It’s not often that you see NaH used with phase-transfer catalysis. US Patent 8,802,724 uses PTC-NaH for an etherification! That is even more unusual since PTC-NaOH etherification is one of the most classic PTC reactions for more than 40 years and anyone who knows about PTC already knows about PTC-NaOH for such reactions. We speculate that NaH was used to avoid racemization in the alpha position to the ester. We’re not sure of that since that C-H has a pKa of about 24 whereas the pKa of the hydroxyl is about 16. We further speculate that the inventors could have used PTC-NaOH but since this reaction was not the focus of the patent, they may not have had the time to explore this reaction in more detail.
It should be noted that the inventors of the patent shown in the August 2014 PTC Reaction of the Month, should have thought to use PTC with NaH since they were also concerned about racemization during an etherification.
If your company has any potential to benefit from choosing the best process conditions to achieve low-cost high performance green chemistry using phase-transfer catalysis, contact Marc Halpern of PTC Organics to explore your options.
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!).
