pH effect on hydrolysis of diazinon and diazoxon in aqueous solution

ENVR 152

Juan He, juanhe77@yahoo.com and Urs Jans, ujans@ccny.cuny.edu. Department of Chemistry, City College of CUNY, 138th Street at Convent Avenue, New York, NY 10031
The hydrolysis of diazinon and diazoxon were carefully investigated from pH 1 to 10 at both 25 and 50 °C. Experimental data indicated that the hydrolysis of diazinon or diazoxon is both acid- and base-catalyzed and the amount of IMP formed is equal to the amount of parent compound degradated. When the pH is in the range of 1 to 5, the kinetics can be expressed by a two-species distribution model. Three possible mechanisms have been proposed: I) at low pH, H2O attacks the carbon-6 in the pyrimidine ring after diazinon or diazoxon gets protonated, II) at medium pH, H2O attacks the phosphorus atom and III) at high pH, OH- attacks the phosphorus atom.
 

General Papers
6:00 PM-8:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Environmental Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007