Ethylene is a colorless, flammable gas with a faint odor that is sweet and musty. It is nontoxic and has been used as an anesthetic (but is generally no longer used for this purpose in the United States and Canada).
Ethylene is widely used in chemical industry, and its worldwide production (over 109 million tons in 2006) exceeds that of any other organic compound. Ethylene is also an important natural plant hormone, used in agriculture to force the ripening of fruits.
The hazardous properties of ethylene are its flammability and its potential to cause asphyxia by displacement of air with the resultant lowering of the oxygen content below that necessary to support life.
Chemically, ethylene reacts chiefly by addition to give saturated paraffins or derivatives of paraffin hydrocarbons. Ethylene is widely used as a raw material in the synthetic, organic chemical industry. It is shipped as a gas at about 1250 psig at 70°F (8620 kPa at 21.1oC). Below 50oF (10.0oC) at such charging pressure, it is a liquefied gas in the cylinder.
Safety, Storage and Handling
Ethylene poses hazards to personnel through its flammability, and the precautions necessary for the safe handling of any flammable gas must be observed in its use. It is important that ignition sources be kept away from containers, including situations in which leakage could cause the gas to be ignited by such sources as a spark from a motor. All piping and equipment used with ethylene should be grounded.
Ethylene should not be stored with cylinders containing oxygen, chlorine, or other oxidizing or combustible materials.
When used for anesthesia, ethylene is a nontoxic gas found pleasant and nonirritating by patients. Prolonged inhalation of substantial concentrations results in unconsciousness; light and moderate anesthesia is attained, and deep anesthesia seldom occurs. Inhalation is fatal only if the gas acts as a simple asphyxiant, depriving the body of necessary oxygen. Because of its flammability, however, other agents have replaced ethylene for use in anesthesia in the United States and Canada.
No deleterious action by ethylene on circulatory, respiratory, or other systems or organs has been observed. Exhalation eliminates the major portion of ethylene within minutes, although complete desaturation from body fat takes several hours. Minute traces can be detected in the blood a number of hours after anesthesia has ended.
Handling Leaks and Emergencies:
To detect leaks from containers, connections, or piping, use a soapy water solution. Leaks will be indicated by the formation of bubbles. Alternative means of detection involve the use of instrumental methods. Never use a flame for leak detection.
All sources of ignition should be eliminated at once. If practical, a leaking ethylene cylinder should be moved to a safe area and plainly tagged as defective. Warnings should be posted in the area to prevent person from approaching the cylinder with lit cigarettes or open flames.
Inhalation – Inhalation of low concentrations can be remedied by promptly going to an uncontaminated area and inhaling fresh air. In the event of a massive exposure wherein the victim has become unconscious or symptoms of asphyxiation may persist, the person should be removed promptly to an uncontaminated atmosphere and given artificial respiration if breathing has stopped. This should be followed by oxygen after breathing has been restored.
Skin Contact – Contact of liquid ethylene with the skin can result in frostbite. In case of frostbite from exposure to ethylene, place the frostbitten part in water between 100oF to 105oF (37.8oC to 40.6oC) and then loosely bandage the area with a dry, sterile dressing. If warm water is not available, or is impractical to use, wrap the affected area gently in blankets. Get professional medical attention as soon as possible.
Eye Contact – In the event of eye contact with liquid ethylene, the affected eyes should be flushed with tap water for 15 minutes. If irritation persists, the patient should be referred to a physician.
Ethylene finds use in the manufacture of ethyl benzene, ethanol, ethylene oxide, ethylene glycol, and ethylene dichloride. About half of the ethylene produced in the United States is used for the production of high- and low-density polyethylene plastics. Other chemical raw materials made with ethylene include ethyl chloride, dichloroethane, vinyl chloride, ethyl ether, methyl acrylate, and styrene.
Ethylene is also used as a refrigerant and a fuel for metal cutting and welding, and it has been used for anesthesia. It is also used to accelerate plant growth and fruit ripening.
Major industrial reactions of ethylene include in order of scale: polymerization, oxidation, halogenation and hydrohalogenation, alkylation, hydration, oligomerization, and hydroformylation. In the United States and Europe, approximately 90% of ethylene is used to produce three chemical compounds—ethylene oxide, ethylene dichloride, and ethylbenzene—and a variety of kinds of polyethylene.
|Chemical Industry||Polymerization: packaging, carrier bags and trash liners|
|Chemical Industry||Oxidation: production of surfactants and detergents by ethoxylation|
|Chemical Industry||Hydrolyzed to produce ethylene glycol (automotive antifreeze)|
|Agriculture||Faster fruit ripening|