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With help from a microreactor, chemists in Japan have combined light-mediated and thermal reactions to improve the synthesis of vitamin D-3. The research was presented Dec. 17, at Pacifichem, a congress in Hawaii of Pacific Rim chemical societies that meets every five years.
Many foods are fortified with vitamin D-3, but industrial routes to vitamin D-3 have yields of less than 20%. The penultimate step in industrial syntheses, a light-mediated isomerization, is not selective, and it's tough to clear away byproducts of the reaction.
Chemists led by Shinichiro Fuse and Takashi Takahashi of Tokyo Institute of Technology have developed a continuous-flow microreactor process that avoids these issues. The microreactor performs the light-mediated isomerization and the next step in the synthesis, a thermal isomerization, at the same time (Chem. Comm., DOI: 10.1039/c0cc02239j). As a result, the product from the first reaction is immediately converted to vitamin D-3, and the reactions' equilibrium shifts to produce more. The process reduces purification waste and has an isolated vitamin D-3 yield of 32%, the highest yield that doesn't involve expensive specialized laser equipment. This is the first time researchers have combined thermal and photoreactions in a single microreactor, Fuse notes. The team is now working to make ogs of vitamin D-3 with their system.
"This proof of concept could be easily scaled up to achieve much larger production," says D. Tyler McQuade, an expert in microreactors at Florida State University.
McQuade also notes that the team's yield as calculated by UV absorption in high-performance liquid chromatography prior to isolation was 60%, much higher than their isolated yield. To further improve isolated yields such as those from the Japanese team, he hopes that ytical chemists will continue to help adapt continuous purification methods, such as simulated moving bed chromatography, for synthesis.
Chemical & Engineering News
