Potential Exposure
A potential danger to those involved
in the manufacture, formulation and application of this tri-
azine pre-emergence selective herbicide used to control
annual broadleaf weeds and grasses.
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, includ-
ing 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 medi-
cal 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.
Chemical Properties
2,4-Bis(isopropylamino)-6-chloro-1,3,5-triazine is a colorless crystalline solid or powder.
Uses
2,4-Bis(isopropylamino)-6-chloro-1,3,5-triazine is used to control annual grasses and broad-leaved weeds in milo and sweet sorghum.
Production Methods
The industrial synthesis of propazine typically begins with the formation of the cyanuric chloride intermediate, which serves as the base for the triazine ring. This compound undergoes sequential nucleophilic substitution reactions with isopropylamine to replace two of the chlorine atoms at the 4- and 6-positions, forming the bis(isopropylamino) derivative. The remaining chlorine atom at the 2-position is retained, giving propazine its herbicidal activity. These reactions are carried out in organic solvents such as acetone or acetonitrile under controlled temperature and pH conditions to ensure high yield and purity.
Agricultural Uses
Herbicide: Atrazine, simazine, and propazine and their common chlorinated degradates have a common mechanism of toxicity. They have similar applications. Propazine is used for control of broadleaf weeds and annual grasses in sweet sorghum. It is applied as a spray at the time of planting or immediately following planting, but prior to weed or sorghum emergence. It is also used as a post-emergence selective herbicide on carrots, celery and fennel. Not approved for use in EU countries. Some formulations are U.S. EPA restricted Use Pesticides (RUPs).
Trade name
GEIGY® 30,028; GESAMIL®; MAXX90®; MILOCEP®; MILOGARD®[C]; MILO-PRO®; PLANTULIN®; PRIMATOL P®; PROPAZIN®; PROPINEX®; PROZINEX®
Mechanism of action
Selective, systemic, absorbed by roots and translocated. Propazine's mode of action involves the inhibition of photosynthesis at Photosystem II (PSII) in plants. This is achieved by binding to the D1 protein in the PSII complex preventing the transfer of electrons from plastoquinone A (QA) to plastoquinone B (QB).
Carcinogenicity
Oral gavage of 46.4 mg/kg to
two strains of mice from 7 through 28 days of age, followed
by feeding of 102 ppm for up to 18 months, produced no
increase in tumors. Subcutaneous injection of a single
1000 mg/kg dose in mice of the same two strains that were
observed for 18 months produced no carcinogenic
response. Rats were given 0, 3, 100, or 1000 ppm of
propazine in the diet for 2 years. At 1000 ppm, there was a
significant decrease in body weight in both sexes and an
increase in mammary tumors in females.
Environmental Fate
Soil. Undergoes microbial degradation in soil forming hydroxypropazine (Harris,
1967). Dealkylation of both substituted amino groups is presumably followed by ring
opening and decomposition (Hartley and Kidd, 1987). Under laboratory conditions, the
half-lives of propazine in a Hatzenbühl soil (pH 4.8) and Neuhofen soil (pH 6.5) at 22°C
were 62 and 127 days, respectively (Burkhard and Guth, 1981).
Groundwater. According to the U.S. EPA (1986) propazine has a high potential to
leach to groundwater.
Photolytic. Irradiation of propazine in methanol afforded prometone (2-methoxy-4,6-
bis(isopropylamino-s-triazine). Photodegradation of propazine in methanol did not occur
when irradiated at wavelengths >300 nm (Pape and Zabik, 1970).
Chemical/Physical. In aqueous solutions, propazine is converted exclusively to hydroxypropazine (2-hydroxy-4,6-bisisopropylamino)-s-triazine by UV light (λ = 253.7 nm)
(Pape and Zabik, 1970). In acidic aqueous soil-free systems, propazine hydrolysis is pH
dependent and follows first-order kinetics. At 23.5°C, the estimated hydrolysis half-lives
at pH 2.0, 3.0, 4.0 and 5.0 are 9, 36, 141 and 550 days, respectively. The rate of hydrolysis
was also found to increase and decrease in the presence of organic matter and calcium
salts, respectively (Nearpass, 1972).
