Fenazaquin

Fenazaquin is a quinazoline acaricide. It has a low aqueous solubility but is highly soluble in many organic solvents. It is not volatile and is not expected to leach to groundwater. It may be persistent in soil and water systems depending on local conditions. Its toxicity to terrestrial and aquatic organisms tends to high to moderate. Fenazaquin is moderately toxic to humans via the oral route and, whilst it may be a respiratory tract irritant no chronic effects have been identified.

Acaricide and insecticide.

Fenazaquin is an acaricide mainly used for control of mites (Eutetranychus, Panonychus and Tetranychus spp.) on pome and citrus fruits and glasshouse-grown ornamental plants.

Fenazaquin is a non-systemic acaricide/insecticide used widely in controlling mites and other related pests in fruits, vegetables and tea.

ChEBI: Fenazaquin is a member of quinazolines. It has a role as an acaricide and a mitochondrial NADH:ubiquinone reductase inhibitor.

Mitochondrial complex I electron transport inhibitor

A novel method for the preparation of the acaricide fenazaquin:

1) 4-tert-butylphenethyl alcohol (5 g, 28.0 mmol) and THF (200 mL) were added in a 500 ml reactor, and PPh₃ (8.80 g, 33.7 mmol) was added in a single addition and N-bromosubstituted butylenediimide (NBS, 6.0 g, 33.7 mmol) was added in batches sequentially, and the reaction solution was stirred at 25C for For 4h, the tetrahydrofuran in the reaction solution was spun dry, dissolved in dichloromethane, washed twice with 150 ml of water, washed once with 150 ml of saturated saline, and separated by column chromatography (petroleum ether: ethyl acetate = 10:1) to give compound 2-(4-tert-butylphenyl)ethyl bromide 5.8 g in 85.8% yield.

2) In a 500mL four-port reactor equipped with a stirrer, a thermometer and a dropping funnel, 4-hydroxyquinazoline (3.5 g, 24.0 mmol) and 200 ml of dichloromethane were added, and the reaction was carried out under stirring at a controlled temperature of 25C with dropwise addition of 50 ml of dichloromethane solution of 2-(4-tert-butylphenyl)ethyl bromide (5.8 g, 24.0 mmol), and the drop was completed in about 1h, and then the reaction was Raise to 40 reaction 3h, add 400mL of water, separation of the organic layer, the aqueous layer was extracted with 2× 50mL of dichloromethane, combined organic layer. Concentrated under reduced pressure, the crude product was recrystallized from n-hexane to obtain a white solid 5.88g, melting point 72-74 , content 98.1%, yield 80%.

Fenazaquin is a lipophilic compound and hence is immobile in soils and is not translocated in plants. The main pathways of metabolism involve cleavage of the bridging group between the quinazoline and phenyl rings, oxidation of the tert-butyl sustituent and of the heterocyclic portion of the quinazoline ring and cleavage of that ring. Most of the information is taken from a pamphlet produced by the manufacturer of the compound in which full experimental details were not given (DowElanco, 1993).

Fenazaquin is hydrolysed under acidic conditions but the rate is slow under neutral and alkaline conditions. Half-lives were 8,442 and 584 days (22 °C) at pH values of 5, 7 and 9, respectively. Hydrolysis occurs by cleavage of the ether linkage to form quinazolin-2-ol (2) and an alcohol (3) as shown in Scheme 1. The major route of degradation in aquatic environments is by photolysis, the main products (2 and 3) being formed by cleavage of the ether lmkage and include the alkene (4) (DowElanco, 1993).

Acaricide; Insecticide