Description
Diniconazole is a triazole fungicide. It has a low aqueous solubility and a low volatility. It tends to be persistent in both soil and water systems. Whilst available ecotoxicology data is limited, diniconazole is moderately toxic to birds, fish and honeybees. It also has a moderate oral mammalian toxicity.
Uses
Diniconazole is used to control leaf and ear diseases in cereals,
powdery mildew in vines, rust and black spot in roses, leaf spot in peanuts,
Sigatoka disease in bananas, and Uredinales in coffee. It is also used
on fruit, vegetables and ornamentals.
Definition
ChEBI: (1E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol is a member of the class of triazoles that is 4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol substituted at position 1 by a 2,4-dichlorophenyl group. It is a dichlorobenzene, an olefinic compound, a secondary alcohol and a member of triazoles.
Mechanism of action
Systemic with curative and protective action. Inhibits the demethylation of steroids distrupting ergosterol biosynthesis.
Synthesis
Example 7: Synthesis of (-)-(E)-1-(2,4-dichlorophenyl)-2-(1,2,4-triazol-1-yl)-4,4-dimethyl-1-penten-3-ol
Preparation (1) (reaction temperature: -15°C).
1. To 10 mL of ether solution containing 0.18 g (4.7 mmol) LiAlH4, 10 mL of ether solution containing 0.84 g (4.7 mmol) (+)-N-methylephedrine was slowly added dropwise for 30 min.
2. After the dropwise addition, the reaction mixture was stirred at room temperature for 20 minutes. 3.
3. 10 mL of an ether solution containing 1 g (9.4 mmol) of N-methylaniline was slowly added dropwise to the above mixture under cooling conditions in an ice bath for a controlled period of 30 minutes, followed by stirring of the mixture for 1 hour at room temperature.
4. The reaction mixture was cooled to -15 °C, 10 mL of an ether solution containing 1 g (3.1 mmol) of (E)-1-(2,4-dichlorophenyl)-2-(1,2,4-triazol-1-yl)-4,4-dimethyl-penta-1-en-3-one was added over 10 minutes and stirring was continued at -15 °C for 2 hours.
5. After completion of the reaction, the mixture was poured into 100 mL of 1N hydrochloric acid and extracted with 100 mL of ether.
6. The organic phase was washed sequentially with aqueous sodium bicarbonate and ice water and dried over anhydrous magnesium sulfate.
7. After the solvent was removed under pressure, the crystalline residue was collected by filtration over 10 mL of hexane and washed to give 0.98 g (98% yield) of the target product (E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol with a spinodolarity of [alpha]D25 -28.0 (c=1, chloroform).
Metabolic pathway
Diniconazole is a mixture of four isomers, which are derived from a
chiral carbon atom and a double bond in the molecule. Diniconazole M
[( E)-( S)-1-(2 ,4-dichlorophenyl)-4,4-dimethyl-2-1(H -1,2,4-triazol-l-yl)pent-
1-en-3-ol] is more potent than diniconazole. The major metabolic pathways
of diniconazole involve oxidative attack on the pentenol side chain
to give products which may form conjugates. In mammals, sulfurcontaining
metabolites may be formed.
Degradation
Diniconazole is stable to heat, light and moisture. It undergoes photolysis
and irradiation of a solution in methanol with light from a high-pressure
mercury lamp for 8 hours gave three major and seven minor products, 2-
11 (Scheme 1). The major photoproduct was identified as the 2-isomer (2).
The other major products (5 and 6) were formed by photooxidation of the
CHOH group to a carbonyl group.
When diniconazole was irradiated as a thin film under ultraviolet light
(254 nm), the major product was identified as the Z-isomer. On the surface
of a sandy loam soil, under the same irradiation conditions rapid degradation
occurred with the formation of 2, 5 and 6. A thin film of diniconazole
applied to a glass plate degraded very slowly in the dark. When the
plate was placed in the sunhght, 70% of the applied material disappeared
after 5 days exposure and isomerisation occurred to give the Z-isomer
(65%). The DT50 in sunlight was 2.5 days. Under ultraviolet light (254 mn),
the Z-isomer was formed after 15 minutes irradiation, and after 5 hours
90% of the material had isomerised (Dureja and Walia, 1992).
References
[1] Patent: US4435203, 1984, A
