Separation of racemate hydrophobic thiourea substrates

The separation of racemic-N-(2-ethylphenyl)-N'-(2-methylphenyl) thiourea, a hydrophobic substrate trap, to collect its atropisomers, was studied using reversed-phase high-performance liquid chromatography (RP-HPLC). Hydroxypropyl-beta-cyclodextrin (HP-?-CD) was used as a complexing additive to the racemic mixture (to obtain chiral molecules) and hexane-ethanol (50% in volume) as a mobile phase. The effects of mobile phase composition, on separation were systematically investigated to establish the optimum conditions of resolution.