en]
cross-coupling, heterogeneous catalysis, hydrogenation, nanoparticles, palladium
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-88678DOI: 10.1002/cctc.201200247ISI: 000314239000029OAI: oai:DiVA.org:su-88678DiVA: diva2:613020
Funder
EU, European Research Council, 247014Knut and Alice Wallenberg Foundation
Note

AuthorCount:5;

Available from: 2013-03-26 Created: 2013-03-25 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Catalytic reactions with palladium supported on mesocellular foam: Applications in hydrogenation, isomerization, and C-C bond forming reactions
Open this publication in new window or tab >>Catalytic reactions with palladium supported on mesocellular foam: Applications in hydrogenation, isomerization, and C-C bond forming reactions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The major part of this thesis concerns the development of catalytic methodologies based on palladium nanoparticles immobilized on aminopropyl-functionalized siliceous mesocellular foam (Pd0-AmP-MCF). The catalytic activity of the precursor to the nanocatalyst, PdII-AmP-MCF is also covered by this work.

In the first part the application of Pd0-AmP-MCF in Suzuki-Miyaura cross-coupling reactions and transfer hydrogenation of alkenes under microwave irradiation is described. Excellent reactivity was observed and a broad range of substrates were tolerated for both transformations. The Pd0-AmP-MCF exhibited high recyclability as well as low metal leaching in both cases.

The aim of the second part was to evaluate the catalytic efficiency of the closely related PdII-AmP-MCF for cycloisomerization of various acetylenic acids. The catalyst was able to promote formation of lactones under mild conditions using catalyst loadings of 0.3 - 0.5 mol% at temperatures of up to 50 oC in the presence of Et3N. By adding 1,4-benzoquinone to the reaction, the catalyst could be recycled four times without any observable decrease in the activity.

The selective arylation of indoles at the C-2 position using Pd-AmP-MCF and symmetric diaryliodonium salts is presented in the third part. These studies revealed that Pd0-AmP-MCF was more effective than PdII-AmP-MCF for this transformation. Variously substituted indoles as well as diaryliodonium salts were tolerated, giving arylated indoles in high yields within 15 h at 20 - 50 oC in H2O. Only very small amounts of Pd leaching were observed and in this case the catalyst exhibited moderate recyclability.

The final part of the thesis describes the selective hydrogenation of the C=C in different α,β-unsaturated systems. The double bond was efficiently hydrogenated in high yields both under batch and continuous-flow conditions. High recyclability and low metal leaching were observed in both cases.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2015. 83 p.
Keyword
Mesocellular foam, Heterogeneous palladium catalysis, nanopalladium
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-122061 (URN)978-91-7649-280-2 (ISBN)
External cooperation:
Public defence
2015-12-11, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Submitted.

 

Available from: 2015-11-19 Created: 2015-10-22 Last updated: 2016-08-25Bibliographically approved
2. New Tools for Green Catalysis: Studies on a Biomimetic Hybrid Catalyst and a Novel Nanopalladium Catalyst
Open this publication in new window or tab >>New Tools for Green Catalysis: Studies on a Biomimetic Hybrid Catalyst and a Novel Nanopalladium Catalyst
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The first part of this thesis describes an improved synthetic route to hybrid (hydroquinone-Schiff base)cobalt catalysts. Preparation of the 5-(2,5-hydroxyphenyl)salicylaldehyde building block was improved by altering the protective groups of the hydroquinone (HQ) starting material. Both protection and deprotection could be carried out under mild conditions, resulting in high yields. By optimizing the reaction conditions of the Suzuki cross-coupling, an efficient and inexpensive synthetic route with a good overall yield was developed.

The second part describes the use of the hybrid catalyst as an electron transfer mediator (ETM) in the palladium-catalyzed aerobic carbocyclization of enallenes. By covalently linking the HQ to the cobalt Schiff-base complex the reaction proceeded at lower temperatures with a five-fold increase of the reaction rate compared to the previously reported system.

The third part describes the application of the hybrid catalyst in the biomimetic aerobic oxidation of secondary alcohols. Due to the effi­ciency of the intramolecular electron transfer, the hybrid catalyst allowed for a lower catalytic loading and milder reaction conditions compared to the previous separate-component system. Benzylic alcohols as well as aliphatic alcohols were oxidized to the corresponding ketones in excellent yield and selectivity using this methodology.

The fourth part describes the synthesis and characterization of highly dispersed palladium nanoparticles supported on aminopropyl-modified siliceous mesocellular foam. The Pd nanocatalyst showed excellent activity for the aerobic oxidation of a wide variety of alcohols under air atmosphere. Moreover, the catalyst can be recycled several times without any decrease in activity or leaching of the metal into solution.

Finally, the fifth part describes the application of the Pd nanocatalyst in transfer hydrogenations and Suzuki coupling reactions. The catalyst was found to be highly efficient for both transformations, resulting in chemoselective reduction of various alkenes as well as coupling of a variety of aryl halides with various boronic acids in excellent yields. Performing the latter reaction under microwave irradiation significantly increased the reaction rate, compared to conventional heating. However, no significant increase in reaction rate was observed for the transfer hydrogenations, under microwave heating.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2011. 74 p.
National Category
Organic Chemistry
Research subject
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-65079 (URN)978-91-7447-418-3 (ISBN)
Public defence
2012-01-20, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrheniusväg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript.

Available from: 2011-12-14 Created: 2011-12-01 Last updated: 2015-10-27Bibliographically approved

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