Chloroprene

Chloroprene
Chloroprene
Identifiers
CAS number 126-99-8 YesY
ChemSpider 29102 YesY
KEGG C19208 YesY
ChEBI CHEBI:39481 YesY
ChEMBL CHEMBL555660 YesY
RTECS number EL9625000
Jmol-3D images Image 1
Properties
Molecular formula C4H5Cl
Molar mass 88.5365 g/mol
Appearance Colorless liquid.
Density 0.9598 g/cm3, liquid.
Melting point

-130 °C, 143 K, -202 °F

Boiling point

59.4 °C, 333 K, 139 °F

Solubility in water 0.026 g/100 mL, liquid.
Hazards
R-phrases R45, R11, R20/22,
R36/37/38, R48/20
S-phrases S53, S45
Main hazards Highly flammable, toxic.
NFPA 704
NFPA 704.svg
3
2
0
Flash point -15.6°C
Related compounds
Related Dienes Butadiene
Isoprene
Related compounds Vinyl chloride
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Chloroprene is the common name for the organic compound 2-chlorobuta-1,3-diene, which has the formula CH2=CCl-CH=CH2. This colorless liquid is the monomer for the production of the polymer polychloroprene, a type of synthetic rubber. Polychloroprene is better known to the public as Neoprene, the trade name given by DuPont.

Contents

Production of chloroprene

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-dichloro-1-butene.

Chlorine adds to 1,3-butadiene to afford a mixture of 3,4-dichloro-1-butene and 2,3-dichloro-2-butene. The 2,3-chloro isomer is subsequently isomerized to 3,4 isomer, which in turn is treated with base to induce dehydrochlorination to 2-chlorobuta-1,3-diene. This dehydrohalogenation entails loss of a hydrogen atom in the 3 position and the chlorine atom in the 4 position thereby forming a double bond between carbons 3 and 4. In 1983, approximately 2,000,000 kg were produced in this manner.[1] The chief impurity in chloroprene prepared in this way is 1-chlorobuta-1,3-diene, which is usually separated by distillation.

Acetylene process

Until the 1960s, chloroprene production was dominated by the “acetylene process,” which was modeled after the original synthesis of vinylacetylene.[2] In this process, acetylene is dimerized to give vinyl acetylene, which is then combined with hydrogen chloride to afford 4-chloro-1,2-butadiene (an allene derivative), which in the presence of cuprous chloride, rearranges to the targeted 2-chlorobuta-1,3-diene:[1]

HC≡C-CH=CH2 + HCl → H2C=C=CH-CH2Cl
H2C=C=CH-CH2Cl → H2C=CCl-CH=CH2

This process is very energy-intensive and has high investment costs. Furthermore, the intermediate vinyl acetylene is unstable.

This "acetylene process" has been replaced by a process which adds Cl2 to one of the double bonds in 1,3-butadiene instead, and subsequent elimination produces HCl instead, as well as chloroprene.

References

  1. ^ a b Manfred Rossberg, Wilhelm Lendle, Gerhard Pfleiderer, Adolf Tögel, Eberhard-Ludwig Dreher, Ernst Langer, Heinz Rassaerts, Peter Kleinschmidt, Heinz Strack, Richard Cook, Uwe Beck, Karl-August Lipper, Theodore R. Torkelson, Eckhard Löser, Klaus K. Beutel, “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry, 2006 John Wiley-VCH: Weinheim.DOI: 10.1002/14356007.a06_233.pub2
  2. ^ Wallace H. Carothers, Ira Williams, Arnold M. Collins, and James E. Kirby (1937). "Acetylene Polymers and their Derivatives. II. A New Synthetic Rubber: Chloroprene and its Polymers". J. Am. Chem. Soc. 53 (11): 4203–4225. doi:10.1021/ja01362a042. 

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Look at other dictionaries:

  • Chloroprène — Général Nom IUPAC 2 cholorobuta 1,3 diène No CAS …   Wikipédia en Français

  • chloroprène — ● chloroprène nom masculin Chlorobutadiène CH2≅CCl―CH≅CH2, dont la polymérisation donne un caoutchouc synthétique (Néoprène ou Duprène). chloroprène [klɔʀopʀɛn] n. m. ÉTYM. Mil. XXe; de chloro , et prène (→ Néoprène). ❖ ♦ Chim., techn. Dérivé du… …   Encyclopédie Universelle

  • chloroprene — [klôr′əprēn΄] n. [ CHLORO + (ISO)PRENE] a colorless liquid, H2C:CHCCl:CH2, made from acetylene: it can be polymerized to form neoprene …   English World dictionary

  • Chloroprene — A possible carcinogen (cancer causing agent) primarily used in the production of the elastomer polychloroprene (neoprene). The US government in 2000 classified chloroprene as reasonably anticipated to be a human carcinogen. In laboratory animal… …   Medical dictionary

  • chloroprene — chlorprenas statusas T sritis chemija formulė CH₂=CClCH=CH₂ atitikmenys: angl. chloroprene rus. хлоропрен ryšiai: sinonimas – 2 chlor 1,3 butadienas …   Chemijos terminų aiškinamasis žodynas

  • chloroprene rubber — chlorpreninis kaučiukas statusas T sritis chemija formulė Formulę žr. priede. priedas( ai) Grafinis formatas atitikmenys: angl. chloroprene rubber rus. найрит; неопреновый каучук; хлоропреновый каучук ryšiai: sinonimas – neopreninis kaučiukas …   Chemijos terminų aiškinamasis žodynas

  • chloroprene — noun Etymology: chlor + isoprene Date: 1931 a colorless liquid C4H5Cl used especially in making neoprene by polymerization …   New Collegiate Dictionary

  • chloroprene — /klawr euh preen , klohr /, n. a colorless, slightly water soluble liquid, C4H5Cl, usually produced by the reaction of vinylacetylene with hydrochloric acid, that polymerizes to neoprene. [1930 35; CHLORO 2 + (ISO)PRENE] * * * …   Universalium

  • chloroprene — noun The chlorinated derivative of butadiene 2 chloro 1,3 butadiene that is used (via polymerization) in the manufacture of synthetic rubber …   Wiktionary

  • chloroprene — chlo·ro·prene …   English syllables

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