We usually criticize the use of PTC with expensive hazardous sodium hydride. However, in this case, if PTC would have been used with NaOH, it is very likely that the product would have been a mixture of dibenzyl ether (preferred product), monobenzyl ether and unreacted diol. This is due to the combination of the alcohol-alkoxide equilibrium with PTC-NaOH and preferred affinity of the quat to pair with the monobenzylated alkoxide instead of the diol mono-anion. This typically results in a higher amount of diether than monoether under PTC-NaOH conditions that reacts a diol with 1 equivalent of an alkylating agent.
In this patent, the inventors were apparently also concerned about diether formation which is probably the reason they used 3 equivalents of diol.
Contact Marc Halpern of PTC Organics to achieve low-cost high-performance green processes for strong base reactions, usually using inexpensive inorganic base INSTEAD OF sodium hydride, sodium alkoxide, sodium amide or sodium metal.
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!).
