ANALYTICAL AND PREPARATIVE SEPARATION OF THE ENANTIOMERS OF PYRAZOLE PHENYL ETHER HERBICIDES ON 3 CHIRAL STATIONARY PHASES

Chiral pyrazole phenyl ethers (PPE) are highly active herbicides which are resolved by direct high-performance liquid chromatography on commercially available chiral stationary phases derived from N-3,5-dinitrobenzoyl derivatives of a-amino acids or amines (Whelk-O 1). The chromatographic data for a series of PPEs is presented and the structure-enantioselectivity comparisions are made for three different chiral stationary phases. Chromatographic resolution obtained is suitable for determination of enantiomeric purities and, in some cases, for preparative resolution of the enantiomers. By collection of material from repetitive chromatographic runs using an automated preparative system, suitable quantities for whole plant biological evaluation of both enantiomers of 2-[5-[[4-chlora-1-methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl]oxy]-2-nitrophenoxy]-N-methyl-butanamide were obtained in greater than 99% enantiomeric purity.