Alachlor

Description

Alachlor is a herbicide. Occupational contact dermatitis was rarely observed in agricultural workers.

Chemical properties

Alachlor is a colorless to yellow crystal chemical substance. It is soluble in most organic solvents, but sparingly in water. Alachlor is an RUP, therefore it should be purchased and used only by certified, trained workers and plant protection applicators. The US EPA categorizes it as toxicity class III, meaning slightly toxic. However, alachlor products bear the signal word danger on their labels because of their potential to cause cancer in laboratory animals. Alachlor is an aniline herbicide used to control annual grasses and broadleaf weeds in field corn, soybeans, and peanuts. It is a selective systemic herbicide, absorbed by germinating shoots and roots. It works by interfering with a plant's ability to produce protein and by interfering with root elongation. Alachlor has extensive use as a herbicide in the United States. It is available as granules or emulsifiable concentrate.

The Uses of Alachlor

Alachlor is used pre- or early post-emergence to control annual grasses and many broadleaved weeds mainly in maize, but also in cotton, brassicas, oilseed rape, peanuts, radish, soy beans, and sugar-cane.

The Uses of Alachlor

Preemergence, early postemergence or soil-incorporated herbicide used to control most annual grasses and many annual broad-leaved weeds in beans, corn, cotton, milo, peanuts, peas, soybeans, sunflower and certain woody ornamentals.

The Uses of Alachlor

Alachlor is one of the most widely used herbicides in the United States and is used as an herbicide for grasses, broadleaf seeds, corn, sorghum, soybeans, peanuts, cotton, vegetables, and forage crops.

What are the applications of Application

Alachlor is a pre-emergence herbicide

Definition

ChEBI: An aromatic amide that is N-(2,6-diethylphenyl)acetamide substituted by a methoxymethyl group at at the nitrogen atom while one of the hydrogens of the methyl group has been replaced by a chlorine atom.

General Description

Crystalline solid. Melting point 104-106°F (40-41°C). Used as a herbicide.

Air & Water Reactions

Hydrolyzes under strongly acidic and strongly basic conditions.

Reactivity Profile

A halogenated acetamide. Organic amides/imides react with azo and diazo compounds to generate toxic gases. Flammable gases are formed by the reaction of organic amides/imides with strong reducing agents. Amides are very weak bases (weaker than water). Imides are less basic yet and in fact react with strong bases to form salts. That is, they can react as acids. Mixing amides with dehydrating agents such as P2O5 or SOCl2 generates the corresponding nitrile. The combustion of these compounds generates mixed oxides of nitrogen (NOx).

Health Hazard

Alachlor is a slightly toxic herbicide. It causes slight to moderate degrees of skin irritation. While a 90-day study on laboratory rats and dogs given diets containing low to moderate amounts of alachlor (1–100 mg/kg/day) showed no adverse effects, a 1-year study indicated that at a dose above 1 mg/kg/day, alachlor causes damage in the liver, spleen, and kidney.

Agricultural Uses

Herbicide: A pre-emergence herbicide for corn, soybeans, and peanuts, and other field crops. It is a selective systemic herbicide, absorbed by germinating shoots and by roots. It works by interfering with a plant's ability to produce protein and by interfering with root elongation. It is available as granules or emulsifiable concentrate. Alachlor is used in mixed formulations with atrazine, glyphosate, trifluralin, and imaquin. Not approved for use in the EU. A U.S. EPA restricted Use Pesticide (RUP).

Trade name

AGIMIX® Araclor; ALAGAM®; ALAGAN®; ALANEX®; ALAPAZ®, suspended; ALAZINE®; ALATOX 480®; ALCLOR 48 LE®; CHIMICHLOR®; LARIAT®; LASAGRIN®; LASSAGRIN®; LASSO®; LASSO MICRO-TECH®; METACHLOR®; PARTNER® Arachlor; PILLARZO®; SANACHLOR®

Contact allergens

Alachlor is a herbicide. Occupational contact dermatitis was rarely observed in agricultural workers.

Safety Profile

Moderately toxic by ingestion, skin contact, and possibly other routes. Questionable carcinogen with experimental carcinogenic data. Human mutation data reported. When heated to decomposition it emits very toxic fumes of Cland NOx.

Potential Exposure

A chloracetanilide herbicide. In manufacture, formulation and application of this preemergence herbicide, personnel may be exposed. Its major use (99%) is as a preemergence herbicide for field crops (corn, soybeans, and peanuts, etc.).

Environmental Fate

Alachlor dissipates from soil mainly through volatilization, photodegradation, and biodegradation. Many metabolites have been identified; diethylaniline, detected in some soil studies, interacts rapidly with humic substances in the soil. A half-life in soil of 7-38 days has been reported. Under certain conditions, alachlor can leach beyond the root zone and migrate to groundwater.

Metabolic pathway

The metabolism of alachlor using in vitro incubations with microsomal fractions prepared from liver and nasal turbinate tissues of rat and mouse (m1) results in conversion to 3,5-diethylbenzoquinone-4-imine via the key intermediate of 2,6-diethylaniline, the formation of which requires catalysis by microsomal arylamidases. 2,6-Diethylaniline is oxidized to 4-amino- 3,5-diethylphenol resulting in quinone imine by further oxidation. Rat nasal tissue possesses high enzymatic activity which can promote the formation of the reactive quinone imine. A methylsulfide metabolite of alachlor is shown to be a precursor to 2,6- diethylaniline. The deposition of radioactivity in the rat nasal tissue is more pronounced following oral administration of the methylsulfide metabolite of alachlor.
The extent of DNA adduct formation by alachlor and its metabolites is used as a guide to deduce the causal agent(s) in the carcinogenicity of this herbicide. Metabolic studies (m2) indicate that 2-chloro-N- hydroxymethoxymethyl-N-(2,6-diethylphenyl)- acetamide is an intermediate in forming 2-chloro-N- (2,6-diethylphenyl)acetamide and presumably formaldehyde in the mouse liver microsomal mixed- function oxidase system and in yielding O-glucuronide of 2-chloro-N-hydroxymethyl-N-(2,6- diethylphenyl)acetamide in the urine of alachlor-treated mice.
Incubation of alachlor in the presence of glutathione (GSH) with the cytosolic fraction from rat, mouse, and monkey (m3) produces the GSH conjugate of alachlor as the initial metabolite. The conjugation occurs through thiol displacement of the chlorine atom of alachlor and is catalyzed by glutathione S-transferase (GST). Kidney cell-free preparations of rats and monkeys readily degrade the alachlor GSH conjugate through the mercapturic acid pathway to the corresponding cysteinylglycine, cysteine, and N-acetylcysteine conjugates of alachlor.
Upon UV irradiation, 14/13C-alachlor is dechlorinated and forms a number of intermediates that retain the aromatic ring and carbonyl carbons. These compounds include hydroxyalachlor, norchloralachlor, 2' ,6'-diethylacetanilide, 2-hydroxy- 2' ,6' -diethyl-N-methylacetanilide, and a lactam. The fungus transforms 98.6% of 14C-alachlor added to the fermentation broth, and metabolism occurs predominantly by benzylic hydroxylation of one of the arylethyl side chains. Two major metabolites are isomers of 2-chloro-N-(methoxymethyl)-N-[2-ethyl-6-(1- hydroxyethyl)-phenyl]acetamide and 2-chloro-N-(2,6- diethylphenyl)acetamide. The minor metabolite is 2-chloro-N-(methoxymethyl)-N-(2-vinyl-6- ethlyphenyl)acetamide. N-Dealkylation by fungal biotransformation is also observed.

Shipping

UN2588 Pesticides, solid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.

Toxicity evaluation

Alachlor has a low persistence in soil, with a half-life ofz8 days. The main means of degradation is by soil microbes. It has moderate mobility in sandy and silty soils, and thus can migrate to groundwater. The largest groundwater-testing program for a pesticide, the National Alachlor Well Water Survey, was conducted throughout the last half of the 1980s. More than sixmillion private and domestic wells were tested for the presence of alachlor. Less than 1% of all of the wells had detectable levels of alachlor. In the wells in which the compound was detected, concentrations ranged from 0.1 to 1.0 mg l
^-1, with themajority having concentrations≈0.2mg l
^-1. Alachlor is relatively stable to hydrolysis and photolysis in water, and degradation in water is not considered as an important environmental fate process. Alachlor appears to be persistent under aquifer biological and geochemical conditions. This means that alachlor can appear in groundwater years after use and can migrate with groundwater away from use areas. Alachlor contamination has resulted in loss of untreated groundwater as a source of drinking water in Florida and other states. The bioaccumulation factor in the channel catfish is 5.8 times the ambient water concentration, indicating that alachlor is not expected to accumulate appreciably in aquatic organisms.

Incompatibilities

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. Corrosive to iron and steel.

Waste Disposal

This compound is hydrolyzed under strongly acid or alkaline conditions, to chloroacetic acid, methanol, formaldehyde and 2,6-diethylanilne. Incineration is recommended as a disposal procedure. Techniques for alachlor removal from potable water have been reviewed by EPA but the data revealed no superior method. Improper disposal of pesticides is a violation of federal law. Dispose In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers.