Green Chemistry Blog

Here are the latest hot papers in Green Chemistry, as recommended by the referees:

A continuous process for glyoxal valorisation using tailored Lewis-acid zeolite catalysts
Pierre Y. Dapsens, Cecilia Mondelli, Bright T. Kusema, René Verel and Javier Pérez-Ramírez  
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42353K, Paper

Solvents for sustainable chemical processes
Pamela Pollet, Evan A. Davey, Esteban E. Ureña-Benavides, Charles A. Eckert and Charles L. Liotta  
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42302F, Critical Review

Branched polyethylene mimicry by metathesis copolymerization of fatty acid-based α,ω-dienes
Thomas Lebarbé, Mehdi Neqal, Etienne Grau, Carine Alfos and Henri Cramail  
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42280A, Communication

All the papers listed above are free to access for the next 4 weeks!

A biotechnological process to transform lignin into an adhesive opens the door on an eco-friendly strategy for recycling carpets, new research shows.

Traditional carpets consist of yarns stuck to a backing fabric by an adhesive – usually synthetic latex. As part of the production process, the latex is cured at high temperatures, but this creates a non-recyclable material as the latex is almost impossible to remove at the end of a carpet’s life. As a result, almost all carpets are disposed of by burning in an incinerator.

With a view to finding a more environmentally friendly solution to carpet disposal, Tzanko Tzanov and his team at the Polytechnic University of Catalonia in Barcelona, Spain, decided to replace the synthetic latex with an organic lignin-based adhesive to produce a renewable woollen floor covering.

Lignin is an aromatic polymer that reinforces cellulose fibres in plants and is readily available as a waste product of paper and biofuel production. 

It can be easily converted into an adhesive using laccase, an enzyme found in plants and fungi. ‘Lignin is transformed by an oxidative enzymatic process that activates the phenolic structures, which can then react chemically with the wool fibres and bind them to the backing,’ explains Tzanov. The process is carried out at much lower temperatures than in latex production – around 50°C rather than 150°C – making it much more environmentally friendly.

The carpets can degrade and be recycled as a soil fertiliser

The laccase enzymes that convert lignin into an adhesive are also involved in its biodegradation, meaning that the carpets can be recycled at the end of their usable life. Instead of being incinerated, the carpets are shredded and returned to nature, where they degrade and can be used as a soil fertiliser.

Diego Moldes Moreira, an expert in natural products and bioprocesses at the University of Vigo in Spain is impressed by the innovative and sustainable solution. ‘We could expect to find the proposed biotech carpets in stores in the short–medium term,’ he says. In fact, Tzanov’s team are already working with Dutch companies, James and Best Wool Carpets, on an industrial scale-up.

You can also read this article in Chemistry World»

Read the original journal article in Green Chemistry – it’s free to access until 27th March:
An enzymatic approach to develop a lignin-based adhesive for wool floor coverings
Elisabetta Aracri, Carlos Díaz Blanco and Tzanko Tzanov  
Green Chem., 2014, Accepted Manuscript, DOI: 10.1039/C4GC00063C, Paper

The 10 most downloaded Green Chemistry articles in 2013 were as follows:

Deconstruction of lignocellulosic biomass with ionic liquids
Agnieszka Brandt, John Gräsvik, Jason P. Hallett and Tom Welton  
Green Chem., 2013,15, 550-583
DOI: 10.1039/C2GC36364J, Critical Review

Catalytic conversion of biomass to biofuels
David Martin Alonso, Jesse Q. Bond and James A. Dumesic  
Green Chem., 2010,12, 1493-1513
DOI: 10.1039/C004654J, Critical Review

Characterization and comparison of hydrophilic and hydrophobic room temperature ionic liquids incorporating the imidazolium cation
Jonathan G. Huddleston, Ann E. Visser, W. Matthew Reichert, Heather D. Willauer, Grant A. Broker and Robin D. Rogers  
Green Chem., 2001,3, 156-164
DOI: 10.1039/B103275P, Paper

Photocatalysis on supported gold and silver nanoparticles under ultraviolet and visible light irradiation
Sarina Sarina, Eric R. Waclawik and Huaiyong Zhu  
Green Chem., 2013,15, 1814-1833
DOI: 10.1039/C3GC40450A, Tutorial Review

Selective oxidation of alcohols and aldehydes over supported metal nanoparticles
Sara E. Davis, Matthew S. Ide and Robert J. Davis  
Green Chem., 2013,15, 17-45
DOI: 10.1039/C2GC36441G, Critical Review

Hydrolysis of cellulose to glucose by solid acid catalysts
Yao-Bing Huang and Yao Fu  
Green Chem., 2013,15, 1095-1111
DOI: 10.1039/C3GC40136G, Tutorial Review

Multicomponent reactions in unconventional solvents: state of the art
Yanlong Gu  
Green Chem., 2012,14, 2091-2128
DOI: 10.1039/C2GC35635J, Critical Review

Green synthesis of metal nanoparticles using plants
Siavash Iravani  
Green Chem., 2011,13, 2638-2650
DOI: 10.1039/C1GC15386B, Critical Review

Technology development for the production of biobased products from biorefinery carbohydrates—the US Department of Energy’s “Top 10” revisited
Joseph J. Bozell and Gene R. Petersen  
Green Chem., 2010,12, 539-554
DOI: 10.1039/B922014C, Critical Review

Gamma-valerolactone, a sustainable platform molecule derived from lignocellulosic biomass
David Martin Alonso, Stephanie G. Wettstein and James A. Dumesic  
Green Chem., 2013,15, 584-595
DOI: 10.1039/C3GC37065H, Critical Review
From themed collection Green Chemistry and the Environment

Take a look at the articles, and if you have any comments, please leave them below.

Interested in submitting your own work to Green Chemistry? You can submit online today, or email us with your ideas and suggestions.

Chitin is a main constituent of the exoskeletons of insects and crustaceans. Utilizing this biopolymer in the production of value-added chemicals, particularly nitrogen-containing aromatic compounds (e.g., furans), is a more sustainable route than their energy-intensive synthesis from ammonia. Chitin may be subjected to hydrolysis reactions to produce N-acetyl-D-glucosamine (NAG), its monomeric constituent. Kerton et al. previously reported a high-yielding synthesis of 3-acetamido-5-acetylfuran (3A5AF) by the direct dehydration of NAG. In this paper, Kerton and researchers from the National University of Singapore aimed to combine the two steps to generate NAG in situ from chitin and convert it to 3A5AF.

In order to dissolve chitin, its extensive hydrogen-bonding network must be tempered. The use of polar, aprotic solvents in combination with metal salts can accomplish this challenging task, enabling the dehydration reaction to occur more easily. Chloride-containing salts or additives also facilitate the reaction, which is suspected to occur through their disruptive effect on the hydrogen bonds. Dual or tri-component additive systems of boric acid with alkali or alkaline earth metal chlorides resulted in the highest yields of 3A5AF. The optimized conditions used boric acid and sodium chloride in NMP (N-methyl-2-pyrrolidone) to give ca. 7.5% 3A5AF, while 50% chitin conversion was achieved, representing an array of other products. Pre-treatment of chitin to initiate the depolymerisation was suggested as a potential means to increase 3A5AF yields.

Read this article now, we’ve made it free to access until 3rd March:

Direct conversion of chitin into a N-containing furan derivative
Xi Chen, Shu Ling Chew, Francesca M. Kerton, and Ning Yan
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42436G

Jenna Flogeras obtained her B.Sc. and M.Sc. in Chemistry from the University of New Brunswick (Fredericton), Canada. She is currently working towards her Ph.D. at Memorial University of Newfoundland, under the supervision of Dr. Francesca Kerton. Her research is focused on the synthesis of biodegradable polymers using main-group metal complexes as catalysts.

Jennifer Lee and George Kraus of Iowa State University have published a new method of producing dimethyl terephthalate, a precursor to polyethylene terephthalate (PET), from renewable sources. In this new work the reaction between methyl coumalate (the esterified dimer of malic acid) and methyl pyruvate (the ester of pyruvic acid) is optimised to provide dimethyl terephthalate in 95% yield.

This is the latest of several approaches currently being developed to supplant the current manufacturing process that produces PET from finite fossil resources. These include the valorisation of citrus waste and the reaction of ethylene with 2,5-dimethylfuran. As is true for the zeolite catalysed fast pyrolysis of certain bio-based resources, these other green methods produce an intermediate aromatic compound, p-xylene or sometimes p-cymene, which must later be oxidised to terephthalic acid. This oxidation reaction is present in the conventional petroleum derived synthesis of PET. The new uncatalysed, solvent-free method of Lee and Kraus circumvents the oxidation stage, and by doing so shortens the synthetic procedure and avoids the use of cobalt or manganese oxidation catalysts, which from an elemental sustainability perspective are vulnerable to depletion.

Free to access until 4th March:

One-pot formal synthesis of biorenewable terephthalic acid from methyl coumalate and methyl pyruvate, J. J. Lee and G. A. Kraus, Green Chemistry, DOI: 10.1039/C3GC42487A