The primary use of tetramethylmmonium hydroxide (TMA OH) is as a KOH-replacement in the manufacture of semiconductors for the chip industry, however it has been used as a phase-transfer catalyst in certain applications since PTC was discovered a few decades ago. With a C# of 4 and a q-value of 4.00, tetramethylammonium is the quat cation with the most accessible positive charge on the nitrogen atom and is also the lowest formula weight quat. These properties make TMA OH among the least optimal quats for many PTC applications, but not always.
TMA cannot undergo Hofmann Elimination, which is the most common mechanism of decomposition of ammonium quats under basic conditions. Thus, TMA OH is more stable than other tetraalkylammonium hydroxides. This is a MAJOR advantage for certain PTC applications that require both base and high temperature.
One way to overcome the low organophilicity of TMA OH is to use a polar solvent and this is sometimes used in PTC applications.
This month, the use of TMA OH was reported, not as a phase-transfer catalyst, but as a base used stoichiometrically in the coupling of aniline with nitrobenzene to produce 4-nitrodiphenylamine, an intermediate for 4-aminodiphenylamine [Nandi, C.; Gangal, N.; Purohit, P.; Ketkar, V.; Kashelikar, D.; (Nocil Ltd) US Patent 9,708,243, 18-Jul-2017].
If your company needs to optimize the choice of phase-transfer catalyst to increase profit by achieving low-cost high-performance green chemistry, now contact Dr. Marc Halpern of PTC Organics.
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!).
