Methyl triphenyl phosphonium salts are used in high temperature PTC applications and strong base PTC applications in which other phase-transfer catalysts are not stable enough. US Patent 9,238,606 (Penney, J.; Vetter, A.; Norman, D.; Eastman Chemical Company, 19-Jan-2016) reported the use of two methyl triphenyl phosphonium salts for the carbonylation of methanol to acetaldehyde.
The catalyst system in this patent for the conversion of methanol to acetaldehyde in the presence of carbon monoxide and hydrogen was a mixture of methyl triphenyl phosphonium iodide (MePPh3I), a phosphonium cobalt iodide (MePPh3)2CoI4 and 1,3-bis(diphenylphosphino)propane. The MePPh3I was used usually at about 0.25%-0.35% and the other catalysts about 1/10 of that.
The reaction temperature was 175C to 205C. The phosphonium salts were good this application. Conversions and selectivities were good though not near quantitative but the products could be separated, so it looks like good technology. One of the advantages of this technology is that methyl iodide is not needed as a co-catalyst and the levels of methyl iodide in the system are low, typically less than 100 ppm.
If you need help choosing the best phase-transfer catalyst for a commercial application or for a PTC process in development, now contact Marc Halpern of PTC Organics Inc.
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!).
