Study On The Synthesis Of α-amino Acid N-ring Anhydride By DMC Metho

α-amino acid N-carboxylic anhydrides(NCAs),as an important monomer of polymer,can be converted into poly amino acid or protein with biocompatibility and biodegradability by ring-opening polymerization.Poly amino acid,as drug carrier and biological tissue,can be widely used in biomedical field.Herein,dimethyl carbonate(DMC)was used as a cyclic agent to synthesize NCAs,which is a new green synthesis method.In this paper,L-phenylalanine-N-carboxyanhydride(Phe-NCA),L-aspartic acid N-carboxyanhydride(H-Asp-Obzl-NCA)and Nε-carbobenzoxy-L-lysine-Ncarboxyanhydride(Cbz-Lys)was prepared from amino acids and DMC through one-pot synthesis,and they were characterized by FT-IR,NMR and GC-MS.HLPC-ELSD was used to quantitatively investigate the effects of reaction temperature,reaction time and other factors on target compound yields.Under the optimal conditions,the maximum yield of NCAs at 160 ℃,120 ℃ and 140 ℃ for 8 h were55.22%,56.30% and 46.46%,respectively.SEM and XPS were used to observe the structure changes of zinc acetate,and its catalytic mechanism was analyzed.In view of the problems of low catalytic efficiency and difficult separation of zinc acetate,a new heterogeneous catalyst,akaline earth oxide supported zeolitic imidazolate framework-8(ZIF-8),was prepared to use in the reaction.The morphology,alkalinity,pore structure and catalytic activity of different catalysts were studied.The effects of calcination temperature,reaction solvent and temperature on the yield of H-Asp-Obzl-NCA were studied,and the optimum catalyst and best reaction conditions were screened.After reaction at 120 ℃ for 8 h in DMF,Mg O@ZIF-8 calcinated at 450 ℃ acting as catalyst,the highest yield of H-ASP-Ob ZL-NCA reached 80.63% and the yield was 58.53% after catalyst was recycled for seven time.The changes of Mg O@ZIF-8 before and after reaction was tested by FT-IR,XRD and other techniques,and the possible catalytic mechanism was proposed.