水滑石负载ZnCl_(2)催化剂的制备及其催化Biginelli反应的性能

Preparation of hydrotalcite-supported ZnCl_(2) catalyst and its catalytic ability in Biginelli reaction

采用浸渍法制备负载型催化剂ZnCl_(2)-水滑石(LDH),通过傅里叶变换红外(FT-IR)光谱、比表面积分析、扫描电子显微镜(SEM)、热重(TG)分析和X射线衍射(XRD)对催化剂进行表征.结果表明:与LDH相比,ZnCl_(2)-LDH比表面积下降,表面粗糙,热稳定性有所提高,层间距变小,出现新的晶形,新晶形的化学组成为Zn_(5)(OH)_(8)Cl_(2)·H_(2)O,说明成功制备ZnCl_(2)-LDH催化剂.以Biginelli反应为探针考察ZnCl_(2)-LDH的催化活性,结果表明:ZnCl_(2)-LDH催化芳香醛、尿素和乙酰乙酸乙酯进行反应可得到一系列二氢嘧啶衍生物,产率为70.8%~91.2%;与LDH负载的AlCl_(3)、NiCl_(2)、CuCl_(2)和FeCl_(3)催化剂相比,在相同反应条件下ZnCl_(2)-LDH催化苯甲醛、乙酰乙酸乙酯和尿素的反应产率最高,为91.2%.

The supported catalyst ZnCl_(2)-hydrotalcite(LDH)was prepared using the staining method.The catalyst was characterized with Fourier transform infrared(FT-IR)spectroscopy,specific surface area analysis,scanning electron microscope(SEM),thermogravimetric(TG)analysis,and X-ray diffraction(XRD).The results show that compared with LDH,the specific surface area of ZnCl_(2)-LDH decreases,the surface is rough,the thermal stability is improved,the interlayer space phase transition is small,and a new crystal form appears.The chemical composition of the new crystal is Zn_(5)(OH)_(8)Cl_(2)·H_(2)O,which indicates that ZnCl_(2)-LDH catalyst is successfully prepared.The catalytic activity of ZnCl_(2)-LDH was investigated using Biginelli reaction as a probe.The results showed that a series of dihydropyrimidine derivatives could be obtained from aromatic aldehydes,urea and ethyl acetoacetate with yields of 70.8%-91.2%.Compared with AlCl_(3),NiCl_(2),CuCl_(2) and FeCl_(3) supported on LDH,ZnCl_(2)-LDH had the highest yield of 91.2%for benzaldehyde,acetylethyl acetate and urea under the same reaction conditions.