Lactate anion catalyzes aminolysis of polyesters with anilines

Abstract

Chemical transformation of spent polyesters into value-added chemicals is substantial for sustainable development but still challenging. Here, we report a simple, metal-free, and efficient aminolysis strategy to upcycle polylactic acid by anilines over lactate-based ionic liquids (e.g., tetrabutylammonium lactate), accessing a series of N -aryl lactamides under mild conditions. This strategy is also effective for degradation of poly(bisphenol A carbonate), affording bisphenol A and corresponding diphenylurea derivatives. It is found that, with the assistance of water, lactate anion as hydrogen-bond donor can efficiently activate carbonyl C atom of polyesters via hydrogen bonding with carbonyl O atom; meanwhile, as hydrogen-bond acceptor, it can enhance nucleophilicity of the N atom of anilines via hydrogen bonding with amino H atom. The nucleophilic attack of N atom of anilines on carbonyl C atom of polyesters results in cleavage of C─O bond of polymers and formation of the target products.

Upcycling of Poly(lactic acid) Waste: A Valuable Strategy to Obtain Ionic Liquids

“…Indeed, our protocol foresees the use of a lower amount of nucleophile, compared with data recently reported by Zhang et al, concerning the same process carried out in the presence of 2-aminoethanol, that gave full conversion of the polymer at 60 °C, but working with a feeding ratio PLA/amine equal to 1:4 . On the other hand, our approach also exhibited better performance than the one recently reported by Liu et al about the aminolysis of PLA carried out using aniline as nucleophile . In the above case, a yield value equal to 94% was obtained, using a comparable amount of nucleophile (1.5 equiv) but operating at 120 °C.…”

Recent advances in plastic recycling and upgrading under mild conditions

“…13d and e). 91 In addition, a large-scale transformation experiment of PLA straw (5.0 g) was performed, and 9.28 g of product was obtained under the optimized conditions, which indicates that [N 4444 ][Lac]-catalyzed aminolysis of PLA has the potential for practical application. In addition to PLA, poly(bisphenol A carbonate) (PC) can also be efficiently upgraded to the monomer bisphenol A and various diphenylurea derivatives with a 100% selectivity under the same conditions.…”

Upgrading Waste Polylactide via Catalyst‐Controlled Tandem Hydrolysis‐Oxidation

“…The authors have cited additional references within the Supporting Information. [23][24][25][26][27][28][29][30][31]…”

“…Supporting Information is available from the Wiley Online Library or from the author. The authors have cited additional references within the Supporting Information [23–31] …”