HYDROLYSIS AND PHOTODEGRADATION OF THE HE RBICIDE FLUOROCHLORIDONE

The degradation during hydrolysis and photolysis of flurochloridone, a weed-killer, which belongs to the chemical class of pyrrolidones was studied in diluted solutions. Hydrolysis reactions, carried out on a l arge pH scale (from 5.5 to 9.5) and for temperatures ranging from 20 d egrees C to 40 degrees C, demonstrated that there was no significant e limination of flurochloridone. The decrease of this compound was at th e very most 2% or 3% for more than 100 days of hydrolysis. The presenc e of aquatic humic substances had no effect on chemical stability of t his molecule. In neutral or basic medium, hydrolysis led to the epimer isation of the molecule of flurochloridone. Thus, a thermodynamic equi librium (70 / 30) was obtained between the trans and cis epimerics. No additional modification of the structure of this molecule could be ob served for long-lasting reactions. UV photolysis (253.7 nm) or polychr omatic irradiation (metallic iodide lamp) allowed a total removal of f lurochloridone for short reaction times. Some reaction by-products cou ld be eliminated by further UV irradiation, however they remained quit e stable with the polychromatic light source. These by-products identi fied by GC/MS had a chemical structure very close to that of flurochlo ridone; they were the result of a substitution of a Cl atom and/or of hydroxylation on the five-member cycle.