Industrial uses of halogenated hydrocarbons
Few organic halides have direct use industrially. They are generally converted into other intermediate substances. For example, one of these substances is used to make vinyl chloride, the building block for polyvinyl chloride. Polyvinyl chloride is noted for its hardness and resistance to chemicals. It is used in the production of floor coverings, pipes, and fabrics. Another important halogenated hydrocar-
Organic chemistry: Halogenated hydrocarbons 79
Long-chain polymer molecule of polyvinyl chloride (PVC)
Polyvinyl chloride(PVC) is
a long-chain halogenated polymer. It can be made from ethene and chlorine in three main stages (illustrated left. In the first stage, ethene is heated with chlorine to produce 1,2-dichloroethane. In the second stage, the 1,2-dichloro-ethane is heated under pressure to produce chloro-ethene and hydrogen chloride. After the hydrogen chloride has been removed, the pure chloroethene then remaining is heated in the presence of a catalyst to form PVC.
bon is methyl chloroform, which is used for degreasing, cleaning drains, and dissolving other substances. It is made via several synthetic steps from vinyl chloride.
Natural gas provides the principal source of compounds containing methane and a halogen. These include trichloromethane (chloroform) and tetrachloromethane (carbon tetrachloride). These two substances are used mainly as starting materials for the manufacture of fluorocarbon refrigerants called Fre-ons. Examples are trichlorofluoromethane (Freon-11) and dichlorodifluoromethane (Freon-12). These are widely used in refrigerators and air conditioners. Teflon (often used to coat the insides of cooking equipment) is also derived from a hydrocarbon containing methane, carbon, and fluorine. A synthetic rubber called Neoprene is also produced from halogen-hydrocarbon compounds.
Date: 2015-12-11; view: 2444