Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs) were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material.
Synthesis and Herbicidal Activity of the D- and L-Methyl 2--propionate Enantiomers
The D- and L-enantiomers of the wild oat herbicide diclofop-methyl (title compound) were prepared utilizing resolution operations and by synthetic routes with optically active compounds as starting material.The dextro-rotatory product which the D(R)-configuration can be attributed to, was found to be the herbicidally active species. - Keywords: Phenoxy-phenoxy-propionic Acid Ester, Diclofop-methyl, Stereoisomers, Grass Herbicide
Nestler, Hans Juergen,Bieringer, Hermann
p. 366 - 371
(2007/10/02)
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