Archive for July, 2013

Turn up the heat – Thermal treatment key to magnetically recoverable AuPd nanoparticles

Aldehydes are valuable synthetic intermediates with many methods for their preparation. But the majority of these approaches employ stoichiometric oxidants that produce toxic waste. Aerobic oxidation with molecular oxygen and a transition metal catalyst offers an environmentally benign alternative. In this advance article, Rossi and colleagues reported the first magnetically recoverable AuPd nanoparticle catalyst applied to the oxidation of primary alcohols to aldehydes.

The removal of metal catalysts supported on magnetic surfaces with an external magnetic field is an innovative and efficient method for separation.  The researchers achieved linkage by dually functionalizing the support with strongly coordinating ligands and impregnating the nanoparticles with weak coordinating groups in the coordination capture method. They found that catalysts with amino-functionalized silica supports exhibited higher activity and stability to catalyst recycling than the analogous thiol supports. The authors achieved a 92% conversion of benzyl alcohol with high selectivity for benzaldehyde using 1 wt% AuPd catalyst (Fe3O4@SiO2-NH2-AuPd) under 6 bar of O2 at 100 °C. However, catalyst separation was impeded by the amino group, which had reacted with the product benzaldehyde to form an aldimine.

This issue was circumvented through the calcination of the Fe3O4@SiO2-NH2-AuPd catalyst at 500 °C for 2 hours, effectively removing the amino groups and promoting highly efficient catalyst recovery. Good yield and selectivity for the oxidation reaction was maintained and the catalyst was used in five successive reactions without loss of selectivity.

To read more, follow the link below:

Magnetically recoverable AuPd nanoparticles prepared by a coordination capture method as a reusable catalyst for green oxidation of benzyl alcohol

Tiago A. G. Silva, Richard Landers and Liane M. Rossi

Catal. Sci. Technol., 2013, Advance Article, DOI: 10.1039/c3cy00261f

Tien Nguyen is a web contributor working towards her PhD in David Nicewicz’s research  group at the University of North Carolina at Chapel Hill, USA. Her current area of research  focuses on anti-Markovnikov hydroamination of alkenes using photoredox catalysis

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Top ten most accessed articles from April – June 2013

During the months April – June, the following articles are in the Top Ten most accessed:-

Metal sulphide semiconductors for photocatalytic hydrogen production 
Kai Zhang and Liejin Guo 
Catal. Sci. Technol., 2013,3, 1672-1690 
DOI: 10.1039/C3CY00018D     

A review of controllable synthesis and enhancement of performances of bismuth tungstate visible-light-driven photocatalysts 
Liwu Zhang and Yongfa Zhu 
Catal. Sci. Technol., 2012,2, 694-706 
DOI: 10.1039/C2CY00411A     

Graphene-based materials for catalysis 
Bruno F. Machado and Philippe Serp 
Catal. Sci. Technol., 2012,2, 54-75 
DOI: 10.1039/C1CY00361E     

New trends in the synthesis of crystalline microporous materials 
Danny Verboekend and Javier Pérez-Ramírez 
Catal. Sci. Technol., 2011,1, 879-890 
DOI: 10.1039/C1CY00150G     

CuFe, CuCo and CuNi nanoparticles as catalysts for higher alcohol synthesis from syngas: a comparative study 
Kang Xiao, Xingzhen Qi, Zhenghong Bao, Xinxing Wang, Liangshu Zhong, Kegong Fang, Minggui Lin and Yuhan Sun   
Catal. Sci. Technol., 2013,3, 1591-1602 
DOI: 10.1039/C3CY00063J    

Advances in conversion of hemicellulosic biomass to furfural and upgrading to biofuels 
Saikat Dutta, Sudipta De, Basudeb Saha  and Md. Imteyaz Alama   
Catal. Sci. Technol., 2012,2, 2025-2036 
DOI: 10.1039/C2CY20235B  

Copper N-heterocyclic carbene complexes in catalysis 
Jonathan D. Egbert, Catherine S. J. Cazin and Steven P. Nolan   
Catal. Sci. Technol., 2013,3, 912-926 
DOI: 10.1039/C2CY20816D     

High CO2 and CO conversion to hydrocarbons using bridged Fe nanoparticles on carbon nanotubes 
Justin P. O’Byrne, Rhodri E. Owen, Daniel R. Minett, Sofia I. Pascu, Pawel K. Plucinski, Matthew D. Jones and Davide Mattia 
Catal. Sci. Technol., 2013,3, 1202-1207 
DOI: 10.1039/C3CY20854K    

Challenge and progress: palladium-catalyzed sp3 C–H activation 
Hu Li, Bi-Jie Li and Zhang-Jie Shi  
Catal. Sci. Technol., 2011,1, 191-206 
DOI: 10.1039/C0CY00076K     

Noble metal-free Ni(OH)2–g-C3N4 composite photocatalyst with enhanced visible-light photocatalytic H2-production activity 
Jiaguo Yu, Shuhan Wang, Bei Cheng, Zhang Lin and Feng Huang 
Catal. Sci. Technol., 2013,3, 1782-1789 
DOI: 10.1039/C3CY20878H     

Why not take a look at the articles today and blog your thoughts and comments below.

Fancy submitting an article to Catalysis Science & Technology? Then why not submit to us today or alternatively email us your suggestions.

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An exuberant event: 20th Organometallic EuCheMS Conference

 

  

Sara Coles is a guest web-writer for Catalysis Science & Technology. She currently works for Johnson Matthey in Royston, UK. 


The 20th EuCheMS Conference on Organometallic  Chemistry was held from 30th June–4th July 2013, and co-sponsored by the RSC’s Catalysis Science & Technology and Dalton Transactions. This was the main international European conference on organometallic chemistry for 2013 and attendees came from all over the UK, Europe and further afield (notably the USA, Japan and various African countries). 

Palladium and ruthenium were by far the most represented metals. The presenters were split between those primarily studying fundamentals such as mechanism or characterisation techniques, and those with a focus on practical applications. Several were sponsored or supported by industrial or commercial companies, and others were clearly interested in developing commercialisable products. During the poster sessions, it was clear that some of the students were thinking about industry either in terms of their careers or of commercialising the products that they were working on. 

Popular catalytic themes included synthesis of novel compounds and complexes; the improvement of existing routes (including some current industrial processes); and waste reduction. Several presenters mentioned valorisation of waste biomass, a hot topic in the current climate. The cost of catalysts came up a few times. Often, though, the cost of the catalytic metal is secondary to other factors such as the cost of the ligand or of ultrapure solvents or reagents that must be added. It does not always follow that an expensive metal means a more expensive process – in fact the reverse is often the case. 

The conference was well attended and the main lecture theatre was full for the final presentation (by Bruno Chaudret, Institut National des Sciences Appliquées, Toulouse, France) at the end of day three. There was standing room only and the mood was exuberant after an inspiring three days. 

There was an unscheduled additional presentation for Professor David Cole-Hamilton, of the University of St Andrews, in celebration of his long career in chemistry. The RSC prepared a special issue of Dalton Transactions, co-ordinated by Professors Duncan Bruce and Derek Woollins. Poster prizes were judged by the Young Plenary lecturers and were presented by Professor Dr Eric Meggers. There were nine winners and the prizes were books on organometallic chemistry contributed by Springer and the RSC. 

The social activities included a musical interlude following Professor Ei-ichi Negishi’s presentation on Sunday evening. This was followed by a whisky tasting on Monday and to finish off the conference in style on Wednesday evening, a banquet and Scottish ceilidh were held in the glorious Scottish sunshine in the famous Old Course Hotel of St Andrews. 

For those who were able to stay, there was an additional morning of chemistry at the RSC Awards Symposium on Thursday 4th July. 

The 21st EuCheMS meeting will be held in Bratislava, Slovakia, from 5th–9th July 2015 and is being co-organised by the Czech and Slovak chemistry societies. The website is www.eucomcxxi.eu and will contain more information shortly. 

Read some papers by speakers at the event in Catalysis Science & Technology: 

Amination and dehydration of 1,3-propanediol by hydrogen transfer: reactions of a bio-renewable platform chemical
Sophie D. Lacroix, Annie Pennycook, Shifang Liu, Thomas T. Eisenhart and Andrew C. Marr 
Catal. Sci. Technol., 2012, 2, 288-290, DOI: 10.1039/C1CY00339A 

Organometallic hydrogen transfer and dehydrogenation catalysts for the conversion of bio-renewable alcohols
Andrew C. Marr
Catal. Sci. Technol., 2012, 2, 279-287, DOI: 10.1039/C1CY00338K 

Direct coupling of alcohols to form esters and amides with evolution of H2 using in situ formed ruthenium catalysts
Martin H. G. Prechtl, Kathrin Wobser, Nils Theyssen, Yehoshoa Ben-David, David Milstein and Walter Leitner 
Catal. Sci. Technol., 2012, 2, 2039-2042, DOI: 10.1039/C2CY20429K 

NOBIN-based phosphoramidite and phosphorodiamidite ligands and their use in asymmetric nickel-catalysed hydrovinylation
Mike Schmitkamp, Walter Leitner and Giancarlo Franciò 
Catal. Sci. Technol., 2013, 3, 589-594, DOI: 10.1039/C2CY20657A 

Controlling selectivity in the reaction network of aldoxime hydrogenation to primary amines
Ewa Gebauer-Henke, Walter Leitner, Angelina Prokofieva, Henning Vogt and Thomas E. Müller 
Catal. Sci. Technol., 2012, 2, 2539-2548, DOI: 10.1039/C2CY20356A 

A latent ruthenium based olefin metathesis catalyst with a sterically demanding NHC ligand
Anita Leitgeb, Mudassar Abbas, Roland C. Fischer, Albert Poater, Luigi Cavallo and Christian Slugovc 
Catal. Sci. Technol., 2012, 2, 1640-1643, DOI: 10.1039/C2CY20311A 

A computational perspective of olefins metathesis catalyzed by N-heterocyclic carbene ruthenium (pre)catalysts
Raffaele Credendino, Albert Poater, Francesco Ragone and Luigi Cavallo 
Catal. Sci. Technol., 2011, 1, 1287-1297, DOI: 10.1039/C1CY00052G 

Gold(I)-catalyzed synthesis of furans and pyrroles via alkyne hydration
Pierrick Nun, Stéphanie Dupuy, Sylvain Gaillard, Albert Poater, Luigi Cavallo and Steven P. Nolan 
Catal. Sci. Technol., 2011, 1, 58-61, DOI: 10.1039/C0CY00055H 

Secondary phosphine oxides as pre-ligands for nanoparticle stabilization
Eoin Rafter, Torsten Gutmann, Florian Löw, Gerd Buntkowsky, Karine Philippot, Bruno Chaudret and Piet W. N. M. van Leeuwen 
Catal. Sci. Technol., 2013,3, 595-599, DOI: 10.1039/C2CY20683H 

NHC-stabilized ruthenium nanoparticles as new catalysts for the hydrogenation of aromatics
David Gonzalez-Galvez, Patricia Lara, Orestes Rivada-Wheelaghan, Salvador Conejero, Bruno Chaudret, Karine Philippot and Piet W. N. M. van Leeuwen 
Catal. Sci. Technol., 2013,3, 99-105, DOI: 10.1039/C2CY20561K

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Hot Articles for July

Catalytic decomposition of ammonium dinitramide (ADN) as high energetic material over CuO-based catalysts
Rachid Amrousse, Kohji Fujisato, Hiroto Habu, Ahmed Bachar, Claudine Follet-Houttemane and Keiichi Hori
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00214D, Paper

Catalytic decomposition of ammonium dinitramide (ADN) as high energetic material over CuO-based catalysts


A silver-free system for the direct C–H auration of arenes and heteroarenes from gold chloride complexes
Nanna Ahlsten, Gregory J. P. Perry, Xacobe C. Cambeiro, Tanya C. Boorman and Igor Larrosa
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00240C, Communication

A silver-free system for the direct C–H auration of arenes and heteroarenes from gold chloride complexes


Highly practical iron-catalyzed C–O cleavage reactions
Dominik Gärtner, Hannelore Konnerth and Axel Jacobi von Wangelin
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00266G, Communication

Highly practical iron-catalyzed C–O cleavage reactions


Tandem ethylene oligomerisation and Friedel–Crafts alkylation of toluene catalysed by bis-(3,5-dimethylpyrazol-1-ylmethyl)benzene nickel(II) complexes and ethylaluminium dichloride
Asheena Budhai, Bernard Omondi, Stephen O. Ojwach, Collins Obuah, Emmanuel Y. Osei-Twum and James Darkwa
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00334E, Paper

Tandem ethylene oligomerisation and Friedel-Crafts alkylation of toluene catalysed by bis-(3,5-dimethylpyrazol-1-ylmethyl)benzene nickel(II) complexes and ethylaluminum dichloride


Evaluation of nanostructured vanadium(V) oxide in catalytic oxidations
Eric T. Drew, Yang Yang, Julia A. Russo, McKenzie L. Campbell, Samuel A. Rackley, JoAn Hudson, Patrik Schmuki and Daniel C. Whitehead
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00183K, Paper

Evaluation of nanostructured vanadium(V) oxide in catalytic oxidations

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Simple Grinding: Key to a highly active bi-metallic catalyst

Posted on behalf of Shreesha Bhat

The trend of employing metal alloys as catalysts in various organic reactions is gaining popularity owing to the considerable advantages it offers. Alloying gold with palladium is known to enhance the activity of the formed catalyst for various oxidation reactions. Present methods employed for the preparation of Au-Pd alloys include wet impregnation, deposition precipitation and sol-immobilization. These methods utilize chloride salts of the gold as a precursor which make the removal of the chloride from the final catalyst difficult. The presence of chloride is known to cause a loss in the catalytic activity of the alloys through blocking of the active sites. Scientists have been trying to find a way to reduce the chlorine content, but the alternatives have been equally discouraging due to various problems associated with them.

In an answer to this challenging problem, Researchers from UK and Pakistan have come up with a simple solution: Simply grind the metal acetates for 10 min with a support and get highly active chloride-free alloys as oxidation catalysts. These catalysts were evaluated against catalysts prepared by impregnation for the oxidation of benzyl alcohol, glycerol and direct H2O2 synthesis.

Various optimization studies on the Au:Pd ratio and the metal loading were carried out using turn over frequency (TOF) as the standard for comparisons. The results indicated that the physical grinding (PG) facilitated the Pd-Au alloy formation (not observed with other methods) which is known to produce a synergistic effect on the catalytic activity. It was also found that an optimum ratio of both metals resulted in higher activity with optimum metal loadings. To provide the icing on the cake, the PG (physically ground) catalysts were further successfully employed for the oxidation of various substrates with equal (or improved) TOFs, thus proving the general applicability of these catalysts.

Thus, the present paper showcases how the conventional physical grinding was successful in providing highly active bimetallic catalysts, where most of the other complex methods faltered!!

Physical mixing of metal acetates: Optimisation of catalyst

To read more, follow the link below:

Physical mixing of metal acetates: optimisation of catalyst parameters to produce highly active bimetallic catalysts
Peter J. Miedziak, Simon A. Kondrat, Noreen Sajjad, Gavin M. King, Mark Douthwaite, Greg Shaw, Gemma L. Brett, Jennifer K. Edwards, David J. Morgan, Ghulam Hussain and Graham J. Hutchings
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00263B, Paper


Shreesha Bhat is a medicinal chemist pursuing his M.S.(Pharm.) in Medicinal Chemistry at the National Institute of Pharmaceutical Education and Research, India

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Separation issues? Not for this heterogeneous reaction

The majority of laboratory scale organic reactions rely on homogenous catalysts which are usually removed via chromatography, often a time-consuming process that generates solvent and silica gel waste. These separation issues become untenable for large scale industrial processes and as a result, heterogeneous catalysts are preferred for ease of isolation. To be adopted as an industrial process, the reaction must also satisfy high standards of conversion to product, costliness and enantioselectivity.

This article details the asymmetric epoxidation of alkenes using heterogeneous iminium micro- and mesoporous supported organocatalysts with TPPP (tetraphenylphoshonium monopersulfate) as a stoichiometric oxidant. This method holds potential for industrial production as the catalyst can be reused after simple filtration and washing and avoids the use of expensive transition metals. Enantiopure epoxides, which are valuable synthetic building blocks, were obtained in high yields and enantioselectivities for select alkenes. Successive uses of the catalyst do however result in lower yields for reasons currently unknown to the authors. Nonetheless this report may serve as valuable precedent for future efforts towards a reusable heterogeneous chiral iminium catalyst for epoxidation.

Read the full article here:

Towards heterogeneous organocatalysis: chiral iminium cations supported on porous materials for enantioselective alkene epoxidation
Philip C. Bulman Page, Andrew Mace,  Damien Arquier, Donald Bethell, Benjamin R. Buckley, David J. Willock, and Graham J. Hutchings
Catal. Sci.Technol., 2013, DOI: 10.1039/c3cy00352c

Tien Nguyen is a web contributor working towards her PhD in David Nicewicz’s research  group at the University of North Carolina at Chapel Hill, USA. Her current area of research  focuses on anti-Markovnikov hydroamination of alkenes using photoredox catalysis.

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