高分子负载钯催化剂中载体主链在催化加氢反应中的作用

EFFECT OF FUNDAMENTAL CHAIN OF SUPPORT ON THE HYDROGENATION BEHAVIORS OF THE POLYMER-SUPPORTED PALLADIUM CATALYSTS

报导几种以聚2,6-二甲基1,4-苯醚(PPO)和聚砜(PSu)为主链的负载钯催化剂对1-辛烯和环戊二烯在温和条件下的催化加氢活性与选择性。官能团化的PPO负载钯催化剂对1-辛烯的催化加氢活性大于官能团化的PSu负载钯催化剂的活性,但前者在加氢过程中的活性下降比后者快得多;官能团化的PPO负载钯催化剂在1-辛烯加氢过程中活性很快下降的原因与其强的异构化性能和异构化产物有关。相同配体的两种负载钯催化剂对环戊二烯的催化加氢表现在活性上,PPO低于PSu,而选择性PPO高于PSu。表明除了按预计与钯直接配位的配体外,载体主链结构对负载钯催化剂的加氢性能也有显著影响。

In this paper, catalysts of palladium dichloride supported on poly-( 2, 6 -dimethyl-1, 4 -phenylene oxide) ( PPO ) and polysulphone ( PSu ) f unctionalized by o-aminobenzoic acid, triphenylphosphine and n-propylamine were prepared and the hydrogenation of 1 -octene and cyclopentadiene catalyzed by these catalysts under mild conditions was studied. The f unctionalized PPO-supported catalysts exhibit higher activities than the corresponding PSu-supported catalysts in the hydrogenation of 1-octene, but the reaction rate of the former falls down much quicker than that of the latter. The isomerization product ( 2-octene) was considerably formed during the hydrogenation of 1-octene catalyzed by the f unctionalized PPO-supported palladium catalysts, while only trace amount of 2-octene was observed when the corresponding PSu-supported palladium catalysts were used. The palladium hydride species, which is possibly formed by the hydrogenation of the immobilized palladium complex, seems not only to be the active species in the hydrogenation of 1-octene but also to be the active species in the isomerization of 1-octene. The isomerization of 1-octene to 2-octene can be shown as follows: See p.114 (11). The activities of the f unctionalized PSu-supported catalysts in the liydrogenation of cyclopentadiene are higher than those of the corresponding PPO-supported catalysts, but the selectivities of cyclopentadiene hydrogenated to cyclopentene are PPO>PSu. All the above facts indicate that besides the effect of the predetermined ligands coordinated with the metal active center, the fundamental chain structure of the support can also affect the hydrogenation behaviors of the polymer-supported palladium catalysts.