Historical Use of Chlorinated Solvents and Their Stabilizing Compounds - Environmental Investigation and Remediation - page 52

created others. Methyl chloroform stabilized with 1,4-dioxane, nitromethane, and sec -butyl alcohol
does not react with aluminum, but its boiling vapor reacts with zinc. The compound 1,4-dioxane
catalyzes the reaction with zinc, leading to damaged degreasing equipment and solvent distillation
equipment made of galvanized steel sheeting. When 1,4-dioxane becomes concentrated in the
degreaser boiling sump, the attack on zinc in galvanized metals can be severe (Spencer and Archer,
1981). Adding a vicinal * monoepoxide such as 1,2-butylene oxide prevents the reaction between
methyl chloroform and zinc in the vapor phase. The most common formulations of methyl chloro-
form contain 1,2-butylene oxide for this reason (Brown, 1962).
Pure 1,4-dioxane is susceptible to forming peroxides over time when stored. The compound 1,3-
dioxolane will also combine with oxygen from the air to form explosive peroxides. Methyl chloro-
form stabilized with 1,4-dioxane or 1,3-dioxolane can develop peroxides or acidity during storage;
however, 1,4-dioxane develops peroxides to a lesser extent than 1,3-dioxolane (Manner, 1977).
Efforts by Dow's competitors to stabilize methyl chloroform against the aluminum reaction
involved other oxygen-containing compounds. Adding tert -butyl alcohol with 1,2-butylene oxide
and nitromethane slows but does not completely inhibit the reaction, as shown by the formation of
an amber precipitate. Pittsburgh Plate and Glass (later PPG), one of the producers of methyl chloro-
form since the 1960s, claimed that the addition of 1,2-dimethoxymethane prevents decomposition
in the presence of aluminum and its salts (Hardies, 1966).

WHEN WAS 1,4-DIOXANE FIRST USED TO STABILIZE METHYL
CHLOROFORM?
1,4-Dioxane was i rst identii ed in 1863 (Lourenço, 1863; Wurtz, 1863). It i rst became avail-
able for commercial use in the late 1920s (Reid and Hofman, 1929). Carbide and Carbon
Chemicals Corporation was supplying 1,4-dioxane in the early 1930s for use as a solvent for
cellulose acetate and plastics manufacturing (Jones et al., 1933). Reid and Hofman (1929)
listed other uses motivating commercial production for 1,4-dioxane as a solvent:

• Degreasing

• Wool scou r ing

• Producing dyes

• Printing and staining

• Va r n ishes

• Paint and varnish removers

• Cosmetics

• Glues

• Shoe creams

• A preservative

• A fumigant

• A deodorant

The earliest mention of 1,4-dioxane as a solvent stabilizer was in 1945 in a patent for
stabilizing solvents, in particular, TCE (Petering and Aitchison, 1945). However, the patent
does not clearly indicate that 1,4-dioxane was preferred for use with TCE (see Box: Was 1,4-
Dioxane a Stabilizer for Trichloroethylene? ).

continued

* Vicinal means any two functional groups bonded to two adjacent carbon atoms; an epoxide is a cyclic ether with only
three ring atoms (one oxygen and two carbons) in the shape of an equilateral triangle.