Difenoconazole
[CAS# 119446-68-3]

Identification

• Classification: Chemical pesticide >> Fungicide >> Pesticide fungicide
• Name: Difenoconazole
• Synonyms: 1-((2-(2-chloro-4-(4-chlorophenoxy)phenyl)-4-methyl-1,3-dioxolan-2-yl)methyl)-1H-1,2,4-triazole
• Molecular Formula: C₁₉H₁₇Cl₂N₃O₃
• Molecular Weight: 406.27
• CAS Registry Number: 119446-68-3
• EC Number: 601-613-1
• SMILES: CC1COC(O1)(CN2C=NC=N2)C3=C(C=C(C=C3)OC4=CC=C(C=C4)Cl)Cl

Properties

• Density: 1.4±0.1 g/cm³ Calc.^*
• Melting point: 76 °C (Expl.)
• Boiling point: 547.0±60.0 °C 760 mmHg (Calc.)^*, 220 °C (Expl.)
• Flash point: 284.6±32.9 °C (Calc.)^*
• Solubility: water: 3.3 mg/L (20 °C) (Expl.)
• Index of refraction: 1.642 (Calc.)^*

Safety Data

• Hazard Symbols: GHS07;GHS08;GHS09 Warning
• Risk Statements: H302-H319:-H351:-H400:-H410:
• Safety Statements: P203-P264-P264+P265-P270-P273-P280-P301+P317-P305+P351+P338-P318-P330-P337+P317-P391-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Serious eye damage	Eye Dam.	1	H318
Carcinogenicity	Carc.	2	H351
Specific target organ toxicity - single exposure	STOT SE	2	H371
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Acute toxicity	Acute Tox.	1	H330

Discovery and Applications

Difenoconazole is a systemic triazole fungicide widely used in agriculture to manage fungal diseases in a variety of crops. It belongs to the class of sterol demethylation inhibitors (DMIs) and functions by disrupting the biosynthesis of ergosterol, a key component of fungal cell membranes. The molecular formula of difenoconazole is C₁₉H₁₇Cl₂N₃O₃, and its structure includes a triazole ring, two chlorinated phenyl groups, and a dioxolane moiety that contribute to its broad-spectrum antifungal activity.

Difenoconazole was developed in the late 20th century and introduced as a second-generation triazole to improve upon the efficacy, spectrum, and environmental stability of earlier fungicides. It is active against a wide range of ascomycetes and basidiomycetes responsible for diseases such as leaf spots, rusts, mildews, and blights. It is registered for use on cereals, fruits, vegetables, oilseeds, and ornamentals.

The mode of action of difenoconazole involves the inhibition of the cytochrome P450-dependent enzyme 14α-demethylase (CYP51), which plays a central role in converting lanosterol to ergosterol during sterol biosynthesis. Disruption of this pathway impairs cell membrane function and inhibits fungal growth and reproduction. Because of its systemic properties, difenoconazole is absorbed by plant tissues and translocated to developing parts, providing both protective and curative effects.

In practical application, difenoconazole is formulated in emulsifiable concentrates, suspension concentrates, or mixed formulations with other fungicides to broaden the spectrum and manage resistance. It is typically applied as a foliar spray, seed treatment, or soil drench depending on the target crop and pathogen.

Difenoconazole exhibits high efficacy at relatively low use rates and maintains residual activity for extended periods. Its moderate persistence in soil and on plant surfaces makes it a reliable component of crop protection programs. However, like other triazoles, repeated use can select for resistant fungal strains. Resistance management strategies often include rotation with fungicides of different modes of action and adherence to recommended application intervals.

Toxicological data indicate that difenoconazole has low acute toxicity to mammals and birds. It is moderately toxic to aquatic organisms and must be used with appropriate environmental safeguards. Its environmental fate includes moderate persistence in soil and water under certain conditions, with degradation primarily via microbial action and photolysis.

In summary, difenoconazole is a broad-spectrum systemic triazole fungicide that inhibits fungal ergosterol biosynthesis. It is widely used in agriculture for the control of foliar and seedborne fungal diseases and plays a key role in integrated pest management systems due to its effectiveness and systemic properties.

References

1998. Joint actions of deltamethrin and azole fungicides on honey bee thermoregulation. Neuroscience Letters, 251(1).
DOI: 10.1016/s0304-3940(98)00494-7

2024. Inhibitory Activities of Five Fungicides on Alternaria suffruticosae and Their Field Control Efficacy Against Tree Peony Black Spot. Plant Disease, 108(9).
DOI: 10.1094/pdis-01-24-0153-re

2024. Recent advances in the toxicological effects of difenoconazole: A focus on toxic mechanisms in fish and mammals. Chemosphere, 362.
DOI: 10.1016/j.chemosphere.2024.143751