Dimethoate

  • O,O-Dimethyl S-methylcarbamoylmethyl phosphorodithioate
  • O,O-Dimethyl S-(2-(methylamino)-2-oxoethyl)phosphorodithioate
  • Phosphorodithioic acid, O,O-dimethyl s-(2-(methylamino)-2-oxoethyl)ester
Formula
C5H12NO3PS2
Structure
Uses
Systemic insecticide-acaricide used for a wide range of insects such as aphids, thrips, planthoppers, white flies, mites on ornamental plants, alfalfa, apples, corn, cotton, grapefruit, grapes, lemons, melons, oranges, pears, pecans, safflower, sorghum, soybeans, tangerines, tobacco, tomatoes, watermelons, wheat, other vegetables, residual wall spray in farm buildings for houseflies. It has not been produced in the U.S. since 1982.

Registry Numbers and Inventories.
CAS
60-51-5
EC (EINECS/ELINCS)
200-480-3
EC Index Number
015-051-00-4
EC Class
Harmful
RTECS
TE1750000
RTECS class
Agricultural Chemical and Pesticide; Tumorigen; Mutagen; Reproductive Effector; Human Data
UN (DOT)
2783
Merck
12,3269
Beilstein/Gmelin
1785339
Beilstein Reference
4-04-00-00252
RCRA
P044
EPA OPP
35001
Swiss Giftliste 1
G-1553
Canada DSL/NDSL
NDSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed

Properties.
Formula
C5H12NO3PS2
Formula mass
229.26
Melting point, °C
52
Vapor pressure, mmHg
0.0000085
Density
1.265 g/cm3 (30 C)
Solubility in water
25 g/L
Refractive index
1.53 (20 C)
Partition coefficient, pKow
0.56

Hazards and Protection.
Storage
Store at liquids above 7 C. Most stable at pH between 4 and 7. Usually stable in water except in alkaline solutions. Incompatible with alkaline.
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
Organic vapor acid gas canister; worn by flaggers and mixer/loaders.
Small spills/leaks
Dimethoate is an organophosphate insecticide. Precautions for organophosphorus pesticides include the following. Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Remove and isolate contaminated clothing at the site. Do not touch spilled material; stop leak if you can do so without risk. Use water spray to reduce vapors. Small spills: absorb with sand or other noncombustible absorbent material and place into containers for later disposal. Small dry spills: with clean shovel place material into clean, dry container and cover; move containers from spill area. Large spills: dike far ahead of spill for later disposal.
Stability
No data.
Incompatibilities
Incompatible with alkaline preparations Corrosive to iron Incompatible with sulfur based formulations.

Fire.
Flash Point,°C
107
Fire fighting
Procedures for organophosphorus pesticides are as follows. Dike fire control water for later disposal, do not scatter the material. Wear positive pressure breathing apparatus and protective clothing. Fight fire from maximum distance.This material is an organophosphate insecticide.Methods for organophosphorus pesticides are as follows. Small fires: dry chemical, carbon dioxide, water spray, and foam. Large fires: water spray, fog, or foam.
Fire potential
Moderate; liquid formulations may be flammable due to their solvent. Dimethoate itself does not easily ignite but burns readily.
Hazards
As with other organophosphorus pesticides, container may explode in heat of fire. The temperature of storage should not exceed 70-80F. Keep away from sources of heat, flames, or spark-generating equipment. Unstable in alkaline solution. Hydrolyzed by aqueous alkali. Stable in aqueous solutions. The compound is stable for 2 years under environmental conditions if stored in undamaged, original containers.
Combustion products
Fire may produce irritating, corrosive and/or toxic gases.

Health.
Poison_Class
3
Exposure effects
Vital sign changes can include slow or rapid heart rate, abnormally low blood pressure or elevated blood pressure, rapid breathing, respiratory paralysis or fever. Headache, dizziness, muscle spasms, profound weakness, paralysis, confusion, slurred speech and loss of reflexes are common symptoms of dichlorvos overexposure. Altered level of consciousness, seizures and coma may occur. Seizures may be more common in children.
   Ingestion
Vomiting, diarrhea, fecal incontinence and abdominal pain may occur.
   Inhalation
Dyspnea, rales, bronchorrhea, or tachypnea may occur; with pulmonary edema in severe cases.
   Skin
Sweating is a consistent but not universal sign.
   Eyes
Constriction of the pupil, tearing, blurred vision, and salivation are common. Prolonged dialation of the pupils may occur in severe poisonings. Opsoclonus has occurred rarely. Acute glaucoma has been reported from dimethoate poisoning.

First aid
 
   Ingestion
Seek medical assistance.
   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 and isolate contaminated clothing and shoes. Immediately flush with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin.
   Eyes
Immediately flush with running water for at least 20 minutes.

Transport.
UN number
2783
Response guide
Hazard class
6.1
Packing Group
I; II; III
 
USCG CHRIS Code
DTO