Imazaquin

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Imazaquin
Imazaquin.svg
Names
Systematic IUPAC name
3-Quinolinecarboxylic acid, 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]- [1]
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.120.551 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • O=C(O)c2c(nc1ccccc1c2)/C3=N/C(C(=O)N3)(C(C)C)C
Properties
C17H17N3O3
Molar mass 311.341 g·mol−1
Appearancecolorless solid

CID 54739 from PubChem </ref>

Density 1.35 g/cm3 [1]
Melting point 219 to 222 °C (426 to 432 °F; 492 to 495 K) [2]
Soluble in water at 25 °C: 60-120 ppm [2]
log P 1.474±0.662 [1]
Vapor pressure 0.013 mPa @ 60 °C [2]
Acidity (pKa)3.10±0.30 [1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
May be harmful if swallowed. Harmful in contact with skin. [3]
GHS labelling:
GHS-pictogram-exclam.svg
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Imazaquin is an imidazolinone herbicide, so named because it contains an imidazolinone core. This organic compound is used to control a broad spectrum of weed species. It is a colorless or white solid, although commercial samples can appear brown or tan.

Contents

Imidazolinone herbicides

Imazaquin along with imazamethabenz-methyl, imazapyr, imazapic, imazethapyr, and imazamox comprise the class of synthetic compounds termed the imidazolinone herbicides. These chemicals all feature an imidazolinone ring with a carboxylic acid group attached to the backbone. [4] They vary in the attached ring structure.

Imidazolinone herbicides kill plants by inhibiting acetohydroxy acid synthase (AHAS). AHAS is the first enzyme in the branched-chain amino acid pathway that leads to the synthesis of amino acids leucine, isoleucine, and valine. [5] Crop varieties have been developed through conventional breeding that are resistant to these herbicides and are marketed by BASF under the Clearfield brand. [6] [7]

History

The imidazolinone herbicides were first discovered in the 1970s. The first U.S. patent was awarded in 1980 for imazamethabenz-methyl. Imazaquin, imazapyr, imazapic, and imazethpyr followed suit and received patents in 1989. Imazamox, the last of the six, received its U.S. patent in 1994. [4]

The imidazolinone herbicides were discovered at American Cyanamid's Agricultural Research Division during the 1970s, starting from the initial lead molecule phthalimide. [8] Years later, the molecule was found to exhibit herbicidal activity. The connection to AHAS was not understood at the time. A derivative of phthalimide showed promise when it exhibited some plant growth inhibition. Optimization ensued and the attempt to enable the production of field trial samples led to the formation of a tricyclic compound. The same reaction was performed on the original phthalimide, resulting in a compound that exhibited broad-spectrum herbicidal activity. Further exploration resulted in the formation of the first imidazolinone herbicide. [9]

Properties

Imazaquin has a water solubility of 60 mg/L [10] and its half-life in soil is 60 days. It is therefore categorized as a moderately persistent pesticide. [10]

When imazaquin is applied to crops its main interaction is with soil humic acids. It was found that the rate at which imazaquin aggregates on soil humic acids was most affected by the environmental pH. Imazaquin has shown greater adsorption at lower pHs. Adsorption is greatest at a pH nearest the pKa of the carboxylic group of imazaquin. At higher pHs, the hydrogen bonds and charge-transfer complexes that form during adsorption interactions are much weaker at higher pHs. [11]

The sorption coefficient is a means of specifying a pesticide's tendency to bind to soil particles. The greater the coefficient, the higher the sorption potential. A higher sorption coefficient means more hindrance of movement and possibly an increase in persistence as a result of protection from degradation. Imazaquin has a sorption coefficient of 20. [10]

Uses

Imazaquin is primarily used as a herbicide to control weed growth on lawns and turf fields. Due to the fact that it is highly effective and selective, it is one of the most commonly used herbicides. [12] It is classified as an imidazolinone herbicide that controls weed growth through the inhibition of specific amino acids that prove to be vital for plant growth. Imazaquin inhibits the acetohydroxy acid synthase (AHAS) enzyme accountable for synthesis of the amino acids valine, leucine, and isoleucine. When applied, imazaquin halts weed growth which eventually kills the weed or causes the weed to die due to its incapability to compete with surrounding vegetation.

Imazaquin may be applied pre-plant incorporated, pre-plant surface, pre-emergence, or early post-emergence. [13]

Synthesis

Synthesis of Imazaquin.svg

The reaction starts with the NH2 group of the benzenamine adding to the second carbonyl group on diethyl 2-oxobutanedioate (diethyl oxaloacetate).

Toxicity

Imazaquin is a relatively nontoxic, non-carcinogenic chemical causing none to minimal eye and skin irritation if contacted upon the dermis, ingested orally, or inhaled. It has a toxicity classification of III, which corresponds to only a slight toxicity. It is a relatively low toxicity pesticide that has the potential to find its way into food, drinking water, and residential areas. Although exposure to residential areas affects infants and children, there is no concern over its presence due to its low estimated aggregated risk which meets the FQPA safety standards. Inhalation, dermal, and oral exposure to imazaquin yielded relatively low Margin of Exposure values issued by the EPA deeming imazaquin as a minimal risk concern. [14]

Animals

A study conducted by Cornell University showed that imazaquin ingested by humans and animals was excreted within 48 hours, 94% through urine and 4% through feces. The LD50 for dogs, rats, rabbits, and female mice were each 1000 mg/kg, 5000 mg/kg, 2000 mg/kg, and 2363 mg/kg, respectively. Chronic toxicity studies were also conducted upon rabbits, rats, and beagle dogs. Chronic dermal exposure to imazaquin in rabbits during a 21-day time period yielded no effects upon the rabbits. A 90-day and one-year study of ingestion of imazaquin in rats also yielded no effects as well. However, in the one year, dietary chronic imazaquin exposure to beagle dogs, the dogs exposed to the highest dose of imazaquin per day, 5000 ppm, experienced effects such as decreased body weight gain, skeletal myopathy, slight anemia, bone marrow hyperplasia, increased blood levels of SGOT, DSGPT and CPK, and increased liver weight. Imazaquin is also nontoxic to birds and fish when properly used. Imazaquin tested negative for mutagen effects, organ toxicity, and reproductive effects. [15]

Environment

Imazaquin is a non-volatile chemical leading to limited movement into soil that eventually breaks down within 4–6 months. The chemical breaks down microbially and is slowly reduced to carbon dioxide and metabolites. When present in soil, imazaquin is absorbed through the roots of plants where the chemical is either metabolized quickly with no effects or slowly metabolized or not metabolized at all which eventually will lead to the death of the plant. As for its breakdown in surface water, imazaquin has a hydrolytic half-life of 5.5 months at pH 9. At pH 3 and 5, it is stable to hydrolysis. [15]

Related Research Articles

<span class="mw-page-title-main">Herbicide</span> Type of chemical used to kill unwanted plants

Herbicides, also commonly known as weed killers, are substances used to control undesired plants, also known as weeds. Selective herbicides control specific weed species while leaving the desired crop relatively unharmed, while non-selective herbicides (sometimes called total weed killers kill plants indiscriminately. Due to herbicide resistance – a major concern in agriculture – a number of products combine herbicides with different means of action. Integrated pest management may use herbicides alongside other pest control methods.

<span class="mw-page-title-main">Glyphosate</span> Systemic herbicide and crop desiccant

Glyphosate is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSP). It is used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. Its herbicidal effectiveness was discovered by Monsanto chemist John E. Franz in 1970. Monsanto brought it to market for agricultural use in 1974 under the trade name Roundup. Monsanto's last commercially relevant United States patent expired in 2000.

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

Dicofol is an insecticide, an organochlorine that is chemically related to DDT. Dicofol is a miticide that is very effective against spider mite. Its production and use is banned internationally under the Stockholm Convention.

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

Ethion (C9H22O4P2S4) is an organophosphate insecticide. Ethion is known to affect a neural enzyme called acetylcholinesterase and prevent it from working.

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

MCPA is a widely used phenoxy herbicide introduced in 1945. It selectively controls broad-leaf weeds in pasture and cereal crops. The mode of action of MCPA is as an auxin, which are growth hormones that naturally exist in plants.

<span class="mw-page-title-main">Atrazine</span> Herbicide

Atrazine is a chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary manufacturer is Syngenta and it is one of the most widely used herbicides in the United States, Canadian, and Australian agriculture. Its use was banned in the European Union in 2004, when the EU found groundwater levels exceeding the limits set by regulators, and Syngenta could not show that this could be prevented nor that these levels were safe.

Chloropicrin, also known as PS (from Port Sunlight) and nitrochloroform, is a chemical compound currently used as a broad-spectrum antimicrobial, fungicide, herbicide, insecticide, and nematicide. It was used as a poison gas in World War I. Its chemical structural formula is Cl3CNO2.

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

Amitraz is a non-systemic acaricide and insecticide and has also been described as a scabicide. It was first synthesized by the Boots Co. in England in 1969. Amitraz has been found to have an insect repellent effect, works as an insecticide and also as a pesticide synergist. Its effectiveness is traced back on alpha-adrenergic agonist activity, interaction with octopamine receptors of the central nervous system and inhibition of monoamine oxidases and prostaglandin synthesis. Therefore, it leads to overexcitation and consequently paralysis and death in insects. Because amitraz is less harmful to mammals, amitraz is among many other purposes best known as insecticide against mite- or tick-infestation of dogs. It is also widely used in the beekeeping industry as a control for the Varroa destructor mite, although there are recent reports of resistance.

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

Picloram is a systemic herbicide used for general woody plant control. It also controls a wide range of broad-leaved weeds, but most grasses are resistant. A chlorinated derivative of picolinic acid, picloram is in the pyridine family of herbicides.

<span class="mw-page-title-main">Glufosinate</span> Broad-spectrum herbicide

Glufosinate is a naturally occurring broad-spectrum herbicide produced by several species of Streptomyces soil bacteria. Glufosinate is a non-selective, contact herbicide, with some systemic action. Plants may also metabolize bialaphos and phosalacine, other naturally occurring herbicides, directly into glufosinate. The compound irreversibly inhibits glutamine synthetase, an enzyme necessary for the production of glutamine and for ammonia detoxification, giving it antibacterial, antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis and resulting in plant death.

<span class="mw-page-title-main">Methoxychlor</span> Synthetic organochloride insecticide, now obsolete.

Methoxychlor is a synthetic organochloride insecticide, now obsolete. Tradenames for methoxychlor include Chemform, Maralate, Methoxo, Methoxcide, Metox, and Moxie.

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

Dicamba is a selective systemic herbicide first registered in 1967. Brand names for formulations of this herbicide include Dianat, Banvel, Diablo, Oracle and Vanquish. This chemical compound is a chlorinated derivative of o-anisic acid.

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

Dinoseb is a common industry name for 6-sec-butyl-2,4-dinitrophenol, a herbicide in the dinitrophenol family. It is a crystalline orange solid which does not readily dissolve in water. Dinoseb is banned as an herbicide in the European Union (EU) and the United States because of its toxicity.

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

Methiocarb is a carbamate pesticide which is used as an insecticide, bird repellent, acaricide and molluscicide since the 1960s. Methiocarb has contact and stomach action on mites and neurotoxic effects on molluscs. Seeds treated with methiocarb also affect birds. Other names for methiocarb are mesurol and mercaptodimethur.

This is an index of articles relating to pesticides.

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

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<span class="mw-page-title-main">Fluazifop</span> ACCase herbicide, fop, anti-grass

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References

  1. 1 2 3 4 5 "3-Quinolinecarboxylic acid, 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]". SciFinder. Retrieved 3 July 2013.
  2. 1 2 3 CID 54739 from PubChem
  3. ↑ "Imazaquin MSDS". SigmaAldrich. Retrieved 3 July 2013.
  4. 1 2 Krieger, Robert; Frederick G. Hess; Jane E. Harris; Kimberly Pendino; Kathryn Ponnock (2001). "Handbook of Pesticide Toxicology". Imidazolinones. 1: 1641–1642.
  5. ↑ Lamberth, Clemens (2012). Bioactive Heterocyclic Compound Classes: Agrochemicals. John Wiley & Sons. pp. 47–49. ISBN   9783527664436.
  6. ↑ Tan, Siyuan; Evans, Richard R; Dahmer, Mark L; Singh, Bijay K; Shaner, Dale L (2005). "Imidazolinone-tolerant crops: history, current status and future". Pest Management Science. 61 (3): 246–257. doi:10.1002/ps.993. ISSN   1526-498X. PMID   15627242.
  7. ↑ Domínguez-Mendez, Rafael; Alcántara-de la Cruz, Ricardo; Rojano-Delgado, Antonia M.; Fernández-Moreno, Pablo T.; Aponte, Raphael; De Prado, Rafael (1 November 2017). "Multiple mechanisms are involved in new imazamox-resistant varieties of durum and soft wheat". Scientific Reports. 7 (1): 14839. Bibcode:2017NatSR...714839D. doi:10.1038/s41598-017-13874-3. PMC   5665993 . PMID   29093532.
  8. ↑ Shaner, Dale (1991). The Imidazolinone Herbicides. CRC Press. pp. 8–14.
  9. ↑ Schirmer, Ulrich (2012). Modern Crop Protection Compounds: Herbicides, Volume 1. John Wiley & Sons. pp. 88–91. ISBN   9783527329656.
  10. 1 2 3 Vogue, Peggy A. "OSU Extension Pesticide Properties Database". National Pesticide Information Center. Retrieved 10 April 2013.
  11. ↑ Patrizia, Leone; Mara Gennari; Michele Negre; Valter Boero (2001). "Role of Ferrihydrite in Adsorption of Three Imidazolinone Herbicides". Journal of Agricultural and Food Chemistry. 49 (3): 1315–1320. doi:10.1021/jf000913c. PMID   11312857.
  12. ↑ McCourt, J.A.; Pang, S. S.; King-Scott, J.; Guddat, L. W.; Duggleby, R. G. (2006). "Herbicide-binding sites revealed in the structure of plant acetohydroxyacid synthase". Proceedings of the National Academy of Sciences. 103 (3): 569–73. Bibcode:2006PNAS..103..569M. doi: 10.1073/pnas.0508701103 . PMC   1334660 . PMID   16407096.
  13. ↑ Roberts, Terence (1998). Metabolic Pathways of Agrochemicals: Insecticides and fungicides. Cambridge: Royal Society of Chemistry. p. 368. ISBN   9780854044948.
  14. ↑ Debra Edwards (December 2005). "Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk Management Decision (TRED) for Imazaquin" (PDF). United States Environmental Protection Agency.
  15. 1 2 Cornell University; Michigan State University; Oregon State University; University of California at Davis (June 1996). "Imazaquin".
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