Taking 2014 as an example, global sales of aryloxyphenoxypropionate herbicides were US$1.217 billion, accounting for 4.6% of the US$26.440 billion global herbicide market and 1.9% of the US$63.212 billion global pesticide market. Although it is not as good as herbicides such as amino acids and sulfonylureas, it also has a place in the herbicide market (ranked sixth in global sales).
Aryloxy phenoxy propionate (APP) herbicides are mainly used for the control of grass weeds. It was discovered in the 1960s when Hoechst (Germany) replaced the phenyl group in the 2,4-D structure with diphenyl ether and developed the first generation of aryloxyphenoxypropionic acid herbicides. “Grass Ling”. In 1971, it was determined that the parent ring structure consists of A and B. Subsequent herbicides of this type were modified based on it, changing the A benzene ring on one side into a heterocyclic or fused ring, and introducing active groups such as F atoms into the ring, resulting in a series of products with higher activity. , more selective herbicides.
APP herbicide structure
The development history of propionic acid herbicides
Mechanism of action
Aryloxyphenoxypropionic acid herbicides are mainly active inhibitors of acetyl-CoA Carboxylase (ACCase), thereby inhibiting the synthesis of fatty acids, resulting in the synthesis of oleic acid, linoleic acid, linolenic acid, and waxy layers and cuticle processes are blocked, resulting in rapid destruction of the plant’s membrane structure, increased permeability, and ultimately the death of the plant.
Its characteristics of high efficiency, low toxicity, high selectivity, safety for crops and easy degradation have greatly promoted the development of selective herbicides.
Another feature of AAP herbicides is that they are optically active, which is characterized by different isomers under the same chemical structure, and different isomers have different herbicidal activities. Among them, the R(-)-isomer can effectively inhibit the activity of the target enzyme, block the formation of auxin and gibberellin in weeds, and show good herbicidal activity, while the S(+)-isomer is basically ineffective. The difference in efficacy between the two is 8-12 times.
Commercial APP herbicides are usually processed into esters, making them more easily absorbed by weeds; however, esters usually have less solubility and stronger adsorption, so they are not easy to leach and are more easily absorbed into the weeds. in the soil.
Clodinafop-propargyl
Propargyl is a phenoxypropionate herbicide developed by ciba-Geigy in 1981. Its trade name is Topic and its chemical name is (R)-2-[4-(5-chloro-3-fluoro). -2-Pyridyloxy)propargyl propionate.
Propargyl is a fluorine-containing, optically active aryloxyphenoxypropionate herbicide. It is used for post-emergence stem and leaf treatment to control gramineous weeds in wheat, rye, triticale and other cereal fields, especially for wheatgrass and wheatgrass. Efficient in controlling difficult weeds such as wild oats. Used for post-emergence stem and leaf treatment to control annual grass weeds, such as wild oats, black oat grass, foxtail grass, field grass, and wheatgrass. The dosage is 30~60g/hm2. The specific usage method is: from the 2-leaf stage of wheat to the jointing stage, apply the pesticide to weeds at the 2-8 leaf stage. In winter, use 20-30 grams of Maiji (15% clofenacetate wettable powder) per acre. 30-40g of extremely (15% clodinafop-propargyl wettable powder), add 15-30kg of water and spray evenly.
The action mechanism and characteristics of clodinafop-propargyl are acetyl-CoA carboxylase inhibitors and systemic conductive herbicides. The drug is absorbed through the leaves and leaf sheaths of the plant, conducted through the phloem, and accumulated in the meristem of the plant, inhibiting acetyl-coenzyme A carboxylase inhibitor. Coenzyme A carboxylase stops fatty acid synthesis, prevents normal cell growth and division, and destroys lipid-containing structures such as membrane systems, eventually leading to plant death. The time from clodinafop-propargyl to the death of weeds is relatively slow, generally taking 1 to 3 weeks.
The mainstream formulations of clodinafop-propargyl are 8%, 15%, 20%, and 30% aqueous emulsions, 15% and 24% microemulsions, 15% and 20% wettable powders, and 8% and 14% dispersible oil suspensions. 24% cream.
Synthesis
(R)-2-(p-hydroxyphenoxy)propionic acid is first produced by the reaction of α-chloropropionic acid and hydroquinone, and then etherified by adding 5-chloro-2,3-difluoropyridine without separation. Under certain conditions, it reacts with chloropropyne to obtain clodinafop-propargyl. After crystallization, the product content reaches 97% to 98%, and the total yield reaches 85%.
Export situation
Customs data shows that in 2019, my country exported a total of 35.77 million U.S. dollars (incomplete statistics, including preparations and technical drugs). Among them, the first importing country is Kazakhstan, which imports mainly preparations, with an amount of 8.6515 million U.S. dollars, followed by Russia, with preparations There is demand for both medicines and raw materials, with an import volume of US$3.6481 million. The third place is the Netherlands, with an import volume of US$3.582 million. In addition, Canada, India, Israel, Sudan and other countries are also the main export destinations of clodinafop-propargyl.
Cyhalofop-butyl
Cyhalofop-ethyl is a rice-specific herbicide developed and produced by Dow AgroSciences in the United States in 1987. It is also the only aryloxyphenoxycarboxylic acid herbicide that is highly safe for rice. In 1998, Dow AgroSciences of the United States was the first to register cyhalofop technical in my country. The patent expired in 2006, and domestic registrations began one after another. In 2007, a domestic enterprise (Shanghai Shengnong Biochemical Products Co., Ltd.) registered for the first time.
Dow’s trade name is Clincher, and its chemical name is (R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]butylpropionate.
In recent years, Dow AgroSciences’ Qianjin (active ingredient: 10% cyhalomefen EC) and Daoxi (60g/L cyhalofop + penoxsulam), which have become popular in the Chinese market, are highly effective and safe. It occupies the mainstream market of rice field herbicides in my country.
Cyhalofop-ethyl, similar to other aryloxyphenoxycarboxylic acid herbicides, is a fatty acid synthesis inhibitor and inhibits acetyl-CoA carboxylase (ACCase). Mainly absorbed through leaves and has no soil activity. Cyhalofop-ethyl is systemic and is rapidly absorbed through plant tissues. After chemical treatment, grass weeds stop growing immediately, yellowing occurs within 2 to 7 days, and the entire plant becomes necrotic and dies within 2 to 3 weeks.
Cyhalofop is applied post-emergent to control gramineous weeds in rice fields. The dosage for tropical rice is 75-100g/hm2, and the dosage for temperate rice is 180-310g/hm2. It is highly effective against Echinacea, Stephanotis, Amaranthus aestivum, Small chaff grass, Crabgrass, Setaria, brangrass, Heart-leaf millet, Pennisetum, Zea mays, Goosegrass, etc.
Take the use of 15% cyhalofop-ethyl EC as an example. At the 1.5-2.5 leaf stage of barnyardgrass in rice seedling fields and the 2-3 leaf stage of stephanotis in direct-seeded rice fields, the stems and leaves are sprayed and sprayed evenly with fine mist. Drain water before applying the pesticide so that more than 2/3 of the weed stems and leaves are exposed to the water. Irrigate within 24 hours to 72 hours after the pesticide application, and maintain a 3-5 cm water layer for 5-7 days. Use no more than once per rice growing season. However, it should be noted that this drug is highly toxic to aquatic arthropods, so avoid flowing into aquaculture sites. When mixed with some broadleaf herbicides, it may exhibit antagonistic effects, resulting in a reduction in the efficacy of cyhalofop.
Its main dosage forms are: cyhalofop-methyl emulsifiable concentrate (10%, 15%, 20%, 30%, 100g/L), cyhalofop-methyl wettable powder (20%), cyhalofop-methyl aqueous emulsion (10%, 15%, 20%, 25%, 30%, 40%), cyhalofop microemulsion (10%, 15%, 250g/L), cyhalofop oil suspension (10%, 20%, 30% , 40%), cyhalofop-ethyl dispersible oil suspension (5%, 10%, 15%, 20%, 30%, 40%); compounding agents include oxafop-propyl and penoxsufen Compound of amine, pyrazosulfuron-methyl, bispyrfen, etc.
Post time: Jan-24-2024