A US patent application publication [Leven; M., Heinz; N., Langanke; J., Heinemann; T., Laemmerhold; K., Tabak; M., Nalbantoglu; T., Leitner; W. (Covestro Deutschland) US Patent Application Publication 2025/0019514, 16-Jan-2025] was published that describes regenerating bisphenol A from used polycarbonates. The bisphenol A is reclaimed after hydrolytic cleavage of the carbonate group by water The inventors write “It thus avoids a loss of such raw materials, such as would arise in the event of disposal by incineration or landfill for instance.”
A hydrolysis catalyst is used that consists of two components [1] a phase-transfer catalyst and [2] a salt of an oxyacid that is interestingly defined as of an element of the fifth, sixth, fourteenth or fifteenth group of the periodic table of the elements.
As shown in the table, the phase-transfer catalyst that was screened was tetrabutylammonium chloride.
The salts of the oxyacids screened were alkali metal carbonates, phosphates, silicates, tungstates, molybdates and vanadates.
A key finding when examining the 12 inventive examples and the 5 comparative examples is that high conversion of more than 95% requires BOTH a phase-transfer catalyst and a salt of the oxyacid.
Editor note: The subscripts a and c shown in the table are not explained in the publication.
About Marc Halpern
Dr. Halpern is founder and president of PTC Organics, Inc., the only company dedicated exclusively to developing low-cost high-performance green chemistry processes for the manufacture of organic chemicals using Phase Transfer Catalysis. Dr. Halpern has innovated PTC breakthroughs for pharmaceuticals, agrochemicals, petrochemicals, monomers, polymers, flavors & fragrances, dyes & pigments and solvents. Dr. Halpern has provided PTC services on-site at more than 260 industrial process R&D departments in 37 countries and has helped chemical companies save > $200 million. Dr. Halpern co-authored five books including the best-selling “Phase-Transfer Catalysis: Fundamentals, Applications and Industrial Perspectives” and has presented the 2-day course “Practical Phase-Transfer Catalysis” at 50 locations in the US, Europe and Asia.
Dr. Halpern founded the journal “Industrial Phase-Transfer Catalysis” and “The PTC Tip of the Month” enjoyed by 2,100 qualified subscribers, now beyond 130 issues. In 2014, Dr. Halpern is celebrating his 30th year in the chemical industry, including serving as a process chemist at Dow Chemical, a supervisor of process chemistry at ICI, Director of R&D at Sybron Chemicals and founder and president of PTC Organics Inc. (15 years) and PTC Communications Inc. (20 years). Dr. Halpern also co-founded PTC Interface Inc. in 1989 and PTC Value Recovery Inc. in 1999. His academic breakthroughs include the PTC pKa Guidelines, the q-value for quat accessibility and he has achieved industrial PTC breakthroughs for a dozen strong base reactions as well as esterifications, transesterifications, epoxidations and chloromethylations plus contributed to more than 100 other industrial PTC process development projects.
Dr. Halpern has dedicated his adult life to his family and to phase-transfer catalysis (in that order!).
