Inclusion separation of cyclodextrin for preparation of octylferrocene isomers in high purity

Octylferrocene is one of the most widely used rocket fuel catalyst. However the current commercial octylferrocene is a mixture of (2-octyl)-ferrocene, (3-octyl)-ferrocene, (4-octyl)-ferrocene (C8-Fc) and multi-substituted ferrocene. The separation and purification of the commercial octylferrocene compounds is crucial for achieving their maximum catalytic efficiency. The C8-Fc was chosen as the raw material for preparation of octylferrocene isomers in high purity with β-cyclodextrin coated silicone as the packing agent (Immo-CD-1). When the C8-Fc was used as the raw material and Immo-CD-1 was the stationary phase, the influencing factors including the content of water, the particle size of supporter and the loading ratio of the silicone coated with cyclodextrins were optimized by orthogonal experiments. The main innovation of this research is that the content of water in the Immo-CD-1 has greatest effect on the separation. A positive column chromatography separation with Immo-CD-1 as the stationary phase, n-hexane as the eluent, C8-Fc as raw material could get the relative content of 97.2% (4-octyl)-ferrocene and relative content of 96.1% (3-octyl)-ferrocene, as well as a mixture of (3-octyl)-ferrocene and (2-octyl)-ferrocene. The separation column of Immo-CD-2 was prepared with hydroxypropyl-β-cyclodextrin coated silicone as the packing and separation of the mixture of (3-octyl)-ferrocene and (2-octyl)-ferrocene was carried out. The relative purity of (2-octyl)-ferrocene can reach 95.3%.