Enantiomeric separation of original heterocyclic organophosphorus compounds in supercritical fluid chromatography.

New and original heterocyclic α-enamido phosphine chiral solutes were prepared: four structurally similar racemates with the chirality center placed on the phosphorus atom, and four other related pairs of enantiomers with chirality borne by the carbon atoms of the phospholane ring. The structural variations were placed on an aliphatic heterocycle (six- or seven-member rings) and on the carbamate function (methyl or t-butyl). Their separation was achieved on a commercial cellulose tris-(3,5-dimethylphenylcarbamate) stationary phase (Lux Cellulose-1, Phenomenex) in supercritical fluid chromatography (SFC). The effects of molecular structure on SFC retention and enantioresolution were studied. Among these eight pairs of enantiomers, some reversal of elution order between similar compounds was observed. The effect of changing the organic solvent (methanol and ethanol) and its proportion (between 5 and 40%) in the mobile phase was investigated. Retention data were collected over the temperature range 0-50 °C, and the results interpreted from thermodynamic aspects.