Green Chemistry Blog

Scientists from Denmark and the USA have achieved efficient conversion of 5-hydroxymethylfurfural (HMF) to valuable chemicals over a Cu-doped porous metal oxide catalyst in supercritical methanol.

HMF (readily obtained from hexose sugars) has been identified as a key platform compound to generate useful renewable chemicals for the fuel industry, such as 2,5-dimethylfuran (DMF) and 2,5-dimethyltetrahydrofuran (DMTHF).  However, achieving selective transformation of HMF to a specific product and preventing the formation of undesired side-products remains a challenge.

In this work, a collaboration between scientists at the Technical University of Denmark, Yale University (USA) and the University of California Santa-Barbara (USA) led by Katalin Barta and Andreas Riisager have developed an one-pot procedure for the reduction of HMF.  The catalyst was prepared in aqueous solution from inexpensive and earth-abundant starting materials before undergoing calcination.  By tuning the reaction temperature, DMF or DMTHF and 2-hexanol could be obtained as the major products, and no formation of higher boiling side products or undesired char was detected. 

This article is free to access until the 28th September 2012!  Click on this link below to fine out more…

One-pot reduction of 5-hydroxymethylfurfural viahydrogen transfer from supercritical methanol, Thomas S. Hansen, Katalin Barta, Paul T. Anastas, Peter C. Ford and Anders Riisager, Green Chem., 2012, 14, 2457-2461

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Synergy of boric acid and added salts in the catalytic dehydration of hexoses to 5-hydroxymethylfurfural in water, Thomas S. Hansen, Jerrik Mielby and Anders Riisager, Green Chem., 2011, 13, 109-114

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Chinese scientists provide a clear picture of the cycloaddition of carbon dioxide (CO₂) and epoxides promoted by the KI/hydroxyl catalytic system.

Over recent years, the KI/hydroxyl catalytic system has been recognised as one of the most successful and important routes to convert CO₂ into value-added chemicals; for example, cyclic carbonates.  However, the catalytic mechanism is not clear.  In this work, Buxing Han and colleagues from the Chinese Academy of Sciences, Beijing, China, demonstrate a theoretical approach to clarify the catalytic mechanism of KI and the co-catalytic mechanism of hydroxyl substances.  The authors employed density functional theory method to determine the transition structures, rate-determining steps and lowest energy barrier reaction pathways for both gas phase and solvent conditions.  It was found that a ternary synergistic catalytic system was formed between the hydroxyl groups, the potassium cation and the iodine anion, I^––(–OH)–K⁺.

This article is free to access until the 4th September 2012!  Click on the link below to find out more…

The catalytic mechanism of KI and the co-catalytic mechanism of hydroxyl substances for cycloaddition of CO₂ with propylene oxide, Jun Ma, Jinli Liu, Zhaofu Zhang and Buxing Han, Green Chem., 2012, DOI: 10.1039/C2GC35711A

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One-pot conversion of CO₂ and glycerol to value-added products using propylene oxide as the coupling agent, Jun Ma, Jinliang Song, Huizhen Liu, Jinli Liu, Zhaofu Zhang, Tao Jiang, Honglei Fan and Buxing Han, Green Chem., 2012, 14, 1743-1748

Organotin-oxomolybdate coordination polymer as catalyst for synthesis of unsymmetrical organic carbonates, Jinliang Song, Binbin Zhang, Tainbin Wu, Guanying Yang and Buxing Han, Green Chem., 2011, 13, 922-927

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Plasticizer alcohols have been synthesised from renewable reagents through a borane-free oxidation/reduction sequence.

Bis(2-ethyl-hexyl) phthalate (DEHP) is one of the most important and widely used industrial plasticizers and is generated from 2-ethyl-1-hexanol (2EH) and phthalic anhydride.  In the process of converting bio-butanol to jet fuels, a significant amount of 2-ethyl-1-hexene is produced as a by-product, and is an attractive feedstock to generate 2EH.  To yield the required 2EH from 2-ethyl-1-hexene, an anti-Markovnikov addition is required. However, the traditional hydroboration method used to achieve this is not ideal for large scale, atom economic production of 2EH.

In this work, Benjamin Harvey and colleagues from the United States Navy-Naval Air Systems Command (NAVAIR) demonstrate an efficient method for formal anti-Markovnikov hydration of 1,1-disubstituted alkenes.  Their approach generates the plasticizer alcohols by the oxidation/hydration/hydrogenation of branched chain alkenes under mild, borane-free conditions.  This process was successfully applied to the production of 2EH from 2-ethyl-1-hexene, and presents an alternative to hydroboration for a challenging subset of hindered olefins.

This article is free to access until the 29th August 2012!  Click on the link below to find out more…

Synthesis of renewable plasticizer alcohols by formal anti-Markovnikov hydration of terminal branched chain alkenes viaa borane-free oxidation/reduction sequence, Benjamin G. Harvey, Heather A. Meylemans and Roxanne L. Quintana, Green Chem., 2012, DOI: 10.1039/C2GC35595G

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Mechanism of efficient anti-Markovnikov olefin hydroarylation catalyzed by homogeneous Ir(III) complexes, Gaurav Bhalla, Steven M. Bischof, Somesh K. Ganesh, Xiang Yang Liu, C. J. Jones, Andrey Borzenko, William J. Tenn, III, Daniel H. Ess, Brian G. Hashiguchi, Kapil S. Lokare, Chin Hin Leung, Jonas Oxgaard, William A. Goddard, III and Roy A. Periana, Green Chem., 2011, 13, 69-81

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Aromatic and aliphatic ketones reacted with aniline and molecular hydrogen in the presence of an easily available copper catalyst to give amines in high yields.

Reductive amination is one of the most important and effective C-N bond forming reactions and provides a general practical way to access amines.  The reaction commonly involves chemicals which act hydrogen donors to be present, such as silanes and formates.  However, utilizing molecular hydrogen instead would give a much more environmentally and atom-economical reducing agent, would give water as the only by-product.

Here, Matthias Beller and colleagues from the Leibniz-Institute for Catalysis in Rostock, Germany report that simple Cu(OAc)2, an inexpensive and easily available catalyst, could catalyse the reductive amination of a variety of ketones with anilines and molecular hydrogen.  The procedure does not require any complicated ligands or additional acid or base and represents the first example of a catalytic approach using copper and molecular hydrogen for reductive aminations.

This article is free to access until the 24th August 2012!  Click on the link below to find out more…

Copper-catalyzed reductive amination of aromatic and aliphatic ketones with anilines using environmental-friendly molecular hydrogen, Svenja Werkmeister, Kathrin Junge and Matthias Beller, Green Chem., 2012, DOI: 10.1039/C2GC35565E

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French scientists report a ruthenium-catalysed cross-metathesis route to produce a C12 nitrile ester with high turnover number.

10-Undecylenic acid derivatives are a valuable feedstock readily available from caster oil and have been used for the industrial production of polyamide.  In this work, scientists from CBRS-University of Rennes and ARKEMA in France demonstrate that the linear C12 α,ω-amino ester, a precursor to polyamide, can be prepared viacross-metathesis of methyl acrylate with 10-undecenenitrile (which is bio-sourced) in the presence of ruthenium-alkylidene catalysts.  Subsequent C=C and nitrile reduction could then be performed to produce the C12 α,ω-amino ester.

This overall tandem procedure provides a sustainable route to linear amino esters, where a single catalyst is used from the outset to perform 3 catalytic transformations (cross-metathesis, carbon-carbon double bond hydrogenation and nitrile reduction) using bio-sourced starting materials.

This article is free to access until the 6th August 2012! Click on the link below to find out more…

Polyamide precursors from renewable 10-undecenenitrile and methyl acrylate via olefin cross-metathesis, X. Miao, C. Fischmeister, P. H. Dixneuf, C. Bruneau, J.-L. Dubois and J.-L. Couturier, Green Chem., 2012, DOI: 10.1039/C2GC35648A

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Ruthenium–alkylidene catalysed cross-metathesis of fatty acid derivatives with acrylonitrile and methyl acrylate: a key step toward long-chain bifunctional and amino acid compounds, X. Miao, R. Malacea, C. Fischmeister, C. Bruneau and P. H. Dixneuf, Green Chem., 2011, 13, 2911-2919

A green route to nitrogen-containing groups: the acrylonitrile cross-metathesis and applications to plant oil derivatives, Xiaowei Miao, Pierre H. Dixneuf, Cédric Fischmeister and Christian Bruneau, Green Chem., 2011, 13, 2258-2271

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UK Scientists report the feasibility of solvent recovery via solvent nanofiltration as an alternative to distillation.

Distillation has been the common technique employed for separating solvent from crystallisation mother liquors for many years.  However, although high purity solvent is generated from this process, it can be very energy-intensive and so a low energy alternative is highly sort after.  Here, Christopher Pink and colleagues from GlaxoSmithKline R&D Ltd and Imperial College London, UK, report the use of organic solvent nanofiltration (OSN) as an alternative to distillation for solvent recovery.  The team report that OSN is capable of recovering the organic solvent with a purity suitable for re-use in subsequent crystallisation processes, and energy-efficiency calculations show that OSN uses 25 times less energy per L of recovered solvent compared to distillation. 

However, the efficiency of this membrane-based solvent recovery is restricted by the solubility of the compounds within the waste stream, and can result in the recovery of less solvent for OSN.  But equivalent recovery volumes can be obtained with a combined distillation/OSN approach, still resulting in 9 times less energy consumption than when using distillation alone. 

This article is free to access until the 31st July 2012!  Click on the link below to find out more…

Organic solvent nanofiltration: a potential alternative to distillation for solvent recovery from crystallisation mother liquors, Elin M. Rundquist, Christopher J. Pink and Andrew G. Livingston, Green Chem., 2012, DOI: 10.1039/C2GC35216H

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Environmentally friendly route for the preparation of solvent resistant polyimide nanofiltration membranes, Iwona Soroko, Yogesh Bhole and Andrew Guy Livingston, Green Chem., 2011, 13, 162-168

Product recovery from ionic liquids by solvent-resistant nanofiltration: application to ozonation of acetals and methyl oleate, Charlie Van Doorslaer, Daan Glas, Annelies Peeters, Angels Cano Odena, Ivo Vankelecom, Koen Binnemans, Pascal Mertens and Dirk De Vos, Green Chem., 2010, 12, 1726-1733

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