Римсульфурон

Description

Rimsulfuron is the active ingredient of post-emergence herbicides of the sulfonylurea group. Developed by DuPont under the code DPX-E 9636, it is known on the market as Titus, Matrix, Cato, Tarot, Tiger, Amurg, Rush, Dontsep, Resolve, Rimel. According to the HRAC classification, it belongs to group 2 - acetolactate synthase inhibitors (ALS, also known as AHAS). Product forms: water-dispersible granules 25 WG, soluble granules 25 SG, oil dispersion 25 OD.

Basic Attributes

• CAS No: 122931-48-0
• Chemical formula: C14H17N5O7S2
• Molecular weight: 431.44
• Exact weight: 431.44
• EU number: 602-908-8
• UNII: 462J071RD7
• DSSTox ID: DTXSID1032642
• PSA Specifications: 183
• XLogP3: 0.288 (pH 5); −1.47 (pH 7)

Physico-chemical characteristics

• Color and shape: colorless crystals
• Appearance of commercial product: white crystal or light yellow powder
• Density: 0.784 at 25 °C
• Melting point: 177 °C
• Boiling point: 760.1±70.0 °C at 760 mm Hg. Art.
• Flash point: above 200 °C
• Refractive index: 1.6460 (estimate)
• Solubility in water: 10 mg/l at 25 °C; less than 10 ppm in distilled water
• Steam pressure: 1.5 × 10⁻³ mPa (1.13 × 10⁻⁸ mmHg) at 25 °C
• Henry's law constant: 6.42 × 10⁻¹⁰ atm m³/mol at 25 °C (calculation)
• Dissociation constant: pKa 4.0
• log Kow: 0.034 (pH 7)
• Rate constant for reaction with hydroxyl radicals: 2.10 × 10⁻¹⁰ cm³/(molecule s) at 25 °C (calculation)
• Storage conditions: 0–6 °C
• Stability: Stable at normal temperatures and pressures

Mechanism of action

The molecule blocks acetolactate synthase, the first enzyme in the synthesis of valine, leucine and isoleucine. Without these amino acids, cell division at the growing points of the weed stops. Growth stops within a few hours after treatment, visible symptoms (chlorosis, anthocyanin coloring, drying out of the growth cone) develop within 7–20 days. The drug is absorbed by the leaves and partially by the roots, moves along the xylem and phloem to the meristems, including the rhizomes of perennials.

Scope of application

• corn crops - treatment for vegetative weeds
• potatoes - post-emergence application
• cereal weeds: creeping wheatgrass, chicken millet, bristle grass, wild oats, Aleppo sorghum
• a number of dicotyledonous weeds: white pigweed, knotweed, ragweed, nightshade, ropeweed

The working solution is prepared with the addition of a surface-active adjuvant - without it, wetting the cereal leaf is insufficient and the effectiveness decreases. Low consumption rates of the active substance per hectare are characteristic of the entire sulfonylurea group.

Toxicology and hazard classification

• LD50 oral, rat: more than 5000 mg/kg
• LD50 when applied to the skin, rabbits: more than 2000 mg/kg
• Hazard Statement: H319 - Causes serious eye irritation
• GHS classification: signal word "Warning", H319 (78.12%). Aggregated data from the ECHA C&L Register - 68 companies, 5 notifications
• Card Precautions: P305 + P351 + P338
• Extended list: P264, P273, P280, P305 + P351 + P338, P337 + P313, P391, P501
• Transport code: UN 3077 (solid)
• WGK Germany: 1
• RTECS number: UT7900000

Protective equipment and work regulations

Applicators and field workers wear a long-sleeve shirt and long pants, chemical-resistant gloves made of any waterproof material - polyethylene or polyvinyl chloride, shoes and socks. The restriction interval for access to treated areas (REI) is 4 hours. For early entry when in contact with plants, soil or water, coveralls, waterproof gloves, shoes and socks are required. Hands are washed before eating, drinking, smoking and using the toilet. Clothing and absorbent materials heavily contaminated with the product are thrown away; PPE is washed separately from other laundry with detergent and hot water.

Emergency measures

Firefighting: Evacuate personnel, wear self-contained breathing apparatus and full protective equipment, use water, foam, dry chemical or CO₂, apply water spray. Effluents from fire protection systems can pollute water bodies. Contain spills, keep material out of drains, waterways and low-lying areas, and shovel or sweep away. Wash the equipment so that washing water does not get into the water.

Disposal

Unused material is sent for approved use or returned to the manufacturer or supplier. Waste is disposed of on site or at an approved facility. The containers are washed three times (or an equivalent procedure is used), then handed over for recycling or pierced and taken to a sanitary landfill; Burning is permitted if permitted by local authorities and smoke should be avoided. After decontamination of equipment, cleaning of personal protective equipment and contaminated areas, wastewater is detained and analyzed for the content of substances and decomposition products - concentrations must be below discharge standards. The choice of disposal method takes into account the impact on air quality, migration in soil and water, impact on animals and plants, environmental protection and public health requirements. The product should not be used directly on water, in areas of surface water or in tidal areas below mean high tide.