Methomyl

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Methomyl [1]
(E)-Methomyl formula structural.svg
(E)-Methomyl
(E)-Methomyl molecule spacefill.png
(Z)-Methomyl formula structural.svg
(Z)-Methomyl
(Z)-Methomyl molecule spacefill.png
Names
IUPAC name
(E,Z)-methyl N-{[(methylamino)carbonyl]oxy}ethanimidothioate
Other names
Lannate, Mesomile, Methomex, Nudrin
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.037.089 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
  • InChI=1S/C5H10N2O2S/c1-4(10-3)7-9-5(8)6-2/h1-3H3,(H,6,8) X mark.svgN
    Key: UHXUZOCRWCRNSJ-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C5H10N2O2S/c1-4(10-3)7-9-5(8)6-2/h1-3H3,(H,6,8)
    Key: UHXUZOCRWCRNSJ-UHFFFAOYAU
  • CNC(=O)ON=C(C)SC
Properties
C5H10N2O2S
Molar mass 162.20
AppearanceWhite crystalline solid [2]
Odor Slight, sulfur-like [2]
Density 1.2946 g/cm3
Melting point 78 to 79 °C (172 to 174 °F; 351 to 352 K)
58 g/L
Vapor pressure 0.00005 mmHg (25°C) [2]
Hazards
Flash point Noncombustible [2]
NIOSH (US health exposure limits):
PEL (Permissible)
none [2]
REL (Recommended)
TWA 2.5 mg/m3 [2]
IDLH (Immediate danger)
N.D. [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Methomyl is a carbamate insecticide introduced in 1966. It is highly toxic to humans, livestock, pets, and wildlife. [3] The EU imposed a pesticide residue limit of 0,01 mg/kg for all fruit and vegetables. [4]

Contents

Methomyl is a common active ingredient in commercial fly bait, for which the label instructions in the United States warn that "It is a violation of Federal Law to use this product in a manner inconsistent with its labeling." "Off-label" uses and other uses not specifically targeted at problem insects are illegal, dangerous, and ill-advised. [5] [6]

Use

Methomyl is a broad-spectrum insecticide that is used to kill insect pests. [7] Methomyl is registered for commercial/professional use under certain conditions on sites including field, vegetable, and orchard crops; turf (sod farms only); livestock quarters; commercial premises; and refuse containers. Products containing 1% Methomyl are available to the general public for retail sale, but more potent formulations are classified as restricted-use pesticides: not registered for homeowner or non-professional application. [7] However, Heliothis virescens developed a resistance to methomyl within 5 years. [8] Other species like Helicoverpa assulta also developed resistance after exposure. [9]

Toxicity

In acute toxicity testing, methomyl is placed in EPA Toxicity Category I (the highest toxicity category out of four) via the oral route and in eye irritation studies. [7] It is in lower Toxicity Categories for inhalation (Category II), acute dermal effects (Category III), and acute skin irritation (Category IV). Methomyl is not likely to be a carcinogen (EPA carcinogen Category E). [7]

Ecotoxicity

Methomyl has low persistence in the soil environment, with a reported half-life of approximately 14 days. [10] Because of its high solubility in water, and low affinity for soil binding methomyl may have potential for groundwater contamination. [7] [11] The estimated aqueous half-life for the insecticide is 6 days in surface water and over 25 weeks in groundwater. [11]

Synthesis

First prepare thioester:

Methomyl Synthesis 1 of 3 V1.svg

Second prepare oxime from thioester:

Methomyl Synthesis 2 of 3 V1.svg

Third prepare product from methyl isocyanate and the finished oxime:

Methomyl Synthesis 3 of 3 V1.svg

Trade names

Common names for methomyl include metomil and mesomile. Trade names include Acinate, Agrinate, DuPont 1179, Flytek, Kipsin, Lannate, Lanox, Memilene, Methavin, Methomex, Nudrin, NuBait, Pillarmate and SD 14999 [11]

Related Research Articles

Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula CH3Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozone-depleting chemical. It was used extensively as a pesticide until being phased out by most countries in the early 2000s.

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

Piperonyl butoxide (PBO) is a pale yellow to light brown liquid organic compound used as an adjuvant component of pesticide formulations for synergy. That is, despite having no pesticidal activity of its own, it enhances the potency of certain pesticides such as carbamates, pyrethrins, pyrethroids, and rotenone. It is a semisynthetic derivative of safrole and is produced from the condensation of the sodium salt of 2-(2-butoxyethoxy) ethanol and the chloromethyl derivative of hydrogenated safrole (dihydrosafrole). Although this route of synthesis has faced a lot of criticism in recent times. The new route of synthesis is through 1,2-Methylenedioxybenzene, developed by The Anthea Group and patented in 2019.

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

Bifenthrin is a pyrethroid insecticide. It is widely used against ant infestations.

<span class="mw-page-title-main">Carbofuran</span> Toxic carbamate pesticide

Carbofuran is a carbamate pesticide, widely used around the world to control insects on a wide variety of field crops, including potatoes, corn and soybeans. It is a systemic insecticide, which means that the plant absorbs it through the roots, and from there the plant distributes it throughout its organs where insecticidal concentrations are attained. Carbofuran also has contact activity against pests. It is one of the most toxic pesticides still in use.

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

Fenvalerate is a synthetic pyrethroid insecticide. It is a mixture of four optical isomers which have different insecticidal activities. The 2-S alpha configuration, known as esfenvalerate, is the most insecticidally active isomer. Fenvalerate consists of about 23% of this isomer.

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

Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin trademark has since been acquired by GardenTech, which has eliminated carbaryl from most Sevin formulations. Union Carbide discovered carbaryl and introduced it commercially in 1958. Bayer purchased Aventis CropScience in 2002, a company that included Union Carbide pesticide operations. Carbaryl was the third-most-used insecticide in the United States for home gardens, commercial agriculture, and forestry and rangeland protection. As a veterinary drug, it is known as carbaril (INN).

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

Diazinon, a colorless to dark brown liquid, is a thiophosphoric acid ester developed in 1952 by Ciba-Geigy, a Swiss chemical company. It is a nonsystemic organophosphate insecticide formerly used to control cockroaches, silverfish, ants, and fleas in residential, non-food buildings. Diazinon was heavily used during the 1970s and early 1980s for general-purpose gardening use and indoor pest control. A bait form was used to control scavenger wasps in the western U.S. Diazinon is used in flea collars for domestic pets in Australia and New Zealand. Diazinon is a major component in the "Golden Fleece" brand sheep dip. Residential uses of diazinon were outlawed in the U.S. in 2004 because of human health risks but it is still approved for agricultural uses. An emergency antidote is atropine.

Chloropicrin, also known as PS 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 Cl3C−NO2.

<span class="mw-page-title-main">Aldicarb</span> Chemical compound (insecticide)

Aldicarb is a carbamate insecticide which is the active substance in the pesticide Temik. It is effective against thrips, aphids, spider mites, lygus, fleahoppers, and leafminers, but is primarily used as a nematicide. Aldicarb is a cholinesterase inhibitor which prevents the breakdown of acetylcholine in the synapse. Aldicarb is considered "extremely hazardous" by the EPA and World Health Organization and has been banned in more than 100 countries. In case of severe poisoning, the victim dies of respiratory failure.

Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one hydrogen atom by an atom of iodine. It is naturally emitted by rice plantations in small amounts. It is also produced in vast quantities estimated to be greater than 214,000 tons annually by algae and kelp in the world's temperate oceans, and in lesser amounts on land by terrestrial fungi and bacteria. It is used in organic synthesis as a source of methyl groups.

<span class="mw-page-title-main">Chlorothalonil</span> Fungicide

Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) is an organic compound mainly used as a broad spectrum, nonsystemic fungicide, with other uses as a wood protectant, pesticide, acaricide, and to control mold, mildew, bacteria, algae. Chlorothalonil-containing products are sold under the names Bravo, Echo, and Daconil. It was first registered for use in the US in 1966. In 1997, the most recent year for which data are available, it was the third most used fungicide in the US, behind only sulfur and copper, with 12 million pounds used in agriculture that year. Including nonagricultural uses, the United States Environmental Protection Agency (EPA) estimates, on average, almost 15 million lb (6.8 million kg) were used annually from 1990 to 1996.

<span class="mw-page-title-main">Toxicity class</span> Pesticide classification system

Toxicity class refers to a classification system for pesticides that has been created by a national or international government-related or -sponsored organization. It addresses the acute toxicity of agents such as soil fumigants, fungicides, herbicides, insecticides, miticides, molluscicides, nematicides, or rodenticides.

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

Azinphos-methyl (Guthion) is a broad spectrum organophosphate insecticide manufactured by Bayer CropScience, Gowan Co., and Makhteshim Agan. Like other pesticides in this class, it owes its insecticidal properties to the fact that it is an acetylcholinesterase inhibitor. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act, and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.

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

Dimethoate is a widely used organophosphate insecticide and acaricide. It was patented and introduced in the 1950s by American Cyanamid. Like other organophosphates, dimethoate is an acetylcholinesterase inhibitor which disables cholinesterase, an enzyme essential for central nervous system function. It acts both by contact and through ingestion. It is readily absorbed and distributed throughout plant tissues, and is degraded relatively rapidly. One of the breakdown products of dimethoate is omethoate, a potent cholinesterase inhibitor, is ten times more toxic than its parent compound.

<span class="mw-page-title-main">Organophosphate poisoning</span> Toxic effect of pesticides

Organophosphate poisoning is poisoning due to organophosphates (OPs). Organophosphates are used as insecticides, medications, and nerve agents. Symptoms include increased saliva and tear production, diarrhea, vomiting, small pupils, sweating, muscle tremors, and confusion. While onset of symptoms is often within minutes to hours, some symptoms can take weeks to appear. Symptoms can last for days to weeks.

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

Acephate is an organophosphate foliar and soil insecticide of moderate persistence with residual systemic activity of about 10–15 days at the recommended use rate. It is used primarily for control of aphids, including resistant species, in vegetables and in horticulture. It also controls leaf miners, caterpillars, sawflies, thrips, and spider mites in the previously stated crops as well as turf, and forestry. By direct application to mounds, it is effective in destroying imported fire ants.

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

Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has been used as a pesticide since the late 1700s. Clothianidin and other neonicotinoids act on the central nervous system of insects as an agonist of nAChR, the same receptor as acetylcholine, the neurotransmitter that stimulates and activating post-synaptic acetylcholine receptors but not inhibiting AChE. Clothianidin and other neonicotinoids were developed to last longer than nicotine, which is more toxic and which breaks down too quickly in the environment.

This is an index of articles relating to pesticides.

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

Acetamiprid is an organic compound with the chemical formula C10H11ClN4. It is an odorless neonicotinoid insecticide produced under the trade names Assail, and Chipco by Aventis CropSciences. It is systemic and intended to control sucking insects (Thysanoptera, Hemiptera, mainly aphids) on crops such as leafy vegetables, citrus fruits, pome fruits, grapes, cotton, cole crops, and ornamental plants. It is also a key pesticide in commercial cherry farming due to its effectiveness against the larvae of the cherry fruit fly.

References

  1. Merck Index, 11th Edition, 5905
  2. 1 2 3 4 5 6 7 NIOSH Pocket Guide to Chemical Hazards. "#0387". National Institute for Occupational Safety and Health (NIOSH).
  3. Methomyl at Extension Toxicology Network
  4. "EU pesticides database".
  5. Conservation Warden Warns: Fly bait to control wild animals – illegal and a bad idea (Wisconsin Department of Natural Resources)
  6. "Farm stores promoted poisoning raccoons, state chemist says". Archived from the original on 2015-09-24. Retrieved 2012-08-09.
  7. 1 2 3 4 5 EPA R.E.D. FACTS - Methomyl (PDF) (Technical report). U. S. Environmental Protection Agency. December 1998. EPA-738-F-98-019.
  8. Blanco, Carlos (2012). "Heliothis virescens and Bt cotton in the United States". GM Crops & Food: Biotechnology in Agriculture and the Food Chain. 3 (3): 201–212. doi: 10.4161/gmcr.21439 . PMID   22892654.
  9. Wang, Kai-Yun; Zhang, Yong; Wang, Hong-Yan; Xia, Xiao-Ming; Liu, Tong-Xian (2010-01-01). "Influence of three diets on susceptibility of selected insecticides and activities of detoxification esterases of Helicoverpa assulta (Lepidoptera: Noctuidae)". Pesticide Biochemistry and Physiology. 96 (1): 51–55. doi:10.1016/j.pestbp.2009.09.003.
  10. Howard, P. H. (1991). Handbook of Environmental Fate and Exposure Data for Organic Chemicals: Pesticides. Chelsea, MI: Lewis Publishers. pp. 3–15.
  11. 1 2 3 "Extoxnet Pip - Methomyl".