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Key WordsChiral stationary phase (brush type) Hydrophobic interaction Ion-pairing Lipophilic buffer Zeolite support SummaryChiral stationary phases have been prepared on a zeolite A support. In addition to polar hydrophilic chiral selector molecules derived from DNB-L-Leu and DNB-L-Phe amides, dynamic modification of the underivatized free surface hydroxyl (silanol) groups of the zeolite can be used to increase the overall hydrophobic character. On these non-capped chiral stationary phases, in the presence of lipophilic buffer salts in the aqueous organic phase, the enantioseparation of ion-paired D,Lmandelic acid was facilitated and was studied in more detail. The enantioseparation might be based on hydrogen bonding and n-n interaction supported by simultaneous hydrophobic interaction.

SummaryA lipophilic buffered aqueous mobile phase, without organic modifier, was used for the high performance liquid chromatographic enantioseparation of D,L-lactic acid on a Merck ChiraSpher (250 mm x 4 mm i.d.) column in which the chiral selector is poly(N-acryloyl-S-phenylalanine ethyl ester) bonded to a spherical silica particle. The lipophilicity of the buffer was achieved by addition of triethylammonium phosphate, the 'ethyl' apolar chains of which dynamically modified the ChiraSpher stationary phase and increased its hydrophobic character. The ion-paired (cethyltrimethylammonium bromide) analyte enantioseparation was realized by hydrogen-bonding and dipole-dipole complexation on the ChiraSpher stationary phase, superimposed on simultaneous reversed-phase partitioning.

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Triehlorueetaldehyd (I) kondensiert mit Benzol (II) in Gegenwart von 9h Steiger Schwefelsäure zum Diphenyl‐trichloretlizui (III), das ein Zwischenprodukt für Pflanzensehutzmittel auf Basis Diphenylessigsiitireamid darstellt.