NEWS OF THE WEEK
U.K. FAST-TRACKS FRACKING SHALE GAS: Government wrestles
some decision-making powers back from local politicians
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celerate large-scale production of onshore shale gas using hydraulic fracturing techniques known as fracking. Effective immediately, the U.K. government will step in to approve or reject drilling wells for fracking if locally elected politicians take longer than the 16-week statutory time frame. The move follows a recent case in which a local government delayed and then rejected applications to drill eight wells at two sites. Additionally, the U.K. government has awarded firms with oil and gas exploration licenses for 27 blocks of land, each covering an area of about 40 sq miles. The winners of these licenses still have to gain local planning consent to drill commercial wells. The U.K. government plans to offer ASSOCIATED PRESS
Ineos’s Grangemouth cracker could benefit from new fracking rules.
HE U.K. GOVERNMENT has taken steps to ac-
DOUBLE METALS FOR DOUBLE ARYLS CROSS-COUPLING: Cooperative
catalysts promote synthesis of unsymmetrical biaryl compounds A new approach to coupling two aryl electrophiles provides a general method for making unsymmetrical biaryl compounds (one example shown).
Br + Aryl bromides
N A SURPRISING TWIST on classical cross-coupling
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chemistry, a research team at the University of Rochester has discovered the first general method for making unsymmetrical biaryl compounds directly from two different aryl electrophiles. The new approach, which involves using two metal catalysts to promote the aryl-aryl coupling of unwilling partners, is being hailed as a means of simplifying the synthesis of OCH3 OCH3 Ni catalyst complex molPd catalyst CF3SO3 ecules such Zn, KF, DMF as pharmaAryl triflates Unsymmetrical biaryls ceuticals. The approach also provides new insight into the selective transfer of ligands between two transition-metal catalysts, a strategy that can be applied to a range of chemical reactions (Nature 2015, DOI: 10.1038/nature14676). The work by Rochester’s Laura K. G. Ackerman, Matthew M. Lovell, and Daniel J. Weix is a variation on the CEN.ACS.ORG
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licenses for a further 132 blocks of land by year-end. While France and Ireland ban fracking for environmental reasons, the U.K. government is a strong proponent. “It’s important we press on and get shale moving,” says U.K. Energy Minister Nick Bourne. Investment in shale could surpass $50 billion and support 64,000 jobs, he says. Petrochemical firm Ineos, which says it has been awarded three of the new exploration licenses covering an area of approximately 100 sq miles, has welcomed the government’s new initiatives. It estimates that it could start producing gas in commercial quantities by 2020. “Shale gas is a once-in-a-lifetime opportunity that the U.K. cannot afford to miss,” says Gary Haywood, CEO for Ineos Shale. “North Sea oil created wealth in the U.K., and shale gas can do the same,” he says. Ineos badly needs more ethane, which can be derived from fracked gas, to run its petrochemical cracker at Grangemouth, Scotland. It is operating below capacity because North Sea gas supplies are dwindling. But Ineos and other companies planning to frack for oil and gas under U.K. soil face vocal public opposition. The U.K. government’s move to accelerate fracking is “an affront to local democracy,” says Daisy Sands, Greenpeace’s head of campaigns. Greenpeace and many local resident groups across the U.K. are opposed to fracking because of its potential impact on climate change and groundwater pollution.—ALEX SCOTT
century-old Ullmann reaction for coupling an aryl halide with itself. Extending the reaction to efficient cross-coupling of different aryl halides with a single metal catalyst has remained challenging, Weix notes. Weix’s group found that pairing two catalysts with similar reactivity but different preferences for aryl electrophiles could streamline the reaction. The researchers used a nickel bipyridine catalyst that reacts with aryl bromides to form a transient intermediate combined with a palladium phosphine catalyst that reacts with aryl triflates to generate a persistent intermediate. The team hasn’t pinned down the exact mechanism, but the two intermediates exchange ligands followed by a reductive elimination step at one of the metals to form the biaryl product. Although the catalysts form less than 5% of the unsymmetrical biaryl product on their own, together they achieve up to 94% yield. The new paper is “fantastic” work, says UCLA’s Neil K. Garg, whose group specializes in cross-couplings. “Cross-electrophile couplings have been building momentum, especially because of the many contributions of the Weix group. This breakthrough methodology is certain to see extensive use in academia and industry.” Catalysis expert Shannon S. Stahl of the University of Wisconsin, Madison, agrees. “It seems ridiculous to say this, given the long history of cross-coupling and the advances made in recent years, but the Weix group’s approach could significantly expand the scope of crosscoupling chemistry.”—STEVE RITTER
AUGUST 24, 2015
