Aiming at the industrial use of clay column chromatography for optical resolution

An ion-exchange adduct of synthetic hectorite and chiral Cu(II) complex, [Cu(SS-oxa)]²+ (SS-oxa = SS-2,2′-isopropylidene-bis(4-phenyl-2-oxazoline)), was prepared. Chromatographic resolution of inorganic and organic compounds was achieved by high performance liquid chromatography (HPLC) on a column packed with the prepared material.

A spherically shaped particle of synthetic hectorite (denoted as Na-HEC) was ion-exchanged with a divalent Cu(II) complex, [Cu(SS-oxa)]²+ (SS-oxa = SS-2,2′-isopropylidene-bis(4-phenyl-2-oxazoline)). The material is denoted as [Cu(SS-oxa)]²+/HEC. A column for high performance liquid chromatography (HPLC) was prepared by packing 4.0 g of [Cu(SS-oxa)]²+/HEC into a stainless tube (25 cm x 0.4 cm (i.d.)). When tris(acetylacetonato)cobalt(III) (denoted as [Co(acac)₃]) was eluted by methanol at the flow rate of 0.2 mLmin^-1at 4oC, the compound was separated to Δ- and Λ-enantiomers nearly to the baseline. Useful organic molecules with two hydroxyl groups such as 1,1’-binaphthyl-2,2’-diol were also partially resolved. With the help of theoretical simulation, it was concluded that the resolution was achieved by the occupation of the enantiomers in a cavity around a Cu(II) ion. The column also exhibited resolution ability toward an organic molecule with two hydroxyl groups indicating that the molecule binds with a Cu(II) ion in a stereoselective way through coordinating interactions.
The results promised the practical utility of clay column chromatography for obtaining enantiomeric compounds in industries.

Reference URL: https://www.sciencedirect.com/science/article/abs/pii/S0169131724000371

Bibliographic Information

Use of an Ion-exchange Adduct of Synthetic Hectorite and Chiral Copper(II) Complex as a Packing Material for Chromatographic Resolution.
Akihiko Yamagishi; Kenji Tamura; Masumi Kamon; Jun Yoshida; Hisako Sato.
Apply Clay Sci. 2024 ,10.1016/j.clay.2024.107290　251, 107290, April

Fundings

• Promotion of Science (JSPS) KAKENHI Grant (JP22H02033, JP22K0526 and JP20K21090).

Media

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  An attempt to obtain industrially important compounds by clay column chromatography

  Chromatographic resolution of tris (acetylacetonato) cobalt(III) on a column packed with an ion-exchange adduct of synthetic hectorite and chiral Cu(II) complex, [Cu(SS-L)]²+ (SS-L = SS-2,2′-isopropylidene-bis (4-phenyl-2-oxazoline)).

  credit : Hisako Sato
  Usage Restriction : Please get copyright permission