Have you heard of the Bargellini Reaction? I didn’t until last month when it was pointed out by Dr. Pat O’Neill of Pfizer, Dr. Reinhard Sommerlade of BASF Switzerland, Dr. Joe Schwab of Hybrid Plastics, Dr. Dan Henton (formerly of Dow Chemical), Dr. Klaus Buescher of Novartis and Dr. Thomas Zierke of BASF.
This reaction, first reported by Guido Bargellini in 1906, is the answer to the question posed in last month’s PTC Tip of the Month to explain the sequence of phase-transfer catalysis reactions shown in the figure.
Dr. Sommerlade of BASF Switzerland AG explained the reaction sequence best: “Once the trithiocarbonate anion is formed, it will readily react with 2,2-dichloro-3,3-dimethyloxirane, a product formed in situ from acetone and dichlorocarbene (addition to the C=O bond), which in turn is formed from chloroform under alkaline conditions. The thioanion opens the epoxide and the intermediate product is saponified to give the product shown in the scheme.”
Again, we thank Pat O’Neill, Reinhard Sommerlade, Joe Schwab, Dan Henton, Klaus Buescher and Thomas Zierke for enlightening us about a reaction that has been around for more than a century.
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!).
Dr. Sommerlade of BASF Switzerland AG explained the reaction sequence best: “Once the trithiocarbonate anion is formed, it will readily react with 2,2-dichloro-3,3-dimethyloxirane, a product formed in situ from acetone and dichlorocarbene (addition to the C=O bond), which in turn is formed from chloroform under alkaline conditions. The thioanion opens the epoxide and the intermediate product is saponified to give the product shown in the scheme.”