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Synthesis of (all‐ rac )‐α‐Tocopherol in Supercritical Carbon Dioxide: Tuning of the Product Selectivity in Batch and Continuous‐Flow Reactors
Author(s) -
Kokubo Yoshiaki,
Hasegawa Aiko,
Kuwata Shigeki,
Ishihara Kazuaki,
Yamamoto Hisashi,
Ikariya Takao
Publication year - 2005
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200404312
Subject(s) - chemistry , selectivity , supercritical fluid , yield (engineering) , supercritical carbon dioxide , catalysis , solubility , batch reactor , organic chemistry , supercritical fluid extraction , thermodynamics , physics
α‐Tocopherol was synthesized using a condensation reaction of 2,3,6‐trimethylhydroquinone with isophytol in supercritical CO 2 using batch and continuous–flow reactors. In the batch reaction catalyzed by a fluorinated molecular catalyst bearing strong Brønsted acidity, C 6 F 5 CHTf 2 (Tf=SO 2 CF 3 ), an increase in the CO 2 pressure causes a marked increase in the product selectivity for α‐tocopherol, albeit with a slight decrease in the product yield. The solubility measurements by extraction experiments and the supercritical fluid NMR (scNMR) indicate that the homogeneous and non‐polar reaction phase in scCO 2 is crucial to obtain α‐tocopherol with high selectivity. A continuous flow scCO 2 process for the condensation reaction can be performed with a strong acid resin, Amberlyst 15, as a solid acid catalyst to give the desired product with high selectivity.