Alkyl triphenyl phosphonium salts are used as phase-transfer catalysts to build the molecular weight of epoxy resins. In US Patent 11,492,457 [Mitchell, M.; Anderson, B.; Dahlke, G.; Fukushi, T.; (3M Innovative Properties Company) US Patent 11,492,457, 08-Nov-2022], benzyl triphenyl phosphonium chloride was reported as being used for the curing and crosslinking of a variety of fluoropolymers produced by the reaction of perfluoroalkenes, polyhydroxy compounds and phthalonitrile compounds.
It is not clear why benzyl triphenyl phosphonium chloride was chosen out of the 24 quaternary ammonium and phosphonium salts cited in the teachings in the patent. The inventors even specify that phenolate is the preferred anion for both quaternary ammonium and phosphonium salts but benzyl triphenyl phosphonium chloride was chosen anyway. We speculate that the choice may have been based on the least expensive phosphonium quat which is made from triphenylphosphine and benzyl chloride.
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!).
