Tetraethyl ammonium hydroxide (TEAH) is an interesting phase-transfer catalyst.
As we teach in Module 1 of our PTC course, with a q-value of 2.0, it is excellent for T-Reactions. In fact, in the publication Halpern, M.; Sasson, Y.; Rabinovitz, M.; Tetrahedron, 1982, 38, 3183, tetraethyl ammonium was found to be the best symmetrical quaternary ammonium phase-transfer catalyst of the nine examined (MUCH better than tetrabutyl ammonium!). Tetraethyl ammonium was the second best phase-transfer catalyst in that publication out of 19 examined with only methyl tributyl ammonium being more active.
With a C# of only 12, TEAH is usually ineffective for I-Reactions.
Some of you may be tempted to buy TEAH as a base since it contains both hydroxide and has a cation suitable for T-Reactions. However, as we teach in Module 1 of our PTC course, tetraethyl ammonium is the quat that is most sensitive to Hofmann Elimination. In other words, the combination of tetraethyl ammonium and hydroxide is almost designed for decomposition. Hofmann Elimination is the #1 mechanism of decomposition of phase-transfer catalysts under basic conditions.
You may get lucky and observe TEAH to be a great phase-transfer catalyst before it decomposes, but I would strongly recommend that you test any TEAH you may have in the lab or plant before using it. You might find a lot of unquaternized triethylamine, even if the certificate of analysis certifies that it was high quality TEAH when it was shipped.
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!).
