Green Chemistry Blog

Albert Matlack, one of the founding educators of green chemistry and author of the seminal book ‘Introduction to Green Chemistry’, selects his favourite papers in Green Chemistry this month…

Characterization, synthesis and catalysis of hydrotalcite-related materials for highly efficient materials transformations, Shun Nishimura, Atsushi Takagaki and Kohki Ebitani, Green Chem., 2013, 15(8),2026–2042, DOI: 10.1039/C3GC40405F

This is a review of hydrotalcites, which are layered magnesium aluminum hydroxy carbonates. They are the strongest bases known and are easy to recover for reuse by filtration. They are known for improved selectivity and yield when reactions are run in the constrained space between layers. Zeolites, metal organic frameworks and clays also offer such advantages. The review covers the synthesis, reactions alone and when used as a support for transition metals.

*Open Access* A prototype device for evaporation in batch and flow chemical processes, Benjamin J. Deadman, Claudio Battilocchio, Eric Sliwinskia and Steven V. Ley, Green Chem., 2013, 15(8), 2050–2055, DOI: 10.1039/C3GC40967H

In this work, Ley et. al. have developed a device for evaporating, concentrating and switching solvents in continuous flow so that all solvents can be recovered for reuse. Twenty one solvents ranging  from dichloromethane to dimethylformamide were recovered satisfactorily. This enlarges the possibilities for the use of microchanneled reactors in process intensification. They offer higher selectivities and yields, safer reactions, easy heating and cooling, no need to worry about explosive limits, no need for a pilot plant with  smaller cheaper chemical plants. Other methods include spinning disc and tube in tube reactors. With the latter, up to 15 tons per hour can be processed. Oxford Catalysts has developed such systems for steaming reforming plus Fischer-Tropsch conversion of stranded natural gas to liquids. Two research groups have developed microchanneled reactors with inline analysis for five variables that are self-optimizing over a period of two to three. The group of Buchwald did it for a Heck Reaction and Poliakoff‘s group did for the reaction of 1-pentanol with dimethyl carbonate.

Highly efficient production of lactic acid from cellulose using lanthanide triflate catalysts, Fen-Fen Wang, Chun-Ling Liu and Wen-Sheng Dong, Green Chem., 2013, 15(8), 2091–2095, DOI: 10.1039/C3GC40836A

In this work, cellulose was converted to lactic acid with an erbium triflate catalyst in water at 240 degrees C, in 30 minutes in 89.6% yield. The catalyst showed no loss of activity after five runs. This avoids the need to hydrolyze cellulose to sugars as a separate step. Lactic acid is the monomer for the commercial poly(lactic acid) which is biodegradable. The conversion of lactic acid to acrylic acid is being commercialized.

Today’s society currently faces two big challenges in the form of resource depletion and waste accumulation.  The result of this is increased cost of raw resources and increasingly restrictive and expensive waste disposal.

In this perspective article, James Clark and colleagues evaluate the potential of food waste biomass as a resource for high-value chemicals.  The team begin at looking at food supply chain waste (FSCW) as a renewable resource more generally, focusing on the practicalities of using such resources and their availability.  In the latter half of the perspective, Clark looks at a biorefinery concept using citrus fruit waste and shows that this is a potentially cost-effective alternative to produce valuable chemicals. 

Clark emphasises throughout the article that it is important to go beyond first generation waste valorisation and so we must try to make use of all the valuable components of the waste.  You can see Professor Clark’s recent lecture on this topic on The Reaction website, given at the Chemistry Centre in October. 

Read the full article for free until the 4th February 2013!

Food waste biomass: a resource for high-value chemicals, Lucie A. Pfaltzgraff, Mario De bruyn, Emma C. Cooper, Vitaly Budarin and James H. Clark, Green Chem., 2013, DOI: 10.1039/C2GC36978H

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Oxidation represents one of the most important reactions in organic synthesis and looks to have a significant role on the development and synthesis of value-added chemicals from biomass.  Efforts to make oxidation reactions more sustainable have led to the development of heterogeneous catalysts and the use of molecular oxygen an alternative to traditional, toxic chemical oxidants.

In this Critical Review, Robert Davis and colleagues from the University of Virginia, USA, evaluate the literature surrounding the use of supported metal nanoparticle catalysts for the selective oxidation of alcohols and aldehydes.  Davis compares the performances of the catalysts studied in this review by categorising reaction rates based on the turnover frequency as a common, consistent denominator.   The authors also look at factors that can affect the evaluation of reaction kinetics, such as catalyst deactivation, and give suggestions regarding how to obtain the best data.

Read this article for free until the 29th November 2012!

Selective oxidation of alcohols and aldehydes over supported metal nanoparticles, Sara E. Davis, Matthew S. Ide and Robert J. Davis, Green Chem., 2012, DOI: 10.1039/C2GC36441G

You may also be interested in these related articles – free to access until the 15th November 2012:

On the mechanism of selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over supported Pt and Au catalysts, Sara E. Davis, Bhushan N. Zope and Robert J. Davis, Green Chem., 2012, 14, 143-147

Inhibition of gold and platinum catalysts by reactive intermediates produced in the selective oxidation of alcohols in liquid water, Bhushan N. Zope and Robert J. Davis, Green Chem., 2011, 13, 3484-3491

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In this tutorial review, Donald Darensbourg and Stephanie Wilson highlight the recent advances in the copolymerisation of carbon dioxide (CO₂) with epoxides (oxiranes) to produce polycarbonates.

The advances in this area are discussed with specific reference to catalysts that have been designed to afford high selectivity for the copolymer versus cyclic carbonate formation.  The authors not only illustrate the advances in poly(propylene carbonate) (PPC) production by also investigate the underlying reasons for the differences in the reactivity of propylene oxide and cyclohexene oxide. 

Darensbourg and Wilson conclude by highlighting the need for improved catalysts which can prevent the degradation of PPC in the presence of azide ions – specifically those catalysts with appended amines or ammonium salts. 

Interested?  Read the full article for free until the 2nd October 2012…

What’s new with CO₂? Recent advances in its copolymerization with oxiranes, Donald J. Darensbourg and Stephanie J. Wilson, Green Chem., 2012, DOI: 10.1039/C2GC35928F

You may also be interested in this critical review article – free to access for 2 weeks:

Synthesis of cyclic carbonates from epoxides and CO₂, Michael North, Riccardo Pasquale and Carl Young, Green Chem., 2010, 12, 1514-1539

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In this perspective, Enrico Drioli and colleagues evaluate how membrane systems can help achieve ‘green process engineering’.

The principles of a process intensification strategy can lead to the development and redesign of new processes which are more compact and efficient than their traditional counterparts.  These new processes can allow for better exploitation of raw materials, lower energy consumption and a reduced plant volume.  Membrane technologies can be seen as contributing to these principles and over the last few years, the scope for membrane operations has become widely recognised.

In this perspective article, the authors provide an overview of membrane applications and their perspectives in the fields of hydrogen production and distillation will be analysied through case studies.  The aim of this review is to show how redesigning traditional operations as membrane systems might contribute to the realization of the goals of process intensification. 

This article is free to access until the 16th May 2012! Click on the link below to find out more…

Process intensification strategies and membrane engineering, Enrico Drioli, Adele Brunetti, Gianluca Di Profio and Giuseppe Barbieri, Green Chem., 2012, DOI: 10.1039/C2GC16668B

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This review article by Christoph Rücker and Klaus Kümmerer critically evaluate various approaches to predict aquatic aerobic biodegradation from a user’s point of view.

The ‘benign by design’ concept is an emerging tool for developing green and sustainable chemistry.  However, in order for this approach to work information on a compound’s biodegradability needs to be available at an early stage, even before synthesis.  In view of this, computer models for predicting biodegradation are increasingly important.

In this critical review, the authors discuss and evaluate some of the fundamental problems in modeling biodegradation, as well as more general issues in modeling compound properties by quantitative structure-property/activity relationships.

This article has been made free to access until the 4th April 2012! Click on the link below to find out more…

Modeling and predicting aquatic aerobic biodegradation – a review from a user’s perspective, Christoph Rücker and Klaus Kümmerer, Green Chem., 2012, DOI: 10.1039/C2GC16267A

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