Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (6): 540-546.DOI: 10.6023/A20020024 Previous Articles     Next Articles

Article

NaZnPO4催化碳酸二甲酯和丙氨酸“一锅法”合成N-羧基丙氨酸酸酐

贾晓燕, 李振环   

  1. 天津工业大学材料科学与工程学院 天津 300387
  • 收稿日期:2020-02-07 发布日期:2020-05-13
  • 通讯作者: 李振环 E-mail:lizhenhuan@tiangong.edu.cn
  • 基金资助:
    项目受国家自然科学基金(Nos.21676202,21376177)资助.

Synthesis of N-Carboxy Alanine Anhydride from Alanine and Dimethyl Carbonate over NaZnPO4 in One-pot

Jia Xiaoyan, Li Zhenhuan   

  1. School of Materials Science and Engineering, Tiangong University, Tianjin 300387
  • Received:2020-02-07 Published:2020-05-13
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 21676202, 21376177).

In this paper, the environmentally friendly synthesis of N-carboxy alanine anhydride (Ala-NCA) from alanine and dimethyl carbonate (DMC) over NaZnPO4 was carried out in one-pot, and the NaZnPO4 catalyst with the acid-base double active sites was prepared by the solid phase synthesis method. The X-ray diffraction spectrometer (XRD) was used to characterize the structure of NaZnPO4, and the reaction products were analyzed by the high performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD). The GC-MS characterized result of obtained Ala-NCA was extremely consistent with that of the standard sample, which indicated that Ala-NCA was synthesized successfully. When the reaction was carried out at 150℃ for 8 h, the maximum 46.84% yield of Ala-NCA can be obtained in DMF solvent. As the reaction temperature increased to 160℃, Ala-NCA yield significantly declined because of the instability of Ala-NCA at higher temperature. However, there was no Ala-NCA formation without catalyst existence because DMC is not easy to undergo carboxymethylation with amino acids. NaZnPO4 could be recycled, but Ala-NCA yield declined to 38.62% after the fifth cycle. The reasons for that were attributed to the catalyst surface area reduction and the active site loss of Na-O and Zn2+. The reaction between DMC and amino acids over NaZnPO4 were characterized by TG-MS-IR, and the possible catalytic mechanism was provided. Namely, Zn2+ and Na-O in NaZnPO4 perform an effective acid-base synergistic catalysis, on the one hand the basic Na-O active sites play an key role on amino group deprotonation, which promotes the carboxymethylation of amino acids with DMC, on the other hand the acid active sites of Zn2+ can well catalyze the cyclization of intermediate into Ala-NCA. In this cyclization process, NaZnPO4 also can transfer the trapped protons to carboxymethylation intermediate to facile the formation of target compounds.

Key words: N-carboxy alanine anhydride, dimethyl carbonate, carboxymethylation, acid-base coordination catalysis, cyclization