Chemical Properties
White Solid
Uses
Metribuzin is an is an aminotriazinone herbicide used in agriculture for both pre- and post-emergence in crops including soy bean, potatoes, tomatoes and sugar cane. Metribuzin acts by inhibiting phot
osynthesis by disrupting photosystem II.
Definition
ChEBI: A member of the class of 1,2,4-triazines that is 1,2,4-triazin-5(4H)-one substituted by an amino group at position 4, tert-butyl group at position 6 and a methylsulfanyl group at position 3.
General Description
Colorless crystalline solid. Used as an herbicide. Non corrosive.
Reactivity Profile
A triazine derivative. Amines are chemical bases. They neutralize acids to form salts plus water. These acid-base reactions are exothermic. The amount of heat that is evolved per mole of amine in a neutralization is largely independent of the strength of the amine as a base. Amines may be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen is generated by amines in combination with strong reducing agents, such as hydrides.
Hazard
Toxic material. Liver damage and hemato-logic effects. Questionable carcinogen.
Potential Exposure
A potential danger to those involved
in manufacture, formulation, and application of this
herbicide. A laboratory chemical. Used to make other
chemicals.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including
resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical
attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Shipping
UN2763 Triazine pesticides, solid, toxic, Hazard
Class: 6.1; Labels: 6.1-Poisonous materials.
Incompatibilities
Liquid is 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.
Description
Metribuzin is a colorless crystalline solid witha mild sulfurous odor; Freezing/Melting point =125- -127*C; Vapor pressure=4X 10-7 mmHg. SlightlyDescription: Metribuzin is a colorless crystalline solid witha mild sulfurous odor; Freezing/Melting point =125- -127*C; Vapor pressure=4X 10-7 mmHg. Slightlysoluble in water. Available in different concentrations (4%,50%, 75%).50%, 75%).
Waste Disposal
In accordance with 40CFR165,
follow recommendations for the disposal of pesticides and
pesticide containers. Must be disposed properly by following
package label directions or by contacting your local or federal
environmental control agency, or by contacting your regional
EPA office. Use a licensed professional waste disposal service
to dispose of this material. Dissolve or mix the material with
a combustible solvent and burn in a chemical incinerator
equipped with an afterburner and scrubber. All federal, state,
and local environmental regulations must be observed.
Production Methods
Commercial production of metribuzin begins with the preparation of the triazine ring, typically starting from precursors like cyanoguanidine and tert-butyl isocyanate. These undergo cyclisation to form the core triazine structure. The amino group is introduced via nitration followed by reduction, and the methylthio group is added through substitution using methyl mercaptan. The process involves careful control of temperature, pH, and solvent conditions, often using sulphuric acid and methanol, to ensure high yield and purity.
Health Hazard
Low to moderate acute toxicity; single highdose may cause depression of central nervoussystem; repeated high doses affect thyroidand stimulate the metabolizing liver enzymes(ACGIH) 1986; excretes out rapidly; noirritant action on skin or eye; no teratogenic,mutagenic or carcinogenic effect observed inanimal studies.
LD50 oral (rat): 1100 mg/kg
LD50 oral (mouse): 698 mg/kg
LD50 oral (guinea pig): 250 mg/kg
LD50 skin (rat): 2000 mg/kg.
Agricultural Uses
Herbicide: Metribuzin is a selective triazine herbicide which
inhibits photosynthesis of susceptible plant species. It is
used for control of annual grasses and numerous broadleaf
weeds in asparagus, potatoes, lucerne, peas, lentils, soya
beans, sugar cane, sainfoin, pineapples and cereals. It is
applied to fallow lands. Metribuzin is available as liquid
suspension, water dispersible granular, and dry flowable
formulations.
Trade name
AUTHORITY®; AXIOM® Metribuzin;
BAY 61597®; BAY DIC 1468®; BAYER 6159H®;
BAYER 6443H®; BAYER 94337®; BOUNDARY®;
CANOPY®; CONQUEST®; DIC 1468®; DOMAIN®;
LEXONE®; LEXONEEX®; PREVIEW®[C];
PYTHON®; SENCOR®; SENCORAL®; SENCOREX®;
SENCORER®; VAPCOR®
Mechanism of action
Selective, systemic with contact and residual activity. Inhibits photosynthesis (photosystem II).
Environmental Fate
Soil. In soils, metribuzin undergoes deamination and further degradation forming water
soluble conjugates (Hartley and Kidd, 1987). Metribuzin degrades rapidly in soil (Kempson-
Jones and Hance, 1979; LaFleur, 1980). The half-lives in soil ranged from 4 to 9
weeks at 22°C and 60% moisture content to 9 to 11 weeks at 10°C and 10% moisture
content. The highest half-life reported ranged from 15 to 43 weeks in a soil having 60%
moisture content maintained at 10°C (Kempson-Jones and Hance, 1979).
The dissipation rates (day–1) for metribuzin on Hillsdale silty loam, Cecil silty loam,
Regina heavy clay, Melfort clay loam and White City silt loam were 0.013-0.017, 0.055-
0.131, >0.017, >0.0016 and >0.023, respectively.
Groundwater. According to the U.S. EPA (1986) metribuzin has a high potential to
leach to groundwater.
Plant. Metribuzin is metabolized in soybean plants to a deaminated diketo derivative
which is nonphytoxic (Duke et al., 1991).
Photolytic. The simulated sunlight (l >230 nm) photolysis as a thin film on silica gel
or sand yielded 6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5-(4H)-one and two
additional photoproducts. In both of the unnamed photoproducts, the methylthio group in
the parent compound is replaced by oxygen and one of the compounds also underwent
N-deamination (Bartl and Korte, 1975).
Chemical/Physical. Emits toxic fumes of nitrogen and sulfur oxides when heated to
decomposition (Lewis, 1990).
storage
Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Store in tightly closed containers in a cool, dry area.
