Diethylene glycol

Description

Diethylene glycol appears as a colorless liquid. Denser than water. Contact may slightly irritate skin, eyes and mucous membranes. Because of its solvent power, low volatility and hygroscopicity, it is used in textile lubricants, cutting oils, dry cleaning soap, printing inks, steam-set inks, and nongrain wood stains. In the textile industry diethylene glycol is used as a conditioning agent for wool, rayon, and cotton. As a solvent for dyes it makes a valuable assistant in dyeing and printing.

Chemical properties

Diethylene glycol is a clear colorless, odorless and stable oily liquid. It is also slightly viscous, noncorrosive and nonvolatile. Because of its ether and alcohol group, diethylene glycol exhibits chemical properties characteristic of both primary alcohols and ethers. Its boiling point is considerably higher than that of ethylene glycol, and its solvent is greater. Diethylene glycol is miscible with water, ethers, lower aliphatic alcohols, aldehydes and ketones and is partially soluble in benzene, carbon tetrachloride, monobenzene, orthodichlorobenzene and toluene.

The Uses of Diethylene glycol

Diethylene glycol has many industrial uses. It is used as a dehydrating agent for natural gas processing; as a lubricating and finishing agent for textiles; a constituent in brake fluids, lubricants, antifreeze formulations, wallpaper strippers and in artificial fog solutions; a solvent for printing inks and textile dyes; and is used as an intermediate in the production of some resins, triethylene glycol, surfactants, and diethylene glycol esters and ethers.

Production Methods

Diethylene glycol is produced commercially as a by-product of ethylene glycol production. It can also be produced directly by reaction between ethylene glycol and ethylene oxide .

Definition

ChEBI: Diethylene glycol is a hydroxyether.

Air & Water Reactions

Slightly soluble in water.

Reactivity Profile

Diethylene glycol is incompatible with strong oxidizing agents. Diethylene glycol is also incompatible with strong bases. Diethylene glycol can react with sulfuric acid and other dehydrating agents, nitric acid, oxygen, hydrogen peroxide, perchloric acid and strong acids. Mixtures with sodium hydroxide decompose exothermically when heated to 446° F.

Health Hazard

Ingestion of large amounts may cause degeneration of kidney and liver and cause death. Liquid may cause slight skin irritation.

Fire Hazard

Diethylene glycol is combustible.

Safety Profile

Moderately toxic to humans by ingestion. Poison experimentally by inhalation. Moderately toxic by ingestion and intravenous routes. Questionable carcinogen with experimental carcinogenic,tumorigenic, and teratogenic data. An eye and human skin irritant. Combustible when exposed to heat or flame; can react with oxidning materials. To fight fire, use alcohol foam, water, Con, dry chemical. Mixtures with sodium hydroxide decompose exothermically when heated to 230℃ and release explosive hydrogen gas. When heated to decomposition it emits acrid smoke and irritating fumes. See also GLYCOL ETHERS.

Toxicology

The toxicity of diethylene glycol is similar to ethylene glycol and clearly is a CNS depressant. It has a low inhalation hazard because of its low vapor pressure; however, inhalation of the mist or aerosol is to be avoided. Workplace levels for vapors and aerosols cannot exceed 50 ppm. In case of accidental release of diethylene glycol, use of a full-face positive air pressure respirator is recommended. Even though the toxicokinetics in humans is not completely understood, its toxic nature is confirmed by animal studies. Several human cases were reported in the medical literature. Several children in Haiti died in 1995 and 1996 following the consumption of medication containing diethylene glycol. Similar other cases in children were reported in other countries as well. A 24-year-old man developed encephalopathy and rapidly became quadriplegic following ingestion of a solution containing diethylene glycol . Thus, the toxicity of diethylene glycol is well established.

Carcinogenicity

Weil et al. , in their longterm studies on rats of three different age levels, found only one bladder tumor in those fed diets that contained 4% diethylene glycol. This tumor was in a rat that also had bladder stones . To clarify the question of the cause of the tumor, Weil et al. implanted calcium oxalate stones or glass beads into the bladders of rats. They found that bladder tumors never developed without the presence of a foreign body in the bladder. This led to the conclusion that diethylene glycol essentially free of ethylene glycol is not a primary carcinogen.

Environmental Fate

Diethylene glycol is metabolized by alcohol dehydrogenase to toxic metabolites predominantly, HEAA and DGA. DEG can cause an anion gap metabolic acidosis, cortical necrosis resulting in permanent renal failure and neurotoxicity. DGA, not HEAA, was recently identified as being the primary nephrotoxic agent causing proximal tubule cell death. The neurotoxicity seen after DEG poisoning is only recently described. The neurotoxicity is delayed and has cranial and peripheral demyelinating sensorimotor polyneuropathy pattern. The exact mechanism of the neurotoxicity remains unclear and in the cases described in the literature, it appears to be prolonged but does show evidence of reversibility.

Toxicity evaluation

Diethylene glycol is miscible with water, has a low vapor pressure of 0.008 hPa at 25°C, a very low log Kow of 1.98, and also a low Koc. Consequently, water is the most relevant environmental compartment. Calculation according to Mackay, Level I indicates the following distribution among environmental compartments: air 0.75%, water 99.25%, soil 0%, sediment 0%; confirming the relevance of the pelagic systems.
The substance is readily biodegradable and the very low log Kow suggests a low potential for bioaccumulation.