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
Hazard class
6.1
Packing Group
I; II; III
 
USCG CHRIS Code
MML