Myclobutanil

Description

Myclobutanil is a broad-spectrum systemic foliar-applied fungicide of the substituted triazole chemical class of compounds, with protective, eradicative, and curative action. It disrupts membrane function in fungi by inhibition of sterol biosynthesis.
It is produced by the alkylation of 4-chlorophenylacetonitrile with butyl chloride, followed by treatment with dibromomethane and sodium hydroxide in dimethyl sulfoxide. The resulting intermediate is then reacted with the potassium salt of 1,2,4-triazole in dimethyl formamide.
Commercially, myclobutanil is presented as different formulations or preparations with concentrations up to 60% active ingredient (a.i.). It is formulated as a wettable powder (2–40% a.i.) or as an emulsifiable concentrate (1–25% a.i.), granular (<1% a.i.), dust (5% a.i.), dry flowable (60% a.i.), and ready to use (<1% a.i.) solutions to be used in agriculture or in domestic activities by homeowners.
It is also used at lower concentrations in combination with other agrochemicals such as pyretroids (permethrin), fludioxonil, mefenoxam, azoxistrobin, mancozeb, sulfur, or fluoxastrobin.

Chemical properties

White to pale yellow crystalline solid. Soluble in alcohols, aromatics, esters, ketones and other organic solvents. Solubility is about 50-100g/L; insoluble in aliphatic hydrocarbons such as hexane; solubility in water is 142mg/L. The degradation half-life is 25 days in aqueous solution under sunlight, and 66 days in soil. It does not degrade under anaerobic conditions, and does not hydrolyze within 28 days under the conditions of pH 5, 7, and 9 (28°C).

The Uses of Myclobutanil

Myclobutanil is an fungicide used on a wide range of food crops. Myclobutanil inhibits the biosynthesis of ergosterol, a critical componet of fungal cell membranes.

The Uses of Myclobutanil

Myclobutanil is used for the control of Ascomycetes, Fungi Imperfecti and Basidiomycetes on a wide variety of crops. These include foliar treatment for scab and powdery mildew in apples and pears, powdery mildew, shot hole, blossom blight, and rust in stone fruit, powdery mildew in vines and cucurbits, powdery mildew and rusts on ornamentals, rusts on perennial grasses grown for seed, and various diseases of wheat. It is also used as a seed treatment for control of seed- and soil-borne diseases in barley, maize, cotton, rice and wheat.

What are the applications of Application

Myclobutanil is an antifungal agent that inhibits ergosterol biosynthesis

Definition

ChEBI: 2-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile is a nitrile that is hexanenitrile substituted at the 2-position by p-chlorophenyl and (1,2,4-triazol-1-yl)methyl groups. It is a nitrile, a member of triazoles and a member of monochlorobenzenes.

Hazard

Moderately toxic by ingestion, inhalation,and skin contact.

Agricultural Uses

Fungicide: Widely used to control powdery mildew, rust, sclerotina, spot blight, rot, black rot and similar fungi on a variety of food and non-food crops.

Trade name

EAGLE®; NOVA®; NU-FLOW®; RALLY®; LAREDO®; RH 3866®; SYSTHANE® TECHNICAL

Safety Profile

Moterately toxic by ingestion, inhalation, and skin contact. Experimental reproductive effects. When heated to decomposition emits toxic fumes of NOx, SO,, Cl-.

Potential Exposure

Myclobutanil is a nitrile compound and a triazole fungicide. It is widely used to control powdery mildew, rust, sclerotina, spot blight, rot, black rot and similar fungi on a variety of food and nonfood crops. Nitriles can be derived from salts of cyanide, but are usually less toxic.

Environmental Fate

Relevant physicochemical properties are estimated Koc value of 950, log Kow of 2.94, estimated Henry’s law constant of 4.3×10^-9 atmm³ mol^-1 at 25 ℃, vapor pressure of 1.6
106 mmHg, and water solubility of 140 mg l^-1.
In soil under aerobic conditions, myclobutanil exhibits high to very high persistence, and medium to low mobility, forming the minor soil metabolite myclobutanil butyric acid which exhibits low to moderate persistence and very high mobility in soil. Both adsorptions are affected significantly by differing soil pH. Volatilization from moist soil surfaces is not expected to be an important fate process. The biodegradation half-life of myclobutanil in silt loam soil is about 66 days. No degradation was observed under anaerobic conditions.
In aquatic environments, it is expected to adsorb to suspended solids and sediment. Volatilization from water surfaces is not expected. In dark natural sediment water systems, myclobutanil partitioned from the water column to sediment, where it exhibited very high persistence. Aqueous solutions of myclobutanil decompose on exposure to light with half-lives of 222 days in sterile water, 0.8 days in sensitized sterile water, and 25 days in pond water. Hydrolysis was not observed after 28 days at pH values of 5, 7, and 9 at 28 ℃.
An estimated bioconcentration factor of 37 suggests the potential for bioconcentration in aquatic organisms is moderate, provided the compound is not metabolized by the organism.
In the ambient atmosphere, it is expected to exist in both the vapor and particulate phases. Vapor-phase myclobutanil is degraded by reaction with photochemically produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 2.3 days. Particulate-phase myclobutanil may be removed from the air by wet or dry deposition.

Metabolic pathway

There is limited published information available on the metabolism of myclobutanil. In plants and mammals, the butyl group is oxidised to an alcohol and a ketone. In soils, substantial degradation of the molecule occurs under aerobic conditions.

Shipping

UN2763 Triazine pesticides, solid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials. UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required. UN3082 Environmentally hazardous substances, liquid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required.

Toxicity evaluation

Target organ in animal studies is the liver, as exposure to myclobutanil resulted in liver hypertrophy or hepatotoxicity mediated byCYP induction; also reproductivemodificationswere reported.
Triazole fungicides are designed to inhibit the fungal CYP51 enzyme but can also modulate the expression and function of mammalian CYP genes and enzymes. Triazoles affected the expression of numerous CYP genes in rat liver and testis, including multiple CYP2C and CYP3A isoforms as well as other xenobiotic metabolizing enzyme (XME) and transporter genes. For some genes, myclobutanil and other triazoles had similar effects on expression, suggesting possible common mechanisms of action. Many of these CYP, XME, and transporter genes are regulated by xenobiotic-sensing nuclear receptors, and hierarchical clustering of CAR/PXR-regulated genes demonstrated the similarities of toxicogenomic responses in liver between all triazoles and in testis between myclobutanil and triadimefon. Triazoles also affected expression of multiple genes involved in steroid hormone metabolism in the two tissues.
Conazole fungicides induce a thyroid response in rats. Myclobutanil produced a dose-dependent decrease in T3 and T4, related to an induction of uridine diphospho-glucuronosyl transferase (UDPGT), the T4-metabolizing enzyme, although thyroid hormone levels did not differ from control values after 90 days and TSH was not increased in any exposure group.

Degradation

Myclobutanil is stable under normal storage conditions (PM). Aqueous solutions decompose on exposure to light. The DT₅₀ is 222 days in sterile water and 25 days in pond water. It was not hydrolysed in 28 days at pH 5,7 and 9 (28 °C).

Incompatibilities

Decomposes on exposure to strong light. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. The triazoles are sensitive to heat, friction, and impact. Sensitivity varies with the type substitution to the triazole ring. Metal chelated and halogen substitution of the triazole ring make for a particularly heat sensitive material. Azido and nitro derivatives have been employed as high explosives. No matter the derivative these materials should be treated as explosives. Nitriles may polymerize in the presence of metals and some metal compounds. They are incompatible with acids; mixing nitriles with strong oxidizing acids can lead to extremely violent reactions. Nitriles are generally incompatible with other oxidizing agents such as peroxides and epoxides. The combination of bases and nitriles can produce hydrogen cyanide. Nitriles are hydrolyzed in both aqueous acid and base to give carboxylic acids (or salts of carboxylic acids). These reactions generate heat. Peroxides convert nitriles to amides. Nitriles can react vigorously with reducing agents. Acetonitrile and propionitrile are soluble in water, but nitriles higher than propionitrile have low aqueous solubility. They are also insoluble in aqueous acids.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Contact a licensed disposal facility about surplus and nonrecyclable solutions. Burn in a chemical incinerator equipped with an afterburner and scrubber. Extra care must be exercised as the material in an organic solvent is highly flammable. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Containers must be disposed of properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office. Incineration or permanganate oxidation.