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Industrial Uses

DEG has numerous industrial applications, including use as an antifreeze agent, chemical intermediary, solvent, heat transfer fluid, brake fluid, cement processing, and lubricant.

Toxicity

While DEG itself has low toxicity, it undergoes biotransformation in the liver, leading to the production of highly toxic metabolites such as 2-hydroxyethoxyacetic (2-HEAA) and diglycolic acid (DGA). These metabolites can persist in the body for a long time and cause acute toxic syndrome, resulting in renal failure due to cortical tubular degeneration and proximal tubular necrosis.

Adulteration in Pharmaceuticals

DEG has been mistakenly used as a less expensive alternative to glycerin in pharmaceutical preparations, resulting in fatal poisonings. Clinical manifestations of DEG poisoning include hepatotoxicity, metabolic acidosis, and acute kidney injury.

Analytical Detection

Various analytical methods, including gas chromatography with flame ionization detection (GC-FID) and ultra-performance liquid chromatography鈥搕ime of flight mass spectrometry (UHPLC-MS), have been developed to detect DEG in pharmaceuticals, healthcare products, alcoholic beverages, toothpaste, food items, and even human plasma.

Textile Printing

DEG has been utilized in digital inkjet printing technology for textile printing. Addition of DEG can improve the printability of reactive dye inks, change the aggregation of dye molecules, inhibit formation of satellite droplets, and enhance color strength and brightness in printed fabrics.

Application

Diethylene glycol has many industrial uses. It is a component of antifreeze, brake fluids, cosmetics, inks, and drying agents, and it is used as a plasticizer. In antifreeze solution for sprinkler systems, water seals for gas tanks, etc. (water with 40% diethylene glycol freezes at -18°; with 50% at -28°); as lubricating and finishing agent for wool, worsted, cotton, rayon, and silk; as solvent for vat dyes; in composition corks, glues, gelatin, casein, and pastes to prevent drying out.

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 .

General Description

Diethylene glycol appears as a colorless liquid. Denser than water. Contact may slightly irritate skin, eyes and mucous membranes. May be slightly toxic by ingestion. Used to make other chemicals.

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.

Flammability and Explosibility

Nonflammable

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.