Editing Metaldehyde

{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 459458259
| Name = Metaldehyde
| ImageFile = Metaldehyde.svg
| ImageSize = 120px
| ImageAlt = Skeletal formula
| IUPACName = 2,4,6,8-tetramethyl-<wbr />1,3,5,7-tetroxocane
| OtherNames = metaldehyde<br />metacetaldehyde<br />ethanal tetramer
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 108-62-3
| ChEBI = 81931
| ChEMBL = 2251334
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 54981
| EC_number = 203-600-2
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C18744
| PubChem = 61021
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 4CI033VJYG
| UNNumber = 1332
| SMILES = CC1OC(C)OC(C)OC(C)O1
| SMILES2 = O1C(OC(OC(OC1C)C)C)C
| InChI = 1/C8H16O4/c1-5-9-6(2)11-8(4)12-7(3)10-5/h5-8H,1-4H3
| InChIKey = GKKDCARASOJPNG-UHFFFAOYAG
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C8H16O4/c1-5-9-6(2)11-8(4)12-7(3)10-5/h5-8H,1-4H3
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = GKKDCARASOJPNG-UHFFFAOYSA-N
 }}
|Section2={{Chembox Properties
| Formula = C<sub>8</sub>H<sub>16</sub>O<sub>4</sub>
| MolarMass = 176.212 g/mol
| Density = 1.27 g/cm<sup>3</sup>
| MeltingPtC = 246
| MeltingPt_notes = 
| BoilingPt= sublimes at
| BoilingPtC = 110 to 120
 }}
|Section7={{Chembox  Hazards
| GHS_ref=<ref>{{cite web |title=Metaldehyde |url=https://pubchem.ncbi.nlm.nih.gov/compound/61021#section=GHS-Classification |website=pubchem.ncbi.nlm.nih.gov |access-date=5 October 2022 |language=en}}</ref>
| GHSPictograms = {{GHS02}}{{GHS06}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|228|301|361f|412}}
| PPhrases = {{P-phrases|203|210|240|241|264|270|273|280|301+316|318|321|330|370+378|405|501}}
 }}
}}
'''Metaldehyde''' is an [[organic compound]] with the [[chemical formula|formula]] ({{chem2|C8H16O4}}). It is used as a [[pesticide]] against [[slug]]s and [[snail]]s.<ref name="Joyner">{{Cite web |last=Joyner |first=Lisa |date=2022-04-01 |title=Slug pellets officially banned in the UK |url=https://www.countryliving.com/uk/homes-interiors/gardens/a39606324/slug-pellets-banned-uk/ |access-date=2022-04-03 |website=Country Living |language=en-GB}}</ref> It is the cyclic [[tetramer]] of [[acetaldehyde]].<ref>Marc Eckert, Gerald Fleischmann, Reinhard Jira, Hermann M. Bolt, Klaus Golka "Acetaldehyde" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH, Weinheim.  {{doi|10.1002/14356007.a01_031.pub2}}.</ref>

==Production and properties==
Metaldehyde is flammable, toxic if ingested in large quantities, and irritating to the skin and eyes. It has a white crystalline appearance with a menthol odor.<ref>{{Cite web |last=PubChem |title=Metaldehyde |url=https://pubchem.ncbi.nlm.nih.gov/compound/61021 |access-date=2022-04-01 |website=pubchem.ncbi.nlm.nih.gov |language=en}}</ref>

Metaldehyde is obtained in moderate yields by treatment of [[acetaldehyde]] with chilled [[mineral acids]]. The liquid trimer, [[paraldehyde]] is also obtained. The reaction is reversible; upon heating to about 80&nbsp;°C, metaldehyde and paraldehyde revert to acetaldehyde.

[[File:Metaldehyde-3D-balls.png|thumb|left|The D{{sub|2d}} stereomer]]
Metaldehyde exists as a mixture of four [[stereoisomers]], molecules that differ with respect to the relative orientation of the [[methyl group]]s on the 8-membered ring. The stereoisomers have respectively the [[molecular symmetries]]  C{{sub|s}} (with symmetry of order 2),  C{{sub|2v}} (order 4), D{{sub|2d}} (order 8), and C{{sub|4v}} (order 8). All have at least one plane of reflexion, so none of them is [[chiral]]. 
{{clear left}}

==Uses==

===As a pesticide===
[[File:Limacide.JPG|thumb|Granules of metaldehyde (trade name Limacide)]]
It is sold under various [[trade name]]s as a [[molluscicide]], including Antimilice, Ariotox, Blitzem (in Australia), Cekumeta, Deadline, Defender (in Australia), Halizan, Limacide, Limatox, Limeol, Meta, Metason, Mifaslug, Namekil, Slug Fest, and Slugit. Typically it is applied in pellet form, but it is also found as a liquid spray, granules, paste, or dust. Often the pesticide includes bran or molasses to attract pests, making it attractive to household pets as well.<ref>{{Cite web |title=Metaldehyde Toxicity Slug Bait Poisoning {{!}} VCA Animal Hospitals |url=https://vcahospitals.com/know-your-pet/metaldehyde-toxicity-slug-bait-poisoning |access-date=2022-04-01 |website=vcahospitals.com}}</ref>

Metaldehyde is effective on pests by contact or ingestion and works by limiting the production of mucus in mollusks making them susceptible to dehydration.<ref name=":0">{{Cite web |last=Armstrong |first=John H. |date=January 18, 2013 |title=Frequently Asked Questions about Metaldehyde For Controlling Snails and Slugs |url=https://www.fdacs.gov/content/download/32845/file/Metaldehyde-QA.pdf |access-date=April 1, 2022 |website=Florida Department of Agriculture and Consumer Services}}</ref>

Metaldehyde products were used to control the invasive African land snail population in Miami-Dade County in Florida. Experimental use permits from the U.S. Environmental Protect Agency authorized the application amount and usage in residential areas.<ref name=":0" />

Due to the contamination of drinking water by metaldehyde's use in agriculture, a specialist organisation was established in 2008 called "The Metaldehyde Stewardship Group (MSG)".

On 19 December 2018, the British government banned the use of metaldehyde slug pellets outdoors from spring 2020; after this date it would only be legal to use it in permanent greenhouses.<ref name=UK-ban>{{citation|url=https://www.gov.uk/government/news/restrictions-on-the-use-of-metaldehyde-to-protect-wildlife|publisher=UK Government |title=Restrictions on the use of metaldehyde to protect wildlife |date=19 December 2018}}</ref> In July 2019, the ban was overturned after the High Court in London agreed with a challenge to its legality. Metaldehyde pellets returned to the UK market until 18 September 2020, when the British government banned the use of metaldehyde slug pellets outdoors after 31 March 2022.<ref name="UK-ban2">{{citation|url=https://www.gov.uk/government/news/outdoor-use-of-metaldehyde-to-be-banned-to-protect-wildlife|publisher=UK Government |title=Outdoor use of metaldehyde to be banned to protect wildlife |date=18 September 2020}}</ref>

===Other uses===
Metaldehyde was originally developed as a solid fuel.<ref>{{cite journal |last1=Eschenmooser |first1=Walter |title=100 Years of Progress with LONZA |journal=CHIMIA |date=June 1997 |volume=51 |issue=6 |pages=259–269 |doi=10.2533/chimia.1997.259 |s2cid=100485418 |doi-access=free }}</ref> It is still used as a camping fuel, also for military purposes, or solid fuel in lamps. It may be purchased in a tablet form to be used in small stoves, and for preheating of Primus type stoves. It is sold under the trade name of "META" by [[Lonza Group]] of Switzerland; it can be included in the [[field ration]] of some nations.

==Safety and toxicity to pets and humans==
Metaldehyde has a toxicity profile identical to that for acetaldehyde, being mildly toxic<ref>[http://www.the-piedpiper.co.uk/th11a%287%29.htm Toxicology of metaldehyde]</ref> and a respiratory irritant at the 50&nbsp;ppm level. In terms of water safety, during periods of rainfall metaldehyde pellets become agitated and can seep into natural water courses. The European Commission restricts metaldehyde levels to 0.1&nbsp;μg/L in drinking water.<ref>{{Cite journal | journal=Scientific Reports | title=Direct Analysis and Quantification of Metaldehyde in Water using Reactive Paper Spray Mass Spectrometry | author=Maher S |display-authors=etal| pages=35643 | volume=6 | date=2016 | doi=10.1038/srep35643| pmc=5073298 | pmid=27767044| bibcode=2016NatSR...635643M }}</ref>

Metaldehyde-containing slug baits are banned in some countries as they are toxic to dogs and cats and disturb the natural ecosystems.<ref name="Joyner"/><ref>{{Cite web | url=http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7427.html | title=Pests in Gardens and Landscapes|publisher=[[University of California, Davis]] | access-date=2010-08-03}}</ref> There is no antidote or specific treatment plan for metaldehyde poisoning. Symptoms of poisoning in dogs and cats vary and are very similar to poisonings by other substances, however they can include tremors, drooling, hyperthermia, vomiting, and restlessness.&nbsp;If left untreated, symptoms will proceed to seizures and death within days. Severity of symptoms and speed of onset depend on the quantity ingested and the other contents of the stomach which affect absorption.<ref name=":1">{{Cite web |title=Metaldehyde Poisoning in Animals - Toxicology |url=https://www.merckvetmanual.com/toxicology/metaldehyde-poisoning/metaldehyde-poisoning-in-animals |access-date=2022-04-01 |website=Merck Veterinary Manual |language=en-US}}</ref>

A diagnosis can be made by an analysis of stomach contents, which tend to have an apple cider vinegar odor, as well as a history of exposure to the chemical. Treatment includes IV fluids, sedation, lowering body temperature, and purging of stomach contents with charcoal. Prompt and aggressive medical attention after a poisoning may make a full recovery possible within 2–3 days.<ref name=":1" />

Due to this toxicity, pet owners may want to investigate alternatives which are not as toxic to pets, such as [[ferric sodium EDTA]] or [[aluminium sulfate]].<ref>{{Cite web | url=http://www.spotmagazine.net/content/slugging-out-spring-pacific-northwest | title=Slugging Out Spring | publisher=Dr. Heidi Houchen, DVM | url-status=usurped | archiveurl=https://web.archive.org/web/20120718193234/http://www.spotmagazine.net/content/slugging-out-spring-pacific-northwest | archivedate=2012-07-18 }}</ref> The metaldehyde tablets resemble [[Candy|candies]] and do not taste bad, making accidental ingestion possible by children or even by adults unaware of their true nature. Their use was popular during the [[interwar period]] and several cases of poisoning resulted.<ref name="adic">{{Cite journal | journal=Archives of Disease in Childhood | title=Poisoning by "Meta Fuel" Tablets (Metacetaldehyde) | first=Reginald | last=Miller | pages=292–295 | volume=3 | date=December 1928 | pmc=1975025 | pmid=21031743 | issue=18 | doi=10.1136/adc.3.18.292}}</ref> Baits may contain a [[bitterant]] to prevent accidental consumption by pets or children.

Oral ingestions of metaldehyde have been described in adults attempting suicide; amongst them, the majority experienced gastrointestinal or neurological symptoms. When compared to humans with accidental ingestion of metaldehyde, those attempting suicide tend to be symptomatic (for example reduced concentrations of GABA causing seizures) and often require care in an intensive care unit and/or long-term hospitalization.<ref>{{Cite journal | journal=Acute Medicine & Surgery | title=Acute metaldehyde poisoning from ingestion: clinical features and implications for early treatment | author=Tan YJ. |display-authors=etal | volume=9 | date=2022 | doi=10.1002/ams2.766| pmc=9209800| pmid=35769386 }}</ref>

==See also==
*[[Methiocarb]]
*[[Paraldehyde]]

==References==
{{Reflist|30em}}

==External links==
* [http://npic.orst.edu National Pesticide Information Center (NPIC)] Information about pesticide-related topics.
** [http://npic.orst.edu/capro/SlugSnailPD.pdf Get Rid of Slugs and Snails, Not Puppy Tails! Case Profile] - National Pesticide Information Center
** [http://npic.orst.edu/pest/slugsnail.html Slugs and Snails] - National Pesticide Information Center
* [http://www.inchem.org/documents/pds/pds/pest93_e.htm WHO/FAO Data sheet at inchem.org]
* [[b:A Wikimanual of Gardening/Slugs|Slug controls]] (on Wikibooks)
* {{PPDB|446}}

[[Category:Molluscicides]]
[[Category:Acetals]]
[[Category:Oxygen heterocycles]]
[[Category:Eight-membered rings]]
[[Category:Heterocyclic compounds with 1 ring]]