N-Heterocyclic Phosphines as Precatalysts for the Highly Selective Degradation of Poly(lactic acid)
N-Heterocyclic Phosphines as Precatalysts for the Highly Selective Degradation of Poly(lactic acid)
复制标题
DOI：
10.1002/cctc.202101904
复制
发表时间：
2022-01-20
期刊：
影响因子：
4.5
通讯作者：
Liptrot, David J.
中科院分区：
文献类型：
--
作者：
English, Laura E.;Jones, Matthew D.;Liptrot, David J.
研究了n -杂环膦（NHP）作为一系列商业聚合物样品酯交换反应的催化剂。NHP催化降解聚乳酸与甲醇提供了高产量的乳酸甲酯（MeLA）在几天的过程中。现场核磁共振光谱和动力学分析提供了催化剂的定量评估，并报道了溶剂筛选。令人惊讶的是，试图解聚聚己内酯（PCL）和聚对苯二甲酸乙二醇酯（PET）是不成功的，PLA/PCL和PLA/PET混合的反应提供了PLA单独的完全特异性降解。对催化剂的核磁共振分析提供了对其溶液形态的洞察，表明NHP在酯交换条件下并没有保持完整。内二胺(thbun （H)CH=CHN(H)tBu）通过NHP的甲醇分解生成，是PLA降解的选择性催化剂。对NHP甲醇分解副产物的解聚合活性的评估表明这是活性催化剂。
An N-heterocyclic phosphine (NHP) has been investigated as a catalyst for transesterification of a range of commercial polymer samples. NHP catalysed degradation of poly(lactic acid) with methanol provides access to methyl lactate (MeLA) in high yields over the course of days. In situ NMR spectroscopy and kinetic analysis has provided quantitative assessment of the catalyst, and a solvent screen is reported. Surprisingly attempts to depolymerise polycaprolactone (PCL) and polyethylene terephthalate (PET) were unsuccessful, and reactions mixed PLA/PCL and PLA/PET provided completely specific degradation of the PLA alone. NMR analysis of the catalyst provides insight into its solution speciation, indicating that the NHP does not remain intact under the transesterification conditions. The enediamine, tBuN(H)CH=CHN(H)tBu, was shown to be formed via methanolysis of the NHP and proved to be a selective catalyst for PLA degradation. Assessment of the depolymerisation activity of by-products of the NHP methanolysis suggest this is the active catalyst.