Two patents issued last week that use catalytic amounts of tetraalkylammonium salts. Such reactions usually mean phase-transfer catalysis, but in both cases, the role of the quats was to solubilize an anion that served in a catalytic capacity. One was tribromide and one was chloride.
Tetrabutylammonium tribromide (TBATB) is a known bromination agent for adding a single bromine at the alpha position of acetophenone (if not used in excess) while generating HBr and TBAB. TBATB is used at a level of 1.5 mole% relative to the iodoacetophenone. Reaction with triethylorthoformate, likely catalyzed by the HBr liberated from the bromination, produces the ketal shown in 85% yield.
In another patent, tetramethylammonium chloride was used to solubilize chloride in DMSO that acted as a catalyst for the esterification shown in the diagram. The chloride opened the epoxide of glycidyl methacrylate that produced an alkylating agent in situ. Esterification followed liberating the chloride for another cycle.
The concept of solubilizing anions in an organic reaction phase using quaternary ammonium salts is obviously useful. In phase-transfer catalysis, the quat transfers a reacting anion for consumption. In the two cases cited here, the quat solubilized anions used as catalysts themselves.
If you are working on organic reactions that require the use of anions as reactants or as catalysts, now contact Marc Halpern of PTC Organics Inc. to improve the process performance and profit of your company AND saving your company weeks or months of development cycle time due to the highly specialized expertise of PTC Organics in industrial phase-transfer catalysis.
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!).
