Oxychlorination

Under oxychlorination is meant the introduction of chlorine into an organic compound by means of hydrogen chloride (HCl) and oxygen (O ₂ ) or air. Both alkanes and olefins can be oxychlorinated.

execution

The oxychlorination of ethene is mainly used in the production of vinyl chloride from ethene via the 1,2-dichloroethane (EDC) stage and the subsequent elimination of hydrogen chloride. The hydrogen chloride can be used again in the original reaction.

As a catalyst , for. B. copper (II) chloride is used. The reaction takes place at temperatures above 180 ° C.

The reaction takes place via the following reaction steps:

${\displaystyle \mathrm {(1)\ C_{2}H_{4}+2\ CuCl_{2}\to \ C_{2}H_{4}Cl_{2}+2\ CuCl} }$

${\displaystyle \mathrm {(2)\ 2\ CuCl+0{,}5\ O_{2}\to \ CuO+CuCl_{2}} }$

${\displaystyle \mathrm {(3)\ CuO+2\ HCl\to \ CuCl_{2}+H_{2}O} }$

The formation of CH ₂ = CHCl takes place by thermal elimination of hydrogen chloride or by washing the EDC with alkali solution.

Alkanes are oxychlorinated at temperatures from 400 to 450 ° C in the presence of copper salts. Even methane can be chlorinated according to:

${\displaystyle \mathrm {(4)\ 2\ CH_{4}+2\ HCl+O_{2}\to \ 2\ CH_{3}Cl+2\ H_{2}O} }$

Oxychlorination requires corrosion-resistant equipment due to the relatively high temperatures and the presence of hydrogen chloride and water.

Individual evidence

1. ↑ Aliphatic intermediates (PDF; 368 kB), by Arno Behr .

literature

• Klaus Weissermel , Hans-Jürgen Arpe : Industrial organic chemistry . 6th edition. Wiley-VCH, Weinheim 2007, ISBN 978-3-527-31540-6 .