Acibenzolar-S-methyl

Last updated
Acibenzolar-S-methyl
Skeletal formula of acibenzolar-S-methyl S-methyl benzo(d)(1,2,3)thiadiazole-7-carbothioate 200.svg
Skeletal formula of acibenzolar-S-methyl
Acibenzolar-S-methyl-3D-spacefill.png
Names
Preferred IUPAC name
S-Methyl 1,2,3-benzothiadiazole-7-carbothioate
Other names
BTH, CGA245704
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.101.876 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 420-050-0
MeSH S-methyl+benzo(1,2,3)thiadiazole-7-carbothioate
PubChem CID
UNII
  • InChI=1S/C8H6N2OS2/c1-12-8(11)5-3-2-4-6-7(5)13-10-9-6/h2-4H,1H3 Yes check.svgY
    Key: UELITFHSCLAHKR-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C8H6N2OS2/c1-12-8(11)5-3-2-4-6-7(5)13-10-9-6/h2-4H,1H3
    Key: UELITFHSCLAHKR-UHFFFAOYAA
  • CSC(=O)c1cccc2nnsc12
  • CSC(=O)C1=C2SN=NC2=CC=C1
Properties [1]
C8H6N2OS2
Molar mass 210.27 g·mol−1
AppearanceWhite to beige crystalline powder
Melting point 133 °C (271 °F; 406 K)
Boiling point 267 °C (513 °F; 540 K)
7.7 mg/L (20 °C)
log P 3.1
Hazards [2]
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-pollu.svg
Warning
H315, H317, H319, H335, H410
P261, P271, P272, P273, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P333+P313, P337+P313, P362, P363, P391, P403+P233, P405, P501
Related compounds
Related compounds
1,2,3-benzothiadiazole-7-carboxylic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Acibenzolar-S-methyl is the ISO common name [3] for an organic compound that is used as a fungicide. Unusually, it is not directly toxic to fungi but works by inducing systemic acquired resistance, the natural defence system of plants. [4] [5] [6]

Contents

History

In the 1980s, researchers at Ciba-Geigy in Switzerland were seeking novel fungicides. They discovered that the methyl ester of 1,2,3-benzothiadiazole-7-carboxylic acid, and many other derivatives, had useful activity on fungal diseases, for example Pyricularia oryzae on rice. [7] In subsequent studies it was shown that the compound responsible for the biological activity was the carboxylic acid itself but that for optimum activity when used commercially it was important to choose a derivative which met requirements of product safety, ease of application and appropriate physical properties for translocation in the crop. After many derivatives of the acid had been tested, the S-methyl thioester was chosen for development under the code name CGA245704. [8] The product was launched in 1996 and is now sold by Syngenta with brand names including Bion [9] and Actigard. [10]

Synthesis

The first synthesis of the parent 1,2,3-benzothiadiazole-7-carboxylic acid was disclosed in patents filed by Ciba-Geigy. [7] The heterocyclic ring of the 1,2,3-benzothiadiazole core is formed by the classic ring-closure of a thiol onto a diazonium group adjacent in its benzene ring. [11] One example from the patent starts with methyl 2-chloro-3-nitrobenzoate, which reacts with benzyl mercaptan to give a thioether, which is converted by catalytic hydrogenation using Raney nickel to 3-amino-2-benzylthiobenzoic acid methyl ester. This intermediate, as its hydrochloride salt, is treated with sodium nitrite in water to give 7-methoxycarbonyl-1,2,3-benzothiadiazole in 86% yield after recrystallization.

Acibenzolar synthesis full.svg

Conversion of the ester into the thioester is by hydrolysis to form the free carboxylic acid followed by its conversion to the S-methyl thioester in a standard chemical transformation via the acid chloride. [7]

Mechanism of action

Acibenzolar-S-methyl has an unusual mechanism of action for a fungicide. It is not directly toxic to the fungus but instead activates the natural defences of the crop in a manner similar to the known role of salicylic acid and methyl jasmonate. [5] [6] [12] The genes for systemic acquired resistance are induced and pathogenesis-related proteins are produced. [13] The thioester is a propesticide for its active carboxylic acid metabolite. This hydrolysis reaction occurs in the plant, catalyzed by methyl salicylate esterase. [14]

Usage

In the USA

Pesticides are required to seek registration from appropriate authorities in the country in which they will be used. [15] In the United States, the Environmental Protection Agency (EPA) is responsible for regulating pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Food Quality Protection Act (FQPA). [16] A pesticide can only be used legally according to the directions on the label that is included at the time of the sale of the pesticide. The purpose of the label is "to provide clear directions for effective product performance while minimizing risks to human health and the environment". A label is a legally binding document that mandates how the pesticide can and must be used and failure to follow the label as written when using the pesticide is a federal offence. [17]

Acibenzolar-S-methyl is registered in the US for use either as a seed treatment or for direct spraying on crops. Since it activates the crop's own defence mechanisms, it is not usually effective in curing established disease, only in protecting against future disease development. As a seed treatment it is registered for use on cotton, sunflower and sorghum while for spraying it is licensed on a wide range of vegetable crops. [18] [19] The estimated annual use of acibenzolar-S-methyl in US agriculture is mapped by the US Geological Survey and shows a growing trend from its introduction in 2000 to 2017, the latest date for which figures are available. However, the total annual use has never exceeded 8000 lb (3600 kg), which is very low for an agrochemical. As expected given the main use on fruit and vegetables, the main areas of use are in California and Florida. [20]

In Europe

The product is also registered in Europe, where there is a monitoring programme to make sure that residues in food are below the limits set by the European Food Safety Authority. It is sometimes mixed with other pesticides to provide an extra degree of control by activating the crop's defence mechanisms in addition to the lethal effect of the main ingredient.

Human safety

Acibenzolar-S-methyl has little toxicity to mammals with an LD50 of over 2000 mg/kg (rats, oral). [1] However, it can cause moderate eye irritation. First aid information is included with the label. [19] The Codex Alimentarius database maintained by the FAO lists the maximum residue limits for acibenzolar-S-methyl and its parent acid in various food products. [21]

Resistance management

Although fungal populations have the ability to develop resistance to fungicides, the mechanism of action of acibenzolar-S-methyl gives it an advantage over conventional pesticides owing to its lack of direct toxicity to fungi. Nevertheless, regulatory bodies such as the EPA and the Fungicides Resistance Action Committee (FRAC) [22] monitor the risks of resistance developing: FRAC has assigned acibenzolar-S-methyl into its own class (group P01 fungicide). [23]

Related Research Articles

A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships.

<span class="mw-page-title-main">Syngenta</span> Global provider of agricultural science and technology

Syngenta is a global agricultural technology company headquartered in Basel, Switzerland. It primarily covers crop protection and seeds for farmers. Syngenta is part of the Syngenta Group, entirely owned by Sinochem, a Chinese state-owned enterprise.

<span class="mw-page-title-main">Metalaxyl</span> Chemical compound

Metalaxyl is an acylalanine fungicide with systemic function. Its chemical name is methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate. It can be used to control Pythium in a number of vegetable crops, and Phytophthora in peas. Metalaxyl-M is the ISO common name and Ridomil Gold is the trade name for the optically pure (-) / D / R active stereoisomer, which is also known as mefenoxam.

Systemic acquired resistance (SAR) is a "whole-plant" resistance response that occurs following an earlier localized exposure to a pathogen. SAR is analogous to the innate immune system found in animals, and although there are many shared aspects between the two systems, it is thought to be a result of convergent evolution. The systemic acquired resistance response is dependent on the plant hormone, salicylic acid.

<span class="mw-page-title-main">Azoxystrobin</span> Chemical compound

Azoxystrobin is a broad spectrum systemic fungicide widely used in agriculture to protect crops from fungal diseases. It was first marketed in 1996 using the brand name Amistar and by 1999 it had been registered in 48 countries on more than 50 crops. In the year 2000 it was announced that it had been granted UK Millennium product status.

<span class="mw-page-title-main">Cyhalothrin</span> Synthetic pyrethroid used as insecticide

Cyhalothrin is an organic compound that, in specific isomeric forms, is used as a pesticide. It is a pyrethroid, a class of synthetic insecticides that mimic the structure and properties of the naturally occurring insecticide pyrethrin which is present in the flowers of Chrysanthemum cinerariifolium. Pyrethroids such as cyhalothrin are often preferred as an active ingredient in agricultural insecticides because they are more cost-effective and longer acting than natural pyrethrins. λ-and γ-cyhalothrin are now used to control insects and spider mites in crops including cotton, cereals, potatoes and vegetables.

<span class="mw-page-title-main">Methomyl</span> Chemical compound

Methomyl is a carbamate insecticide introduced in 1966. It is highly toxic to humans, livestock, pets, and wildlife. The EU imposed a pesticide residue limit of 0,01 mg/kg for all fruit and vegetables.

<span class="mw-page-title-main">Saflufenacil</span> Chemical compound

Saflufenacil is the ISO common name for an organic compound of the pyrimidinedione chemical class used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase to control broadleaf weeds in crops including soybeans and corn.

<span class="mw-page-title-main">Thiamethoxam</span> Chemical compound

Thiamethoxam is the ISO common name for a mixture of cis-trans isomers used as a systemic insecticide of the neonicotinoid class. It has a broad spectrum of activity against many types of insects and can be used as a seed dressing.

<span class="mw-page-title-main">Tefluthrin</span> Synthetic pyrethroid used as insecticide

Tefluthrin is the ISO common name for an organic compound that is used as a pesticide. It is a pyrethroid, a class of synthetic insecticides that mimic the structure and properties of the naturally occurring insecticide pyrethrin which is present in the flowers of Chrysanthemum cinerariifolium. Pyrethroids such as tefluthrin are often preferred as active ingredients in agricultural insecticides because they are more cost-effective and longer acting than natural pyrethrins. It is effective against soil pests because it can move as a vapour without irreversibly binding to soil particles: in this respect it differs from most other pyrethroids.

<span class="mw-page-title-main">Mesotrione</span> Chemical compound used as an herbicide

Mesotrione is a selective herbicide used mainly in maize crops. It is a synthetic compound inspired by the natural substance leptospermone found in the bottlebrush tree Callistemon citrinus. It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) and is sold under brand names including Callisto and Tenacity. It was first marketed by Syngenta in 2001.

<span class="mw-page-title-main">Fluxapyroxad</span> Chemical compound

Fluxapyroxad is a broad-spectrum pyrazole-carboxamide fungicide used on a large variety of commercial crops. It stunts fungus growth by inhibiting the succinate dehydrogenase (SQR) enzyme. Application of fluxapyroxad helps prevent many wilts and other fungal infections from taking hold. As with other systemic pesticides that have a long chemical half-life, there are concerns about keeping fluxapyroxad out of the groundwater, especially when combined with pyraclostrobin. There is also concern that some fungi may develop resistance to fluxapyroxad.

<span class="mw-page-title-main">Fludioxonil</span> Chemical compound

Fludioxonil is a synthetic phenylpyrrole chemical introduced by Ciba-Geigy in 1993 for use as a non-systemic fungicide. It is a structural analog of the natural fungicide pyrrolnitrin.

<span class="mw-page-title-main">Sedaxane</span> Chemical compound

Sedaxane is a broad spectrum fungicide used as a seed treatment in agriculture to protect crops from fungal diseases. It was first marketed by Syngenta in 2011 using their brand name Vibrance. The compound is an amide which combines a pyrazole acid with an aryl amine to give an inhibitor of succinate dehydrogenase.

<span class="mw-page-title-main">Carboxin</span> Chemical compound used to kill fungi

Carboxin is a narrow-spectrum fungicide used as a seed treatment in agriculture to protect crops from fungal diseases. It was first marketed by Uniroyal in 1969 using their brand name Vitavax. The compound is an anilide which combines a heterocyclic acid with aniline to give an inhibitor of succinate dehydrogenase (SDHI).

<span class="mw-page-title-main">Fomesafen</span> PPOi herbicide

Fomesafen is the ISO common name for an organic compound used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase (PPO) which is necessary for chlorophyll synthesis. Soybeans naturally have a high tolerance to fomesafen, via metabolic disposal by glutathione S-transferase. As a result, soy is the most common crop treated with fomesafen, followed by other beans and a few other crop types. It is not safe for maize/corn or other Poaceae.

<span class="mw-page-title-main">Butafenacil</span> Chemical compound

Butafenacil is the ISO common name for an organic compound of the pyrimidinedione chemical class used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase to control broadleaf and some grass weeds in crops including cereals and canola.

<span class="mw-page-title-main">Boscalid</span> Chemical compound used to kill fungi

Boscalid is a broad spectrum fungicide used in agriculture to protect crops from fungal diseases. It was first marketed by BASF in 2002 using their brand name Endura. The compound is an biphenyl amide derived inhibitor of succinate dehydrogenase.

<span class="mw-page-title-main">Pydiflumetofen</span> Chemical compound used to kill fungi

Pydiflumetofen is a broad spectrum fungicide used in agriculture to protect crops from fungal diseases. It was first marketed by Syngenta in 2016 using their brand name Miravis. The compound is an amide which combines a pyrazole acid with a substituted phenethylamine to give an inhibitor of succinate dehydrogenase, an enzyme that inhibits cellular respiration in almost all living organisms.

3-(Difluoromethyl)-1-methyl-1<i>H</i>-pyrazole-4-carboxylic acid Chemical compound

3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid is a chemical compound which is used commercially as an intermediate to seven fungicides which act by inhibition of succinate dehydrogenase (SDHI). It consists of a pyrazole ring with difluoromethyl, methyl and carboxylic acid groups attached in specific positions.

References

  1. 1 2 Pesticide Properties Database. "Acibenzolar-S-methyl". University of Hertfordshire.
  2. ↑ "Acibenzolar-S-Methyl". US National Library of Medicine. Retrieved 2020-09-07.
  3. ↑ "Compendium of Pesticide Common Names: acibenzolar". BCPC.
  4. ↑ "Fact Sheet: Acibenzolar-S-Methyl" (PDF). EPA. 2000-08-11. Retrieved 2020-09-03.
  5. 1 2 Vlot, A.C.; Klessig, D.F.; Park, S.W. (August 2008). "Systemic acquired resistance, the elusive signal(s)". Current Opinion in Plant Biology. 11 (4): 436–442. Bibcode:2008COPB...11..436V. doi:10.1016/j.pbi.2008.05.003. hdl: 11858/00-001M-0000-0012-36EC-0 . PMID   18614393.
  6. 1 2 Gozzo, Franco; Faoro, Franco (2013). "Systemic Acquired Resistance (50 Years after Discovery): Moving from the Lab to the Field". Journal of Agricultural and Food Chemistry. 61 (51): 12473–12491. doi:10.1021/jf404156x. PMID   24328169.
  7. 1 2 3 USpatent 4931581,Schurter, R.; Kunz, W.& Nyfeler, R.,"Process and a composition for immunizing plants against diseases",issued 1990-06-05, assigned to Ciba-Geigy Corporation
  8. ↑ Kunz, W.; Schurter, R.; Maetzke, T. (September 1996). "The Chemistry of Benzothiadiazole Plant Activators". Pesticide Science. 50 (4): 275–282. doi:10.1002/(SICI)1096-9063(199708)50:4<275::AID-PS593>3.0.CO;2-7.
  9. ↑ Syngenta US. "Bion 500 FS Seed Treatment" . Retrieved 2020-09-04.
  10. ↑ Syngenta US. "Actigard 40WG fungicide" . Retrieved 2020-09-04.
  11. ↑ Storr; Gilchrist, eds. (2004). "Product Class 9: 1,2,3-Thiadiazoles". Category 2, Hetarenes and Related Ring Systems. doi:10.1055/sos-SD-013-00386. ISBN   9783131122810.
  12. ↑ Ryals JA, Neuenschwander UH, Willits MG, Molina A, Steiner HY, Hunt MD (October 1996). "Systemic Acquired Resistance". The Plant Cell. 8 (10): 1809–1819. doi:10.1105/tpc.8.10.1809. PMC   161316 . PMID   12239363.
  13. ↑ Cooper, Bret; Beard, Hunter S.; Garrett, Wesley M.; Campbell, Kimberly B. (2020). "Benzothiadiazole Conditions the Bean Proteome for Immunity to Bean Rust". Molecular Plant-Microbe Interactions. 33 (4): 600–611. doi: 10.1094/MPMI-09-19-0250-R . PMID   31999214.
  14. ↑ Jeschke, Peter (2016). "Propesticides and their use as agrochemicals". Pest Management Science. 72 (2): 210–225. doi: 10.1002/ps.4170 . PMID   26449612.
  15. ↑ Willson HR (1996). "Pesticide Regulations". In Radcliffe EB, Hutchison WD, Cancelado RE (eds.). Radcliffe's IPM World Textbook. St. Paul: University of Minnesota. Archived from the original on July 13, 2017.
  16. ↑ "Pesticides and Public Health". Pesticides: Health and Safety. US EPA. 2015-08-20. Archived from the original on January 14, 2014. Retrieved 2020-02-04.
  17. ↑ EPA (2013-02-27). "The Pesticide Label" . Retrieved 2020-02-02.
  18. ↑ Syngenta US. "Bion 500FS (label)" . Retrieved 2020-09-04.
  19. 1 2 Syngenta US. "Actigard plant activator (label)" . Retrieved 2020-09-04.
  20. ↑ US Geological Survey (2020-06-18). "Estimated Agricultural Use for Acibenzolar, 2017" . Retrieved 2020-09-05.
  21. ↑ FAO / WHO (2017). "Acibenzolar-S-methyl" . Retrieved 2020-09-04.
  22. ↑ "Fungicides Resistance Action Committee website".
  23. ↑ "Fungal control agents sorted by cross resistance pattern and mode of action" (PDF). 2020. Archived from the original (PDF) on 2021-08-16. Retrieved 2020-09-04.

Further reading

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