Green Chemistry Blog

Issue 12 of Green Chemistry is now available to read online.

The front cover this month (pictured left) features work by Peter C. K. Lau and co-workers from Quebec, Canada. In their work they engineer sinapic acid decarboxylaseas an alternative to chemistry-based or thermal decarboxylation to produce canolol from canola meal.

Read the full article:
Antioxidant canolol production from a renewable feedstock via an engineered decarboxylase
Krista L. Morley, Stephan Grosse, Hannes Leisch and Peter C. K. Lau  
Green Chem., 2013, 15, 3312-3317, DOI: 10.1039/C3GC40748A

The inside front cover this month (pictured right) features work by Joerg Schrittwieser, Frank Hollmann and co-workers from Deltf, The Netherlands. In their work they show how the one-pot combination of alcohol dehydrogenase (ADH) and palladium nanoparticle (Pd-NP) catalysis provides access to aromatic 1,2-amino alcohols in high yields and excellent optical purities.

Read the full article:
One-pot combination of enzyme and Pd nanoparticle catalysis for the synthesis of enantiomerically pure 1,2-amino alcohols
Joerg H. Schrittwieser, Francesca Coccia, Selin Kara, Barbara Grischek, Wolfgang Kroutil, Nicola d’Alessandro and Frank Hollmann  
Green Chem., 2013, 15, 3318-3331, DOI: 10.1039/C3GC41666F

Both of these articles are free to access for 6 weeks!

Keep up-to-date-with the latest content in Green Chemistry by registering for our free table of contents alerts.

Olefin metathesis is a route to the formation of new C=C bonds, and is, thus, ubiquitous in organic chemistry. Reactions of this type include cross metathesis (CM) and ring-closing metathesis (RCP), among others, where Grubbs-type ruthenium (Ru) complexes bearing N-heterocyclic carbene (NHCs) ligands are commonly used commercial catalysts. Traditionally, chlorinated and aromatic solvents, e.g., DCM and toluene, are employed; their use, however, is accompanied by health and environmental concerns. Less hazardous reaction media, including water and ionic liquids (ILs), have been previously investigated, but special reaction conditions, or catalysts that are not readily available, are required for their success.

In this paper, the authors sought to evaluate the performance of several types of commercial metathesis catalysts in non-traditional solvents, viz., MeOH, i-PrOH, EtOAc, DMC, CPME, and 2-MeTHF. These solvents were chosen based on their adherence to “green” solvent selection criteria. A series of ten Ru-based catalysts with varied (NHC) ligand architecture was chosen for this study. The most effective solvent/catalyst combinations for ROP of dienes and CM of esters were first determined using model compounds. A number of substrates, having motifs prevalent in natural products, were subsequently tested in the best performing solvent, i.e., EtOAc. The results indicated that the catalyst systems, when used in ester solvents at 70 °C, produced similar yields and selectivites to analogous reactions in toluene and DCM. These results were obtained in air rather than under an inert gas. Moreover, the reactions were carried out in solvents that had not been degassed or distilled, as is typically the case. This presents a valuable alternative to the less sustainable conditions commonly used in industry and academia.

By Jenna Flogeras

To read the full article, please click the link below. The paper is free to access for 4 weeks!

In an attempt to provide green solvent selection guide for olefin metathesis, Tomasz Krzysztof Olszewski, Krzysztof Skowerski, Andrzej Tracz and Jacek Bialecki, Green Chem., 2013, DOI: 10.1039/C3GC41943F

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

Mimicking mineral neogenesis for the clean synthesis of metal–organic materials from mineral feedstocks: coordination polymers, MOFs and metal oxide separation
Feng Qi, Robin S. Stein and Tomislav Friščić  
Green Chem., 2013, Advance Article. DOI: 10.1039/C3GC41370E

One-pot combination of enzyme and Pd nanoparticle catalysis for the synthesis of enantiomerically pure 1,2-amino alcohols
Joerg H. Schrittwieser, Francesca Coccia, Selin Kara, Barbara Grischek, Wolfgang Kroutil, Nicola d’Alessandro and Frank Hollmann  
Green Chem., 2013, Advance Article, DOI: 10.1039/C3GC41666F

Sunlight, electrochemistry, and sustainable oxidation reactions
Bichlien H. Nguyen, Alison Redden and Kevin D. Moeller  
Green Chem., 2013, Advance Article, DOI: 10.1039/C3GC41650J

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

Cross coupling reactions are immensely useful in the construction of organic molecules, a fact recognised with the award of the 2010 Nobel Prize in chemistry to Akira Suzuki, Richard Heck, and Ei-ichi Negishi. Now scientists in Beijing have discovered that adding common salts like sodium chloride, in a large excess, to Pd/C catalysed Suzuki-Miyaura reactions can more than double the achievable yield. This use of cheap and abundant materials would appear to be an excellent way to improve the productivity of the reaction without drastically increasing its burden on the environment.

It is known that Suzuki-Miyaura reactions can be conducted without any catalyst specifically being added to the reaction. Instead, the reaction is catalysed by trace amounts of palladium in the inorganic base. The authors of this present work report that the inorganic salts are not catalytic themselves, but enhance the activity of the true catalyst. The nature of this synergetic effect was deduced from infra-red and X-ray photoelectron spectroscopy studies, showing evidence of the auxiliary salt interacting with both the bromoarene reactant and the palladium catalyst. The polarisation of the reactive C-Br bond, and the increased electron density placed on the metal catalyst, is said to enhance the rate determining oxidative addition step of the reaction.

By James Sherwood

Click below to read the full article, free until December 1st:

Acceleration of Suzuki coupling reaction by abundant and non-toxic salt particles, Binbin Zhang, Jinliang Song, Huizhen Liu, Jinghua Shi, Jun Ma, Honglei Fan, Weitao Wang, Peng Zhang and Buxing Han, Green Chem., 2013, DOI: 10.1039/C3GC42088D

Chlorophyll formation was enhanced when algae were grown in a flask surrounded by a solution of gold and silver nanoparticles

Scientists in Australia have developed a nanoparticle light filter system that only lets through wavelengths favourable for microalgae growth. The system could make producing algal biofuels more efficient.

Photosynthetic systems, particularly microalgae, are at the forefront of the search for new renewable fuels and feedstock chemicals. The speed and efficiency at which microalgae grow is currently limiting them from becoming a commercially viable product so optimising their production is obviously a priority.

Colin Raston from Flinders University and his co-workers at the University of Western Australia have developed a new technique to enhance the formation and accumulation of photopigments, namely chlorophyll, in algae. They cultured Chlorella vulgaris in flasks that were surrounded by a solution of gold and silver nanoparticles. Tweaking the composition and size of the nanoparticles alters the wavelengths of light allowed through to the algae.

Read the full article in Chemistry World»

Read the original journal article in Green Chemistry:
Enhanced accumulation of microalgal pigments using metal nanoparticle solutions as light filtering devices
Ela Eroglu, Paul K. Eggers, Matthew Winslade, Steven M. Smith and Colin L. Raston  
Green Chem., 2013, 15, 3155-3159, DOI: 10.1039/C3GC41291A