The Jul 2012 PTC Reaction of the Month uses tetrabutyl phosphonium chloride. We don’t often encounter this phase-transfer catalyst, but in this case, it is the right catalyst. The reaction is performed at 160 C for 12 hours, so a thermally stable phase-transfer catalyst is needed. The P-quat is more stable than the corresponding N-quat. In addition, the reaction shown is a chloride-fluoride exchange, so it is good to avoid the introduction of a bromide anion. As a result, the inventors appropriately chose Bu4P Cl and not Bu4P Br.
As always, the choice of phase-transfer catalyst should be customized to meet the needs of the specific application.
Phosphonium salts are available from Dishman and from Cytec
Need to learn more about which phase-transfer catalyst to choose for a specific PTC application? Contact Marc Halpern of PTC Organics by E-mail.
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!).
