Chemical Reactivity of Ethylene Glycol with Oxygen

The basic member of the glycol group of organic molecules is ethylene glycol, commonly abbreviated as ethane-1,2-diol. An alcohol having two hydroxyl groups on adjacent carbon atoms is classified as a glycol (a 1,2-diol). Ethylene glycol’s common name simply translates to “ethylene glycol.”

Ethylene Glycol

Ethylene glycol is a natural product. It’s also referred to as Ethane-1,2-diol or Monoethylene glycol and is extremely poisonous. It has no odour and is viscous. Ethylene glycol has a sweet taste and is colourless. It looks to be a colourless, transparent liquid. Ethylene glycol is widely used in the plastic industry like an antifreeze and a raw ingredient. Whenever ethylene oxide combines with water, it produces ethylene oxide.

The most commonly produced diol is ethylene glycol. It’s one of the polyethylene terephthalate monomers. 

Production

Industrial routes

Ethylene glycol is made from ethylene (ethene) and ethylene oxide as an intermediate. As per the chemical equation, ethylene oxide interacts with water to generate ethylene glycol:

C₂H₄O + H₂O → HO – CH₂CH₂ – OH  

This reaction can be catalysed by acids or bases, and it can take place at neutral pH and at high temperatures. Ethylene glycol production is maximum whenever the pH is acidic or neutral and there is a substantial amount of water present. Ethylene glycol productivity of 90% can be obtained under these conditions. The oligomers diethylene glycol, triethylene glycol, and tetraethylene glycol are the most common byproducts. It takes a lot of energy to separate these oligomers from water. A total of 6.7 million tonnes are manufactured each year.

Biological routes

Galleria mellonella, the caterpillar of the Greater wax moth, possesses stomach bacteria that can convert polyethylene (PE) into ethylene glycol.

Historical routes

According to most sources, ethylene glycol was first produced in 1856 by French chemist Charles-Adolphe Wurtz (1817–1884).  He used silver acetate to treat “ethylene iodide”, then potassium hydroxide to hydrolyze the resulting “ethylene diacetate.” Wurtz gave his new molecule the name “glycol” since it has properties similar to both ethyl alcohol (which has one hydroxyl group) and glycerin (with three hydroxyl groups). Wurtz created ethylene glycol by hydrating ethylene oxide in 1859. Prior to World War I, there appears to have been no commercial synthesis or use of ethylene glycol, which was produced from ethylene dichloride in Germany and employed as a glycerol alternative in the explosives industry.

Learn About the Chemical Reactivity of Ethylene Glycol with Oxygen

The Chemical Reaction of Ethylene Glycol

For carbonyl groups, ethylene glycol is used as a protective group. 1,3-dioxolane is produced by reacting a ketone or aldehyde with ethylene glycol in the presence of an acid catalyst. This is resistant to nucleophiles and bases. Following that, acid hydrolysis operations remove the 1,3-dioxolane protective group. Isophorone, for instance, is protected by ethylene glycol and p-toluenesulfonic acid. To shift the equilibrium to the right, water is eliminated using an azeotropic distillation method.

C₂H₆O₂ + 5/2O₂ –> 2CO₂ + 3H₂O  △H⁰ = -1,120kJmol^-1

Formula of Ethylene Glycol

The formula of Ethylene Glycol is given as

C₂H₆O₂ 

Uses

Coolant and heat-transfer agent

Ethylene glycol is most frequently employed as an antifreeze agent in coolants in autos and air-conditioning systems where the chiller or air handlers are located outside or must cool below the freezing temperature of water. Ethylene glycol is the fluid which carries heat through a geothermal heat pump in geothermal heating and cooling systems. Based on whether the system is employed for heating or cooling, the ethylene glycol either acquires energy from the source (lake, ocean, water well) or dissipates heat to the sink.

Precursor to polymers

Ethylene glycol is a key ingredient in the production of polyester fibres and resins in plastics industry. Ethylene glycol is used to create polyethylene terephthalate, which is used to make soft drink bottles.

Dehydrating agent

Ethylene glycol, like triethylene glycol, is employed in natural gas industry to remove water vapour from natural gas before further processing (TEG).

Hydrate inhibition

Ethylene glycol is an effective desiccant due to its high boiling point and affinity for water. In long multiphase pipelines that transport natural gas from remote gas fields to a gas processing facility, ethylene glycol is extensively employed to prevent the formation of natural gas clathrates (hydrates). After purification to remove water and inorganic ions, ethylene glycol can be retrieved from natural gas and employed as an inhibitor.

Toxicity of Ethylene Glycol

Humans are somewhat hazardous to ethylene glycol. Its sweet fragrance attracts children and animals, posing a serious threat. Whenever ethylene glycol is consumed, it is converted to glycolic acid. This oxidised to form oxalic acid, that is poisonous. It and its poisonous metabolites have the greatest impact on the body’s central nervous system, followed by the heart, and finally the kidneys. If more ethylene glycol is consumed, it can be lethal if left untreated. Ethylene glycol is responsible for several deaths per year in the United States alone.

Conclusion

Ethylene glycol is a common industrial component that can be found in a variety of consumer goods. Antifreeze, hydraulic brake fluids, stamp pad inks, ballpoint pens, solvents, paints, plastics, films, and cosmetics are just a few instances. It could also be used as a delivery system for pharmaceuticals. Ethylene glycol has a sweet flavour and is frequently swallowed, either accidentally or intentionally. In the body, ethylene glycol degrades into harmful chemicals. The central nervous system (CNS), then the heart, and ultimately the kidneys are all affected by ethylene glycol and its harmful metabolites. It is possible to die if you consume too much. Ethylene glycol has no odour.