title: Reactivity of neonicotinoid insecticides with carbonate radicals.
abstract: The reaction of three chloronicotinoid insecticides, namely Imidacloprid (IMD), Thiacloprid (THIA) and Acetamiprid (ACT), with carbonate radicals (CO·₃⁻) was investigated. The second order rate constants (4 ± 1) × 10⁶, (2.8 ± 0.5) × 10⁵, and (1.5 ± 1) × 10⁵ M⁻¹ s⁻¹ were determined for IMD, THIA and ACT, respectively. The absorption spectra of the organic intermediates formed after CO·₃⁻ attack to IMD is in line with those reported for α-aminoalkyl radicals. A reaction mechanism involving an initial charge transfer from the amidine nitrogen of the insecticides to CO·₃⁻ is proposed and further supported by the identified reaction products. The pyridine moiety of the insecticides remains unaffected until nicotinic acid is formed. CO·₃⁻ radical reactivity towards IMD, ACT, and THIA is low compared to that of HO• radicals, excited triplet states, and ¹O₂, and is therefore little effective in depleting neonicotinoid insecticides.
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas-INIFTA, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata, Argentina.
authors.forename: María Laura
authors.initials: ML
authors.lastname: Dell'Arciprete
authors.forename: Juán M
authors.initials: JM
authors.lastname: Soler
authors.forename: Lucas
authors.initials: L
authors.lastname: Santos-Juanes
authors.forename: Antonio
authors.initials: A
authors.lastname: Arques
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Mártire
authors.forename: Jorge P
authors.initials: JP
authors.lastname: Furlong
authors.forename: Mónica C
authors.initials: MC
authors.lastname: Gonzalez
mesh_terms: D002254:Carbonates / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D007306:Insecticides / Q000737:chemistry*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*; D013843:Thiazines / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D002254:Carbonates; D005609:Free Radicals; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D011725:Pyridines; D013843:Thiazines; D014867:Water; C082359:imidacloprid; C464485:acetamiprid; C417209:thiacloprid