Environmental Engineering Reference
In-Depth Information
2 1,4-Dioxane
Chemistry, Uses, and Occurrence
Thomas K.G. Mohr
1,4-Dioxane has many uses beyond its key role as a stabilizer for methyl chloroform. It is used
directly in several industrial and commercial processes and is found in a wide range of consumer
products. 1,4-Dioxane also occurs as a by-product in the production of certain surfactants, synthetic
textiles, plastics, and resins. As a result of its widespread use, 1,4-dioxane is found to a limited
extent in ambient air, surface water, and groundwater, but it occurs more commonly in wastewater,
landi ll leachate, and landi ll gas. Documenting the uses, occurrence, and history of 1,4-dioxane
production provides practical information for those investigating 1,4-dioxane releases in soil and
groundwater. Knowledge of the many uses of 1,4-dioxane may also be helpful in reconstructing
release histories by forensic investigative techniques, as discussed in Chapter 9.
1,4-Dioxane possesses some unique and surprising chemical properties, upon which its industrial
utility and environmental fate depend. A comprehension of both the basic chemical structure of
1,4-dioxane and the many implications of that structure provides the foundation for (1) developing
analytical methods capable of reliably separating low levels of this hydrophilic contaminant from
water samples and (2) designing remedial technologies capable of removing the contaminant from
affected water supplies. The chemical properties governing environmental fate and transport are
described further in Chapter 3. Analytical methods for quantifying 1,4-dioxane in soil, water, air,
and other media are described in detail in Chapter 4. Remedial engineering considerations for
designing treatment technologies are reviewed in Chapter 7.
2.1 CHEMISTRY OF 1,4-DIOXANE
1,4-Dioxane was i rst described by A. V. Lourenço in 1863 as the product of reacting ethylene
glycol and 1,2-dibromoethane (Stumpf, 1956; Flick, 1998). Lourenço published his discovery of
1,4-dioxane in Annales de Chimie et de Physique (Lourenço, 1863). In the same year, the derivation
of 1,4-dioxane from ethylene oxide was described by A. Wurtz in a later issue of the same journal
(Wurtz, 1863).
1,4-Dioxane is also known by the synonyms p -dioxane, diethylene oxide, 1,4-diethylene dioxide,
and glycol ethylene ether. A complete list of synonyms is given in Table 2.1 , and Table 2.2 lists
identii ers for 1,4-dioxane as assigned by various organizations and agencies. 1,4-Dioxane is a cyclic
ether that has four carbon atoms and two oxygen atoms, resulting in two ether functional groups in
the same molecule. Cyclic ethers have a ring structure in which the oxygen has become part of
the ring. In 1,4-dioxane, the oxygen atoms occur directly opposite each other to form symmetrical
ether linkages. This structure makes 1,4-dioxane highly stable and relatively immune to reaction
with acids, oxides, and oxidizing agents. The 1,4-dioxane ring does not rupture except in the pres-
ence of concentrated acids and strong oxidizing agents, under the inl uence of high temperature and
pressure (Reid and Hoffman, 1942). The symmetry of the 1,4-dioxane ring should impart only a
very small dipole moment to the molecule; nevertheless, it has good solvency (Stoye, 2005). The
solvency and solubility of 1,4-dioxane are attributed to the polarity it acquires when a pair of 1,4-
dioxane rings forms a dimer with two intermolecular hydrogen bonds (a dimer refers to a molecule
75
Search WWH ::




Custom Search