Cloquintocet-mexyl is a colourless crystalline herbicide safener. It is categorized as Class III toxin.
Cloquintocet-mexyl is used as a herbicide.
Cloquintocet-mexyl is a herbicide. It is used to control coarse annual grass of the family poaceae (gramineae). lt was developed by the swiss ciba geigy in the 1980s and the patent has expired.
ChEBI: Heptan-2-yl [(5-chloroquinolin-8-yl)oxy]acetate is a member of the class of quinolines that is quinoline which is substituted by a chloro group at position 5 and by a 2-[(heptan-2-yl)oxy]-2-oxoethoxy group at position 8. It is an aromatic ether, an organochlorine compound, a member of quinolines and a carboxylic ester.
Cloquintocet-mexyl is commercially produced through a multi-step synthesis starting with 5-chloro-8-hydroxyquinoline as the primary raw material. The process begins with a nucleophilic substitution reaction where 5-chloro-8-hydroxyquinoline reacts with methyl chloroacetate in a solvent such as dimethylformamide, using potassium carbonate or a combination of sodium carbonate and sodium hydroxide as the base to form the intermediate methyl (5-chloro-8-quinolyloxy)acetate, typically at elevated temperatures to drive the alkylation at the 8-position oxygen. This ester is then subjected to alkaline hydrolysis with sodium hydroxide, followed by acidification (e.g., with hydrochloric acid) to yield the free acid, (5-chloro-8-quinolyloxy)acetic acid, which is isolated in high purity to minimize impurities. Finally, the acid undergoes esterification with 2-heptanol in the presence of an acid catalyst like sulfuric acid or p-toluenesulfonic acid, often under Dean-Stark azeotropic distillation conditions to remove water and shift equilibrium, producing cloquintocet-mexyl. An alternative direct transesterification route bypasses hydrolysis by reacting the methyl ester with 2-heptanol under similar catalytic conditions but may suffer lower yields due to equilibrium limitations and potential decomposition above 60DegC.
Cloquintocet-mexyl is a safener that can be used in conjunction with various herbicides to reduce phytotoxicity to crops. Though effective as a safener, the manufacture, storage, and use of cloquintocet-mexyl containing products can present challenges owing to its sensitivity to water and its low melting temperature (i.e., 61-69° C. for technical material). When products containing cloquintocet-mexyl are prepared, stored, or used in the presence of water, cloquin tocet-mexyl can undergo hydrolysis to form cloquintocet acid, and/or form a needle-shaped, crystalline hydrate that can, lead to clogged spray nozzles during spray applications and/or possibly increased levels of crop phytotoxicity.
Accelerates the herbicide detoxification process
In accordance with the EPA Proposed EPA Weight-of-the-Evidence Categories, August 1999, the HIARC classified cloquintocet-mexyl as "not likely to be a human carcinogen." Carcinogenicity studies in rats and mice did not show increased incidence of spontaneous tumor formation. With negative mutagenic test battery, it is suggested that cloquintocet-mexyl (CGA 185072) is not likely to be a human carcinogen.
Metabolism studies in rats indicated that approximately 40% of the administered dose of cloquintocet-mexyl was absorbed through the gastrointestinal tract and subsequently excreted via the urine. Fecal excretion accounted for approximately 60% of the administered dose. The chemical was rapidly eliminated (more than 80% of the administered dose) via feces and urine within 48 hours post-dosing. Sex, dosing regime, and dose levels had little effect on the excretion pattern. Excretion patterns were similar between the biliary cannulated and non-cannulated animals indicating that there was no enterohepatic circulation of the chemical. Three days after administration, tissue radioactivity accounted for less than 0.3% of the administered dose (or was non-detectable) and was not detectable in the expired air. At day three post-dosing, most tissue residues of radioactivity were below the limit of detection. The major metabolic pathway of cloquintocet-mexyl was ester hydrolysis to yield 5-chloro-8-quinolinoxy acetic acid, the major metabolite in the fecal and urinary pools.
Cloquintocet-mexyl has a low order of acute oral, dermal, and inhalation toxicity. It is slightly irritating to the eyes and non-irritating to the skin. Cloquintocet-mexyl is a skin sensitizer. The chemical is not genotoxic and is not a reproductive and developmental toxicant. There is no evidence of neurotoxicity in the available studies. Cloquintocet-mexyl is classified as “not likely to be a human carcinogen.” The main metabolite for cloquintocet-mexyl is 5-chloro-8-quin-linoxyacetic acid, and testing on the metabolite is part of the toxicology database for cloquintocet-mexyl.
