Ethylene

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Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula C_2H_4. It is a colorless flammable gas with a faint "sweet and musky" odor when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds).

Production

Ethylene is produced in the petrochemical industry by steam cracking. In this process, hydrocarbon feedstocks such as ethane, propane, butane, and naphtha are heated to 750–950 °C, inducing numerous free radical reactions. Ethylene is separated from the resulting complex mixture by repeated compression and distillation.

Uses

Ethylene is widely used in the chemical industry, and its worldwide production (over 150 million tonnes in 2016) exceeds that of any other organic compound. Much of this production goes toward the manufacture of polyethylene, a widely used plastic containing polymer chains of ethylene units in various chain lengths. Ethylene is also an important natural plant hormone, used in agriculture to force the ripening of fruits.

Polyethylene Production

Polyethylene, the most common plastic, is primarily produced from ethylene. It is used in a variety of products, from plastic bags to bottles and toys. The polymerization of ethylene can be carried out using different catalysts, including Ziegler-Natta catalysts and metallocene catalysts.

Ethylene Oxide

Ethylene is also used to produce ethylene oxide, which is subsequently converted into ethylene glycol. Ethylene glycol is used as an antifreeze and in the production of polyester.

Other Uses

Ethylene is used in the production of styrene, which is the precursor to polystyrene, a common plastic material. It is also used in the production of vinyl chloride, which is used to make polyvinyl chloride (PVC).

Biological Role

Ethylene acts as a plant hormone, influencing a wide range of biological processes. It is involved in the regulation of fruit ripening, flower wilting, and leaf fall. Ethylene is produced by plants in response to stress conditions such as drought, flooding, mechanical wounding, and infection.

Safety

Ethylene is highly flammable and poses a significant fire and explosion hazard. It is classified as an asphyxiant gas, which can displace oxygen in the air and pose a suffocation risk in confined spaces.

See also

• Alkene
• Polyethylene
• Ethylene oxide
• Plant hormone
• Petrochemical industry