Green Chemistry Blog

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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