Archive for August, 2011

Magnetically separable nanomaterial as a photocatalyst

A magnetically separable nanomaterial has been developed which showed good photocatalytic activity under visible light in the selective transformation of malic acid in aqueous solution.

Titanium dioxide (TiO2) is well known as a photocatalyst, but its application in various processes is hindered due to several limitations.  The most important of these limitations is its lack of photocatalytic activity under visible light.  In addition, efficient separation of the catalyst once the reaction is complete can be difficult, with additional filtration steps and/or a tedious work-up required. 

However, in this work scientists from Spain and the USA led by Rafael Luque and Rajender Varma have developed a novel nanomaterial which overcomes these problems.  The TiO2-guanidine-(Ni,Co)Fe2O4nanomaterial was shown to have good activity in the selective transformation of malic acid.  Not only did the reaction proceed well under visible light, the material was also shown to have superior activity over the commercial catalyst Degussa P25.  The catalyst could be separated from the reaction mixture simply by using a magnet and the catalyst could be reused several times, preserving most of its activity.

To read more, please click on the link below.  This article is free to access until the 30th September 2011!

Magnetically separable nanocomposites with photocatalytic activity under visible light for the selective transformation of biomass-derived platform molecules, Alina M. Balu, Babita Baruwati, Elena Serrano, Jaume Cot, Javier Garcia-Martinez, Rajender S. Varma and Rafael Luque, Green Chem., 2011, DOI: 10.1039/C1GC15692F

Click here to read Anna Simpson’s recent interview with Rafael Luque!

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Ionic liquid pretreatment of ligonocellulosic biomass with ionic liquid-water mixtures

Ionic liquids containing methyl sulfate, hydrogen sulfate and methanesulfonate anions were used to pretreat lignocellulose in the presence of water.

Ionic liquids (ILs) are salts which are liquid at room or slightly elevated temperatures, and the majority have negligible vapour pressures.  One of the applications of ILs is in the pretreatment and processing of biomass (e.g. cellulose and lignocellulose).  However, the presence of water in these processes reduces the solubility of the biomass in the ILs and therefore the effectiveness of the pretreatment.  ILs currently have to be dried before use which requires heat and vacuum, but as biomass contains significant quantities of water, it would be far more beneficial to have an IL pretreatment process that tolerates moisture.

In this work, Welton and co-workers from Imperial College London have used IL and water mixtures of 1-butyl-3-methylimidazolium methyl sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate to pretreat ground lignocellulosic biomass.  These ILs were shown to work effectively in the presence of significant quantities of water thereby eliminating the need for anhydrous conditions during the process.

To find out more, please click on the link below:

Ionic liquid pretreatment of lignocellulosic biomass with ionic liquid–water mixtures, Agnieszka Brandt, Michael J. Ray, Trang Q. To, David J. Leak, Richard J. Murphy and Tom Welton, Green Chem., 2011, DOI: 10.1039/C1GC15374A

This article is free to access until the 21st September 2011

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Ecofriendly hydrogen production from hydrogen sulfide using a nanostructured photocatalyst driven by solar light

The photocatalyst ZnIn4S4was synthesized hydrothermally and applied to the conversion of hydrogen sulfide to hydrogen under solar light.

Scientists from India have demonstrated that a zinc nanostructured photocatalyst could be used to decompose hydrogen sulfide (H2S) into hydrogen (H2).  H2S is commonly converted into water and sulfur using the Claus process. However this process is not considered to be environmentally viable due to its high cost and the fact that it usually creates further environmental problems.  This has switched interest into converting H2S into H2 in order to try and avoid these issues.

Kale and colleagues report here the controlled synthesis of ZnIn4S4by a hydrothermal method and its application to H2S conversion to H2 using solar energy.  The H2 evolution rate obtained is much higher compared to earlier reported photocatalysts.

To read more, just click on the link below.  This article is free to access until the 21st September 2011!

Ecofriendly hydrogen production from abundant hydrogen sulfide using solar light-driven hierarchical nanostructured ZnIn2S4photocatalyst, Nilima S. Chaudhari, Ashwini P. Bhirud, Ravindra S. Sonawane, Latesh K. Nikam, Sambhaji S. Warule, Vilas H. Rane and Bharat B. Kale, Green Chem., 2011, DOI: 10.1039/C1GC15515F

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Dimethyl phosphorothioate and phosphoroselenoate ionic liquids as solvent media for cellulosic materials

A series of novel ionic liquids have been synthesized and applied to the dissolution of cellulose materials without causing considerable degradation of the polymer.

Hummel and co-workers from Finland and Austria have prepared by a facile route, a series of novel ionic liquids (ILs) which comprise of two asymmetric anions – dimethyl phosphorothioate and dimethyl phosphoroselenoate – and several imidazolium and non-imidazolium cations.  The principle of the work was to design an ionic liquid with reduced viscosity, while preserving its ability to dissolve lignocellulosic material, by altering the anion.

Hummel tested these new ionic liquids in the dissolution of cellulose, and the dimethyl phosphorothioate ionic liquids were able to dissolve cellulose with a high degree of polymerization but without extensive degradation.

To read more, please click on the link below.  This article is free to access until the 14th September 2011!

Dimethyl phosphorothioate and phosphoroselenoate ionic liquids as solvent media for cellulosic materials, Michael Hummel, Carmen Froschauer, Gerhard Laus, Thomas Röder, Holger Kopacka, Lauri K. J. Hauru, Hedda K. Weber, Herbert Sixta and Herwig Schottenberger, Green Chem., 2011, DOI: 10.1039/C1GC15407A

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Eco-friendly synthesis of β-nitro ketones

A variety of β-nitro ketones have been synthesised at room temperature using a supported nitrite.

Scientists from Italy have developed a more eco-friendly route to synthesize β-nitro ketones.  Nitroalkanes are an important class of organic substrates as the nitro group can be converted into many other functionalities, which makes them key starting materials for many fine chemicals.  Currently, the main method to make these compounds is by a Miyakoshi procedure – however, the method is limited to simple α,β-unsaturated ketone starting materials, gives only moderate yields and requires the presence of volatile organic solvents.

However, in this work, β-nitro ketones could be synthesized from a variety of α,β-unsaturated ketones using a solid supported nitrite, acetic acid and cyclopentyl methyl ether (CPME), an emerging ‘green solvent’.  This method works well with complex starting materials and it is able to preserve other functionalities, thereby minimizing work-up procedures (simple filtration and evapouration of the acetic acid and solvent) and decreasing the E-factor.

To read more, please click the link below:

Eco-friendly synthesis of β-nitro ketones from conjugated enones: an important improvement of the Miyakoshi procedure, Serena Gabrielli, Alessandro Palmieri, Alvise Perosa, Maurizio Selva and Roberto Ballini,  Green Chem., 2011, 13, 2026-2028, DOI: 10.1039/C1GC15616K

This article is free to access until 14th September!

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Green ruthenium-catalysed reactions

Recyclable mesoporous silica-supported chiral ruthenium-(NHC)NN-pincer catalysts for asymmetric reactions.  Scientists from Spain have reported two new stable chiral Ru-pincer complexes with a pendant silyloxy group, which were grafted onto a mesoporous silica (MCM-41).  These supported complexes were shown to be highly active and recyclable catalysts for the asymmetric hydrogenation of alkenes and the cyclopropanation of styrenes.  These catalysts avoid the draw-backs associated with homogeneous catalysts such as high catalyst loadings and difficulties in catalyst recovery.  The supported catalysts reported here showed no deactivation after repeated recycling. (Green Chem., 2011, DOI 10.1039/c1gc15412e)

C-H bond functionalisation with [RuH(codyl)2]BF4 catalyst precursor.  Scientists from the CNRS-University of Rennes, France have employed a ruthenium catalyst, assisted by a coordinating base, for the direct diarylation of arenes with (hetero)arylhalides.  This reaction under these conditions is milder that the classical organometallic cross-coupling reactions.  The coordinating ligand/base has an important role by promoting the initial cleavage of the C-H bond.  The efficiency of the system strongly depends on the nature of both the assisting ligand/base and the (hetero)aryl halides. (Green Chem., 2011, DOI: 10.1039/c1gc15642j)

These articles are free to access until September 9th!

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Top ten most accessed articles in June

This month sees the following articles in Green Chemistry that are in the top ten most accessed:-

Searching for green solvents
Philip G. Jessop
Green Chem., 2011, Advance Article, DOI: 10.1039/C0GC00797H, Perspective

Viable methodologies for the synthesis of high-quality nanostructures
Jonathan M. Patete, Xiaohui Peng, Christopher Koenigsmann, Yan Xu, Barbara Karn and Stanislaus S. Wong
Green Chem., 2011, 13, 482-519, DOI: 10.1039/C0GC00516A, Critical Review

Selective catalytic oxidation of glycerol: perspectives for high value chemicals
Benjamin Katryniok, Hiroshi Kimura, Elżbieta Skrzyńska, Jean-Sébastien Girardon, Pascal Fongarland, Mickaël Capron, Rémy Ducoulombier, Naoki Mimura, Sébastien Paul and Franck Dumeignil
Green Chem., 2011, 13, 1960-1979, DOI: 10.1039/C1GC15320J, Critical Review

Examples of heterogeneous catalytic processes for fine chemistry
Carlo Lucarelli and Angelo Vaccari
Green Chem., 2011, 13, 1941-1949, DOI: 10.1039/C0GC00760A, Tutorial Review

Algae as a source of renewable chemicals: opportunities and challenges
Patrick M. Foley, Evan S. Beach and Julie B. Zimmerman
Green Chem., 2011, Advance Article, DOI: 10.1039/C1GC00015B

Levulinic esters from the acid-catalysed reactions of sugars and alcohols as part of a bio-refinery
Xun Hu and Chun-Zhu Li
Green Chem., 2011, 13, 1676-1679, DOI: 10.1039/C1GC15272F, Communication

Sustainable hydrogen production by the application of ambient temperature photocatalysis
Michael Bowker
Green Chem., 2011, Advance Article, DOI: 10.1039/C1GC00022E, Critical Review

From biomass to feedstock: one-step fractionation of lignocellulose components by the selective organic acid-catalyzed depolymerization of hemicellulose in a biphasic system
Thorsten vom Stein, Philipp M. Grande, Henning Kayser, Fabrizio Sibilla, Walter Leitner and Pablo Domínguez de María
Green Chem., 2011, 13, 1772-1777, DOI: 10.1039/C1GC00002K, Paper

5-Hydroxymethylfurfural (HMF) as a building block platform: Biological properties, synthesis and synthetic applications
Andreia A. Rosatella, Svilen P. Simeonov, Raquel F. M. Frade and Carlos A. M. Afonso
Green Chem., 2011, 13, 754-793, DOI: 10.1039/C0GC00401D, Critical Review

Green materials synthesis with supercritical water
Tadafumi Adschiri, Youn-Woo Lee, Motonobu Goto and Seiichi Takami
Green Chem., 2011, 13, 1380-1390, DOI: 10.1039/C1GC15158D, Tutorial Review

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

Fancy submitting an article to Green Chemistry? Then why not submit to us today or alternatively email us your suggestions.

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Conference News: 3rd Asia-Oceania Conference on Green and Sustainable Chemistry

The 3rd Asia-Oceania Conference on Green and Sustainable Chemistry (AOC-3) will be held in Melbourne, Australia on December 4 – 7, 2011. The aim of the conference is to provide a platform for interaction and exchange of ideas between practitioners in Green Chemistry, and to promote Green Chemistry in the Asia-Oceania region. Program highlights will include presentations by the ‘father of green chemistry’, Dr Paul Anastas and 2010 Nobel Prize Winner, Dr Akira Suzuki. Abstract submission is still open for oral consideration and earlybird rates are available. Please visit http://www.greenoz2011.org/ to register and lodge your abstract!

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Sustainable synthesis of nitrogen-doped carbon aerogels

Scientists from Germany and Japan have developed a method to synthesize nitrogen-doped carbon aerogels (CA) from sustainable starting materials.

Aerogels are coherent, highly porous solid materials with attractive physical properties such as low density, excellent mass-transfer properties, low thermal conductivity, and low dielectric permittivity.  Previous methods to synthesize nitrogen-doped CA have several disadvantages, as the materials are phenol-based with low conductivity and relatively inert, making post-chemical modification challenging.

In this work, White and co-workers employed D-glucose and ovalbumin as sustainable precursors to produce nitrogen-doped CA, with the protein acting as the nitrogen donor and surface stabilizing agent.  The resulting aerogels have high surface area with large diameter mesopores and excellent hierarchical transport architecture.  Post-carbonization treatment controls the surface chemistry giving tunable physicochemical properties on a unique continuous 3D carbonaceous pore structure.  This method should help the development of sustainable carbon aerogels suitable for a range of applications.

To read the full article, please click on the link below!  This article is free to access until September 6th.

A sustainable synthesis of nitrogen-doped carbon aerogels, Robin J. White, Noriko Yoshizawa, Markus Antonietti and Maria-Magdalena Titirici, Green Chem., 2011, DOI: 10.1039/C1GC15349H

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Green Chemistry Volume 13 Issue 8 online now!

Green Chemistry Volume 13 Issue 8 Front Cover by Itamar Daube

Drawn by Itamar Daube; http://www.itamardaube.com

Green Chemistry issue 8 features an artist’s impression* of the problematic situation of Fischer-Tropsch bimetallic catalysis, it highlights a critical review from Advisory Board member Gadi Rothenberg and co-workers from The Netherlands and France.  Their short critical review summarises and analyses the developments in Fischer–Tropsch catalysis using bimetallic alloys, read the full article online here.

Green Chemistry Volume 13 Issue 8 Inside Front CoverThe inside front cover highlights the article ‘Controlled polymerisation of lactide using an organo-catalyst in supercritical carbon dioxide’ by Idriss Blakey and co-workers from the University of Queensland, Australia and the University of Nottingham, UK.  Their article, previously highlighted on this blog, reports the ‘green’ synthesis of well defined polylactic acid (PLA) via organo-catalysis, without using any organic solvents.  Read the full article online here.

*The copyright owner, Prof. Dr. Gadi Rothenberg, hereby gives all persons permission to use this cover image for any purpose, provided that the artist’s name and website is correctly cited.  Drawn by Itamar Daube; http://www.itamardaube.com

 
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