12,022 ppm (cat, 7 hr)
2085 ppm (mouse, 8 hr)
US health exposure limits (NIOSH):
TWA 100 ppm (360 mg/m3) [skin]
Ca C 1 ppm (3.6 mg/m,3) [30-minute]
IDLH (Immediate danger)
Ca [500 ppm]
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
1,4-Dioxane (/daɪˈɒkseɪn/) is a heterocyclic organic compound,
classified as an ether. It is a colorless liquid with a faint sweet
odor similar to that of diethyl ether. The compound is often called
simply dioxane because the other dioxane isomers (1,2- and 1,3-) are
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 of chlorinated hydrocarbons in aluminum containers.
3.1 Trichloroethane transport
3.2 As a solvent
4.2 Explosion hazard
5 See also
Dioxane is produced by the acid-catalysed dehydration of diethylene
glycol, which in turn is obtained from the hydrolysis of ethylene
In 1985, the global production capacity for dioxane was between 11,000
and 14,000 tons. In 1990, the total U.S. production volume of
dioxane was between 5,250 and 9,150 tons.
The dioxane molecule is centrosymmetric, meaning that it adopts a
chair conformation, typical of relatives of cyclohexane. However, the
molecule is conformationally flexible, and the boat conformation is
easily adopted, e.g. in the chelation of metal cations.
In the 1980s, most of the dioxane produced was used as a stabilizer
for 1,1,1-trichloroethane for storage and transport in aluminium
containers. Normally aluminium is protected by a passivating oxide
layer, but when these layers are disturbed, the metallic aluminium
reacts with trichloroethane to give aluminium trichloride, which in
turn catalyses the dehydrohalogenation of the remaining
trichloroethane to vinylidene chloride and hydrogen chloride. Dioxane
"poisons" this catalysis reaction by forming an adduct with aluminum
As a solvent
Binary phase diagram for the system 1,4-dioxane/water
Dioxane is used in a variety of applications as a versatile aprotic
solvent, e. g. for inks, adhesives, and cellulose esters. It is
substituted for tetrahydrofuran (THF) in some processes, because of
its lower toxicity and higher boiling point (101 °C, versus
66 °C for THF).
While diethyl ether is rather insoluble in water, dioxane is miscible
and in fact is hygroscopic. At standard pressure, the mixture of water
and dioxane in the ratio 17.9:82.1 by mass is a positive azeotrope
that boils at 87.6 C.
The oxygen atoms are Lewis-basic, and so dioxane is able to solvate
many inorganic compounds and serves as a chelating diether ligand. It
reacts with Grignard reagents to precipitate the magnesium dihalide.
In this way, dioxane is used to drive the Schlenk equilibrium.
Dimethylmagnesium is prepared in this manner:
2 CH3MgBr + (C2H4O)2 → MgBr2(C2H4O)2 + (CH3)2Mg
Dioxane is used as an internal standard for nuclear magnetic resonance
spectroscopy in deuterium oxide.
Dioxane has an LD50 of 5170 mg/kg in rats. This compound is
irritating to the eyes and respiratory tract. Exposure may cause
damage to the central nervous system, liver and kidneys. In a 1978
mortality study conducted on workers exposed to 1,4-dioxane, the
observed number deaths from cancer was not significantly different
from the expected number. Dioxane is classified by the National
Toxicology Program as "reasonably anticipated to be a human
carcinogen". It is also classified by the IARC as a Group 2B
carcinogen: possibly carcinogenic to humans because it is a known
carcinogen in other animals. The United States Environmental
Protection Agency classifies dioxane as a probable human carcinogen
(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.
Under California Proposition 65, dioxane is classified in the U.S.
State of California to cause cancer. Animal studies in rats
suggest that the greatest health risk is associated with inhalation of
vapors in the pure form.
Like some other ethers, dioxane combines with atmospheric oxygen upon
prolonged exposure to air to form potentially explosive peroxides.
Distillation of dioxanes concentrates these peroxides, increasing the
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. In the State of New Hampshire alone in 2010 it had been
found at 67 sites, 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. It also has low toxicity to aquatic life
and can be biodegraded via a number of pathways. The problems are
exacerbated since dioxane is highly soluble in water, 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 dioxane plume can be larger (and further
downgradient) than the associated solvent plume.
As a byproduct of the ethoxylation process, a route to some
ingredients found in cleansing and moisturizing products, dioxane can
contaminate cosmetics and personal care products such as deodorants,
shampoos, toothpastes and mouthwashes. The ethoxylation
process makes the cleansing agents, such as ammonium laureth sulfate
and sodium laureth sulfate, less abrasive and offers enhanced foaming
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.
In 2008, testing sponsored by the U.S. Organic Consumers Association
found dioxane in almost half of tested organic personal-care
products. Since 1979 the
U.S. Food and Drug Administration
U.S. Food and Drug Administration (FDA)
have conducted tests on cosmetic raw materials and finished products
for the levels of 1,4-dioxane.
1,4-Dioxane was present in
ethoxylated raw ingredients at levels up to 1410 ppm, and at levels up
to 279 ppm in off the shelf cosmetic products. Levels of
1,4-dioxane exceeding 85 ppm in children's shampoos indicate that
close monitoring of raw materials and finished products is
warranted. While the FDA encourages manufacturers to remove
1,4-dioxane, it is not required by federal law.
The three isomers of dioxane
Sodium laureth sulfate
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