Green Chemistry Blog

Andrea Robinson and colleagues from Monash University, Australia, have developed an immobilized catalyst for ring closing metathesis (RCM) of olefins allowing for easy removal and recovery of the catalyst. 

A quaternary ammonium Hoveyda-Grubbs metathesis pre-catalyst was made in one step from the commercially available second generation Grubbs catalyst, before electrostatic immobilization onto magnetic iron oxide particles.  The resulting catalyst provided pseudo-homogeneous reactivity but coupled with an easy recovery option.  The catalyst could simply be magnetically retrieved from the reaction media and the catalyst reused up to six times.

This article is free to access until the 23rd December 2011!  Click on the link below to find out more…

Electrostatic immobilization of an olefin metathesis pre-catalyst on iron oxide magnetic particles, Matthew J. Byrnes, Andrew M. Hilton, Clint P. Woodward, William R. Jackson and Andrea J. Robinson, Green Chem., 2012, DOI: 10.1039/C1GC16084B

A new porous co-ordination polymer has been synthesised in near-critical water which could broaden the synthetic strategies available for the environmentally friendly construction of metal-organic frameworks.

Metal-organic frameworks (MOFs) have received a lot of attention in recent years due to their potential applications in several areas, but in particular for hydrogen storage.  However, MOFs are often prepared using solvothermal routes typically involving significant quantities of toxic organic solvents. 

In this work Martyn Poliakoff and Martin Schröder and colleagues from the University of Nottingham and Diamond Light Source, UK, have developed a route to synthesise these Zn co-ordination polymers using near-critical water (300°C) as a cleaner alternative to organic solvents.  The zinc complex can be isolated without any water molecules bound to the Zn(II) centres, in contrast to solvothermal synthesis in DMF.  In addition, the use of water in this synthetic strategy potentially allows for the reuse and recovery of water from the reaction opening up possible industrial applications.

This article is free to access until the 20th December 2011!  Click on the link below to find out more…

Near-critical water, a cleaner solvent for the synthesis of a metal–organic framework, Ilich A. Ibarra, Peter A. Bayliss, Eduardo Pérez, Sihai Yang, Alexander J. Blake, Harriott Nowell, David R. Allan, Martyn Poliakoff and Martin Schröder, Green Chem., 2012, DOI: 10.1039/C1GC15726D

Hydrogen peroxide (H₂O₂) could be synthesized directly from molecular H₂ and O₂ using a supported heteropolyacid catalyst and water as solvent at ambient temperature.

Graham Hutchings and colleagues from Cardiff University, UK, prepared several Au-Pd exchanged supported Cs-heteropolyacid catalysts for application in the synthesis of H₂O₂.  Currently, H₂O₂ is prepared from alkyl anthraquinone but this process requires high capital investment and the production and transport of very concentrated H₂O₂ solutions.  By developing a direct synthesis process, these drawbacks could be avoided by giving small scale production of dilute H₂O₂ at the point of use.

In this work, the Au-Pd exchanged supported Cs-heteropolyacid catalysts developed by Hutchings showed excellent H₂O₂ synthesis activity and were considerably more effective in achieving high yields than previously reported catalysts.  By performing the reaction at ambient temperature in water in the absence of acid or halide additives, this method offers a potentially cleaner and more sustainable route to H₂O₂. 

This article is free to access until 15th December 2011!  Click the link below to find out more…

Direct synthesis of hydrogen peroxide using Au–Pd-exchanged and supported heteropolyacid catalysts at ambient temperature using water as solvent, Edwin N. Ntainjua, Marco Piccinini, Simon J. Freakley, James C. Pritchard, Jennifer K. Edwards, Albert F. Carley and Graham J. Hutchings, Green Chem., 2012, DOI: 10.1039/C1GC15863E

A recyclable Ru(II) complex has been found to be highly active for the aqueous phase nitrile hydration at 100°C in air.

Brian Frost and Wei-Chih Lee from the University of Nevada, USA, used the Ru complex [RuCl₂(PTA)₄] for the aqueous or biphasic hydration of nitriles.  Other approaches to this reaction suffer air-sensitive or non-recyclable catalysts as well as requiring organic solvents.  However, in the method developed by Frost, the reaction can be performed under an air atmosphere and the catalyst can be reused more than five times without significant loss of activity.  This reaction can convert aromatic, alkyl, and vinyl nitriles to their corresponding amides in near quantitative conversions.

This article has been made free to access until the 9th December 2011!  Click the link below to find out more…

Aqueous and biphasic nitrile hydration catalyzed by a recyclable Ru(II) complex under atmospheric conditions, Wei-Chih Lee and Brian J. Frost, Green Chem., 2012, DOI: 10.1039/C1GC15950J

Scientists from Italy have developed a new series of ionic liquids from renewable starting materials.

The team of scientists led by Cinzia Chiappe and Fabio Bellina synthesized a series of trialkyl(2,3-dihydroxypropyl)phosphonium salts prepared from 3-chloropropane-1,2-diol or (2,2-dimethyl-1,3-dioxolan-4-yl)methanol – two compounds that can be obtained easily from glycerol.  Phosphonium salts are emerging as promising alternatives to imidazolium analogues, as they are inert in basic reaction media and possess superior stability. Chiappe and Bellina have developed an efficient route to these compounds from cheap and commercially available starting materials.

This article is free to access until 9th December 2011!  To find out more, click on the link below…

Synthesis and properties of trialkyl(2,3-dihydroxypropyl)phosphonium salts, a new class of hydrophilic and hydrophobic glyceryl-functionalized Ils, Fabio Bellina, Cinzia Chiappe and Marco Lessi, Green Chem., 2011, DOI: 10.1039/C1GC16035D