Methomyl

  • S-Methyl-N-(methylcarbamoyloxy)thioacetimidate
  • Methyl N-{(methylamino)carbonyloxy}ethanimidothioate
  • Ethanimidothioic acid, n-{{(methylamino)carbonyl}oxy}-, methyl ester
Formula C5H10N2O2S
Structure
Description White crystalline solid with slight sulfurous smell.
Uses Nematocide, inceticide.

Registry Numbers and Inventories.
CAS 16752-77-5
EC (EINECS/ELINCS) 240-815-0
EC Index Number 006-045-00-2
EC Class Very toxic; Dangerous for the Environment
RTECS AK2975000
RTECS class Agricultural Chemical and Pesticide; Mutagen
UN (DOT) 2757
Merck 12,6062
Beilstein/Gmelin 2042050
RCRA P066
EPA OPP 549400
Swiss Giftliste 1 G-4584
Austrailia AICS Listed
New Zealand Listed
Korea ECL Listed

Properties.
Formula C5H10N2O2S
Formula mass 162.21
Melting point, °C 78-79
Boiling point, °C 228
Vapor pressure, mmHg 5E-5 (25 C)
Vapor density (air=1) 1.2946
Critical temperature 425
Critical pressure 31.8
Density 1.2946 g/cm3 (20 C)
Solubility in water 58 g/L
pKa/pKb 13,27 (pKa)
Partition coefficient, pKow 0.60

Hazards and Protection.
Storage Keep in a cool, dry, dark location in a tightly sealed container or cylinder. Keep away from incompatible materials, ignition sources and untrained individuals. Secure and label area. Protect containers/cylinders from physical damage.
Handling All chemicals should be considered hazardous. Avoid direct physical contact. Use appropriate, approved safety equipment. Untrained individuals should not handle this chemical or its container. Handling should occur in a chemical fume hood.
Protection Wear appropriate protective gloves, clothing and goggles.
Respirators Wear positive pressure self-contained breathing apparatus (SCBA).
Small spills/leaks Caution : Flammable. Avoid sources of extreme heat or ignition including sparks or fire. Methomyl will liberate toxic nitrogen and sulfur oxide fumes when heated to decomposition. (Non-Specific -- Carbamate Pesticide, Solid) Keep unnecessary people away; isolate hazard areas and deny entry. Stay upwind and keep out of low areas. Do not touch spilled material, or handle broken packages without protective equipment. Do not breathe dust, vapors, or the fumes from burning material.
Stability Stable in neutral or slightly acidic solution aqueous solutions decompose slowly at room temperature, more rapidly on aeration, in sunlight, in alkaline media or at higher temperatures.
Incompatibilities Incompatible with strong acids and bases, and especially

Fire.
Fire fighting (Non-Specific -- Carbamate Pesticide, Solid) Wear self-contained breathing apparatus.(Non-Specific -- Carbamate Pesticide, Solid) Use agent suitable for type of surrounding fire. Use water in flooding quantities as a fog. Use alcohol foam, carbon dioxide, or dry chemical.
Fire potential Liquid formulations are flammable.
Hazards When heated to decomposition, it emits very toxic fumes of nitrogen oxides and sulfur oxides. Do not subject liquid formulations to temperatures below 32F.
Combustion products Fire may produce irritating, corrosive and/or toxic gases.

Health.
Exposure limit(s) TLV: ppm; 2.5 mg/m3 (ACGIH 1993). NIOSH REL: TWA 2.5 mg/m3
Poison_Class 2
Exposure effects Blurred vision, miosis, tremor, muscle twitching, convulsions, mental confusion, and coma may occur. Delayed peripheral neuropathy similar to that seen with organophosphates has been described in one case. Dystonic reaction may occur following parenteral injection. Methomyl has not been teratogenic in rats or rabbits, and did not affect fertility in multi-generation rat studies. <br>No data were available to assess the potential effects of exposure to this agent during pregnancy or lactation. <br>Methomyl affected sperm morphology in mice.
   Ingestion Nausea, vomiting, diarrhea, and abdominal cramping may be noted.
   Inhalation Dyspnea, rales, and pulmonary edema may occur.
   Skin Avoid any skin contact. See Inhalation.
   Eyes Pinpoint pupils may be seen.

First aid
 
   Ingestion Do not induce emesis. Activated charcoal: administer charcoal as a slurry (240 ml water/30 g charcoal). Usual dose: 25 to 100 g in adults/adolescents.
   Inhalation Move victim to fresh air. Apply artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; induce artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult.
   Skin Remove contaminated clothing and jewelry. Wash the skin, including hair and nails, vigorously; do repeated soap washings. Discard contaminated clothing.
   Eyes Irrigate exposed eyes with copious amounts of tepid water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility.

Transport.
UN number 2757
Response guide 151
Hazard class 6.1
Packing Group I; II; III  
USCG CHRIS Code MML