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Chlorohydrination

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chlorohydrination of 2-methyl-2-butene.

Chlorohydrination is the addition of hypochlorous acid to an olefinic double bond. The result is chloroalcohols, so-called chlorohydrins, in which the chlorine and the hydroxyl group are bonded to adjacent carbon atoms.[1]

Use

General structure of chlorohydrins -X=Cl

Chlorohydrins can be converted to epoxides by elimination of hydrogen chloride.

The production of epichlorohydrin is of technical importance. Chlorohydrinization of allyl chloride with hypochlorous acid yields 1,3-dichloropropan-2-ol and 2,3-dichloropropan-1-ol:

Epichlorohydrin-manufacture-step1-2D-skeletal.png

Reaction with sodium hydroxide gives racemic epichlorohydrin:

Epichlorohydrin-manufacture-step2-2D-skeletal.png

Similarly, propylene chlorohydrin (PCH) and propylene oxide are accessible by chlorohydration of propene.[2]

Literature

  • E. Bartholomé (ed.), E. Biekert (ed.), H. Hellmann (ed.): Ullmanns Encyklopädie der technischen Chemie. Wiley-VCH, 1984, ISBN 978-3527200009.

Individual references


  1. E. Buss, A. Rockstuhl, F. R. D. Schnurpfeil: Studies on the mechanism of chlorohydrination of olefins. In: Journal of Practical Chemistry. 324, 1982, pp. 197-208, doi:10.1002/prac.19823240204.
  2. Patent DE 19614683, Process for the preparation of propylene oxide by chlorohydrination and alkali metal saponification, filed April 13, 1996.