氮化硼纳米片负载Pd（OAc）2催化剂的制备及催化微波辅助Heck反应

Synthesis of Boron Nitride Nanosheets Supported Pd（OAc）2 and the Catalytic Microwaves-assisted Heck Reactions

以液相超声剥离的氮化硼纳米片(BNNSs)为载体,通过表面羟基、氨基、席夫碱共价功能化后与Pd^2+配位,制备负载型催化剂Pd@BNNSs-Schiff,并将该催化剂应用于微波辅助的Heck反应.通过傅里叶红外光谱(FTIR)、激光拉曼(Raman)光谱、X射线衍射(XRD)、同步热分析(TGA)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和元素分布分析(EDS mapping)对催化剂的结构和形貌进行了表征.结果表明,当苯乙烯与碘苯摩尔比为1.25∶1,溶剂为N,N-二甲基甲酰胺,缚酸剂为三乙胺,催化剂Pd用量为0.08%(质量分数)时,以450 W功率微波辐射20 min收率最高为95.6%;催化活性明显优于以相同方法制备的催化剂Pd@GO-Schiff(78.3%)(GO=氧化石墨烯);Pd@BNNSs-Schiff循环利用6次后仍具有较高的催化活性,参照催化剂在循环3次后活性明显降低,7次后失活.

Using h BN as starting material,BNNSs were prepared by liquid phase exfoliation,then BNNSs Schiff were synthesized through surface hydroxylation,amination and aldimine condensation reaction.Pd@BNNSs Schiff were obtained by complexing BNNSs Schiff with Pd^2+.The structure and morphology of the catalyst were characterized by means of Fourier transform infrared spectroscopy(FTIR),laser Raman spectrum,X Ray diffraction(XRD),thermogravimetric analyzer(TGA),X Ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscopy(TEM),elemental distribution analysis(EDS mapping).The Pd@BNNSs Schiff composite was used for microwave assisted Heck reaction and the optimized conditions were investigated.When the molar ratio of styrene and iodobenzene was 1.25∶1,the dosage of catalyst(Pd)was 0.08%,and the highest yield of 1,2 diphenylethylene was 96.5%with N,N dimethylformamide formide as solvent,triethylamine as acid binding agent under 450 W power microwave irradiation for 20 min.The cataly tic activity was significantly better than the Pd@GO Schiff(78.3%)prepared by the same method.Furthermore,the catalytic performance of Pd@BNNSs Schiff main tained a high level after 6 cycles,but that of Pd@GO Schiff decreased sharply after 3 cycles and was inactived after 7 cycles.