Archive for the ‘Hot Article’ Category

Catalytic upgrading of fermentation alcohols

Direct self-condensation of bio-alcohols in the aqueous phase

Fermentation strategies for the production of bio-fuels will continue to grow in importance, and as they do, problems with retrieving the products from dilute fermentation broths and the low energy content of short-chain alcohols will be magnified. A partnership between the energy company Shell and the Qingdao Institute of Bioenergy and Bioprocess Technology is addressing this challenge by using catalysis to condense bio-ethanol or bio-butanol via the Guerbet reaction to give improved, higher-alcohol biofuels.

An immobilised iridium catalyst was successful in converting 1-butanol in aqueous solution to 2-ethyl-1-hexanol with >85% selectivity over five consecutive reactions. The upgrading of ethanol was less selective to a single product: In addition to 1-butanol, 2-ethyl-1-butanol and even traces of 1-octanol were observed. A phenanthroline ligand is required to facilitate the aqueous phase reaction, conditions that mimic the environment of a fermentation broth. This approach also negates the usual requirement of hydrogen gas to reduce the β-unsaturated aldehyde intermediate, with the reaction proceeding under air.

These results all indicate that this reaction shows great potential for producing biofuels, as well as many other useful chemicals, in a cheaper and more efficient way.

Check out the full article – online now!

Direct self-condensation of bio-alcohols in the aqueous phase

G. Xu, T. Lammens, Q. Liu, X. Wang, L. Dong, A. Caiazzo, N. Ashraf, J. Guan and X. Mu, Green Chem., 2014, Advance Article.
DOI: 10.1039/C4GC00510D
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A cellulose/superbase catalyst for the synthesis of cyclic carbonates

A wide variety of metal complexes act as efficient catalysts for the synthesis of cyclic carbonates from carbon dioxide and epoxides; organic bases, such as pyridine, are often useful co-catalysts in the reaction. Metal-free catalyst systems are also effective, and polymers having abundant hydroxyl groups, such as cellulose, are known to catalyze cycloaddition when combined with an alkali metal halide. Building upon these findings, researchers from the Chinese Academy of Sciences have developed a metal-free and halide-free catalyst system using a combination of a superbase and a hydrogen bond donor.

Among the bases and hydrogen bond donors investigated, a cellulose-DBU catalyst system exhibited the highest conversion to propylene carbonate. Optimization of the reaction conditions led to a further study using an array of terminal epoxides; the highest yield and selectivity was observed for ethylene oxide, with lower yields for more sterically hindered substrates. The catalyst system also proved to be recyclable for up to four trials without an appreciable loss of activity or selectivity.

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Superbase/cellulose: an environmentally benign catalyst for chemical fixation of carbon dioxide into cyclic carbonates
Jian Sun, Weiguo Cheng, Zifeng Yang, Jinquan Wang, Tingting Xu, Jiayu Xin and Suojiang Zhang
Green Chem. 2014, Advance Article, DOI: 10.1039/C3GC41850B

Jenna Flogeras obtained her B.Sc. and M.Sc. in Chemistry from the University of New Brunswick (Fredericton), Canada. Currently a Ph.D. student at Memorial University of Newfoundland, she is excited to spend some time outside the laboratory this summer to explore Thailand and Southeast Asia.

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Inexpensive ionic liquids: Process intensification the key to affordability

Green Chemistry DOI: 10.1039/C4GC00016AIonic liquids have been touted as green solvents since even before the definition of green chemistry was presented in Anastas and Warner’s seminal text. Academic research on ionic liquids, across many varied applications, is a strong and still growing area of interest. Despite this, the commercialisation of ionic liquid products, and their utilisation as solvents in manufacturing processes, has been limited because of their high costs.

In this latest work from Jason Hallett and colleagues from Imperial College London, the economic feasibility of two ionic liquids synthesized by acid–base neutralization has been assessed. It was found that process intensification dramatically reduces the end cost of these ionic liquids, and is recommended in this latest work as a means of reducing the cost of ionic liquids so that their potential in commercial applications may be realised.

The prices of triethylammonium hydrogen sulfate and 1-methylimidazolium hydrogen sulfate produced with optimised manufacturing methods are estimated to be as little as $1.24 kg−1 and $2.96 kg−1 respectively, which are largely dictated by the raw material costs. These prices are similar to conventional organic solvents such as acetone, while at present typical ionic liquid prices can be two orders of magnitude greater than this. The authors conclude that  more effort should be dedicated to developing new ionic liquids that can be synthesised from affordable raw materials in very few steps.

Inexpensive ionic liquids: [HSO4]-based solvent production at bulk scale

L. Chen et al., Green Chem., 2014. DOI: 10.1039/C4GC00016A

http://pubs.rsc.org/en/content/articlelanding/2014/gc/c4gc00016a#!divAbstract

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HOT articles in Green Chemistry

Take a look at the latest selection, which are free for you to read for the next four weeks! Graphical abstract: Preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives in aqueous media with β-cyclodextrin-SO3H as a recyclable catalyst

Polyethylene glycol (PEG) as a reusable solvent medium for an asymmetric organocatalytic Michael addition. Application to the synthesis of bioactive compounds
Karla S. Feu, Alexander F. de la Torre, Sandrina Silva, Marco A. F. de Moraes Junior, Arlene G. Corrêa and Márcio W. Paixão
Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00098F, Paper

Pressurized hot water flow-through extraction system scale up from the laboratory to the pilot scale
P. O. Kilpeläinen, S. S. Hautala, O. O. Byman, L. J. Tanner, R. I. Korpinen, M. K-J. Lillandt, A. V. Pranovich, V. H. Kitunen, S. M. Willför and H. S. Ilvesniemi
Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00274A, Paper

A one-pot biosynthesis of reduced graphene oxide (RGO)/bacterial cellulose (BC) nanocomposites
Avinav G. Nandgaonkar, Qingqing Wang, Kun Fu, Wendy E. Krause, Qufu Wei, Russel Gorga and Lucian A. Lucia
Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00264D, Paper

Preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives in aqueous media with β-cyclodextrin-SO3H as a recyclable catalyst
Jian Wu, Xianli Du, Juan Ma, Yuping Zhang, Qingcai Shi, Lijun Luo, Baoan Song, Song Yang and Deyu Hu
Green Chem., 2014, Advance Article
DOI: 10.1039/C3GC42400F, Paper

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HOT articles in Green Chemistry

Take a look at the latest selection, which are free for you to read for the next four weeks! Graphical abstract: Laccase/TEMPO-mediated system for the thermodynamically disfavored oxidation of 2,2-dihalo-1-phenylethanol derivatives

Laccase/TEMPO-mediated system for the thermodynamically disfavored oxidation of 2,2-dihalo-1-phenylethanol derivatives
Kinga Kędziora, Alba Díaz-Rodríguez, Iván Lavandera, Vicente Gotor-Fernández and Vicente Gotor
Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00066H, Communication

Guidelines based on life cycle assessment for solvent selection during the process design and evaluation of treatment alternatives
Antonio Amelio, Giuseppe Genduso, Steven Vreysen, Patricia Luis and Bart Van der Bruggen
Green Chem., 2014, Advance Article
DOI: 10.1039/C3GC42513D, Paper

Multicomponent reactions: advanced tools for sustainable organic synthesis
Răzvan C. Cioc, Eelco Ruijter and Romano V. A. Orru
Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00013G, Perspective

Aerobic homocoupling of arylboronic acids catalysed by copper terephthalate metal–organic frameworks
Pillaiyar Puthiaraj, Palaniswamy Suresh and Kasi Pitchumani
Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00056K, Paper

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Seeing the fuel for the trees

The European Commission has established a target for EU member states to obtain 20% of their energy from renewable sources by the year 2020. Although production of electricity from solar energy and hydropower are crucial technologies in achieving this goal, liquid hydrocarbon fuels are seemingly irreplaceable in certain heavy transportation sectors (specifically sea freight and aviation).

Direct thermocatalytic transformation of pine wood into low oxygenated biofuel

Scientific advances are now being made in the use of non-food crops to produce liquid hydrocarbon fuels, complementing the established oxygenated biofuels made of ethanol and bio-diesel. The latest research demonstrates that pine wood can be successfully converted into a mixture of liquid hydrocarbons. The resulting fuel has a similar calorific value to diesel, and contains less than 5% oxygen.

The necessary catalyst is made through a simple wet impregnation technique to give copper and ruthenium supported on phosphotungstic acid, which is then calcined. The transformation of the lignocellulosic biomass is conducted under hydrogen at an elevated temperature to produce the liquid fuel (30 wt%), which separates from an aqueous phase and any residual solid. The organic liquid was found to contain a number of mostly cyclic aliphatic hydrocarbons and also aromatic compounds, and thus is an attractive option as a next generation biofuel.

Direct thermocatalytic transformation of pine wood into low oxygenated biofuel
Walid Al Maksoud, Cherif Larabi, Anthony Garron, Kai C. Szeto, Jean J. Walter and Catherine C. Santini
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42596G

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Hot papers in Green Chemistry

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

Water at elevated temperatures (WET): reactant, catalyst, and solvent in the selective hydrolysis of protecting groups
Wilmarie Medina-Ramos, Mike A. Mojica, Elizabeth D. Cope, Ryan J. Hart, Pamela Pollet, Charles A. Eckert and Charles L. Liotta  
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42569J


Laccase/TEMPO-mediated system for the thermodynamically disfavored oxidation of 2,2-dihalo-1-phenylethanol derivatives
Kinga Kędziora, Alba Diaz-Rodriguez, Iván Lavandera, Vicente Gotor-Fernández and Vicente Gotor  
Green Chem., 2014, Accepted Manuscript, DOI: 10.1039/C4GC00066H


Multicomponent Reactions: Advanced Tools for Sustainable Organic Synthesis
Razvan Cioc, E. Ruijter and Romano Orru  
Green Chem., 2014, Accepted Manuscript, DOI: 10.1039/C4GC00013G

 

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

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Combining Carbon Dioxide Capture and Cellulose Dissolution

Utilization of renewable materials, such as carbon dioxide and cellulose, is a prevailing goal of green chemistry. Homogenous conditions promote the use of cellulose, but finding solvent systems that appreciably dissolve this robust polymer is a difficult task. Processing cellulose with minimal waste and economic cost are additional considerations, and existing methods warrant improvement in these regards. In another fashion, the utilization of carbon dioxide is dependent upon novel methods for capture and storage (CCS). Researchers at the Dalian National Laboratory for Clean Energy, China, have integrated the goals of CCS and cellulose dissolution in their latest research effort.

It is well known that mixtures of organic liquids, comprised of a strong base and an alcohol, form reversible ionic compounds upon the introduction of carbon dioxide. By using 1,1,3,3-tetramethyl guanidine in combination with dimethylsulfoxide (DMSO) and ethylene glycol, in particular, they observed microcrystalline cellulose dissolution of up to 10 wt% under mild conditions. The presence of the co-solvent DMSO was integral to achieve this extent of dissolution, and cellulose regeneration and recovery could be accomplished by several methods.

Learn more about their exciting results here:

Capturing CO2 for cellulose dissolution
Haibo Xie, Xue Yu, Yunlong Yang, and Zongbao Kent Zhao
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42395F 
 

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.

 

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Hot papers in Green Chemistry

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

Physical properties and hydrolytic degradability of polyethylene-like polyacetals and polycarbonates
Patrick Ortmann, Ilona Heckler and Stefan Mecking  
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42592D

C3GC42592D ga


Efficient chemical fixation of CO2 promoted by a bifunctional Ag2WO4/Ph3P system
Qing-Wen Song, Bing Yu, Xue-Dong Li, Ran Ma, Zhen-Feng Diao, Rong-Guan Li, Wei Li and Liang-Nian He 
Green Chem., 2014,16, 1633-1638, DOI: 10.1039/C3GC42406E

C3GC42406E ga


Water at elevated temperatures (WET): reactant, catalyst, and solvent in the selective hydrolysis of protecting groups
Wilmarie Medina-Ramos, Mike A. Mojica, Elizabeth D. Cope, Ryan J. Hart, Pamela Pollet, Charles A. Eckert and Charles L. Liotta  
Green Chem., 2014, Advance Article. DOI: 10.1039/C3GC42569J

C3GC42569J ga

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

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Vanillin derived polymers

Vanillin building blocks polymersResearch by French scientists has identified 18 vanillin derived chemicals for application in the synthesis of bio-based polymers. Vanillin is interesting as a chemical intermediate because of its different functional groups, and because it is manufactured in different ways. Extraction of natural vanillin and fermentation of bio-based ferulic acid are high cost options compared to the petroleum derived synthesis from guaiacol. An alternative route to vanillin has recently been proposed starting from p-cresol, but this approach is also based on non-renewable feedstocks. Another procedure that presently has a minority share of global vanillin production is the valorisation of lignin. This process had fallen out of favour somewhat, but cleaner technologies have revitalised research into vanillin derived from Kraft lignin, benefiting from the growing interest in producing chemicals from lignin more generally.

Polymers of vanillin are known, but are not often significantly diversified from the parent molecule. This latest work lead by Sylvain Caillol has resulted in the synthesis of difunctionalised epoxides, carbonates, alkenes, alcohols, amines and carboxylic acids, all with obvious potential as monomers for bio-based polymers. Different polymer types have been targeted, including epoxy resins, polyesters and polyurethanes. Through this research a number of opportunities for new and interesting renewable polymers have been opened up, which utilise the abundant resource of lignin via the important chemical intermediate vanillin.

Vanillin, a promising biobased building-block for monomer synthesis
Maxence Fache, Emilie Darroman, Vincent Besse, Auvergne Rémi, Sylvain Caillol and Bernard Boutevin
Green Chem., 2014, Advance Article, DOI: 10.1039/C3GC42613K

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