1,4-DIOXANE

Note: May contain acetic acid, 2-methyl-1,3-dioxolane, and bis(2-chloroethyl) ether as impurities. May be inhibited with butylated hydroxytoluene. CASRN: 123-91-1; DOT: 1165; DOT label: Flammable liquid; molecular formula: C4H8O2; FW: 88.11; RTECS: JG8225000; Merck Index: 12, 3353 Physical state, color, and odor: Clear, colorless, very flammable, volatile liquid with a faint pleasant, ether-like odor. Experimentally determined detection and recognition odor threshold concentrations were 2.9 mg/m3 (800 ppbv) and 6.5 mg/m3 (1.8 ppmv), respectively (Hellman and Small, 1974). Melting point (°C): 11.8 (Weast, 1986) Boiling point (°C): 101.37 (Reyes et al., 2003) Density (g/cm3): 1.0337 at 20 °C (Weast, 1986) 1.0280 at 25.00 °C, 1.0221 at 30.00 °C, 1.0110 at 40.00 °C, 0.9994 at 50.00 °C, 0.9886 at 60.00

°C, 0.9766 at 70.00 °C (Abraham et al., 1971) 1.03920 at 15.00 °C, 1.02793 at 25.00 °C, 1.01657 at 35.00 °C (Calvo et al., 1998) 1.02666 at 25.00 °C (Govender et al., 1996) 1.02809 at 25.00 °C, 1.01110 at 40.00 °C (Comelli et al., 1996) 1.016595 at 35.00 °C (Contreras, 2001) Diffusivity in water (x 10-5 cm2/sec): 1.10 (x = 0.000180), 1.10 (x = 0.000905), 1.09 (x = 0.00183), 1.06 (x = 0.00508), 0.95 (x = 0.0222), 0.82 (x = 0.0407), 0.71 (x = 0.0806), 0.59 (x = 0.120), 0.52 (x = 0.170), 0.42 (x = 0.234), 0.34 (x = 0.323), 0.32 (x = 0.449), 0.47 (x = 0.664), 0.85 (x = 0.798), 1.41 (x = 0.901), 1.92 (x = 0.950), 2.38 (x = 0.988) (Leaist et al., 2000) Flash point (°C): 12.8 (NIOSH, 1997) 18.3 (open cup, Hawley, 1981) Lower explosive limit (%): 2.0 (NIOSH, 1997) Upper explosive limit (%): 22 (NIOSH, 1997)

2.978 (quoted, Riddick et al., 1986) Henry’s law constant (x 10-6 atm⋅m3/mol): 6.92 at pH 7.1 and 30 °C (headspace-GC, Friant and Suffet, 1979) 5.00 (Cabani et al., 1971) 4.55 (Rohrschneider, 1973) 9.07 (Amoore and Buttery, 1978) 209 (Hakuta et al., 1977) 4.89 (static headspace-GC, Welke et al., 1998) Ionization potential (eV): 9.13 ± 0.03 (Franklin et al., 1969) Soil organic carbon/water partition coefficient, log Koc: 0.54 (calculated, Mercer et al., 1990) Octanol/water partition coefficient, log Kow: -0.42 at 20.0 °C (shake flask-chemical reaction, Collander, 1951) -0.27 (shake flask, Hansch and Leo, 1979) Solubility in organics: Soluble in acetone, alcohol, benzene, and ether (Weast, 1986). Miscible with most organic solvents (Huntress and Mulliken, 1941) including 2-methylpropanol, toluene, cychexanone, and cyclopentanone. Solubility in water: Miscible (Palit, 1947). Vapor density: 3.60 g/L at 25 °C, 3.04 (air = 1) Vapor pressure (mmHg): 29 at 20 °C (NIOSH, 1997) 37.3 at 25.0 °C, 47.5 at 30.0 °C, 60.5 at 35.0 °C, 76.2 at 40.0 °C (Xu et al., 1996) 38.1 at 25 °C (Banerjee et al., 1990) 34.28 at 25.00 °C (GC, Hussam and Carr, 1985) Environmental fate: Biological. Heukelekian and Rand (1955) reported a 10-d BOD value of 0.00 g/g which is 0.0% of the ThOD value of 1.89 g/g. Photolytic. Irradiation of pure 1,4-dioxane through quartz using a 450-W medium-pressure mercury lamp gave meso and racemic forms of 1-hydroxyethyldioxane, a pair of diastereomeric dioxane dimers (Mazzocchi and Bowen, 1975), dioxanone, dioxanol, hydroxymethyldioxane, and hydroxyethylidenedioxane (Houser and Sibbio, 1977). When 1,4-dioxane is subjected to a megawatt ruby laser, 4% was decomposed yielding ethylene, carbon monoxide, hydrogen, and a trace of formaldehyde (Watson and Parrish, 1971). Chemical/Physical. Anticipated products from the reaction of 1,4-dioxane with ozone or OH radicals in the atmosphere are glyoxylic acid, oxygenated formates, and OHCOCH2CH2OCHO (Cupitt, 1980). Storage of 1,4-dioxane in the presence of air resulted in the formation of 1,2ethanediol monoformate and 1,2-ethane diformate (Jewett and Lawless, 1980). Stefan and Bolton

Degradation follows pseudo-first-order kinetics at a rate of 8.7 x 10-3/sec. Within 5 min of direct photolysis of hydrogen peroxide to generate OH radicals, almost 90% of the 1,4-dioxane reacted. Four primary intermediate formed were 1,2-ethanediol monoformate, 1,2-ethanediol diformate, formic acid, and methoxyacetic acid. These compounds were attacked by OH radicals yielding glycolic, glyoxylic, and acetic acids which led to oxalic acid as the last intermediate. Malonic acid was also identified as a minor intermediate. Twelve minutes into the reaction, the pH decreased rapidly to 3.25 from 5.0, then less rapidly to 3.25 after 23 min. After 1 h, the pH rose to 4.2 min. The decrease of pH during the initial stages of reaction is consistent with the formation of organic acids. Oxidation of organic acid by OH radicals led to an increase of pH. The investigators reported that the lower pH at the end of the experiment was due to carbonic acid formed during the mineralization process. Beckett and Hua (2000) investigated the sonolytic decomposition of 1,4-dioxane in aqueous solution at 25 °C at discrete ultrasonic frequencies. They found that the highest first-order decomposition rate occurred at 358 kHz followed by 618, 1,071, and 205 kHz. At 358 kHz, 96% of the initial 1,4-dioxane concentration was decomposed after 2 h and the pH of the solution decreased to 3.75 from 7.50. Major decomposition intermediates were ethylene glycol diformate, methoxyacetic acid, formaldehyde, glycolic acid, and formic acid. Schnoor et al. (1997) studied the feasibility and efficacy of phytoremediation of sites contaminated with 1,4-dioxane. Hybrid poplar trees (Populus deltoides nigra, DN34, Imperial Carolina) were utilized because of their resistance to contamination and their high growth rates. The poplars were ground in hydroponic solutions for 2 wk in an inorganic nutrient solution. The reactors containing plant, soil, and dioxane (200 ppm) were placed in a growth chamber which was maintained at 25 °C. After 7 d, >95% of the dioxane was removed from the hydroponic solution. Losses due to volatilization and sorption to glassware were minor. The rate constant for the reaction of 1,4-dioxane and OH radicals in the atmosphere was 1.22 x 10-11 cm3/molecule⋅sec at 298 K (Moriarty et al., 2003). 1,4-Dioxane will not undergo hydrolysis because it does not contain a hydrolyzable functional group (Kollig, 1993). Exposure limits: Potential occupational carcinogen. NIOSH REL: 30-min ceiling 1 ppm (3.6 mg/m3), IDLH 500 ppm; OSHA PEL: TWA 100 ppm; ACGIH TLV: TWA 20 ppm (adopted). Symptoms of exposure: Ingestion or skin absorption may cause drowsiness, headache, respiratory distress, nausea, and vomiting (Patnaik, 1992). Toxicity: LC84 values for white rats following 2 and 4 h of inhalation were 52 and 69.5 mg/L, respectively (Pilipiuk et al., 1977). LC50 (96-h static bioassay) for bluegill sunfish >10,000 mg/L, Menidia beryllina 6,700 mg/L (quoted, Verschueren, 1983). LC50 (48-h) for red killifish 81,280 mg/L (Yoshioka et al., 1986). LC50 (4-h inhalation) for white rats 46 mg/L (Pilipiuk et al., 1977). LC16 values for white rats following 2 and 4 h of inhalation were 61 and 40 mg/L, respectively (Pilipiuk et al., 1977). Acute LC50 for Menidia beryllina 6.7 g/L (Dawson et al., 1975-1976). Acute oral LD50 for mice 5,700 mg/kg, cats 2,000 mg/kg, guinea pigs 3,150 mg/kg, rats 4,200 mg/kg, rabbits 2,000 mg/kg (quoted, RTECS, 1985). Drinking water standard: No MCLGs or MCLs have been proposed although 1,4-dioxane has been listed for regulation (U.S. EPA, 1996).