Ethylene oxide is a flammable, colorless gas. At temperatures above 51.3 ºF it smells like ether at toxic levels. Ethylene oxide is found in the production of solvents, antifreeze, textiles, detergents, adhesives, polyurethane foam, and pharmaceuticals. It is also useful in fumigants, sterilants for spices and cosmetics, as well as during hospital sterilization of surgical equipment.
The chemical compound ethylene oxide is an important industrial chemical used as an intermediate in the production of ethylene glycol, other chemicals, and sterile for the manufacturing of rubber, paint, leather processing, Industrial Surfactants, Paper, Textile, Metal processing, Latex & Waxes, Household surfactants, Detergents, Pharmaceuticals Raw materials, Dyeing & finishing, Agrochemicals, Cosmetics raw material. Ethylene oxide is also used in other industries where heat-sensitive goods are sterilised and in the manufacture of choline chloride, glycol ethers and polyglycols. Other minor uses world-wide include its application in the manufacture of rocket propellant and petroleum demulsifiers.
History of Ethylene oxide
In 1859, French chemist Charles-Adolphe Wurtz first prepared Ethylene oxide. He prepared it by treating 2-chloroethanol with a base. Its industrial significance achieved during First World War as a precursor to both the coolant ethylene glycol and the chemical weapon mustard gas. In 1931, another French chemist discovered a means to prepare ethylene oxide directly from ethylene and oxygen, using silver as a catalyst. This method is used to produces ethylene oxide industrially.
Ethylene oxide: Production
In industry ethylene oxide is produced while ethylene and oxygen reacting on a silver catalyst at 200–300 °C. Pressures used are in the region of 1-2MPa.
Formula for this reaction is
CH2=CH2 + ½ O2 → C2H4O
The typical yield for this reaction is 70-80%, the major side reaction being combustion of ethylene to produce carbon dioxide.
Many other methods are proposed to produce ethylene oxide but no other methods are accepted by industry.
Ethylene oxide: Chemical Reactivity
The Ethylene oxide is highly reactive chemical and can react specially in the presence of a catalyst with compounds such as water, alcohols, ammonia, amines, and organic acids.
These reactions can be self-accelerating and generate considerable quantities of heat. Therefore it is most important to ensure inadvertent mixing with other chemicals, including water does not occur. It is the reactivity of ethylene oxide which makes it as important as the feedstock for the preparation of other useful chemicals. Ethylene oxide itself is used as a disinfectant, sterilising agent in controlled circumstances.
Ethylene oxide: Reactions
Most reactions are ring openings by nucleophiles.
In industry, epoxyethane is reacted with water in the presence of a sulfuric acid catalyst. A ten-fold molar excess of water is used to obtain ethylene glycol:
C2H4O + H2O → HOCH2CH2OH
Despite the large excess of water, various types of polyethylene glycol (PEG) or polyethylene oxide (PEO) are still formed as secondary products. The degree of polymerization increases as a smaller proportion of water is used:
n(CH2CH2O) + H2O → HO(CH2CH2O)nH
For example, under the right conditions it can give diethylene glycol (HOCH2CH2OCH2CH2OH), triethylene glycol, etc.
Similarly, reaction with ammonia can yield ethanolamine, diethanolamine, or triethanolamine.
Ethylene oxide is also important in the manufacture of surfactants and other detergents, in a process called ethoxylation.
One class of ethylene oxide derivatives that has attracted much scientific attention is the crown ethers, which are cyclic oligomers of ethylene oxide. These compounds have the ability to make ionic compounds such as salts soluble in nonpolar solvents which they otherwise could not dissolve in. However, the high cost of these compounds has largely confined their use to the laboratory rather than industrial practice.
Ethylene oxide: Physical and Chemical Properties
- Ethylene oxide is a colorless gas with a sweet odor.
- The chemical formula for ethylene oxide is C2H4O and the molecular weight is 44.1 g/mol.
- The vapor pressure for ethylene oxide is 1,095 mm Hg at 20 °C, and it has an octanol/water partition coefficient of -0.30.
- Ethylene oxide is very soluble in water and is flammable.
- Ethylene oxide has an odor threshold of 430 ppm.
- Ethylene oxide has an estimated half-life in air ranging from 69 to 149 days, while its half-life in water is about 50 years.
- Density: 1.80 g/L @ 25ºC
- Boiling point: 10.6ºC
- Melting point: 111.6ºC
- Vapor pressure: 1095 torr @ 20ºC
- Conversion factor: 1 ppm = 1.80 mg/m3
Ethylene oxide: Health effects
Ethylene oxide is toxic by inhalation. Symptoms of overexposure include headache and dizziness, progressing with increasing exposure to convulsions, seizure and coma. It is also an irritant to skin and the respiratory tract, and inhaling the vapors may cause the lungs to fill with fluid several hours after exposure.
Ethylene oxide is usually stored as a pressurized or refrigerated liquid. At room temperature and pressure, it rapidly evaporates, potentially causing frostbite in cases of skin exposure. Laboratory animals exposed to ethylene oxide for their entire lives have had a higher incidence of liver cancer. However, studies on human beings who have worked with ethylene oxide for extended periods and may have experienced low doses during that time have found no increase in cancer risk. Chronic ethylene oxide exposure may increase the risk of cataracts in humans.
In animals, ethylene oxide can cause numerous reproductive effects, including mutations and a higher rate of miscarriages. Its reproductive effects on humans have not been well studied, but it is considered probable that ethylene oxide exposure has similar effects on human reproduction.
A chemical compound is a chemical substance consisting of chemically bonded chemical elements, with a fixed ratio determining the composition. For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to every oxygen atom.
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