Publications                      Robert Stan Brown CV

Metal ion catalyzed destruction of Organophosphate pesticides and Chemical Weapons

Dinuclear ZN(II) catalyst mediates Rapid Cleavage of Phosphate diesters in alcohol solvent. If you want fast reactions, the Medium is the Message.

 


Contact Information

C
hernoff Hall,  CHE 507 (Office)
                       CHE 539 (Lab)
Department of Chemistry
Queen's University
Kingston, Ontario K7L 3N6
Tel:   (613) 533-2400 (Office)
         (613) 533-6000 ext. 75688 (Lab)
Fax:  (613) 533-6669
e-mail:  rsbrown@chem.queensu.ca
 

 

Robert Stan Brown
Professor 

B.Sc., 1968, University of Alberta;
M.Sc., 1970, Ph.D., 1972, University of California, San Diego;
NSERC Postdoctoral Fellow, 1972-74, Columbia University;
 

Awards:

CIC Catalysis Award of the Canadian Catalysis Foundation 2010

McCalla Research Professorship, 1991, University of Alberta;

Syntex Lecture Award, 1991, Canadian Society for Chemistry;

Fellow of the Chemical Institute of Canada, 1991;

Killam Annual Professorship, 1993, University of Alberta;

Alfred Bader Award, Canadian Society for Chemistry, 2004;

2006 Prof. of the Year, awarded by 4th Year Graduating Chemistry Class, Queen’s University;

Queens University Excellence in Research Prize, 2006;

Killam Research Fellowship, Canada Council for the Arts, 2006-2008;

R. U. Lemieux Award of the Canadian Society for Chemistry, 2007

Montreal Medal, Chemical Institute of Canada, 2008;

Fellow of the Royal Society of Canada, 2009
 

 

Several diverse areas of chemistry are currently under investigation in our laboratory. These comprise biomimetic, or model enzyme projects, studies of the acyl transfer reactions of amides in acid, base and neutral media, catalysis of these acyl transfers, and studies of electrophilic addition to olefins. Most recently we have been investigating metal ion catalysis of alcoholysis reactions of carboxylate and phosphate esters and developing catalysts for the chiral resolution of such esters and lactones. Each of the projects presents the researcher with a wide variety of training in organic and inorganic coordination chemistry, including compound synthesis and purification as well as various analytical and spectroscopic techniques, and training in the various kinetic methods to study the mechanisms of reactions.

The biomimetic projects are mainly aimed at elucidating the mechanisms by which enzymes catalyze various molecular transformations, notably acyl transfers to water (hydrolysis) and other acceptors such as alcohols. Since enzymes are considered to be the ultimate catalysts, an understanding of their mechanisms of action is important not only for biological chemistry, but also for the future development of man-made catalysts. Our biomimetic research involves the synthesis and study of enzyme models that incorporate reasonable approximation for the catalytically important functional groups known to be inside the enzyme active site. Studies are then undertaken to determine how well the models mimic the catalytic tasks of the enzymes for which they are designed. Currently, we are engaged in model studies of metallo-enzymes such as:
  1. carbonic anhydrase, a ubiquitous Zn(II)-containing enzyme found in all living systems that catalyzes the interconversion of CO2 and HCO3-;
  2. the RNAse and DNAse Zn(II)-containing enzymes that catalyze the hydrolysis and phosphory transfer of the phosphate diesters found in RNA and DNA that are responsible for storage of genetic information;
  3. Zn(II)-containing phosphotriesterases such as paraoxonase that catalyze the hydrolysis of neutral phosphates and phosphonates such as those that are prevalent in organophosphorus pesticides and chemical warfare agents.

We are also interested in the application of metal-catalyzed alcoholysis reactions to the development of simple catalysts that promote the chiral resolution of esters via transesterification. In this study we explore the ability of some chiral metal-ion-containing complexes to react preferentially with one enantiomer of a racemic mixture of esters, amides and lactones.

We have pioneered the preparation and study of stable halonium ions, such as the 3-membered bromonium and iodonium ions of adamantylideneadamantane, and the nitrogen coordinated brominuim ions of collidine. Recent work has shown that these can transfer the Br+ or I+ to acceptor olefins with surprising ease. Our long-term goals are to prepare chiral, stable halonium ions that can be used as reagents to transfer the X+ asymmetrically to alkene acceptors for the purposes of chiral synthesis.