Phase-transfer catalysis excels in specialty esterifications between carboxylates and alkyl halides. PTC esterifications are typically performed at temperatures of 60-100 C. The esterification shown in the diagram is a relatively rare example of a PTC esterification run at room temperature.
Esterifications run with benzyl bromide and allyl bromide can be performed at temperatures lower than those using other alkyl bromides. This esterification utilizes tetrabutylammonium iodide as the phase-transfer catalyst that not only transfers the carboxylate anion from the solid surface of the potassium carbonate/carboxylate into the bulk acetone phase as quat carboxylate, it also provides the iodide anion that forms benzyl iodide in-situ that further reduces the energy of activation that enables working at lower temperature.
We teach in our 2-day course “Industrial Phase-Transfer Catalysis” another use of PTC-iodide co-catalysis in the presence of acetone and that is for an old commercial PTC esterification for the antibiotic Ceclor [Greene, J.; Bunnell, C.; (Eli Lilly) 1982, U.S. Patent 4,334,079].
In addition, as we teach in our course “Industrial Phase-Transfer Catalysis”, it is always less expensive to use catalytic tetrabutylammonium bromide with catalytic potassium iodide than purchase tetrabutylammonium iodide. The very high affinity of quat cations to iodide enables the highly efficient in-situ formation of TBAI for the Finkelstein reaction.
If your company wants to develop low-cost high-performance green chemistry processes, now contact Marc Halpern of PTC Organics to benefit from 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!).
