Acta Chimica Sinica ›› 2021, Vol. 79 ›› Issue (9): 1113-1117.DOI: 10.6023/A21060300 Previous Articles     Next Articles



许昕彤a, 谭伟民b,*(), 姬梦圆a, 杨悦a, 饶兴兴b, 雒新亮b, 张延华a,*(), 陈虹宇a   

  1. a 南京工业大学 化学与分子工程学院 先进化学制造研究院 南京 211816
    b 国家涂料工程技术研究中心 中海油常州涂料化工研究院有限公司 常州 213016
  • 投稿日期:2021-06-29 发布日期:2021-08-02
  • 通讯作者: 谭伟民, 张延华
  • 基金资助:
    项目受国家自然科学基金(21673117); 项目受国家自然科学基金(91956109); 江苏省特聘教授基金和南京工业大学科研启动基金(39837126); 江苏省特聘教授基金和南京工业大学科研启动基金(39837102)

Synthesis of Piperazine Quaternary Ammonium Alkali Catalyst and Its Application in Isocyanate Polymerization

Xintong Xua, Weimin Tanb(), Mengyuan Jia, Yue Yanga, Xingxing Raob, Xinliang Luob, Yanhua Zhanga(), Hongyu Chena   

  1. a Institute of Advanced Synthesis, and School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China
    b National Engineering Research Center for Coatings, CNOOC Changzhou Paint and Coating Industry Research Institute Co., Ltd., Changzhou, Jiangsu 213016, China
  • Received:2021-06-29 Published:2021-08-02
  • Contact: Weimin Tan, Yanhua Zhang
  • Supported by:
    National Natural Science Foundation of China(21673117); National Natural Science Foundation of China(91956109); Jiangsu Provincial Foundation for Specially-Appointed Professor, and Start-up Fund from Nanjing Tech University(39837126); Jiangsu Provincial Foundation for Specially-Appointed Professor, and Start-up Fund from Nanjing Tech University(39837102)

Aliphatic isocyanate trimer has the advantage of excellent thermal stability, radiation resistance, corrosion resistance and flame retardancy. It is an important unit for various chemical products. Hexamethylene diisocyanate trimer (HDIT) is one of the popular trimers, which is mainly synthesized through the polymerization of monomers. A variety of catalysts have been applied in this procedure, including metal salts, phosphines, aminosilanes, N-heterocyclic carbenes and N-heterocyclic olefins. However, HDI monomer is usually expensive, while low catalyst activity, harsh preparation conditions, and easy-formation of polymer are often observed in the polymerization process. Pentamethylene diisocyanate (PDI), a cheap bio-based linear aliphatic polyisocyanate with similar structure to traditional HDI, has the potential to replace HDI. Since the activity of PDI is lower, it is found that the catalysts applicable for HDI work not well for PDI. Herein, we design and synthesize 1,4-bis(2-hydroxy-isopropyl)-1,4-dimethylpiperazine bisquaternary ammonium base (PQ-OH) as the catalyst for the production of both HDI trimer and PDI trimer (PDIT). Due to having two hydroxide ions, PQ-OH catalyst can attack the -NCO groups of two monomers at the same time, thus improving the reaction efficiency. Moreover, the β-OH groups on the catalyst molecule also promote the polymerization process. The piperazine ring structure in the catalyst has obvious steric hindrance effect, which can enhance the reaction between small molecules, and inhibit the reaction between large molecules and small molecules. Thus, the product with high trimer content is obtained. A general synthesis procedure for PQ-OH is described as followed. Propylene epoxide (70.0 mL, 1.0 mol) is added to a mixture of 1,4-dimethylpiperazine (67.6 mL, 0.5 mol) and water (18 mL, 1.0 mol) dropwisely under argon. After stirring at room temperature for 4 h, the solution turns to brown and stratifies. The lower layer is separated and concentrated in vacua to remove excess propylene oxide, water and possible alcohol by-products. The obtained crude product is dissolved in methanol, followed by decolorizing with activated carbon and drying with molecular sieve. After filtering and concentration, the desired product is obtained as a white viscous liquid.

Key words: quaternary ammonium catalyst, synthesis, pentamethylene diisocyanate, trimer