Stereoselectivity of Acetylene Hydrochlorination over Supported PdCl₂/С Catalysts

Abstract

The products of catalytic hydrochlorination of acetylene-D2 over palladium chloride complexes supported on activated carbon are a mixture of vinyl chloride stereoisomers resulting from syn- and anti-addition of the hydrogen chloride molecule to the triple bond. The reaction is accompanied by isomerization of primary trans-vinyl chloride into its cis-stereoisomer, but the characteristic isomerization times exceed significantly the duration of acetylene hydrochlorination. This fact allowed us to estimate the portion of products formed exclusively during the catalytic reaction, the difference in the effective activation energies of the syn- and anti-addition routes (~21 kJ/mol), and to demonstrate a monotonic increase in the part of the syn-addition product with increasing mass loading ω of the active metal, reaching saturation at ω 2 wt %.