Common name: piperonyl butoxide; piperonyl butoxyde
IUPAC name: 5-[2-(2-butoxyethoxy)ethoxymethyl]-6-propyl-1,3-benzodioxole; 2-(2-butoxyethoxy)ethyl 6-propylpiperonyl ether
Chemical Abstracts name: 5-[[2-(2-butoxyethoxy)ethoxy]methyl]-6-propyl-1,3-benzodioxole
Other names: PBO
CAS RN: [51-03-6]
PHYSICAL CHEMISTRY
Composition: 95% min. piperonyl butoxide. Mol. wt.: 338.4; M.f.: C19H30O5; Form: Colourless liquid; (tech. is a slight yellowish liquid). B.p.: 180 ºC/1 mmHg (tech.) V.p.: 2.0x10-2 mPa (60 °C) (gas saturation method). KOW: logP = 4.75; Henry: <2.3x10-6 Pa m3 mol-1 (calc.) S.g./density: 1.060 (20 °C) (ENDQC-4 method). Solubility: In water 14.3 mg/l (25 °C). Soluble in all common organic solvents including mineral oils and fluorinated aliphatic hydrocarbons (aerosol propellants). Stability: Essentially stable to hydrolysis at pH 5, 7 and 9 in sterile buffers in the dark at 25 °C. Rapidly degraded in aqueous solution (pH 7) in sunlight (DT50 8.4 h). F.p.: 140 °C (ASTM D93). Other properties Viscosity 40 cP (25 °C).
APPLICATIONS
Biochemistry: Inhibits mixed function oxidases (MFO) of the insect so that its natural detoxification system is blocked and the efficacy of applied insecticides is increased.
Uses: A synergist for the pyrethrins and related insecticides.
Formulation types: Aerosol; Emulsion; Oil.
MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for rats and rabbits c. 7500 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats >7950, rabbits 1880 mg/kg. Not irritant to eyes or skin; not a skin sensitiser.
Inhalation: LC50 for rats >5.9 mg/l.
NOEL: (2 y) for mice and rats 30 mg/kg b.w. daily; (1 y) for dogs 16 mg/kg b.w. daily.
ADI: 0.2 mg/kg b.w.
Other: Not teratogenic, mutagenic or carcinogenic.
Toxicity class: WHO (a.i.) III (Table 5); EPA (formulation) IV
ECOTOXICOLOGY
Birds: Acute oral LD50 for bobwhite quail >2250 mg/kg.
Fish: LC50 (24 h) for carp 5.3 mg/l.
Daphnia: LC50 (24 h) 2.95 mg/l.
Algae: EC50 (cell volume) for Chlorella fusca 44 umol/l.
Bees: LD50 >25 ug/bee.
ENVIRONMENTAL FATE
Animals: In mammals (and also in insects), oxidative attack on the carbon atom of the methylenedioxy group leads to the formation of the dihydroxyphenyl compound. Oxidative degradation of the side-chain also occurs. Elimination is as the glucoside or amino acid derivative.
Soil/Environment DT50 for aerobic soil metabolism c. 14 d. Koc 399-830. Although mobile in sandy soil, it is not expected to leach under outdoor conditions, where rapid degradation occurs. Degradation in soil or water is mainly via oxidation of the butyl side-chain to form methylenedioxypropylbenzyl alcohol followed by the corresponding aldehyde, ultimately with mineralisation to CO2; there is no accumulation of metabolites.
