Neal Anderson of Anderson’s Process Solutions LLC (excellent process chemistry consultant) brought to our attention a very good article that shows how innovators approach problem solving when combining the advantages of phase-transfer catalysis with the advantages of continuous flow reactors to achieve high yield and a controllable exotherm. The C-alkylation shown is a PTC T-Reaction that appropriately uses methyl tributyl ammonium chloride as the phase-transfer catalyst. PTC T-Reactions are especially amenable to efficient mixing concepts.
In this case, the right type of flow was achieved by using self-made Raschig rings from 1 mm diameter Teflon tube. When using two strategically placed static mixers with these Raschig rings in a three reactor system (each at different temperatures) a yield of 95% was achieved with a residence time of 25 min.
One of the challenges was to avoid solids that hinder the operation of small diameter flow reactors. The use of 30% NaOH instead of 50% NaOH while working at an optimized phase-transfer catalyst level prevented solid build up.
This system is impressive because after optimization, the yield was 95% which is much better than the 75% yield achieved in a batch reactor, the type of reactor that most of us process chemists use in our comfort zone.
We recommend reading this article that was well written with well-designed experiments.
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!).
