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| Names | |||
|---|---|---|---|
| Preferred IUPAC name 1,4-Dioxane | |||
| Systematic IUPAC name 1,4-Dioxacyclohexane | |||
| Other names [1,4]Dioxane p-Dioxane [6]-crown-2 Diethylene dioxide Diethylene ether Dioxane solvent | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 102551 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| DrugBank |
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| ECHA InfoCard | 100.004.239 | ||
| EC Number |
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| KEGG |
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| RTECS number |
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| UNII | |||
| UN number | 1165 | ||
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| Properties | |||
| C4H8O2 | |||
| Molar mass | 88.106 g·mol−1 | ||
| Appearance | Colorless liquid[1] | ||
| Odor | Mild,diethyl ether-like[1] | ||
| Density | 1.033 g/mL | ||
| Melting point | 11.8 °C (53.2 °F; 284.9 K) | ||
| Boiling point | 101.1 °C (214.0 °F; 374.2 K) | ||
| Miscible | |||
| Vapor pressure | 29 mmHg (20 °C)[1] | ||
| −52.16·10−6 cm3/mol | |||
| Thermochemistry | |||
Std molar entropy(S⦵298) | 196.6 J/K·mol | ||
Std enthalpy of formation(ΔfH⦵298) | −354 kJ/mol | ||
Std enthalpy of combustion(ΔcH⦵298) | −2363 kJ/mol | ||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | Suspected human carcinogen[1] | ||
| GHS labelling: | |||
   | |||
| Danger | |||
| H225,H302,H305,H315,H319,H332,H336,H351,H370,H372,H373 | |||
| P201,P202,P210,P233,P240,P241,P242,P243,P260,P261,P264,P270,P271,P280,P281,P302+P352,P303+P361+P353,P304+P312,P304+P340,P305+P351+P338,P307+P311,P308+P313,P312,P314,P321,P332+P313,P337+P313,P362,P370+P378,P403+P233,P403+P235,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 12 °C (54 °F; 285 K) | ||
| 180 °C (356 °F; 453 K) | |||
| Explosive limits | 2.0–22%[1] | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) |
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LC50 (median concentration) |
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LCLo (lowest published) | 1000–3000 ppm (guinea pig, 3 hr) 12,022 ppm (cat, 7 hr) | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 100 ppm (360 mg/m3) [skin][1] | ||
REL (Recommended) | Ca C 1 ppm (3.6 mg/m3) [30-minute][1] | ||
IDLH (Immediate danger) | Ca [500 ppm][1] | ||
| Related compounds | |||
Related compounds | Oxane Trioxane | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
1,4-Dioxane (/daɪˈɒkseɪn/) is aheterocyclicorganic compound, classified as anether. It is a colorless liquid with a faint sweetodor similar to that ofdiethyl ether. The compound is often called simplydioxane because the other dioxaneisomers (1,2- and1,3-) are rarely encountered.
1,4-Dioxane is miscible in water, essentially nonvolatile when dissolved in water, not well adsorbed by activated carbon, not readily oxidized by common oxidants.
Dioxane is used as a solvent for a variety of practical applications as well as in the laboratory, and also as a stabilizer for the transport ofchlorinated hydrocarbons in aluminium containers.[3]
The compound was discovered by Portuguese professorAgostinho Vicente Lourenço in 1860 by a reaction ofdiethylene glycol with1,2-dibromoethane.[4] He initially designated itether of glycol and correctly identified itsempirical formula, but measured its boiling point at about 95°C.[5] Three year laterC. A. Wurtz obtained it by another method, called itdioxyethylene and studied some of its chemical properties.[6]
Dioxane is industrially produced since the 1920s[7][8] by the acid-catalyseddehydration of diethylene glycol, which in turn is obtained from thehydrolysis ofethylene oxide. This method was developed byAlexey Favorsky in 1906, who also determined the structure of the compound.[9]
In 1985, the global production capacity for dioxane was between 11,000 and 14,000 tons.[10] In 1990, the total U.S. production volume of dioxane was between 5,250 and 9,150 tons.[11]
Three isomers of dioxane exist, but only the 1,3- and 1,4- isomers are significant. The 1,4-dioxane molecule is conformationally flexible: the centrosymmetric chair and theboat conformations easily interconvert such that the H NMR spectrum shows only one signal. For this reason, it is sometimes used as an internal standard fornuclear magnetic resonance spectroscopy indeuterium oxide.[12] With only two ethyleneoxyl units, dioxane is one of the smallestcrown ethers.
In the 1980s, most of the dioxane produced was used as a stabilizer for1,1,1-trichloroethane for storage and transport inaluminium containers. Normally aluminium is protected by a passivating oxide layer, but when these layers are disturbed, the metallic aluminium reacts with trichloroethane to givealuminium trichloride, which in turn catalyses thedehydrohalogenation of the remaining trichloroethane tovinylidene chloride andhydrogen chloride. Dioxane "poisons" this catalysis reaction by forming anadduct with aluminium trichloride.[10]
Dioxane is used in a variety of applications as a versatileaprotic solvent (usually considered non-polar,[13] although some sources state otherwise[14]), e.g. for inks, adhesives, and cellulose esters. It is substituted fortetrahydrofuran (THF) in some processes, because of its lower toxicity and higher boiling point (101 °C, versus 66 °C for THF).[15]
While diethyl ether is rather insoluble in water, dioxane ismiscible and in fact ishygroscopic. At standard pressure, the mixture of water and dioxane in the ratio 17.9:82.1 by mass is a positiveazeotrope that boils at 87.6 °C.[16]
The oxygen atoms are weaklyLewis-basic. It forms adducts with a variety of Lewis acids. It is classified as ahard base and its base parameters in theECW model are EB = 1.86 and CB = 1.29.
Dioxane produces insolublecoordination polymers by linking metal centers.[17] In this way, it is used to drive theSchlenk equilibrium, allowing the synthesis of dialkyl magnesium compounds.[10]Dimethylmagnesium is prepared in this manner:[18][19]
Dioxane has anLD50 of 5170 mg/kg in rats.[10] It is irritating to the eyes and respiratory tract. Exposure may cause damage to the central nervous system, liver and kidneys.[20] In a 1978 mortality study conducted on workers exposed to 1,4-dioxane, the observed number of deaths from cancer was not significantly different from the expected number.[21] Dioxane is classified by the National Toxicology Program as "reasonably anticipated to be a human carcinogen".[22] It is also classified by theIARC as aGroup 2B carcinogen:possibly carcinogenic to humans because it is a known carcinogen in other animals.[23] TheUnited States Environmental Protection Agency classifies dioxane as a probable humancarcinogen (having observed an increased incidence of cancer in controlled animal studies, but not in epidemiological studies of workers using the compound), and a known irritant (with a no-observed-adverse-effects level of 400 milligrams per cubic meter) at concentrations significantly higher than those found in commercial products.[24] Studies with rats suggest that the greatest health risk may be associated with inhalation.[25][26][27] The State of New York has adopted a first-in-the-nation drinking water standard for 1,4-Dioxane and set the maximum contaminant level of 1 part per billion.[28]
Like some other ethers, dioxane combines with atmospheric oxygen upon prolonged exposure to air to form potentially explosiveperoxides.Distillation of these mixtures is dangerous. Storage over metallic sodium could limit the risk of peroxide accumulation.[29]
It biodegrades through a number of pathways.[30][31]
Dioxane has affected groundwater supplies in several areas. Dioxane at the level of 1 μg/L (~1 ppb) has been detected in many locations in the US.[11] In the U.S. state of New Hampshire, it had been found at 67 sites in 2010, ranging in concentration from 2 ppb to over 11,000 ppb. Thirty of these sites are solid waste landfills, most of which have been closed for years. In 2019, the Southern Environmental Law Center successfully sued Greensboro, North Carolina's Wastewater treatment after 1,4-Dioxane was found at 20 times above EPA safe levels in the Haw River.[32]
As a byproduct of theethoxylation process, a route to some ingredients found in cleansing and moisturizing products, traces of dioxane can be found in cosmetics and personal care products such as deodorants, perfumes, shampoos, toothpastes,, and mouthwashes.[33][34] The ethoxylation process makes the cleansing agents, such assodium laureth sulfate and ammonium laureth sulfate, less abrasive and offers enhanced foaming characteristics. 1,4-Dioxane is found in small amounts in some cosmetics, a yet unregulated substance used in cosmetics in both China and the U.S.[35] Research has found the chemical in ethoxylated raw ingredients and in off-the-shelf cosmetic products. TheEnvironmental Working Group (EWG) found that 97% of hair relaxers, 57% of baby soaps and 22 percent of all products in Skin Deep, their database for cosmetic products, are contaminated with 1,4-dioxane.[36]
Since 1979 theU.S. Food and Drug Administration (FDA) have conducted tests on cosmetic raw materials and finished products for the levels of 1,4-dioxane.[37] 1,4-Dioxane was present in ethoxylated raw ingredients at levels up to 1410 ppm (~0.14%wt), and at levels up to 279 ppm (~0.03%wt) in off the shelf cosmetic products.[37] Levels of 1,4-dioxane exceeding 85 ppm (~0.01%wt) in children's shampoos indicate that close monitoring of raw materials and finished products is warranted.[37] While the FDA encourages manufacturers to remove 1,4-dioxane, it is not required by federal law.[38]
On 9 December 2019, New York passed a bill to ban the sale of cosmetics with more than 10 ppm of 1,4-dioxane as of the end of 2022. The law will also prevent the sale of household cleaning and personal care products containing more than 2 ppm of 1,4-dioxane at the end of 2022.[39]
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