Asymmetric Kinetic Resolution Polymerization of Racemic Lactide Mediated by Axial-Chiral Thiourea/Phosphazene Binary Organocatalyst.
Chemistry
; 30(53): e202402201, 2024 Sep 19.
Article
en En
| MEDLINE
| ID: mdl-39008613
ABSTRACT
Asymmetric kinetic resolution polymerization (AKRP) provides an ideal way to obtain highly isotactic polylactide (PLA) with superior thermal-mechanical properties from racemic lactide (rac-LA). However, the development of a new catalytic system with concurrent high activity and selectivity at ambient temperature remains a great callenge. Here, a series of simple and effective binary organocatalytic pairs containing axial-chiral thioureas and commercially available phosphazene bases were designed. These chiral binary organocatalytic pairs allow for both high polymerization activity and moderate enantioselectivity for AKRP of rac-LA at room temperature, yielding semi-crystalline and metal-free stereoblock PLA with a melting temperature as high as 186 °C. The highest kinetic resolution coefficient (krel) of 8.5 at 47 % conversion was obtained, and D-LA was preferentially polymerized via kinetic resolution with a maximum selectivity factor (kD/kL) of 18.1, indicating that an enantiomorphic site control mechanism (ESC) was involved.
Texto completo:
1
Base de datos:
MEDLINE
Idioma:
En
Revista:
Chemistry
Asunto de la revista:
QUIMICA
Año:
2024
Tipo del documento:
Article
País de afiliación:
China