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| Names | |||
|---|---|---|---|
| IUPAC name 1-Methyl-4-(1-methylethyl)-2,3-dioxabicyclo[2.2.2]oct-5-ene | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 121382 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.007.408 | ||
| EC Number |
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| KEGG | |||
| UNII | |||
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| Properties[1] | |||
| C10H16O2 | |||
| Molar mass | 168.23 g/mol | ||
| Appearance | Colorless liquid | ||
| Density | 1.010 g/cm3 | ||
| Melting point | 3.3 °C (37.9 °F; 276.4 K) | ||
| Boiling point | 40 °C (104 °F; 313 K) at 0.2 mmHg | ||
| Hazards | |||
| GHS labelling: | |||
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| Danger | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Ascaridole is a naturalorganic compound classified as a bicyclic monoterpenoid that has an unusual bridgingperoxide functional group. It is a colorless liquid with a pungent smell and taste that is soluble in most organic solvents. Like other low molecular weightorganic peroxides, it is unstable and prone to rapid decomposition when heated or treated with organic acids. Ascaridole determines the specific flavor of the Chilean treeboldo and is a major constituent of the oil ofMexican tea (wormseed). It is a component of natural medicine, tonic drinks and food flavoring in Latin American cuisine. As part of the oil, ascaridole is used as ananthelmintic drug that expelsparasitic worms from plants, domestic animals, and the human body.
Ascaridole was the first, and for a long time only, discovered naturally occurringorganic peroxide. It was isolated fromChenopodium oil and named by Hüthig in 1908. He found that when heated to between 130° and 150 °C "there occurs, with sudden boiling in which the temperature momentarily rises to about 250°, a decomposition of an explosive character, occasionally accompanied by ignition. At the same time a very disagreeable skatol-like odour, difficult to define, is observed. In the course of the examination it was found that during the decomposition a gas is split off." He determined its chemical formula as C10H16O2.[2] Hüthig also noted the indifference of ascaridole toaldehydes,ketones orphenols that characterized it as non-alcohol. When reacted withsulfuric acid, or reduced withzinc powder andacetic acid, ascaridole formedcymene.[3][4] A detailed study was done by E. K. Nelson in 1911. He described the decomposition as apparently a molecular rearrangement, and found that it reacts with sulfuric,hydrochloric,nitric, orphosphoric acids. Nelson showed that the new substance contained neither ahydroxyl nor acarbonyl group and that upon reduction withiron(II) sulfate it formed aglycol, now known asascaridole glycol, C10H18O3. The glycol is more stable than ascaridole and has a highermelting point of about 64 °C,boiling point of 272 °C, anddensity of 1.098 g/cm3. Nelson also predicted the chemical structure of ascaridole which was almost correct, but had the peroxide bridge not along the molecular axis, but between the other, off-axis carbon atoms.[5] This structure was corrected byOtto Wallach in 1912.[6][7][8]
The first laboratory synthesis was demonstrated in 1944 by Günther Schenck andKarl Ziegler and might be regarded as mimicking the natural production of ascaridole. The process starts from α-terpinene which reacts with oxygen under the influence ofchlorophyll and light. Under these conditionssinglet oxygen is generated which reacts in aDiels–Alder reaction with the diene system in the terpinene.[8][9][10] Since 1945, this reaction has been adopted into the industry for large-scale production of ascaridole in Germany. It was then used as an inexpensive drug against intestinal worms.[11]
Ascaridole is a colorless liquid that is soluble in most organic solvents. It is toxic and has a pungent, unpleasant smell and taste. Like other pure, low molecular weightorganic peroxides, it is unstable and prone to violent decomposition when heated to a temperature above 130 °C or treated with organic acids. When heated, it emits fumes which are poisonous and possibly carcinogenic.[1][6][12]Ascaridole (organic peroxide) is forbidden to be shipped as listed in theUS Department of Transportation Hazardous Materials Table 49 CFR 172.101.[13]
The specific flavor of the Chilean treeboldo (Peumus boldus) primarily originates from ascaridole. Ascaridole is also a major component ofepazote (or Mexican tea,Dysphania ambrosioides, formerlyChenopodium ambrosioides)[14][15] where it typically constitutes between 16 and 70% of the plant'sessential oil.[16][17] The content of ascaridole in the plant depends on cultivation and is maximal when thenitrogen tophosphorus ratio in thesoil is about 1:4. It also changes through the year peaking around the time when the plant seeds become mature.[18]
Ascaridole is mainly used as ananthelmintic drug that expelsparasitic worms (helminths) from the human body and plants. This property gave the name to the chemical, afterAscaris – a genus of the large intestinal roundworm. In the early 1900s, it was a major remedy against intestinal parasites in humans, cats, dogs, goats, sheep, chickens, horses, and pigs, and it is still used in livestock, particularly in the Central American countries. The dosage was specified by the ascaridole content in the oil, which was traditionally determined with anassay developed by Nelson in 1920. It was later substituted with moderngas chromatography andmass spectrometry methods.[19] The worms and their larvae were killed by immersion in a solution of ascaridole in water (about 0.015 vol%) for 18 hours at 50 °F (10 °C) or 12 hours at 60 °F (16 °C) or 6 hours at 65 to 70 °F (18 to 21 °C). Meanwhile, such immersion did not damage the roots and stems of plants such asIris,Phlox,Sedum and others at 70 °F (21 °C) for 15 hours or longer.[12]
The wormseed plant itself (Mexican tea) is traditionally used inMexican cuisine for flavoring dishes and preventingflatulence frombean-containing food.[17] It is also part oftonic drinks and infusions to expelintestinal parasites and treatasthma,arthritis,dysentery,stomach ache,malaria, andnervous diseases infolk medicine practiced in North and South America, China, and Turkey.[18][19]
The usage of wormseed oil on humans is limited by the toxicity of ascaridole and has therefore been discouraged. In high doses, wormseed oil causesirritation of skin andmucous membranes,nausea,vomiting,constipation,headache,vertigo,tinnitus, temporarydeafness andblindness. Prolonged action induces depression of thecentral nervous system anddelirium which transits intoconvulsions andcoma. Long-term effects includepulmonary edema (fluid accumulation in thelungs),hematuria, andalbuminuria (presence ofred blood cells and proteins in theurine, respectively) andjaundice (yellowish pigmentation of the skin). Fatal doses of wormseed oil were reported as one teaspoon for a 14-month-old baby (at once) and daily administration of 1 mL over three weeks to a 2-year-old child. Ascaridole is also carcinogenic in rats.[17]
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