2. Scalable Depolymerizing Transesterification and Amidation of (Poly)lactic Acid (PLA) enabled by Resonant Acoustic Mixing
Anton S. Makarov, Magnus Rueping
Green Chem., 2025, 26,
DOI: 10.1039/d4gc04623d
Abstract:
This study presents a scalable mechanochemical method for the upcycling of (poly)lactic acid (PLA) into industrially valuable alkyl lactate esters via organocatalytic depolymerizing transesterification enabled by resonant acoustic mixing (RAM). The process is characterized by its simplicity, requiring neither grinding media nor a co-solvent and utilizing nearly stoichiometric amounts of an alcohol reaction partner in the presence of an inexpensive, easily accessible catalyst. Additionally, the mechanochemistry is successfully extended to the upcycling of post-consumer PLA for the synthesis of various substituted esters and lactamides.
1. Ba/Ti MOF: A Versatile Heterogeneous Photoredox Catalyst for Visible-Light Metallaphotocatalysis
I. S. Khan, L. Garzon-Tovar, R. Kancherla, N. Kolobo, A. Dikhtiarenko, M. Almalki, A. Shkurenko, V. Guillerm, K. N. Le, G. Shterk, C. H. Hendon, M. Eddaoudi, J. Gascon, M. Rueping
Adv. Mater. 2025, 37, 2405646
DOI: 10.1002/adma.202405646
Abstract:
The field of sustainable catalysis is evolving rapidly, with a strong emphasis on developing catalysts that enhance efficiency. Heterogeneous photocatalysis has emerged as a promising and mild approach to address the persistent challenges. Among various heterogeneous photocatalysts, Metal-Organic Frameworks (MOFs) have gained significant attention for their exceptional performance and recyclability in photocatalytic reactions. In this context, contrary to the conventional homogeneous Ir or Ru-based photocatalysts, which face significant challenges in terms of availability, cost, scalability, and recyclability, we have developed a new Ba/Ti MOF (ACM-4) as a heterogeneous catalyst that could mimic/outperform the conventional photocatalysts, offering a more sustainable solution for efficient chemical processes. Its redox potential and triplet energy are comparable to or higher than the conventional catalysts, organic dyes, and metal semiconductors, enabling its use in both electron transfer and energy transfer applications. It facilitates a broad range of coupling reactions involving pharmaceuticals, agrochemicals, and natural products, and is compatible with various transition metals such as Ni, Cu, Co, and Pd as co-catalysts. Notably, ACM-4 can be easily recovered and reused multiple times with minimal loss in efficiency. The effectiveness of the ACM-4 as a photocatalyst is supported by comprehensive material studies and photophysical experiments. These significant findings underscore the potential of ACM-4 as a highly versatile and cost-effective photoredox catalyst, providing a sustainable, one-material solution for efficient chemical processes.