text: Chlorination is one of the oldest known substitution reactions in chemistry. The French chemist Jean-Baptiste Dumas investigated the substitution of hydrogen for chlorine by acetic acid in candle wax as early as 1830. He showed that for each mole of chlorine introduced into a hydrocarbon, one mole of hydrogen chloride is also formed and noted the light-sensitivity of this reaction.
  The idea that these reactions might be chain reactions is attributed to Max Bodenstein (1913). He assumed that in the reaction of two molecules not only the end product of the reaction can be formed, but also unstable, reactive intermediates which can continue the chain reaction.
  Photochlorination garnered commercial attention with the availability of cheap chlorine from chloralkali electrolysis.
  Chlorinated alkanes found an initial application in pharyngeal sprays. These contained chlorinated alkanes in relatively large quantities as solvents for chloramine T from 1914 to 1918. The Sharpless Solvents Corporation commissioned the first industrial photochloration plant for the chlorination of pentane in 1929. The commercial production of chlorinated paraffins for use as high-pressure additives in lubricants began around 1930. Around 1935 the process was technically stable and commercially successful. However, it was only in the years after World War II that a greater build-up of photochloration capacity began. In 1950, the United States produced more than 800,000 tons of chlorinated paraffin hydrocarbons. The major products were ethyl chloride, tetrachlorocarbon and dichloromethane. Because of concerns about health and environmentally relevant problems such as the ozone depletion behavior of light volatile chlorine compounds, the chemical industry developed alternative procedures that did not require chlorinated compounds. As a result of the following replacement of chlorinated by non-chlorinated products, worldwide production volumes have declined considerably over the years.