Navigation Links
Fair trade
Date:6/16/2008

This release is available in German.

Because of its toxicity and the dangers involved in handling it, tetrachloromethane (carbon tetrachloride, CCl4) can no longer be used or produced in many countries. However, the processes used in the production of other chlorinated hydrocarbons, such as chloroform (trichloromethane, CHCl3), also produce CCl4 as a byproduct. What is the best way to get rid of this unwanted substance? A team headed by Bert M. Weckhuysen at the University of Utrecht (Netherlands) has now found an interesting new approach that may lead to effective recycling. As the researchers report in the journal Angewandte Chemie, a lanthanum chloride catalyst induces CCl4 and its reaction partner dichloromethane (CH2Cl2) to exchange one chlorine atom for a hydrogen atom, forming nearly 100 % of the desired CHCl3.

In order to increase the catalyst surface, lanthanum chloride (LaCl3) was deposited onto carbon nanofiber supports. This results in a highly active, selective, and stable catalyst to facilitate the hydrogenchlorine exchange between CCl4 and CH2Cl2. "Computer calculations suggest," says Weckhuysen, "that the mechanism occurs by way of two separate hydrogenchlorine exchange reactions." It appears that the surface of the LaCl3 catalyst contains not only the terminal chlorine atoms of the crystal lattice, but also other weakly adsorbed species. CH2Cl2 swaps one of its hydrogen atoms for one such weakly bound chlorine atom. It leaves behind the hydrogen atom, which is in turn weakly adsorbed to the catalyst surface. This hydrogen atom can be taken up by CCl4, which in turn leaves one of its chlorine atoms behind on the catalyst surface. Both of these reaction steps produce chloroform exclusively; no byproducts come into play.

This new catalytic reaction is astonishing in that it was previously assumed that the presence of oxygeneither in the gas phase or bound to the crystal lattice of the catalystis required for such reactions. Says Weckhuysen: "We are reporting for the first time a lanthanum-based catalyst material that can activate both C-H and C-Cl bonds in the absence of oxygen." (2193 characters)


'/>"/>

Contact: Bert M. Weckhuysen
b.m.weckhuysen@uu.nl
31-302-534-328
Wiley-Blackwell
Source:Eurekalert  

Related biology news :

1. Stinger Systems To Offer Taser Trade-In Program
2. Global trade in tiger shrimp threatens environment
3. Markets of biodiversity and equity in trade: An illusion?
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Fair trade
(Date:6/22/2016)... -- The American College of Medical Genetics and Genomics was once ... one of the fastest-growing trade shows during the Fastest 50 ... Las Vegas . Winners ... each of the following categories: net square feet of paid ... The 2015 ACMG Annual Meeting was ranked 23 out of ...
(Date:6/22/2016)... On Monday, the Department of Homeland Security ... solutions for the Biometric Exit Program. The Request for ... (CBP), explains that CBP intends to add biometrics to ... United States , in order to deter visa ... Logo - http://photos.prnewswire.com/prnh/20160622/382209LOGO ...
(Date:6/20/2016)... , June 20, 2016 Securus Technologies, ... technology solutions for public safety, investigation, corrections and ... prisons involved, it has secured the final acceptance ... facilities for Managed Access Systems (MAS) installed. Furthermore, ... facilities to be installed by October, 2016. MAS ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... 2016 /PRNewswire/ - BIOREM Inc. (TSX-V: BRM) ("Biorem" or "the ... major shareholders, Clean Technology Fund I, LP and Clean ... based venture capital funds which together hold approximately ... fully diluted, as converted basis), that they have entered ... equity holdings in Biorem to TUS Holdings Co. Ltd. ...
(Date:6/27/2016)... ... 27, 2016 , ... Rolf K. Hoffmann, former senior vice ... University of North Carolina Kenan-Flagler Business School effective June 27. , ... with a focus on the school’s international efforts, leading classes and participating in ...
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... While the ... such as the Cary 5000 and the 6000i models are higher end machines that ... the height of the spectrophotometer’s light beam from the bottom of the cuvette holder. ...
(Date:6/23/2016)... /PRNewswire/ - FACIT has announced the creation of ... company, Propellon Therapeutics Inc. ("Propellon" or "the Company"), ... portfolio of first-in-class WDR5 inhibitors for the treatment ... represent an exciting class of therapies, possessing the ... cancer patients. Substantial advances have been achieved with ...
Breaking Biology Technology: