1,4-Dioxane

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1,4-Dioxane
Chemical structure of dioxane
1,4-dioxane
IUPAC name 1,4-Dioxane
1,4-Dioxacyclohexane
Other names [1,4]Dioxane
p-Dioxane
[6]-crown-2
Identifiers
CAS number [123-91-1]
EINECS number 204-661-8
SMILES C1OCCOC1
Properties
Molecular formula C4H8O2
Molar mass 88.11 g/mol
Density 1.033 g/cm³
Melting point

11.8°C
Boiling point

101.1°C
Thermochemistry
Std enthalpy of
formation ΔfHo298		 -354 kJ/mol
Std enthalpy of
combustion ΔcHo298		 -2363 kJ/mol
Standard molar
entropy So298		 196.6 J.K–1.mol–1
Hazards
EU classification Flammable (F)
Carc. Cat. 3
Irritant (Xn)
R-phrases R11, R19, R36/37,
R40, R66
S-phrases (S2), S9, S16,
S36/37, S46
Flash point 12 °C
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Not to be confused with dioxin.

1,4-Dioxane, often just called dioxane, is a clear, colorless heterocyclic organic compound which is a liquid at room temperature and pressure. It has the molecular formula C4H8O2 and a boiling point of 101°C. It is commonly used as an aprotic solvent. 1,4-Dioxane has a weak smell similar to that of diethyl ether. There are also two other less common isomeric compounds, 1,2-dioxane and 1,3-dioxane. 1,2-Dioxane is a peroxide which forms naturally in old bottles of tetrahydrofuran.

1,4-Dioxane is classified as an ether, with each of its two oxygen atoms forming an ether functional group. It is more polar than diethyl ether, which also has four carbons, but only one ether functional group. Diethyl ether is rather insoluble in water, but 1,4-dioxane is miscible with water and is hygroscopic. Its higher polarity and slightly higher molecular mass also gives it a substantially higher boiling point than diethyl ether. When used as a solvent for a Grignard reaction, Dioxane favorably affects the formation of magnesium halide salts in the Schlenk equilibrium.

The name dioxane should not be confused with dioxin, which is a different compound but is also a diether (two ether functional groups).

Isomers of DioxaneSmall blue numbers show numbering of atoms in rings.
Isomers of Dioxane

Small blue numbers show numbering of atoms in rings.


Contents

[edit] Uses

1,4-Dioxane is primarily used in solvent applications for the manufacturing sector; however, it is also found in fumigants and automotive coolant. Additionally, the chemical is also used as a foaming agent and appears as an accidental byproduct of the ethoxylation[1] process in cosmetics manufacturing. It may contaminate cosmetics and personal care products such as deodorants, shampoos, toothpastes and mouthwashes.[2]

It is also commonly used as an internal standard for calibrating chemical shifts in NMR, as tetramethylsilane (the compound to which all chemical shifts are ultimately referenced) is not soluble in D2O.

[edit] Safety and environmental concerns

Dioxanes combine with atmospheric oxygen on standing to form explosive peroxides, similar to many other ethers. Distillation of dioxanes concentrates these peroxides increasing the danger. Appropriate precautions should be taken.

1,4-dioxane is a known eye and respiratory tract irritant. It is suspected of causing damage to the central nervous system, liver and kidneys.[3] Accidental worker exposure to 1,4-dioxane has resulted in several deaths.[4] Dioxane is classified by the IARC as a Group 2B carcinogen: possibly carcinogenic to humans due to the fact that it is a known carcinogen in animals.[5]

Like many solvents, 1,4-dioxane forms contamination plumes in groundwater when released to the environment. Groundwater supplies have been adversely impacted in several areas.

1,4-dioxane is highly soluble in groundwater, does not readily bind to soils, and readily leaches to groundwater. It is also resistant to naturally occurring biodegradation processes. Due to these properties, a 1,4-dioxane plume is often much larger (and further downgradient) than the associated solvent plume.[6]

[edit] See also

[edit] References

  1. ^ Roderick E. Black. Occurrence of 1,4-Dioxane in Cosmetic Raw Materials and Finished Cosmetic Products. Journal of IAOC International. Retrieved on 2006-02-02.
  2. ^ CHEC Chemical Summary: 1,4-dioxane. Children's Health Environmental Coalition. Retrieved on 2006-02-02.
  3. ^ International Chemical Safety Card. National Institute for Occupational Safety and Health. Retrieved on 2006-02-02.
  4. ^ OPPT Chemical Fact Sheets 1,4-Dioxane (CAS No. 123-91-1). United States Environmental Protection Agency. Retrieved on 2006-02-02.
  5. ^ Eleventh Report on Carcinogens. United States Department of Health and Human Services’ National Toxicology Program. Retrieved on 2006-02-02.
  6. ^ Crawford, Scott. "Down N' Dirty With 1,4-Dioxane.". XDD, LLC's Xpert Solutions Newsletter (Fall 2007/Winter 2008). Retrieved on 2008-01-16.

[edit] External links