Simplest olefin (CH2CH2), a colourless, flammable gas with a sweetish taste and odour. The petrochemical having the highest volume, it occurs in petroleum and natural gas but is usually produced by heating higher hydrocarbons (usually ethane and ethane-propane mixtures). Ethylene is polymerized to polyethylene either at high pressures and temperatures or by catalysis. It reacts with numerous other chemicals to produce ethanol, solvents, gasoline additives, antifreeze, detergents, and various plastics. In plants, ethylene is a hormone that inhibits growth and promotes leaf fall and fruit ripening.
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