Is the Bisphenol A Biradical Formed in the Pyrolysis of Polycarbonate?

Abstract

An unknown species has been detected in the analysis of the products in a pyrolysis of polycarbonate using Li(+) ion-attachment mass spectrometry (IAMS). The mass spectra exhibited a Li(+) adduct peak at m/z 233 that was tentatively assigned to bisphenol A (BPA) biradical. Experimentally, this assignment was supported by the observation that the production rate increased under an inert nitrogen atmosphere. To further confirm the assignment, the stability of the BPA biradical to intramolecular rearrangement reactions as well as unimolecular decomposition has been analyzed via density functional theory calculations [B3LYP/6-311+G(3df,2p)]. The results show that the bisphenol A biradical is an open-shell biradical singlet that is stable to unimolecular decomposition. Although some of the proposed intramolecular rearrangement products have lower energies than those of the BPA diradical, these pathways have large reaction barriers and the kinetic lifetime of the radical is expected to be of the order of hours under the conditions of the experiment. The calculations also reveal that the bisphenol A diradical has large Li(+) affinities supporting the fact that these Li(+) complexes could be detected in the Li(+) ion attachment mass spectrometry. On the basis of these results the Li(+) adduct peak at m/z 233 detected in the pyrolysis of polycarbonate is assigned to the bisphenol A biradical.

Chemical degradation of amine-cured DGEBA epoxy resin in supercritical 1-propanol for recycling carbon fiber from composites

“…First, bisphenol A biradical could be generated during the degradation of the epoxy resin. Bisphenol A biradical was formed in the pyrolysis of polycarbonate and its kinetic lifetime was of order of hours [30] . It was reasonable to speculate that a simple homolytic cleavage of aromatic ether linkages in the epoxy resin could produce the bisphenol A biradical.…”

“…LC-MS further identified that the degradation product has a molecular weight of 226. On the basis that (1) bisphenol A was one of the two components of the epoxy resin and (2) non-aromatic compounds were not measured by an UV detector, an intramolecular rearrangement product of bisphenol A biradical, 4,4'-(cyclopropane-1,1-diyl)diphenol, was assigned to the peak [30] .…”

Mono‐ and bifunctional six‐membered cyclic carbonates synthesized by diphenyl carbonate toward networked polycarbonate films

“…DPC was supplied by Asahi Kasei Chemicals. A series of magnesium salts with different counter ions (F 2 , Cl 2 , or ClO 4 2 ) and DBU were purchased from Wako Pure Chemical. THF was refluxed with sodium and benzophenon for longer than 12 h and distilled and then used for the ROP of six-membered cyclic carbonates.…”

“…Aromatic polycarbonates, as exemplified by bisphenol A‐based polycarbonates, are one of widely‐used polymers in various industrial applications because of their well transparency, high thermal stability, and mechanical properties . While, aliphatic polycarbonates feature biocompatibility and degradability, which inspires many scientists to explore the application to carriers of drugs and genes .…”

“…Aromatic polycarbonates, as exemplified by bisphenol A-based polycarbonates, are one of widely-used polymers in various industrial applications because of their well transparency, high thermal stability, and mechanical properties. [1][2][3][4][5][6][7][8] While, aliphatic polycarbonates feature biocompatibility and degradability, which inspires many scientists to explore the application to carriers of drugs and genes. [9][10][11][12][13] Furthermore, antimicrobial activities of the aliphatic polycarbonates have been studied by introduction of quaternary ammonium ions in the side chains and/or main chains of the polycarbonates for several years.…”