Hexamethyl guanidinium chloride (HMG Cl) performed the best out of 19 phase-transfer catalysts, including thermally stable tetraphenyl phosphonium salts. This was for the high temperature fluoride chloride halex exchange shown in the diagram.
We usually see hexaethyl guanidinium chloride (HEG Cl) used for high temperature PTC reactions. HEG Cl was not reported at all in this patent. We speculate that the fluoride ion may act as a base and cause side reactions at the beta-hydrogen of the ethyl group of HEG Cl. Since HMG Cl has no beta-hydrogens, perhaps HMG Cl may be better for high-temperature fluoride-chloride halex reactions than HEG Cl.
If your company needs help in choosing the best phase-transfer catalyst to reduce cost and/or optimize performance of your commercial process, now contact Marc Halpern of PTC Organics to benefit from the most highly specialized expertise in industrial phase-transfer catalysis.
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!).
