Depolymerization of End‐of‐Life Poly(bisphenol A carbonate) via Alkali‐Metal‐Halide‐Catalyzed Methanolysis

Abstract

The recycling of poly(lactide) (PLA) is studied. Using methanol and alkali‐metal‐halides as catalyst, PLA is degraded to produce methyl lactate, which is a suitable chemical for the regeneration of PLA. An excellent degree of degradation (conversions: >99%, yields: >99%) is achieved in less than 20 min utilizing microwave heating. Remarkably, PLA goods are successfully converted into methyl lactate.

Selective Degradation of End‐of‐Life Poly(lactide) via Alkali‐Metal‐Halide Catalysis

“…[13][14][15] One example from this group is poly(lactide) (1), which is accessible from lactic acid (via polycondensation) or the lactic acid derivative lactide (via ring-opening-polymerization, ROP). [76][77][78] Furthermore, alkali metal salts can have benefits regarding "Green Chemistry" and SDGs considerations. [63][64][65][66][67][68][69][70] As second product methanol is produced, which can be recycled for further degradation; therefore, reduced amounts of waste are generated and the whole process is made highly atom efficient.…”

“…[76] Polycarbonate 3 was converted in the presence of methanol and potassium fluoride as catalyst to the building blocks bisphenol A and dimethyl carbonate, which can be reused as starting materials for fresh polycarbonate. Recently, we have demonstrated the abilities of alkali metal halides as catalyst in the depolymerization of end-of-life poly(bisphenol A carbonate) (3).…”

“…In this context, we wondered if straightforward alkali metal halides can mimic the action of ILs. [76][77][78] Furthermore, alkali metal salts can have benefits regarding "Green Chemistry" and SDGs considerations. [79] For instance, we recently studied the potential of the organocatalyst 4-N,N-dimethylaminopyridine (DMAP).…”

“…Recently, we have demonstrated the abilities of alkali metal halides as catalyst in the depolymerization of end-of-life poly(bisphenol A carbonate) (3). [76] Polycarbonate 3 was converted in the presence of methanol and potassium fluoride as catalyst to the building blocks bisphenol A and dimethyl carbonate, which can be reused as starting materials for fresh polycarbonate. [82,83] Since the reaction conditions are comparable, we investigated the combination of the degradation of a mixture of (solvent-assisted mixing) endof-life poly(lactide) 1a and the depolymerization of end-of-life poly(bisphenol A carbonate) 3 (Scheme 5).…”

Chemical Upcycling of Waste Poly(bisphenol A carbonate) to 1,4,2‐Dioxazol‐5‐ones and One‐Pot C−H Amidation

“…[12,13] In particular, the carbonyl moiety could replace the highly toxic phosgene and carbon monoxide in carbonylation reactions. [14][15][16] Besides hydrolysis, which yields BPA and carbon dioxide, [17,18] alcoholysis, [19][20][21][22][23] aminolysis, [24][25][26] and hydrogenation [27][28][29] yield value-added organic carbonates, carbamates, and urea under mild conditions.…”