壳聚糖基聚合物负载钯配合物的制备及对Heck反应催化性能

以壳聚糖为基本原料制得壳聚糖缩水杨醛负载钯配合物(S-CTS-Pd)和交联壳聚糖缩水杨醛负载钯配合物(CL-S-CTS-Pd)两种催化剂,利用XPS、TG、DTA等手段对其进行了表征.两种催化剂不需在惰性气体氛围中就能有效地催化芳基碘与丙烯酸、苯乙烯的Heck反应,高产率地得到反式肉桂酸、1,2二苯乙烯,芳基碘上吸电子和供电子取代基的存在对反应没有明显影响.与S-CTS-Pd相比,CL-S-CTS-Pd在较低的温度或较少的催化剂用量下,对Heck反应仍有较高的催化活性.负载催化剂CL-S-CTS-Pd重复使用性能的研究表明,在催化碘苯与丙烯酸反应重复10次后,肉桂酸的产率仍达75.3%.

SYNTHESIS OF CHITOSAN-BASED POLYMER SUPPORTED-PALLADIUM CATALYSTS AND THEIR CATALYTIC PERFORMANCES FOR HECK REACTION

Two kinds of chitosan derivatives,chitosan condensed with salilylaldehyde and crosslinked chitosan condensed with salilylaldehyde,supported palladium complexes(S-CTS-Pd and CL-S-CTS-Pd) were synthesized and characterized by XPS,TG,DTA etc.TG analysis showed that both S-CTS-Pd and CL-S-CTS-Pd were stable up to 230℃.The complexes were efficient catalysts for Heck arylations of iodoarenes with acrylic acid or styrene under atmospheric condition,and the trans-cinnamic acid or trans-stilbene was obtained in high yield(≥90%).Neither electrondonating groups nor electron-withdrawing groups on iodoarenes had much effect on the yield of products.The catalytic activities of S-CTS-Pd and CL-S-CTS-Pd decreased slowly while the temperature decreased from 100℃ to 80℃.With reducing reaction temperature continuously,the catalytic activity of S-CTS-Pd reduced remarkably,however,the catalytic activity of CL-S-CTS-Pd remained at a very high level.The influence of amount of catalyst on catalytic performance of S-CTS-Pd and CL-S-CTS-Pd showed that CL-S-CTS-Pd had better performance than S-CTS-Pd.The recyclability of CL-S-CTS-Pd showed that the yield of cinnamic acid was 75.3% for Heck reaction of acrylic acid with iodobenzene even though the supported catalyst was used 10 times.