What are the characteristics of 4-dihydropyran application from esollink's blog

The 4-dihydropyran application class of herbicides began to be developed in the late 1950s. This kind of herbicide has the characteristics of wide insecticidal spectrum, quick contact and non-selectivity. Main physical and chemical properties: ionic paraquat colorless or light yellow solid. The relative density is 1.24 (20℃/20℃). The vapor pressure is close to 0 (20℃).

Soluble in water, almost insoluble in organic solvents. Corrosive to metal. Pure white crystal. Melting point 300℃ (decomposition). Vapor pressure < 1.330-5kPa. Soluble in water, insoluble in hydrocarbons, a small amount soluble in low alcohols. The preparation contains a corrosion control agent. Both are stable under acidic and neutral conditions. It can be hydrolyzed by alkali and decomposed by ultraviolet light. Inert clays and anionic surfactants can passivate it. Non-ignitability of water agent. Decomposition products are hydrogen chloride, nitrogen oxide, carbon monoxide.

Toxicity: 2, 2-4-Dihydropyran application is highly toxic. The symptoms of digestive tract irritation and corrosion are followed by pulmonary edema, pulmonary fibrosis, respiratory failure, and various organ injuries. Improper spraying may result in dermatitis and eye damage. Acute toxicity: extensive injury of oral and esophageal mucosa accompanied by multisystemic toxicity, especially in lung. After 3 ~ 6 days of acute poisoning, the rats died of pulmonary edema and alveolar hemorrhage. If the lung survived for more than 10 days, the main pulmonary fibrosis changes. Chronic toxicity: Nail damage, nosebleed and dermatitis can be seen in workers with long-term exposure.

Biological activity: It is a rapid contact type of exterminative quaternary amine salt herbicide. The active components have a strong destructive effect on chloroplast membrane, which leads to the termination of photosynthesis and chlorophyll synthesis quickly. The leaves begin to become discolored 2 ~ 3h after drug application, and have a strong destructive effect on the green tissues of monocotyledon and dicotyledon plants. But no conductivity, can only make the drug site damage, can not penetrate the cork bark, easy to passivation after contact with soil. The root of the plant and the seeds hidden in the soil can not be destroyed, so the weeds can regenerate after application. Paraquat loses its activity soon after entering the soil and has no residual toxicity in the soil. Normal use does not cause harm to wildlife and the environment. Stable in neutral and acidic media. The herbicide had poor effect on sedge weeds such as plantain, Polygonum, foxgloves, thatch, duck plantain, and epiphyte.

4-dihydropyran application https://www.clentpharma.com/3-4-dihydropyran.html