Hexythiazox

Chemical Properties

The pure product is white crystal, odorless. m.p.108~108.5℃, vapor pressure 3.4×10-6Pa (20℃). Solubility at 20 ℃: acetone 160g/L, methanol 20.6g/L, acetonitrile 28.6g/L, xylene 362g/L, n-hexane 3.9g/L, water 0.5mg/L. It is stable at 50℃ for 3 months and it can be hydrolyzed in acid-base medium with the half-life of 7×104h (pH=5~7) and 1.2×104h (pH=9). The half-life in the soil is 8d. Stable to heat.

Insect growth regulator & Acaricide

As a thiadiazine insect growth regulator, hexythiazox has high selectivity, strong contact toxicity and stomach toxicity. It has good control effects on homopteran such as planthoppers, leafhoppers, whitefly and coccid hydrocarbon pests, as well as lasting larvicidal activities on some coleoptera pests and mites. It can effectively prevent rice pests like planthopper and leafhopper, leafhopper on tea and potato, whitefly on citrus and vegetable, shield scale and powder scale on citrus. According to domestic researches, there are some systemic actions and tracking effects on rice plants. Its mechanism of action is causing nymphs not molting, molting abnormally or feathering abnormally to slowly die by inhibiting chitin synthesis of insect and interfering with metabolism, which means it has high activity of killing nymphs. The general recommended dose cannot kill the adult directly, but it can reduce spawning, hatching rate and shorten the life span of insect. Generally, the effects cannot been seen until 3~7 days after the application.
It belongs to the thiazolidone acaricide with good penetration to the epidermis of plants but without inner-absorption conduction. The product has no direct killing effects on adults, but it can shorten the lifespan, reduce egg hatchability and produce mostly sterile eggs. The larvae die soon even if hatched. It has a good control effect on hemipteran planthoppers, leafhoppers, whitefly and scale pests with effective period of 30 days or more.
It is safe to natural enemies of insects. It has no cross resistance problems with other insecticides hexythiazox, but good comprehensive effects. The effect of the drug is slow, and the pest damage can be controlled 3~7 days after the application. When the population density of insects is high, it should be mixed with quick acting agents. This product has a strong killing effect on many kinds of plant mites with the characteristics of killing young nymphs, but it is ineffective against adult mites. The eggs produced by female mites exposed to liquid medicine are inhibited.
The drug belongs to non-temperature coefficient acaricide without significant differences at different temperatures but with long residual effects. The drug has good control effects on leaf mite but poor control effects on rust mite and gall mite. Common concentration is safe for crops. It can be mixed with a variety of pesticides such as bordeaux mixture and lime sulfur.

Toxicity

Acute toxicity of rats and mice LD50> 5000mg/kg, acute percutaneous LD50> 5000mg/kg, and acute inhalation of rats LC50>2mg/L (4h). It has no irritation to the skin of rabbit but a slight irritation to the eyes. In the 2-year feeding test, the non-effect dose was 23.1mg/kg. In animal tests, there are no teratogenesis, carcinogenesis and mutagenesis found. Carp LC503.7mg/L (48h), quail acute oral LD50>5000mg/kg, bee LD50>0.2mg/ only.

Uses

It belongs to thiazolidone acaricide. This product has broad insecticidal spectrum and high acaricidal activities on spider mite, mocking mite, and panonychus citri. It has good effects in the use of low concentrations and better residual effects. It has no cross resistance problems with organophosphorus, dicofol and so on. It is safe for crops and beneficial insects feeding on mites with main contact effects. It has good penetration to the epidermis of plants, poor effect on adults but no inner-absorption conduction. It has a strong killing effect on many kinds of plant mites with the characteristics of killing young nymphs, but it is ineffective against adult mites. The eggs produced by female mites exposed to liquid medicine are inhibited. The effect is slow, but the residual effect can last as long as more than one month. Like the prevention and treatment of apple red spiders, during full incidence period of young nymphs, if there are 3 to 4 mites per leaf on average, 5 % EC or 5 % WP can be sprayed in 1500～2000 times. Stop using it at least 7 days before the harvest.

Production

The preparation of erythro-2-amino -1-p-chlorophenyl propanol sulfate
A mixture of 20g of erythro-2-amino-1-p-chlorophenyl propanol and 21.9g of 50% sulfuric acid is azeotropically distilled together with benzene to remove moisture to give the corresponding sulfate in a yield of 99%.
The preparation of trans-5-(4- chlorophenyl)-4-methyl-2-oxo thiazolidone
It is obtained by cyclization with carbon disulfide and oxidation and in the presence of ethanol medium and acid binding agent. Operation method: 5g of potassium hydroxide formulated as an aqueous solution is added to a mixture of 10.6g of erythro-2-amino-1-p-chlorophenyl propanol sulfate and 6.1g of carbon disulfide in ethanol at room temperature. The cyclization intermediate can be obtained by controlling the reaction temperature at 40℃ and the reaction time of 3h. Then put 2.44g intermediate with 2.7g sodium methoxide into methanol solution to react with each other at room temperature. The substitutional intermediate of trans-thiazolidone is obtained by oxidation with 5.2g 30% hydrogen peroxide at 40℃. The total yield of above two-step reaction is 79.8%. Use sulfate of erythro-2-amino-1-p-chlorophenyl propanol as raw material, react with excessive oxygen sulphide carbon in the presence of acid binding agent. Trans--5-(4-chlorobenzyl)-4-methyl-2-chlorothiazolidone can be obtained by one-step synthesis with a yield of 71%.
The preparation of cyclohexyl isocyanate vinegar
1 mol of carbon dioxide is reacted with 2 mol of cyclohexylamine to form substituted carbonic acid with xylene as solvent. Then the resultant is reacted with silicon tetrachloride or trimethyl silicon nitride to form corresponding ester. After pyrolysis, cyclohexyl isocyanate can be obtained. The yield of this method is high.
Cyclohexyl isocyanate vinegar can also be prepared by pyrolysis in inert solvent through cyclohexyl carbamyl chloride with cyclohexylamine hydrochloride and phosgene as materials.
The synthesis of cyclohexyl isocyanate by catalytic pressure reaction with cyclohexylamine and carbon monoxide as materials needs further exploration.
The synthesis of thioacarone
It is prepared by the addition reaction of trans-5-(4-chlorophenyl)-4-methyl-2-oxo thiazolidon with cyclohexyl isocyanate vinegar. Method of operation: Add 20.9g trans-thiazolidone and 11.9g cyclohexyl isocyanate into benzene solvent. Then stir the mixture at room temperature. Thiacarone is prepared after post-processing in a yield of 94.8%. It has also been reported that the catalyst used is strongly basic 1,8-diazabicyclo-5,4-undec-7-ene (DBU).

Description

Hexythiazox is an acaricide that induces toxicity in larvae of the two-spotted spider mite T. urticae and the European red mite P. ulmi (LC₅₀s = 0.15-0.58 and 0.23-0.62 mg AI/L, respectively), as well as in the summer and winter eggs of P. ulmi (LC₅₀s = 2.2 and 20 ppm, respectively). Hexythiazox is toxic to bluegill (L. macrochirus; LC₅₀ = 3.2 mg/L) and D. magna (EC₅₀ = 0.36 mg/L) but not rats (LD₅₀ = >5,000 mg/kg). Formulations containing hexythiazox have been used in the control of mites in agriculture.

Uses

Nonsystemic acaricide.

Uses

Hexythiazox is a mite growth regulator and a thiazolidine based acaricide that has long-lasting effects against many kinds of mites and is applied at any stage of the plant growth from budding to frui ting.

Definition

ChEBI: (S,S)-hexythiazox is a hexythiazox.

Environmental Fate

Soil. Though no products were reported, the half-life in a clay loam at 15°C is 8 days (Worthing and Hance, 1991).