Cyclic carbonates are useful in the safe synthesis of non-isocyanate polyurethane resins (avoiding the use of phosgene). This patent describes the very efficient reaction of epoxides with carbon dioxide to form cyclic carbonates using phase-transfer catalysis.
The optimum catalyst system for the reaction of epoxides with carbon dioxide to form cyclic carbonates was found to be tetrabutylammonium bromide (TBAB) with cobalt diacetate tetrahydrate and triphenylphosphine. As can be seen in the diagram, a conversion of >99% was achieved with 1,4-butanediol diglycidyl ether as the substrate.
The presence of the phase-transfer catalyst was found to be the most crucial catalyst component. When TBAB was used without triphenylphosphine and without the cobalt catalyst, the conversion was 67%, presumably due to ring opening of the epoxide with bromide and subsequent attack of the alkoxide on carbon dioxide. When TBAB was used with triphenylphosphine and no cobalt catalyst, the conversion was essentially the same at 68%. However, when the cobalt catalyst was used without TBAB and without triphenylphosphine, the conversion was 0%. When all three catalyst components were used, >99% conversion was achieved.
It is interesting to note that phase-transfer catalysis could very likely be used to produce the starting material by hydrogen peroxide epoxidation of 1,4-butadiene. This reaction was not mentioned in the patent.
If your company needs help in choosing the most effective phase-transfer catalyst for reactivity, safety and processing to achieve the highest profit, now contact Marc Halpern of PTC Organics to explore how we can work together to improve your process performance from development to commercialization.
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!).
