Archive for September, 2013

One size does not fit all: Encapsulation of a NHC-Au(I) catalyst for alkyne hydration

Synthetic chemists have long been attempting to attain the exquisite levels of substrate selectivity offered by enzymes. Heterogeneous catalysts can provide high selectivities through the control of their porosity. While there are some strategies for achieving selectivity with homogeneous catalysis, this field still lags behind its enzymatic and heterogeneous counterparts.

In this advance article, Strukul and co-workers demonstrated substrate selectivity in the hydration of alkynes using a NHC-Au(I) catalyst encapsulated in a hexameric resorcin host. In the presence of the encapsulated catalyst the cyclic aliphatic alkyne was converted to product faster than the longer chain linear substrates. The authors ascribe this effect to the better fit of the cyclic substrate into the host cavity. Aromatic substrates were also tested and showed low yields likely due to their increased rigidity. Overall, aliphatic and aromatic alkynes were hydrated in low to modest yields but the observed trends serve as a valuable proof of concept.

To read more, click the link below:

Substrate selectivity in the alkyne hydration mediated by NHC-Au(I) controlled by encapsulation of the catalyst within a hydrogen bonded hexameric host
Alessandra Cavarzan, Joost N. H. Reek, Francesco Trentin, Alessandro Scarso, and Giorgio Strukul
Catal. Sci. Technol. 2013, Advance Article, DOI: 10.1039/c3cy00300k

Tien Nguyen is 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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Spinel Cobalt catalysts: Potential solution to reduce tailpipe emissions in LPG

Watching an automobile expert converting a gasoline engine to a LPG engine (using conversion kits) may leave the witness in awe of the technological advances which man has achieved ever since the invention of the wheel. But, this Jugaad comes with its own set of problems and issues which may not leave the environmentalists in the right frame of mind. Pollution has been raising concerns ever since the inception of automobiles (particularly two and three wheelers) and has been a serious concern in both developed as well as developing nations like India and China. To curb the menace of pollution, LPG has been considered an attractive alternative in terms of  low CO2 production, lower emission of other greenhouse gases, cheaper cost and more efficient fuel usage.

However, the use of conversion kits almost kills the purpose of  LPG as it results in emission of high concentrations of light hydrocarbons  (HCs) along with other pollutants such as CO and NOx, as LPG must be run on custom-made engines rather then gasoline engines. The HCs and CO can be oxidized to H2O and CO2 in presence of oxygen, but due to reduced availability of oxygen in LPG engines, the demand of oxidation catalysts has risen in order to facilitate the conversion of HCs into CO2 and H2O. Three-way catalysts (TWC) which include the platinum group metals, fail to oxidize HCs at low temperatures (between 200 to 300 °C), resulting in the maximum emissions of HCs after a cold-start. (Engines started when they are cold generally have initial temperatures around this range)

To come up with a low-temperature catalyst, researchers from Indian Institute of  Technology (IIT-BHU) tried their hands with cobaltite spinel oxidation catalysts (MCo2O4) and had immediate success with their experiments. They studied different metal cobaltites (M = Zn, Ni, Cu) and found Ni cobaltite to exhibit the best performance for oxidation of LPG at low temperatures, with the effectiveness of the catalysts following the order: NiCo2O4 > CuCo2O4 > ZnCo2O4.

Due to the synergistic effect of simultaneous oxidation of LPG and CO, total LPG oxidation was found to occur at 185 °C, which is 10°C less than that for oxidation of LPG alone. Thus, the researchers were able to devise a new spinel catalyst which catalyse the oxidation of HCs and CO at low temperatures and were able to solve the problem of  cold-start of LPG fuelled vehicles to some extent.

Low Temperature Complete Combustion of Lean Mixture of LPG Emissions over Cobaltite Catalysts

Read more about the preparation and characterization of spinel cobaltite catalysts from the article:

Low Temperature Complete Combustion of Lean Mixture of LPG Emissions over Cobaltite Catalysts
Ram Prasad, Sony Chaddha and Pratichi Singh
Catal. Sci. Technol., 2013, Accepted Manuscript
DOI: 10.1039/C3CY00537B


Shreesha Bhat, Web Writer Shreesha Bhat is a M.S.(Pharm.) in Medicinal Chemistry from National Institute  of  Pharmaceutical  Education and Research,  India. His area of interests  include chemical  synthesis of biologically important  molecules  and developing  newer methods for organic  synthesis using novel catalysts.

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European Federation of Catalysis Societies Young Researcher’s Award

We would like to congratulate Professor Javier Perez-Ramirez, associate editor of Catalysis Science & Technology, who won this year’s EFCATS (European Federation of Catalysis Societies) Young Researcher’s Award. This award recognizes his many contributions to the field of heterogeneous catalysis, especially his research on the rational design of hierarchical zeolites for catalytic applications and the development of novel catalysts for chlorine production. The award will be presented on the 5th September at the EuropaCat meeting in Lyon, France.


Javier Perez-RamirezJavier Pérez-Ramírez has been the Chair of Catalysis Engineering at the Institute for Chemical and Bioengineering, ETH Zurich since January 2010. Born and raised in Benidorm, Spain, Javier studied chemical engineering at the University of Alicante and later earned his PhD degree at the Delft University of Technology, The Netherlands in 2002. After spending some time in industry (2002-2005), holding several positions at Norsk Hydro and Yara International in Porsgrunn (Norway) where he was responsible of core projects related to catalyst development within fertilizer production, he was appointed ICREA research professor at ICIQ in Tarragona, Spain where he remained until his move to Zurich in 2010. The goal of this research is the discovery of energy-efficient chemical transformations that minimize byproducts, separation of waste and eliminate precious metals.

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