Catalytic hydrochlorination of acetylene on mechanochemically-activated K2PdCl4

Abstract

We report the catalysis of the hydrochlorination of acetylene on the surface of dry K 2 PdCl 4 subjected to prior mechanical activation in an atmosphere of acetylene or propylene. The stereochemistry of the reaction corresponds to trans addition of the halogen and hydrogen atoms to the C-C triple bond. The hydrogen halide is the source of the halogen atom in the reaction product. The mechanical activation of K 2 PdCl 4 , in contrast to the case of K 2 PtCl 4 , is also capable of activating the C-C double bond: propylene is hydrochlorinated under similar conditions to isopropyl chloride.Petroleum and natural gas are the major raw material sources for basic organic synthesis. Starting in the middle of the twentieth century, the use of these sources led to a change in the technology of the large-scale manufacture of many chemical products with reorientation to the use of olefinic raw materials and synthesis gas. Nevertheless, some processes for the large-scale manufacture of products such as vinyl ethers, pyrrolidone, N-methylpyrrolidone, and butanediol and the smaller-scale production of drugs, fragrances, and plant protection chemicals using acetylene have certain advantages and continue to be employed. Furthermore, acetylenic hydrocarbons are inevitably formed in the preparation of olefins from petroleum and natural gas. The use of these acetylenic hydrocarbons is dictated by the current scale of production and the cost of raw materials. On the other hand, in contrast to the case of petroleum, the reserves of coal and natural gas permit us to regard these materials as virtually inexhaustible sources of acetylene. In particular, the increasing interest in the chemistry of acetylene is clearly a function of these considerations (see the reviews of Beletskaya [1, 2]).One of the industrial methods for the manufacture of vinyl chloride involves the hydrochlorination of acetylene catalyzed by HgCl 2 on activated charcoal [3]. The high toxicity of this mercury catalyst and its relative instability [4] have led to a search for other catalytic systems. The hydrochlorination of acetylene under homogeneous conditions is catalyzed by various metal salts containing Cu I , Au III , Pd II , and Pt II [3]. The Pt II and Pd II complexes in solution have high activity but are very unstable. Under heterogeneous conditions, Au III [5, 6] and Rh III complexes [7] on activated charcoal catalyze the hydrochlorination of acetylene but these reactions require elevated temperature (170-180°C). Recently, we have discovered the catalysis of acetylene hydrochlorination on the surface of mechanically-activated K 2 PtCl 6 [8] and K 2 PtCl 4 [9]. We might 316 0040-5760/08/4405-0316

Effect of mechanicochemical treatment on the activity of K2PdCl4 in the heterogeneous catalytic hydrochlorination of acetylene

“…The preparation of the catalyst and the kinetic study with gas-liquid monitoring of the substrate and product concentrations were carried out as in our previous work [8]. The relative acetylene concentration ö(RH) was defined as the ratio of the areas of the chromatographic peaks for acetylene and the internal standard (ethane).…”

“…The observed reaction rate constant was found using the equation k ef = -d(ln ö(RH))/dt. The specific dose of the mechanical energy absorbed by the powder (D sp ) was determined using the equation D sp = It [9], where I is the specific energy intensity of the mill (~15 W/kg [8]) and t is the mechanical activation time. The specific surface was determined by the BET method relative to argon desorption.…”

“…In recent work [8], we found that mechanical activation of a similar palladium salt, namely, K 2 PdCl 4 , also leads to the formation of an acetylene hydrochlorination catalyst. As in the system with K 2 PtCl 4 , the reaction on the surface of K 2 PdCl 4 mechanically activated in the air proceeds very slowly.…”

Hydrochlorination of Acetylene Over the Activated‐Carbon‐Supported Au Catalysts Modified by N−P−O‐Containing Ligand

“…[19,20] Due to the relatively lower activity and shorter lifetime of non-metallic catalysts, some distance remains from industrialization. As for metal catalysts, a series of metal chlorides, including Pt 4 + , [8,[21][22][23] Pd 2 + , [21,[24][25][26][27] Ru 2 + , [12,[28][29][30][31][32] Cu 2 + , [33,34] Sn 2 + , [35] have been explored as potential Hg-free catalysts, but Au-based catalysts possessing a higher standard reduction potential are considered as the most promising replacement. [4,[36][37][38][39] The coking deposition and the agglomeration or the reduction of active species are the main reasons for the deactivation of Au-based catalyst, which have been briefly introduced in the previous literatures.…”

Synthesis of Au/C Catalysts by Ultrasonic-Assisted Technique for Vinyl Chloride Monomer Production

“…Various mercuric-free liquid catalysts such as Cu + , Au 3+ , Pd 2+ and Pt 3+ have been investigated. Pt 3+ and Pd 2+ complexes in solution show high activity but they are very unstable [7]. For solid catalysts, gold-based catalyst has been considered as a promising catalyst to replace the mercury-based catalysts among various metal salts i.e., Au 3+ [5,8,9], Cu 2+ [10], Pd 2+ [11], Pt 2+ [12,13] and Bi 3+ [14].…”