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:3/9/2017)... and MOUNTAIN VIEW, Calif. , ... Well Made Simple," and 23andMe , the leading ... better food choices.  Zipongo can now provide customers with ... preferences, health goals and biometrics, but also genetic markers ... choices. Zipongo,s personalized food decision support platform ...
(Date:3/2/2017)... Summary This report provides all ... and its partnering interests and activities since 2010. ... The Partnering Deals and Alliance since 2010 report provides ... of the world,s leading life sciences companies. ... ensure inclusion of the most up to date deal ...
(Date:2/28/2017)... 28, 2017 News solutions for biometrics, bag ... ... from 14 to 16 March, Materna will present its complete ... seamless travel is a real benefit for passengers. To accelerate ... their passenger touch point solutions to take passengers through the complete ...
Breaking Biology News(10 mins):
(Date:3/28/2017)... WASHINGTON , March 28, 2017  (AACR17, ... single-cell sequencing during the American Association for Cancer Research ... Center in Washington, D.C. , April ... gene expression of thousands of cells at the individual ... Experts on-hand at AACR to discuss expanded ...
(Date:3/28/2017)... SACRAMENTO, Calif. , March 28, 2017 /PRNewswire/ ... Officer of international life sciences corporation Anpac ... company set a new, international record, processing and ... proprietary, "Cancer Differentiation Analysis" (CDA) liquid ... in World Nobel Prize Laureate Summit publications, Anpac ...
(Date:3/28/2017)... 28, 2017 Focus is ... sector due to the scientifically intensive operations of ... agricultural, environmental, and industrial. In today,s pre-market research, Stock-Callers.com ... Inc. (NASDAQ: PTLA), OvaScience Inc. (NASDAQ: OVAS), Ocera ... (NASDAQ: OCUL ). Learn more about ...
(Date:3/28/2017)... ... 28, 2017 , ... Executive search firm, Slone Partners, announces ... Harvill is a distinguished life sciences expert with a proven track record in ... a wide range of services related to laboratory testing and analysis for the ...
Breaking Biology Technology: