Synthesis of polycarbonate diol catalyzed by metal-organic framework Zn4O[CO2-C6H4-CO2]3

The metal-organic framework Zn4O[1,4-benzenedicarboxylate]3 (Zn4O[CO2-C6H4-CO2]3, commonly known as MOF-5, was prepared by the ultrasonic irradiation method. The catalyst was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was then used as the catalyst for the preparation of polycarbonate diol (PCDL) via the transesterification between diphenyl carbonate (DPC) and 1, 6-hexandiol (1, 6-HD). Its catalytic activity in the transesterification process is evaluated by the yield of phenol, and its catalytic activity in the polycondensation process is determined by the number-average molecular weight (Mn) and the hydroxyl value. Compared to the triethylenediamine (C6H12N2), Mg-Al layered double hydroxide (Mg-Al LDH), sodium ethoxide (C2H5ONa) and sodium methoxide (CH3ONa), MOF-5 exhibits highest catalytic activity for the preparation of PCDL. Under reaction conditions (n (1,6-HD)/n(DPC) = 1.2, w(catalyst) = 0.03%, 198 °C), the yield of phenol is up to 90.1% and the PCDL shows highest Mn and lowest hydroxyl value.