Description
Dicyclanil is an insect growth regulator belonging to the group of pyrimidinamines.
Dicyclanil is a pyrimidin derivative. Dicyclanil is an insect development inhibitor very specific for the prevention of blowfly strike in sheep. It does not control any other external parasites of sheep. It is used mainly as a spray-on. It is not used in other livestock, horses or pets.
Uses
Dicyclanil is a veterinary medication for the protection against early season myiasis.
Application
Dicyclanil may be used as an analytical reference standard for the quantification of the analyte in biological samples, bovine, porcine and chicken muscle using various chromatography techniques.
Pharmacokinetics
Dicyclanil has a long lasting action which interferes with moulting and pupation in dipteran species. However, the precise mode of action of this compound on ectoparasites is not known.
A variety of in vitro and in vivo pharmacodymanic tests were performed with dicyclanil in rats, mice and guinea pigs. In vitro, dicyclanil was devoid of significant effects on the neuromuscular junction at concentrations below 3 mM. Slight antagonistic effects on smooth muscle were reported at concentration levels above 0.1 mM. Dicyclanil caused a statistically significant increase in heart rate, tidal volume and minute volume at a dose level of 100 mg/kg bw in studies on the cardiovascular and respiratory systems in the rat. In various in vivo studies, dicyclanil was devoid of significant effects on behavior at a dose level of 1 mg/kg bw in mice.
Synthesis
In the first step, the condensation reaction was carried out. A methanol solution of 270 g of anhydrous methanol and 500 g of sodium methanolate was added to a 2L four-neck flask. Cooled to 0-5 °C in an ice-water bath, 72.8 g of malononitrile was added and stirred for 30 min, keeping the temperature at 0-5 °C. 146.5 g of N-cyanoimido-S,S-dimethyl dithiocarbonate was added in batches and the reaction was stirred at 0-5 °C for 12 hours. The reaction was completed and filtered and the filter cake was washed with 100 mL of cold anhydrous methanol and drained. The wet product was used directly in the next step of the reaction. In the second step, the cyclization reaction was carried out. The above wet product was dissolved in 860 g of water and added to a four-necked flask. After dissolving with stirring, the ice water bath was cooled to 0-5 °C and 1200 g of industrial hydrochloric acid was added slowly and dropwise for about 4-5 hours. The reaction was carried out overnight at 0-5°C. Upon completion, the reaction was filtered and the filter cake was washed twice with 10% sodium carbonate solution and dried to give 157 g of dried product. In the third step, the cyclopropylation reaction was carried out. 315 g of the product of the second step, 1000 g of ethanol and 66.7 g of cyclopropylamine were added to a 2L four-necked flask, stirred and heated to reflux. The reaction was cooled to 0-5°C overnight, filtered, and the filter cake was washed, drained, and dried to give 147 g of dried product. Step 4, oxidation reaction. To a 5L four-necked flask were added 414 g of the third step product, 810 g of acetic acid and 5.5 g of sodium tungstate and heated to 50-55 °C. 230g of hydrogen peroxide was added slowly under stirring, and the reaction was carried out at 50-55°C for 4 hours after the addition. After the reaction was completed, the acetic acid was recovered under reduced pressure, and the residue was cooled to below 10°C with 800g of water, filtered, and the filter cake was washed to pH 5-6, drained, and then used directly in the next step of the reaction. The fifth step, ammoniation reaction. Add the product of the fourth step, 610g of ethanol and 1450g of ammonia in a 5L four-necked flask and stir at 20-25°C for 5 hours. After the reaction was completed, it was cooled to 5-10°C, filtered, and the filter cake was washed and dried to obtain 88g of dried product. The 88g of dry product was dissolved in 560mL of N,N-dimethylformamide and heated to 90°C to dissolve. 5g of powdered activated carbon was added, stirred for 10 minutes, filtered, cooled and refrigerated overnight. Filtered on the next day, the filter cake was washed with deionized water, drained and dried to obtain 80g of white powder.
Toxicity evaluation
Dicyclanil was investigated in a series of acute toxicity studies. The acute LD50 by the oral route in the rat was 520 mg/kg bw. The acute LD50 by the dermal route was greater than 2000 mg/kg bw in the rat. An acute inhalation toxicity study also conducted in the rat showed the acute LC50 to be 3,184 mg/m3 of air. The toxic effects were dyspnoea and reduced locomotor activity.
References
[1] Patent: CN107698519, 2018, A. Location in patent: Paragraph 0008
