Butadiene, 2-chloro

As the demand for rubber increased so did the chemical industry s efforts to prepare a synthetic sub stitute One of the first elastomers (a synthetic poly mer that possesses elasticity) to find a commercial niche was neoprene discovered by chemists at Du Pont in 1931 Neoprene is produced by free radical polymerization of 2 chloro 1 3 butadiene and has the greatest variety of applications of any elastomer Some uses include electrical insulation conveyer belts hoses and weather balloons... 

Chloro 1 3 butadiene (chloroprene) is the monomer from which the elastomer neoprene IS prepared 2 Chloro 1 3 butadiene is the thermodynamically controlled product formed by addi tion of hydrogen chloride to vinylacetylene (H2C=CHC=CH) The principal product under conditions of kinetic control is the allenic chlonde 4 chloro 1 2 butadiene Suggest a mechanism to account for the formation of each product... 

Using cuprous chloride as catalyst, hydrogen chloride adds to acetylene, giving 2-chloro-1,3-butadiene [126-99-8], chloroprene, C H Cl, the monomer for neoprene mbber. 

At one time, the only commercial route to 2-chloro-1,3-butadiene (chloroprene), the monomer for neoprene, was from acetylene (see Elastomers, synthetic). In the United States, Du Pont operated two plants in which acetylene was dimeri2ed to vinylacetylene with a cuprous chloride catalyst and the vinyl-acetylene reacted with hydrogen chloride to give 2-chloro-1,3-butadiene. This process was replaced in 1970 with a butadiene-based process in which butadiene is chlorinated and dehydrochlorinated to yield the desired product (see Chlorocarbonsandchlorohydrocarbons). 

Chloroprene (qv), 2-chloro-1,3-butadiene, [126-99-8] is produced commercially from butadiene in a three-step process. Butadiene is first chlorinated at 300°C to a 60 40 mixture of the 1,2- and 1,4-dichlorobutene isomers. This mixture is isomeri2ed to the 3,4-dichloro-l-butene with the aid of a Cu—CU2CI2 catalyst followed by dehydrochlorination with base such as NaOH (54). 

Chloroprene (2-chloro-1,3-butadiene), [126-99-8] was first obtained as a by-product from tbe synthesis of divinylacetylene (1). Wben a mbbery polymer was found to form spontaneously, investigations were begun tbat prompdy defined tbe two methods of synthesis that have since been the basis of commercial production (2), and the first successbil synthetic elastomer. Neoprene, or DuPrene as it was first called, was introduced in 1932. Production of chloroprene today is completely dependent on the production of the polymer. The only other use accounting for significant volume is the synthesis of 2,3-dichloro-l,3-butadiene, which is used as a monomer in selected copolymerizations with chloroprene. 

Chemistry of polychloroprene rubber. Polychloroprene elastomers are produced by free-radical emulsion polymerization of the 2-chloro-1,3-butadiene monomer. The monomer is prepared by either addition of hydrogen chloride to monovinyl acetylene or by the vapour phase chlorination of butadiene at 290-300°C. This latter process was developed in 1960 and produces a mixture of 3,4-dichlorobut-l-ene and 1,4-dichlorobut-2-ene, which has to be dehydrochlorinated with alkali to produce chloroprene. 

Chloroprene (2-chloro 1,3-butadiene), a conjugated non-hydrocarbon diolefm, is a liquid that boils at 59.2°C and while only slightly soluble in water it is soluble in alcohol. The main use of chloroprene is to polymerize it to neoprene rubber. 

Polychloroprene is the oldest synthetic rubber. It is produced by the polymerization of 2-chloro-1,3-butadiene in a water emulsion with potassium sulfate as a catalyst ... 

Chlorobenzylidene malononitrile (OCBM) Chlorobromomethane/bromochloromethane 2-Chloro-1,3-butadiene, see (l-Chloroprene Chlorodiphenyl (42% chlorine)... 

Chloro pink, 9 310-311 Chloroplast transit peptide, 72 489 TV-Chloropolyacrylamides, 7 316 Chloroprene, 6 242, 246. See also 2-Chloro-1,3- butadiene from butadiene, 4 369 chlorocarbon/chlorohydrocarbon of industrial importance, 6 227t copolymerization of, 79 829-830 end use of chlorine, 6 134t removal in vinyl chloride manufacture, 25 642... 

See Nitrogen oxide Dienes, Oxygen See 2-Chloro-1,3-butadiene Preparative hazard f 1-Butene, 1577 f c/.s-2-Butenc, 1578 f tram-2-Butene, 1623... 

Bis-(2-methoxyethyl) ether, 2549 f 1,3-Butadiene, 1480 f 1,3-Butadiyne, 1385 f 2-Butanol, 1695 f Buten-3-yne, 1423 f Butyl ethyl ether, 2540 f Butyl vinyl ether, 2484 f 2-Chloro-1,3-butadiene, 1451 f Chloroethylene, 0730 f 2-Chloroethyl vinyl ether, 1557... 

Synonyms CCRIS 873 Chlorobutadiene 2-Chlorobutadiene-l,3 2-Chlorobuta-1,3-diene 2-Chloro-1,3-butadiene p Chloroprene EINECS 204-818-0 Neoprene NSC 18589 UN 1991. 

Chloroprene Elastomers. Polychloroprene is a polymer of 2-chloro-1,3-butadiene. The elastomer is largely composed of the trans isomer. There are two basic polymer types the W-type and the G-type. G-types are made by using a sulfur-modified process W-types use no sulfur modification. As a result, G-types possess excellent processing and dynamic properties, and tend to be used in V-belts. However, they have poorer aging properties than W-types. The W-types tend to be used in applications requiring better aging, such as rolls and mechanical goods (see Elastomers,... 

---