Tuning a robust system: N,O zinc guanidine catalysts for the ROP of lactide

Abstract

Four non-toxic, highly active and robust complexes have been used in the ring opening polymerisation of non-purifed lactide to substitute Sn(Oct)2.

Next Generation of Zinc Bisguanidine Polymerization Catalysts towards Highly Crystalline, Biodegradable Polyesters

“…A long known active and robust catalyst family for the ROP of LA are guanidine complexes, which have relevant properties for industrial use [12c,e, 21, 25] . In the last few years, very active N , O ‐donor zinc guanidine complexes have been reported [12d, 22] . However, the activity was slightly less compared to Sn(Oct) 2 .…”

Towards New Robust Zn(II) Complexes for the Ring‐Opening Polymerization of Lactide Under Industrially Relevant Conditions

“…By polymerization experiments at different catalyst concentrations (up to 2000 : 1 per zinc), it was possible to obtain the rate constant k p from the linear fit by plotting the different k app values against the catalyst concentration. Compared with the k p from the recently published zinc guanidine catalyst [ZnCl 2 (TMG5NMe 2 asme)] with a value of 6.10±0.34×10 −2 L mol −1 s −1 complex 2 with k p =8.59±0.36×10 −2 L mol −1 s −1 is slightly faster. In a comparison to the active zinc catalyst Zn(CH 3 COO) 2 with a conversion of 69 % after 24 h ([M]/[I]=500 : 1) the herein presented systems with a conversion of 79 % after 41 min ([M]/[I]=500 : 1) are significantly faster …”

“…Despite an anionic ligand system, the complexes show a high degree of tolerance to the impurities in the monomer and produce industrially useful PLA with molar masses of up to 71 000 g mol −1 and a conversion of 78 %. With a k p =8.59±0.36×10 −2 L mol −1 s −1 , the systems are slightly faster than the recently published zinc guanidine complex and show that this class of ligands in combination with zinc also has a high potential to replace the currently industrially used catalyst Sn(Oct) 2 . Mechanistic investigations have shown that the dinuclear complex is present in melt of lactide as a mononuclear unit.…”

Mit der nächsten Generation von Zink‐Bisguanidin‐Polymerisationskatalysatoren zu hochkristallinen, biologisch abbaubaren Polyestern

“…Folglich ist Komplex 1 fast dreimal so schnell wie der bisher schnellste, robuste Katalysator für die ROP von LA unter industriellen Bedingungen: ein Eisen‐Guanidin‐Komplex mit einem k p ‐Wert von 0.554±0.02 L mol −1 s −1 [14c] . Ein Vergleich von Komplex 1 mit dem industriell verwendeten Sn(Oct) 2 ergibt eine um fast eine Größenordnung erhöhte Geschwindigkeitskonstante ( k p =0.167 L mol −1 s −1 ) [12d] . Die resultierenden farblosen und transparenten Polymere haben hohe Molmassen von bis zu 100 000 g mol −1 , also typische Molmassen für verschiedene Anwendungen etwa Verpackungen oder im medizinischen Bereich [11b] …”

“…Eine seit langem bekannte aktive und robuste Katalysatorfamilie für die ROP von LA sind Guanidinkomplexe, die für den industriellen Einsatz relevante Eigenschaften aufweisen [12c,e, 21, 25] . In den letzten Jahren wurde über sehr aktive N,O ‐Donor Zink‐Guanidin‐Komplexe berichtet [12d, 22] . Allerdings war die Aktivität im Vergleich zu Sn(Oct) 2 etwas geringer.…”