Beta-Chloroprene

Chloroprene is the common name for 2-chlorobuta-1,3-diene (IUPAC name) with the chemical formula CH2=CCl−CH=CH2. Chloroprene is a colorless volatile liquid, almost exclusively used as a monomer for the production of the polymer polychloroprene, a type of synthetic rubber. Polychloroprene is better known as Neoprene, the trade name given by DuPont.Although it may have been discovered earlier, the chemistry of chloroprene was largely developed by DuPont during the early 1930's, specifically with the formation of neoprene in mind. The chemists Elmer K. Bolton, Wallace Carothers, Arnold Collins and Ira Williams are generally accredited with its development and commercialisation although the work was based upon that of Julius Arthur Nieuwland, with whom they collaborated.Chloroprene is produced in three steps from 1,3-butadiene: (i) chlorination, (ii) isomerization of part of the product stream, and (iii) dehydrochlorination of 3,4-dichlorobut-1-ene.Transportation of uninhibited chloroprene has been banned in the United States by the US Department of Transportation. Stabilized chloroprene is in hazard class 3 (flammable liquid). Its UN number is 1991 and is in packing group 1.As a way to visually communicate hazards associated with chloroprene exposure, the United Nations Globally Harmonized System of Classification and Labeling of Chemicals (GHS) has designated the following hazards for exposure to chloroprene: flammable, toxic, dangerous to the environment, health hazard and irritant. Chloroprene poses fire hazard (flash point -4 °F). OSHA identifies chloroprene as a category 2 flammable liquid and emphasizes that at least one portable fire extinguisher should be within 10 and no more than 25 feet away from the flammable liquid storage area. OSHA provides resources on addressing flammable liquids at industrial plants which is where the likely exposure to chloroprene exists (see external resources). As a vapor, chloroprene is heavier than air.Since chloroprene usage is limited to those facilities producing Neoprene, the occupational health risks are isolated to those facilities. However, insufficient control of chloroprene emissions may extend the health and safety concerns of chloroprene beyond the facility and into the surrounding areas. Chloroprene release is predominately as an air pollutant, but other feasible fates and transport of chloroprene in the environment are discussed below.