Syntheses, structures and catalytic activity of tetranuclear Mg complexes in the ROP of cyclic esters under industrially relevant conditions.,Dalton Transactions

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Syntheses, structures and catalytic activity of tetranuclear Mg complexes in the ROP of cyclic esters under industrially relevant conditions.
Dalton Transactions ( IF 3.5 ) Pub Date : 2019-11-27 , DOI: 10.1039/c9dt04359d
Swarup Ghosh ₁ , Christoph Wölper , Alexander Tjaberings , André H Gröschel , Stephan Schulz

Affiliation

Four tetranuclear magnesium complexes were synthesized and fully characterized. They are excellent catalysts for the ring-opening polymerization (ROP) of bulk racemic-lactide (rac-LA) and ε-caprolactone (ε-CL) even with low catalyst loading under industrially relevant conditions without additional co-initiators, yielding polymers with high molecular weight (M_n) and moderately controlled molecular weight distribution (MWD). The polymerization activity depends on the steric and electronic properties of the imino(phenolate) ligands. Kinetic studies of the most active catalyst 1 confirmed that the ROP of rac-LA and ε-CL has a first order dependence on monomer concentration. The ROP of rac-LA and ε-CL using 1–4 with BnOH gave polymers with narrow MWD and a close correlation between M^obs_n and M^theo_n values. Catalyst 1 was also capable of polymerizing technical-grade rac-LA and ε-CL even with large monomer-to-catalyst ratios ([M]₀/[C]₀) of up to 10 000 : 1 and without any additional co-initiator. The very high turnover frequencies (TOF) of 9600 h⁻¹ (rac-LA) and 24 000 h⁻¹ (ε-CL) prove that 1 belongs to the most active biocompatible, sustainable and nontoxic ROP catalysts under industrially relevant conditions.

中文翻译：

在工业相关条件下，环酯的ROP中四核Mg配合物的合成，结构和催化活性。

合成了四种四核镁配合物并进行了充分表征。它们是本体消旋丙交酯（rac -LA）和ε-己内酯（ε-CL）的开环聚合（ROP）的极佳催化剂，即使在工业上相关的条件下催化剂用量较低，而无需其他助引发剂的情况下，也可得到高分子量（M _n）和适度控制的分子量分布（MWD）。聚合活性取决于亚氨基（酚盐）配体的空间和电子性质。活性最高的催化剂1的动力学研究证实，rac -LA和ε-CL的ROP对单体浓度具有一级依赖性。的ROP外消旋-LA和使用ε-CL 1-4与BnOH，得到具有窄MWD和之间的密切相关性的聚合物中号^OBS_Ñ和中号^西奥_Ñ值。催化剂1也能够聚合工业级rac -LA和ε-CL，即使单体与催化剂的比例（[M] ₀ / [C] ₀）高达10000：1，也没有任何额外的助催化剂。启动器。9600 h ^-1（rac -LA）和24000 h ^-1（ε-CL）的极高周转率（TOF ）证明了1 在工业上相关的条件下属于最活跃的生物相容性，可持续性和无毒的ROP催化剂。

更新日期：2019-11-27

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