1,4-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]
EC 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
NFPA 704	3 2 1
Flash point	12 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references

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).

The three dioxanes Small blue numbers show numbering of atoms in rings.

Synthesis

1,4-Dioxane is one of the many compounds which can be produced by the hydrolysis of ethylene oxide. Two molecules of ethylene oxide dimerize to form dioxane with ethylene glycol as an intermediate.

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.

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 because it is a known carcinogen in animals.^[5]

The State of California, under proposition 65, listed 1,4-dioxane as a chemical known to cause cancer on January 1, 1988.^[6]

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.^[7]

In 2008, testing sponsored by an independent consumers organization found 1,4-dioxane in almost half of tested personal-care products.^[8]

See also

• Ether
• Crown ether
• Sodium laureth sulfate
• Tetrahydrofuran
• Diethyl ether
• Oxalic anhydride

References

1. ^ Roderick E. Black (May 2001). Occurrence of 1,4-Dioxane in Cosmetic Raw Materials and Finished Cosmetic Products. 84. Journal of IAOC International. p. 666-670. http://www.atypon-link.com/AOAC/doi/abs/10.5555/jaoi.2001.84.3.666. Retrieved on 2006-02-02. 
2. ^ "CHEC Chemical Summary: 1,4-dioxane". Children's Health Environmental Coalition. http://www.checnet.org/HealtheHouse/chemicals/chemicals-detail.asp?Main_ID=273. Retrieved on 2006-02-02. 
3. ^ "International Chemical Safety Card". National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/ipcsneng/neng0041.html. Retrieved on 2006-02-02. 
4. ^ "OPPT Chemical Fact Sheets 1,4-Dioxane (CAS No. 123-91-1)". United States Environmental Protection Agency. http://www.epa.gov/opptintr/chemfact/dioxa-fs.txt. Retrieved on 2006-02-02. 
5. ^ "Eleventh Report on Carcinogens". United States Department of Health and Human Services’ National Toxicology Program. http://ntp-server.niehs.nih.gov/ntp/roc/eleventh/profiles/s080diox.pdf. Retrieved on 2006-02-02. 
6. ^ "Proposition 65 Chemicals". http://www.oehha.ca.gov/prop65/prop65_list/files/032108list.pdf. 
7. ^ "Crawford, Scott. "Down N' Dirty With 1,4-Dioxane."". XDD, LLC's Xpert Solutions Newsletter (Fall 2007/Winter 2008). http://xdd-llc.com/images/XDD_Newsletter_Fall-Winter_2007.pdf. Retrieved on 2008-01-16. 
8. ^ http://www.organicconsumers.org/bodycare/DioxaneRelease08.cfm

External links

• Safety (MSDS) data for 1,4-dioxane
• Hazard Database
• Safety (MSDS) data for 1,3-dioxane
• Press conference on 1,4-dioxane found in children's bath products (2/8/07)
• Press conference on 1,4-dioxane found in personal care products labeled "natural" or "organic" (3/14/08)
• Press conference on major brands cleaning up 1,4-dioxane in their consumer products (3/6/09)
• California Attorney General sues companies with personal care products containing 1,4-dioxane (6/10/08)
• XDD, LLC: Developers of remediation options for 1,4-dioxane.