Ethylene glycol

Description

Ethylene glycol was first synthesized in 1859; however, it did not become a public health concern until after World War II. In fact, the first published series of deaths from ethylene glycol consumption involved 18 soldiers who drank antifreeze as a substitute for ethanol. Despite the early recognition that patients who drank ethanol in addition to ethylene glycol had prolonged survival when compared to those drinking ethylene glycol alone, antidotal treatment of ethylene glycol toxicity with ethanol was not evaluated until the 1960s. Today, ethylene glycol poisoning continues to be a public health problem, particularly in the southeastern United States. In 2009, US poison control centers received 5282 calls about possible ethylene glycol exposures, and the toxicology community believes these exposures are underreported.

Description

As much of the country enters the deep freeze of winter, becomes important as a radiator antifreeze and as a major component of many aircraft deicing solutions.

Chemical properties

Ethylene glycol,CH20HCH20H, also known as glycol,ethylene alcohol, glycol alcohol, and dihydric alcohol, is a colorless liquid. It is soluble in water and in alcohol. Ethyleneglycol has a low freezing point,-25°C (-13 OF), and is widely used as an antifreeze in automobiles and in hydraulic fluids. It is used as a solvent for nitrocellulose and in the manufacture of acrylonitrile, dynamites, and resins.

Chemical properties

Ethylene glycol is a colorless, viscous, hydroscopic liquid with a sweetish taste. Often colored fluorescent yellow-green when used in automotive antifreeze. Ethylene glycol is odorless and does not provide any warning of inhalation exposure to hazardous concentrations. The Odor Threshold in air is 25 ppm.

The Uses of Ethylene glycol

Ethylene glycol is used as an antifreeze inheating and cooling systems (e.g., automobileradiators and coolant for airplane motors).It is also used in the hydraulic brake fluids;as a solvent for paints, plastics, and inks; as a softening agent for cellophane; and in themanufacture of plasticizers, elastomers, alkydresins, and synthetic fibers and waxes.

The Uses of Ethylene glycol

Reagent typically used in cyclocondensation reactions with aldehydes1 and ketones1,2 to form 1,3-dioxolanes.

The Uses of Ethylene glycol

Antifreeze in cooling and heating systems. In hydraulic brake fluids and de-icing solutions. Industrial humectant. Ingredient of electrolytic condensers (where it serves as solvent for boric acid and borates). Solvent in the paint and plastics industries. In the formulation of printers' inks, stamp pad inks, ball-point pen ink. Softening agent for cellophane. Stabilizer for soybean foam used to extinguish oil and gasoline fires. In the synthesis of safety explosives, glyoxal, unsatd ester type alkyd resins, plasticizers, elastomers, synthetic fibers (Terylene, Dacron), and synthetic waxes. To create artificial smoke and mist for theatrical uses.

What are the applications of Application

Ethylene glycol is a useful chemical for immuno-affinity chromatography

Definition

ChEBI: A 1,2-glycol compound produced via reaction of ethylene oxide with water.

Production Methods

Historically, ethylene glycol has been manufactured by hydrolyzing ethylene oxide. Presently, it is also produced commercially by oxidizing ethylene in the presence of acetic acid to form ethylene diacetate, which is hydrolyzed to the glycol, and acetic acid is recycled in the process .

Preparation

Ethylene glycol is prepared by the hydration of ethylene oxide:

This reaction is carried out in a manner comparable to that described for the preparation of propylene glycol from propylene oxide . Ethylene glycol is a colourless liquid, b.p. 197??C.

Reactions

Glycol reacts (1) with sodium to form sodium glycol, CH2OH · CH2ONa, and disodium glycol, CH2ONa·CH2ONa; (2) with phosphorus pentachloride to form ethylene dichloride, CH2Cl·CH2Cl (3) with carboxy acids to form mono- and disubstituted esters, e.g., glycol monoacetate, CH2OH·CH2OOCCH3, glycol diacetate, CH3COOCH2 · CH2OOCCH3; (4) with nitric acid (with sulfuric acid), to form glycol mononitrate, CH2OH·CH2ONO2, glycol dinitrate, CH2ONO2 · CH2ONO2; (5) with hydrogen chloride, heated, to form glycol chlorohydrin (ethylene chlorohydrin, CH2OH·CHCl); (6) upon regulated oxidation to form glycollic aldehyde, CH2OH·CHO, glyoxal, CHO · CHO, glycollic acid, CH2OH·COOH, glyoxalic acid, CHO·COOH, oxalic acid, COOH·COOH.

General Description

Ethylene glycol is a clear, colorless syrupy liquid. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. Since Ethylene glycol is a liquid Ethylene glycol can easily penetrate the soil and contaminate groundwater and nearby streams.

Reactivity Profile

Mixing Ethylene glycol in equal molar portions with any of the following substances in a closed container caused the temperature and pressure to increase: chlorosulfonic acid, oleum, sulfuric acid, [NFPA 1991].

Hazard

Questionable carcinogen. Toxic by ingestion and inhalation. Lethal dose reported to be 100 cc.

Health Hazard

Inhalation of vapor is not hazardous. Ingestion causes stupor or coma, sometimes leading to fatal kidney injury.

Health Hazard

The acute inhalation toxicity of 1,2-ethanediolis low. This is due to its low vaporpressure, 0.06 torr at 20°C (68°F). Its saturationconcentration in air at 20°C (68°F)is 79 ppm and at 25°C (77°F) is 131 ppm(ACGIH 1986). Both concentrations exceedthe ACGIH ceiling limit in air, which is50 ppm. In humans, exposure to its mist orvapor may cause lacrimation, irritation ofthroat, and upper respiratory tract, headache,and a burning cough. These symptoms maybe manifested from chronic exposure toabout 100 ppm for 8 hours per day for severalweeks.
The acute oral toxicity of 1,2-ethanediol islow to moderate. The poisoning effect, however,is much more severe from ingestionthan from inhalation. Accidental ingestion of80–120 mL of this sweet-tasting liquid canbe fatal to humans. The toxic symptoms inhumans may be excitement or stimulation,followed by depression of the central nervoussystem, nausea, vomiting, and drowsiness,which may, in the case of severe poisoning,progress to coma, respiratory failure, anddeath. When rats were administered sublethaldoses over a long period, there was depositionof calcium oxalate in tubules, causinguremic poisoning.
LD50 value, oral (rats): 4700 mg/kg
Ingestion of 1,2-ethanediol produced reproductiveeffects in animals, causing fetotoxicity, postimplantation mortality, andspecific developmental abnormalities. Mutagenictests proved negative. It tested negativeto the histidine reversion–Ames test.

Fire Hazard

Ethylene glycol is combustible.

Flammability and Explosibility

Not classified

Biochem/physiol Actions

Ethylene glycol is a low toxicity molecule and is used for embryo cryopreservation in many domestic animals.Ethylene glycol 5M solution is an additive screening solution of Additive Screening Kit. Additive Screen kit is designed to allow rapid and convenient evaluation of additives and their ability to influence the crystallization of the sample. The Additive Kit provides a tool for refining crystallization conditions.

Safety Profile

Human poison by ingestion. (Lethal dose for humans reported to be 100 mL.) Moderately toxic to humans by an unspecified route. Moderately toxic experimentally by ingestion, subcutaneous, intravenous, and intramuscular routes. Human systemic effects by ingestion and inhalation: eye lachrymation, general anesthesia, headache, cough, respiratory stimulation, nausea or vomiting, pulmonary, kidney, and liver changes. If ingested it causes initial central nervous system stimulation followed by depression. Later, it causes potentially lethal kidney damage. Very toxic in particulate form upon inhalation. An experimental teratogen. Other experimental reproductive effects. Human mutation data reported. A skin, eye, and mucous membrane irritant. Combustible when exposed to heat or flame; can react vigorously with oxidants. Moderate explosion hazard when exposed to flame. Iptes on contact with chromium trioxide, potassium permanganate, and sodium peroxide. Mixtures with ammonium dichromate, silver chlorate, sodium chlorite, and uranyl nitrate ipte when heated to 100°C. Can react violently with chlorosulfonic acid, oleum, H2SO4, HClO4, and Pass. Aqueous solutions may ignite silvered copper wires that have an applied D.C. voltage. To fight fire, use alcohol foam, water, foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes.

Potential Exposure

Ethylene glycol is used in antifreeze (especially as car radiator antifreeze) and in production of polyethylene terephthalate fibers and films; in hydraulic fluids; antifreeze and coolant mixtures for motor vehicles; electrolytic condensers; and heat exchangers. It is also used as a solvent and as a chemical intermediate for ethylene glycol dinitrate, glycol esters; resins, and for pharmaceuticals.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, getmedical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit

Environmental Fate

Ethylene glycol is considered an inert ingredient in pesticides. It typically enters the environment through waste streams after use of deicing products, where it is highly mobile in soil and contaminates groundwater. Ethylene glycol is considered ‘readily biodegradable.’ It biodegrades relatively quickly; its half-life (t1/2) is 2–12 days in soil.
Ethylene glycol is biodegraded in water under both aerobic and anaerobic conditions within a day to a few weeks. In the atmosphere, ethylene glycol photochemically degrades with a t1/2 of approximately 2 days.

Solubility in organics

Miscible with water and alcohol, soluble in lower atifatic alcohols and ketones, Propylene glycol and Glycerin, poorly soluble in Hydrocarbons such as Terpenes as well as in Terpene alcohols, esters, etc.

storage

Color Code—Green: General storage may be used.Prior to working with this chemical you should be trainedon its proper handling and storage. Before entering confinedspace where this chemical may be present, check to makesure that an explosive concentration does not exist.Ethylene glycol must be stored to avoid contact with sulfuric acid since violent reactions occur. Store in tightly closedcontainers in a cool, well-ventilated area away from oxidizing agents (such as perchlorates, peroxides, permanganates,chlorates, and nitrates).

Shipping

UN3082 Environmentally hazardous substances, liquid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required

Purification Methods

It is very hygroscopic, and also likely to contain higher diols. Dry it with CaO, CaSO4, MgSO4 or NaOH and distil it under vacuum. Dry further by reaction with sodium under nitrogen, reflux for several hours and distil. The distillate is then passed through a column of Linde type 4A molecular sieves and finally distil under nitrogen, from more molecular sieves. Then fractionally distil it. [Beilstein 1 IV 2369.]

Toxicity evaluation

Ethylene glycol has low toxicity but it is metabolized to a variety of toxic metabolites. Ethylene glycol and glycolaldehyde have an intoxicating effect on the central nervous system that can lead to ataxia, sedation, coma, and respiratory arrest similar to ethanol intoxication. However, the profound metabolic acidosis reported in toxicity is secondary to accumulation of acid metabolites, especially glycolic acid. The oxalic acid metabolite complexes with calcium and precipitates as calcium oxalate crystals in the renal tubules, leading to acute renal injury. Further, oxalate’s ability to chelate calcium may cause clinically relevant serum hypocalcemia.

Incompatibilities

Reacts with sulfuric acid, oleum, chlorosulfonic acid; strong oxidizing agents; strong bases; chromium trioxide; potassium permanganate; sodium peroxide. Hygroscopic (i.e., absorbs moisture from the air)

Waste Disposal

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed. Alternatively, ethylene glycol can be recovered from polyester plant wastes