The inventors of US Patent Application Publication 2025/0026720 describe the manufacture of triacetonamine from acetone and ammonia that also produces as undesired byproducts diacetone alcohol (DAA) and mesityl oxide (MO). One of the inventions in this publication is the regeneration of acetone from these two byproducts using catalytic tetrabutylammonium hydroxide.
The simple procedure generates acetone from a mixture of DAA and MO is described as follows: “100 g of MO, 25 g of DAA, 100 g of water, and 25.0 g of an aqueous solution of tetrabutylammonium hydroxide (TBAH, 40 wt %) were mixed in a round bottle with a dean-stark device and then heated to 85° C. to react for 3 hours. The reaction product was distilled to obtain 120.6 g of acetone (yield=84%).”
The diacetone alcohol decomposes thermally via an E1cB elimination mechanism facilitated by the basicity of tetrabutylammonium hydroxide (TBAOH) to produce acetone. TBAOH acts as a base, deprotonating the alpha-hydrogen to the carbonyl to generate an enolate intermediate. Two molecules of acetone are produced.
The mesityl oxide mechanism also starts with deprotonation by TBAOH generating an enolate intermediate. Then the enolate breaks into two molecules of acetone by retro-aldol cleavage.
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!).
