Tetrabutylphosphonium Dodecylbenzene Sulfonate was used as a “catalyst neutralizer” in the formation of polycarbonate by transesterification of diphenyl carbonate with a bisphenol and an aliphatic diol (2,2,4,4-tetramethyl-1,3-cyclobutanediol) as described in Tsunemori; H., Imazato; K., Yamanaka; K. (Teijin Limited) US Patent 11,198,759, 14-Dec-2021. The catalyst for the polymerization is a mixture of tetramethylammonium hydroxide and NaOH. The polymerization is carried out at a high temperature to distill the phenol as it is liberated during the transesterification while adjusting the pressure/vacuum in the reactor. The progress of the polycondensation is monitored and the reaction is terminated when a predetermined agitation power is reached. The catalyst neutralizer was added to the product in the molten form. We may speculate that the organophilic phosphonium quat may have been useful for dissolution of the sulfonate neutralizer. The amount of quat sulfonate added to stop the reaction is twice the molar amount of hydroxide catalyst.
As described in earlier issues of the PTC Tip of the Month, phosphonium salts are used as phase-transfer catalysts to build molecular weight of epoxy resins when reacting bisphenols with lower molecular weight epoxides (glycidyl ethers). Though not the same as building molecular weight of polycarbonate, it is interesting to note that sulfonic acids are known to deactivate phosphonium salt catalysts for epoxy resins. A reference for this is expired US Patent 4,692,504.
Now contact Marc Halpern of PTC Organics when your company can benefit from effective choice of phase-transfer catalyst or catalyst neutralizer to achieve low-cost high-performance green chemistry.
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!).
