This patent from UC Berkeley describes what appears to be a significant breakthrough in both phase-transfer catalysis as well as chiral phase-transfer catalysis.
The first report of an anionic phase-transfer catalyst that I recall was in the late 1970’s and it was based on a highly polarizable tetraarylborate anion that supposedly transferred a proton into an organic phase, then performed an acid-catalyzed reaction. However, the claims in that report were subsequently withdrawn. Over the years there have been occasional rare reports of various types of anionic phase-transfer catalysts but none seemed to enjoy wide application.
This patent describes an anionic phase-transfer catalyst that incorporates structures similar to the Maruoka chiral phase-transfer catalysts with the big difference being that instead of a nitrogen center forming a chiral quat, there is a phosphate center that when deprotonated forms an anion. This creates an organophilic chiral anion that is able to pair with and transfer a cation into a non-polar organic phase for reaction.
The examples in the patent focus on the transfer and reaction of the di-cation of “Selectfluor” (a trademark of Air Products and Chemicals) that is effective for a variety of fluorine reactions. We will highlight these reactions in future issues of the PTC Catalyst of the Month and we will also show some of these reactions in the 2-day course “Industrial Phase-Transfer Catalysis” that you can conduct in-house or attend in Philadelphia on October 2-3, 2018.
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!).
