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University of Arkansas, Fayetteville ScholarWorks@UARK Technical Reports Arkansas Water Resources Center 9-1-1978 Hydrolytic and Photochemical Degradation of Organophosphorus Pesticides James F. Hinton University of Arkansas, Fayetteville Follow this and additional works at: https://scholarworks.uark.edu/awrctr Part of the Fresh Water Studies Commons, and the Water Resource Management Commons Recommended Citation Hinton, James F.. 1978. Hydrolytic and Photochemical Degradation of Organophosphorus Pesticides. Arkansas Water Resources Center, Fayetteville, AR. PUB063. 74 This Technical Report is brought to you for free and open access by the Arkansas Water Resources Center at ScholarWorks@UARK. It has been accepted for inclusion in Technical Reports by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Hydrolytic and Photochemical Degradation of Organophosphorus Pesticides Principal Investigator: James F. Hinton Department of Chemistry AWRRC Arkansas Water Resources Research Center University of Arkansas Fayetteville, Arkansas Publication No. 63 1978 ARKANSAS WATER RESOURCES RESEARCH CENTER OWRT Project No. A-030-ARK Project Title: Hydrolytic and Photochemical Degradation of Organophosphorus Pesticides Matching Grant Agreement No. 14-34-0001-6004 FCST Research Category, V-B Project Began - June 1974 Scheduled Completion - September 1978 Name and Location of Institution Where Project University of Arkansas, Fayetteville, Arkansas Principal Investigators Degree Discipline James F. Hinton Ph.D. Physical Chemistry Postdoctoral K.H. Ladner Ph.D. Physical Chemistry Student Assistants Richard W. Briggs B.S. Chemistry ACKNOWLEDGEMENTS The work upon this publication was supported with funds provided by the Office of Water Research and Technology, U. S. Department of the Interior, through the Water Resources Research Center of the University of Arkansas under grant A-041-ARK as authorized under Water Resource Research Act of 1964, P.L. 88-379 as amended by P.L. 89-404 and P.L. 92-175. ii TABLE OF CONTENTS Page A. General Introduction ..................................................................... 1 B. Experimental............................ 7 1 . Chemi cals........................................................... 7 2. Sample Preparation..................................................... 8 3. Acquisition of Spectra..................................................10 C. Results and Discussion......................................................................12 1. Ethyl Parathion..............................................................12 2. Methyl Parathion..............................................................17 3. Supracide..........................................................................17 4. Summary..............................................................................39 D. Future Research......................................................................................52 E. References..............................................................................................54 F. Appendix..................................................................................................57 i i i LIST OF TABLES Table Page 1 Structures and Nomenclature for Some Organophosphorus Pesticides ................................................................ 9 31 2 P Chemical Shifts of Some Phosphorus Compounds........................................................................................................13 31 3 Relative P Peak Areas of Ethyl Parathion and Its Degradation Products at 60° c ....................................................24 31 4 Relative P Peak Areas of Ethyl Parathion and Its Degradation Products at 70° c ........................................................25 31 5 Relative P Peak Areas of Ethyl Parathion and Its Degradation Products at 90° c .................................................... 31 6 Relative P Peak Areas of Methyl Parathion and Its Degradation Products at 60 c ....................................................34 31 7 Relative P Peak Areas of Methyl Parathion and Its Degradation Products at 70° c ....................................................... 35 31 8 Relative P Peak Areas of Methyl Parathion and Its Degradation Products at 900 c ....................................................36 31 9 Relative P Peak Areas of Supracide and Its Degradation Products at 60° c ............................................................44 10 Relative 31P Peak Areas ofQSupracide and Its Degradation Products at 70u c ................................................................ 45 31 11 Relative P Peak Areas of Supracide and Its Degradation Products at 90° c ................................................................ 46 12 Rate Constants and Half-Lives of the Pesticides as a Function of Temperature.................................................................... 48 13 Thermodynamic Data From Arrhenius Plots of Kinetic Data....................... 48 31 14 Effective Relaxation Reagents for P NMP Observation of Organophosphorus Compounds .................................. 52 iv LIST OF FIGURES Figure Page 1 The Degradation of Ethyl Parathion as Monitored by 31 p NMR at 36.43 MHz...............................................15 2 Time Course of the Degradation of Ethyl Parathion at +62.15 ppm and the Formation and Reaction of the Hydrolysis Product PS(OH) (0C2H5)2 at +64.0 ppm...........................................................18 3 Time Course of the Degradation of Ethyl Parathion at +62.15 ppm and the Buildup and Decay of Products at +64.0 ppm, +53.05 ppm, and +0.8 to +1.9 ppm at 70° c ............................... 20 4 The Decomposition of Ethyl Parathion at +62.15 ppm and the Formation and Decay of Products at +64.0 ppm, +53.05 ppm and +0.8 to +1.9 ppm at 90° c ...............................................................22 5 The Degradation of Methyl Parathion as Monitored by 31 p NMR at 36.43 MHz...............................................28 31 6 Plot of Relative P Peak Areas vs. Time for Methyl Parathion at +65.75 ppm, and for Degradation Products at +55.4 ppm, +17.0 ppm, and +1.5 ppm................................................................................................30 31 7 Relative P Peak Areas as Functions of Time for Methyl Parathion at +65.75 ppm, and for Degradation Products at +55.4 ppm, +17.0 ppm and +1.5 ppm................................................................................................32 8 The Degradation of Supracide as Monitored by 31 P NMR at 36.43 MHz................................................................................37 31 9 Time Dependence of the P Peak Areas During the Degradation of Supracide at +95.20 ppm to Products at +65.2 ppm, +34.2 ppm, and +1.85 ppm....................40 31 10 Time Dependence of the P Peak Areas During the Degradation of Supracide at +95.20 ppm to Products at +65.2 ppm, +34.2 ppm, and +1.85 ppm....................42 11 Arrhenius Plot for Degradation of Ethyl Parathion, Methyl Parathion, and Supracide....................................49 v 1 A. General Introduction To keep pace with demands for increasing food supplies to satisfy the expanding world population, modern agriculture has utilized the latest scientific and technological knowledge available. Increases in crop production through the use of growth regulators, fertilizers, herb­ icides, and insecticides have been lit t le short of phenomenal, and drugs, feed additives, and higher-quality grain and forage have dramatically increased livestock production. But, as is usually the case, this progress has been accompanied by problems, one of the more serious being contamination of our environment by chemicals. Only in recent years have the full effects of these pollutants on the ecological balance of nature begun to be understood in all their intricacies and implications. While probably not as guilty of air and water pollution as are urban industries, rural argiculture is doubtless one of the major contributors to pollution of our natural water systems, in large part because of the widespread use of herbicides and pesticides. Granting that use of these chemicals should be continued, of necessity, to maintain and increase present levels of food production, the problem remains of how to accomplish this with minimum adverse environmental effects. The ultimate goal - an increasingly d iffic u lt one in view of today's increasingly sensitive and sophisticated instrumentation - is to do so with no detectable destruction of the ecological balance. With regard to environmental contamination by pesticides and herbicides, there are several important questions to be considered: (1) What are the biological effects of these chemicals? Are they harmful to desirable flora or fauna, and i f so, in what way, and in 2 what quantities? (2) What are the stabilities of these compounds? How quickly do they degrade? This is a critical consideration for potentially harmful substances. (3) What is (are) the mode(s) of degradation? How do sunlight, temperature, and additional chemicals and substances native to the environment affect the rates and path­ ways of decomposition? (4) How is the pesticide transported in the environment? Will factors (l)-(3) vary with geographical region? Will the pesticide be transported through the wildlife food chain and threaten the well-being or even existence of some animal species? This research project was begun with

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