Phase-transfer catalysts are often added to Suzuki coupling reactions. We have noticed that while both TBAB and Aliquat 336 are used for Suzuki couplings, Aliquat 336 is used more often and maybe more importantly, in lower quantity.
This might be due to the higher thermal stability of Aliquat 336 relative to TBAB at temperatures, such as 120 deg C used in this reaction. This might also be a result of its high organophilicity (27 carbon atoms vs 16) that assures its distribution into the toluene phase. We do not think that the inclusion of a chloride ion in Aliquat 336 instead of a bromide ion in TBAB would make a difference in this application since bromide accumulates during the reaction.
The use of the hydrophobic Aliquat 336 and potassium carbonate as the base (and desiccator of the toluene phase?) may contribute to reducing hydrolysis of the ester at 120 deg C even though is present in the reactor.
Phase-transfer catalysis is used in many transition metal co-catalyzed reactions. Now contact Marc Halpern of PTC Organics if your company needs help in developing or optimizing a low-cost high-performance green chemistry commercial process using 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!).
