水溶性钯－膦配合物催化1－己烯加氢反应研究

Hydrogenation of 1 Hexene Catalyzed by Water Soluble PdCl 2(TPPTS) 2

研究了水溶性钯－膦配合物ＰｄＣｌ２（ＴＰＰＴＳ）２催化１－己烯加氢反应，考察了两相催化体系中添加表面活性剂ＣＴＡＢ，膦配体ＴＰＰＴＳ，以及溶液ｐＨ值等对反应的影响，证明了１－己烯加氢反应中有一诱导期．反应中涉及两种催化活性物种．一种是由ＰｄＣｌ２（ＴＰＰＴＳ）２还原生成的低氧化态催化物种，它在一定的ＣＴＡＢ浓度下，可以保持相当的稳定性．另一种是被ＴＰＰＴＳ或Ｈ２还原形成的钯黑．根据ＰｄＣｌ２和ＴＰＰＴＳ反应过程的３１ＰＮＭＲ研究。

Hydrogenation of 1 hexene catalyzed by water soluble PdCl 2(TPPTS) 2 [TPPTS=P( m C 6H 4SO 3Na) 3] was studied at 35℃ and atmospheric pressure. The introduction of surfactant CTAB[C 16 H 33 (CH 3) 3NBr] into the biphasic catalytic system was favourable for stabilization of the active species of palladium complex in water, but its catalytic activity decreased with increasing the concentration of CTAB. The addition of TPPTS caused also the decrease of hydrogenationn rate. When / ratio was over 10 the reaction was completely inhibited. The induction period which was about 1 h has been observed in the presence of CTAB. pH value of the solution influenced the hydrogenation of 1 hyexene strongly. When pH value decreased from 6.7 to 2.1, the conversion of 1 hexene decreased from 49.8% to 0.4%. The redox reaction of PdCl 2(TPPTS) 2 occurred in the reaction process. The palladium ion was reduced to Pd black while TPPTS was oxidized to O=P( m C 6H 4SO 3Na) 3. 31 P NMR spectra showed that the decrease of peak intensity of 31 P chemical shift at δ=35.1 ppm, assigned to 31 P in PdCl 2(TPPTS) 2, was accompanied by the increase of that at δ=34.6 ppm, assigned to 31 P in O=P( m C 6H 4SO 3Na) 3. Therefore there were two kinds of the catalytic species in the biphasic system of 1 hexene hydrogenation. One was palladium black and another was labile palladium complex in which Pd was in low oxidation state.