Uses
Triadimefon is used for the control of powdery mildews in cereals,
pome fruit, stone fruit, berry fruit, vines, hops, cucurbits, tomatoes,
vegetables, sugar beet, mangoes, ornamentals, turf, flowers, shrubs and
trees, Monilinia spp. in stone fruit, black rot of grapes, leaf blotch, leaf
spot and snow mould in cereals, pineapple disease butt rot in pineapples
and sugar cane, leaf spots and flower blight in flowers, shrubs and trees
and many other diseases of turf.
Agricultural Uses
Fungicide: Triadimefon is a systemic fungicide that is used to
control powdery mildews, rusts, and other fungi on coffee,
seed grasses, cereals, fruits, grapes, vegetables, vines,
pineapple, sugar cane, sugar beets, turf, shrubs, and trees.
Not approved for use in EU countries. Registered for
use in the U.S.
U.S. Maximum Allowable Residue Levels for Triadimefon
Synthesis
A, ammonium formate and hydrazine hydrate into the condensation kettle, warming, when the temperature is 140 , dropwise addition of hydrazine hydrate, dropwise addition of the end of the temperature, warming to 160 , holding reaction for 3 hours, dehydration for 1 hour, after the end of the reaction, the ammonia generated by the tertiary absorption of water, crystal centrifugation, the solid is a triazole;
B, will be p-chlorophenol, potassium carbonate dissolved in dichloromethane, to get a mixed System, warming to 100 to the mixed system dropwise addition of monochloropinacolone, holding time 4h, to get intermediate 1;
C, thionyl chloride drops added to intermediate 1 dichloromethane solution (thionyl chloride and intermediate 1 of the molar ratio of 1.5:1), and then at 50 holding time of 3 hours, sampling qualitatively qualified, the use of water circulating vacuum pump with a negative pressure, slowly warm up, pumping the exhaust to the tertiary water absorption, and then into the tertiary alkali absorption. Then enter the three-stage alkali absorption. Decrease the temperature to 50 , transfer to the condensation kettle;
D, triazole added to the mixed system of step C, and then warmed to 100 insulation for 3 hours, the end of the insulation, cooled down to less than 100 , add water stirring for 30 minutes, static separation of the water layer, put the material into the filtration, filtration of toluene solution into the distillation kettle, the product centrifugal drying and then drying to get triazolone.
Environmental Fate
Soil. In a culture study, the microorganism Aspergillus niger degraded 32% of tri-
adimefon to triadimenol after 5 days (Clark et al., 1978).
Plant. In soils and plants, triadimefon degrades to triadimenol (Clark et al., 1978;
Rouchaud et al., 1981). In barley plants, triadimefon was metabolized to triadimenol and
p-chlorophenol (Rouchaud et al., 1981; Rouchaud, 1982). In the grains an
Photolytic. When triadimefon was subjected to UV light for one week, p-chlorophenol,
4-chlorophenyl methyl carbamate and a 1,2,4-triazole formed as products (Clark et al.,
1978).
Metabolic pathway
Enzymic reduction of triadimefon is an important pathway in plants, soils
and fungi and may be regarded as an activation process, which produces
fungicidally active triadimenol. Two diastereoisomers of triadimenol, A
and B [( 1RS,2SR)-l-(4-chlorophenoxy)-3,3-dimethyl
-1-(1H-1,2,4-triazol
-1-yl)
butan-2-ol is referred to as diastereoisomer A; 1RS,2RS- is referred to as
diastereoisomer β], are produced in different amounts by plants and fungi
and the proportions may differ within the plant. Similar metabolic pathways
are followed in mammals where reduction of the keto group yields
triadimenol as the principal metabolite and oxidation of the butyl group
gives alcohol and carboxylic acid derivatives.
Degradation
Triadimefon is stable to hydrolysis with a DT
50 of more than 1 year at pH
3,6 and 9 (22 °C).
On photolysis in methanol in borosilicate glass apparatus using a
medium pressure mercury lamp, triadimefon undergoes cleavage of the
C-1-N bond giving 1,2,4-triazole (2), 4-chlorophenyl methyl carbonate
(3) and 4-chlorophenol(4) (Clark et al., 1978) (Scheme 1).
Sensitised photolysis of triadimefon irradiated by light from a highpressure
mercury lamp, with a Pyrex filter to exclude wavelengths below
290 nm, in the presence of fulvic acid and humic acid gave a variety of
products. In water, the products formed were 4 and a dihydroxychlorobenzene
(5). Although there are some ambiguities in the report concerning
the allocation of structures to the compounds obtained, these included a dihydroxybenzaldehyde (6) and 5-chlorosalicylaldehyde (7). Major
products in the presence of fulvic acid were 4 and a dihydroxychlorobenzene
(5). In the presence of humic acid 4,5, a dihydroxybenzaldehyde
(6) and 1-phenoxy-33-dimethyl
-1- ( 1H-1,2,4-triazol-l- yl) -2-butanone (8)
were formed (Moza et al., 1995).
Toxicity evaluation
Triadimefon inhibits the lanosterol demethylase, thereby
interfering with ergosterol synthesis that is necessary for the
integrity of fungal cell walls. This action confers specificity for
fungi over vertebrates; however, by a similar mechanism
triazoles have been reported to disrupt steroid and cholesterol
metabolism in mammals. Perturbations of fatty acid, steroid,
and xenobiotic metabolism pathways in liver through specific
nuclear signaling pathways (constitutive androstane receptor
(CAR) and pregnane X receptor (PXR)) have been suggested to
contribute to the observed reproductive and hepatic toxicities.
Triadimefon also both inhibits and induces specific hepatic
cytochrome P-450 enzymes. A series of studies comparing
triadimefon with other two conazoles (propiconazole and
myclobutanil) have shown different modes of action in terms
of carcinogenicity, hepatotoxicity, and developmental and
reproductive toxicities.
Studies in several species have shown that neurotoxicity is the
endpoint of concern with both acute and repeated exposures to
triadimefon and triadimenol. Triadimefon causes accumulation
of synaptic dopamine, both in vivo and in vitro. Pharmacological
challenges and neurochemical studies have shown that
triadimefon blocks dopamine reuptake by binding to the
dopamine transporter in a manner similar to other indirect
dopamine agonists, such as cocaine and d-amphetamine.
Pesticide Type
Fungicide; Metabolite
