Propiconazole

Common name: propiconazole
IUPAC name: 1-[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole
Chemical Abstracts name: 1-[[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole
CAS RN: [60207-90-1] unstated stereochemistry

PHYSICAL CHEMISTRY
Mol. wt.: 342.2; M.f.: C15H17Cl2N3O2; Form: Yellowish, odourless, viscous liquid (tech.). B.p.: 120 °C (1.9 Pa); >250 °C (101 kPa); V.p.: 2.7x10-2 mPa (20 °C); 5.6x10-2 mPa (25 ºC). KOW: logP = 3.72 (pH 6.6, 25 ºC). Henry: 9.2x10-5 Pa m3 mol-1 (20 °C, calc.) S.g./density: 1.29 (20 ºC). Solubility: In water 100 mg/l (20 ºC). In n-hexane 47 g/l. Completely miscible with ethanol, acetone, toluene and n-octanol (25 °C). Stability: Stable up to 320 ºC; no significant hydrolysis. pKa: 1.09, v. weak base.

APPLICATIONS
Biochemistry: Steroid demethylation (ergosterol biosynthesis) inhibitor.
Mode of action: Systemic foliar fungicide with protective and curative action, with translocation acropetally in the xylem.
Uses: Systemic foliar fungicide with a broad range of activity, at 100-150 g/ha. On cereals, it controls diseases caused by Cochliobolus sativus, Erysiphe graminis, Leptosphaeria nodorum, Puccinia spp., Pyrenophora teres, Pyrenophora tritici-repentis, Rhynchosporium secalis, and Septoria spp. In bananas, control of Mycosphaerella musicola and Mycosphaerella fijiensis var. difformis. Other uses are in turf against Sclerotinia homoeocarpa, Rhizoctonia solani, Puccinia spp. and Erysiphe graminis; in rice against Rhizoctonia solani, Helminthosporium oryzae, and dirty panicle complex; in coffee against Hemileia vastatrix; in peanuts against Cercospora spp.; in stone fruit against Monilinia spp., Podosphaera spp., Sphaerotheca spp. and Tranzschelia spp.; in maize against Helminthosporium spp.
Formulation types: EC; SC; Emulsifiable gel.

MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for rats 1517, mice 1490 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats >4000, rabbits >6000 mg/kg. Non-irritating to skin and eyes (rabbits). No sensitisation (guinea pigs).
Inhalation: LC50 (4 h) for rats >5800 mg/m3.
NOEL: (2 y) for rats 3.6, mice 10 mg/kg b.w. daily; (1 y) for dogs 1.9 mg/kg b.w. daily.
ADI: 0.04 mg/kg b.w.
Other: Not mutagenic, not teratogenic. No carcinogenic potential of relevance for human exposure.
Toxicity class: WHO (a.i.) II
EC hazard: (R22)

ECOTOXICOLOGY
Birds: Acute oral LD50 for Japanese quail 2223, bobwhite quail 2825, mallard ducks >2510, Pekin ducks >6000 mg/kg. LC50 (8 d) for Japanese quail >1000, bobwhite quail >5620, mallard ducks >5620, Pekin ducks >1000 ppm.
Fish: LC50 (96 h) for carp 6.8, rainbow trout 5.3, golden orfe 5.1, spot 2.6 mg/l.
Daphnia: EC50 4.8 mg/l.
Algae: EC50 0.02-13.6 mg/l for three freshwater algae and two diatom species.
Other aquatic spp.: LC50 (96 h) for crayfish 42 mg/l. EC50 (96 h) for mysid shrimp (Mysidopsis bahia) 0.5 mg/l.
Bees: Not toxic to bees; LD50 (contact and oral) >100 ug/bee.
Worms: No toxic effects against Lumbricus rebellus.
Other beneficial spp.: Under field conditions, not expected to have any significant impact.

ENVIRONMENTAL FATE
Animals: After oral administration to the rat, propiconazole is rapidly absorbed and also rapidly and almost completely eliminated with urine and faeces. Residues in tissues were generally low and there was no evidence for accumulation or retention of propiconazole or its metabolites. The major sites of enzymic attack are the propyl side-chain and the cleavage of the dioxolane ring, together with some attack at the 2,4-dichlorophenyl and 1,2,4-triazole rings. In the mouse, the major metabolic pathway is via cleavage of the dioxolane ring.
Plants: Degradation proceeds through hydroxylation of the n-propyl side-chain and deketalisation of the dioxolan ring. After cleavage of triazole, triazole-alanine is formed as the main metabolite. Metabolites are conjugated mostly as glucosides.
Soil/Environment: DT50 in aerobic soils (25 ºC) 40-70 d. The main degradation pathways are hydroxylation of the propyl side-chain and the dioxolane ring, and finally formation of 1,2,4-triazole. Koc (ads) 950 ml/g, immobile in soil.