Fungicide
FRAC  3; DMI: triazole



NOMENCLATURE
Common name penconazole (BSI, draft E-ISO, (m) draft F-ISO)
IUPAC name 1-(2,4-dichloro-b-propylphenethyl)-1H-1,2,4-triazole 
Chemical Abstracts name 1-[2-(2,4-dichlorophenyl)pentyl]-1H-1,2,4-triazole 
CAS RN [66246-88-6]  EEC no. 266-275-6  Development codes CGA 71818 (Ciba-Geigy)

PHYSICAL CHEMISTRY
Mol. wt. 284.2  M.f. C₁₃H₁₅Cl₂N₃  Form Fine white powder.  M.p. 57.6-60.3 ºC  V.p. 0.17 mPa (20 °C); 0.37 mPa (25 °C)  K_OW logP = 3.72 (pH 5.7, 25 ºC).  Henry 6.6 × 10^-4 Pa m³ mol^-1 (20 °C, calc.).  S.g./density 1.30 (20 ºC)  Solubility In water 73 g/m³ (20 ºC). In ethanol 730, acetone 770, toluene 610, n-hexane 22, n-octanol 400 (all in g/l, 25 ºC).  Stability Stable to hydrolysis (pH 1-13), and to temperatures up to 350 ºC.  pKa 1.51, v. weak base

APPLICATIONS
Biochemistry Sterol demethylation inhibitor; inhibits cell membrane ergosterol biosynthesis, stopping development of the fungi.  Mode of action Systemic fungicide with protective and curative action. Absorbed by the leaves, with translocation acropetally.  Uses Control of powdery mildew, pome fruit scab and other pathogenic Ascomycetes, Basidiomycetes and Deuteromycetes on vines, pome fruit, stone fruit, ornamentals, hops and vegetables, at 25-75 g/ha.  Formulation types EC; EW; WP.

ANALYSIS
Product analysis by glc. Residues determined by glc. Details available from Syngenta.

MAMMALIAN TOXICOLOGY
Reviews FAO/WHO 65, 67 (see part 2 of the Bibliography).  Oral Acute oral LD₅₀ for rats 2125, mice 2444 mg/kg.  Skin and eye Acute percutaneous LD₅₀ for rats >3000 mg/kg. Not a skin irritant; irritating to eyes (rabbits). Not a skin sensitiser (guinea pigs).  Inhalation LC₅₀ (4 h) >4000 mg/m³.  NOEL (2 y) for rats 3.8, mice 0.71 mg/kg b.w. daily; (1 y) for dogs 3.3 mg/kg b.w. daily.  ADI (JMPR) 0.03 mg/kg b.w. [1992].  Other Not mutagenic, not teratogenic, not oncogenic.  Toxicity class WHO (a.i.) III (Table 5)

ECOTOXICOLOGY
Birds Acute oral LD₅₀ (8 d) for Japanese quail 2424, Pekin ducks >3000, mallard ducks >1590 mg/kg. LC₅₀ (8 d) for bobwhite quail and mallard ducks >5620 ppm.  Fish LC₅₀ (96 h) for rainbow trout 1.7-4.3, carp 3.8-4.6, bluegill sunfish 2.1-2.8 mg/l.  Daphnia IC₅₀ (48 h) 7-11 mg/l.  Algae IC₅₀ (5 d) for Scenedesmus subspicatus 3.0 mg/l; EC₅₀ (5 d) for Selenastrum capricornutum 0.83 mg/l.  Bees Non-toxic to bees; LD₅₀ (oral and topical) >5 mg/bee.  Worms LC₅₀ (14 d) for earthworms >1000 mg/kg.

ENVIRONMENTAL FATE
Animals After oral administration, penconazole is rapidly eliminated practically to entirety with urine and faeces. Residues in tissues were not significant and there was no evidence for accumulation.  Plants Metabolic pathways are hydroxylation of the propyl side-chain, conjugation to glucosides or metabolism to triazolylalanine and triazolylacetic acid.  Soil/Environment DT₅₀ in soil is 133-343 d, depending on soil type. DT₅₀ for photolysis is 4 d (natural sunlight).