ON ENANTIOSELECTIVE SEPARATION OF PHENOXYPROPIONATES USING PERMETHYLATED BETA-CYCLODEXTRIN HPLC AND GC COLUMNS

Investigations on chiral phenoxypropionates using permethylated beta-c yclodextrin HPLC and GC columns showed a decrease in enantioselective separation efficiency from mecoprop-methyl and dichlorprop-methyl to t he threefold chlorinated fenoprop-methyl. This corresponded to decreas ing electron density in the aromatic system due to the increasing nega tive inductive effect of 3 chlorine substituents. Investigation on (RS )2-(2,4-dichloro-3,6-dinitrophenoxy)-propionate confirmed the influenc e of electrophilic substituents while determination of ethyl-(RS)-2-me thoxypropionate emphasized the necessity of an aromatic system for ena ntioselective separation on beta-cyclodextrin stationary phases. For f enoprop-methyl as well as for the aryloxyphenoxypropionates diclofop-m ethyl and fluazifop-butyl, reversed phase HPLC showed higher separatio n performance than high resolution capillary GC. (C) 1997 Elsevier Sci ence Ltd.