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8


Teoret. i eksperim. khimiya. 2006. Vol.42 No. 5. p. 306-311

Mechanism of Catalytic Action of Mechanically Pre-Activated K2PtCl4 Salt
for Gas-Phase Acetylene Hydrochlorination

 

R. S. Mitchenko1, A. A. Shubin1, T. V. Krasnyakova2


1 Donetsk State University for Trade and Economics
Vul. Shchorsa, 31, Donetsk 83050, Ukraine. Е-mail: samit@skif.net

2 Lugansk National Pedagogic University
Vul. Oboronna, 2, Lugansk 91011, Ukraine


The heterogeneous catalyst for acetylene hydrochlorination by gaseous HCl can be formed by mechani- cal activation of solid K2PtCl4 salt in the atmosphere of acetylene, ethylene or propylene as a result of for- mation in the solid matrix surface layers of π-complexes which serve as active sites. The limiting stage for the catalytic reaction is chloroplatination of π-coordinated acetylene under the action of HCl molecule. The reaction proceeds as a result of concert breaking of H-Cl and Pt-Cl bonds in the chloro platinum complex located nearby to π-acetylene complex and simultaneous formation of intermediate β-chlorovinyl platinum(II) derivative, platinum complex with a coordination vacancy [PtCl*3]-, and a new НСl molecule. Fast protonolysis of the formed Pt-C σ-bond under the action of HCl closes the cata- lytic cycle yielding the final product and starting [PtCl4]2- complex.


Key word acetylene, hydrochlorination, heterogeneous catalysis, reaction mechanism, mechanical activation, plati-
num complexes.