In the reaction shown in the diagram, equimolar amounts of cannabidiol and terephthaloyl chloride in were reacted in methylene chloride as the solvent with 2.00 equiv NaOH and 0.6 mole% TBAB to produce the polyester in 95% yield after two crystallizations that had a molecular number of 47,000 and polydispersity index of 1.87. This is a classic example of a mild high yield PTC esterification of an acyl chloride with a phenol. The use of the exact amount of NaOH to deprotonate the phenolic OH’s obviously minimized hydrolysis of the acid chloride, aided by the very low heat history.
Two other phase-transfer catalysts were screened. Cetyl trimethyl ammonium bromide gave 92% yield, Mn = 25,100 and PDI of 2.3. Benzyl triethyl ammonium chloride gave 88% yield, Mn = 23,000 and PDI 2.1.
Polyesters produced from cannabinoid diols and aromatic bis-acyl chlorides (e.g., phthaloyl chloride) can serve as radical scavengers and anti-oxidants then can be biodegraded by hydrolysis. The antioxidant, biodegradability and mechanical properties of these commodity polyesters can be tunable by choosing different diacyl chlorides and cannabinoid diols.
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!).
In the reaction shown in the diagram, equimolar amounts of cannabidiol and terephthaloyl chloride in were reacted in methylene chloride as the solvent with 2.00 equiv NaOH and 0.6 mole% TBAB to produce the polyester in 95% yield after two crystallizations that had a molecular number of 47,000 and polydispersity index of 1.87. This is a classic example of a mild high yield PTC esterification of an acyl chloride with a phenol. The use of the exact amount of NaOH to deprotonate the phenolic OH’s obviously minimized hydrolysis of the acid chloride, aided by the very low heat history.